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Sonnet User's Manual Volume I

1. 275 Validation Example ss skn nn Kn 279 Far Field Viewer selon eee eee eee eee ens 280 Analysis Limitations 2 2 0 0 cee eens 281 Spherical Coordinate System 004 282 Normalization seen a ee ee ee 285 Polarization oa ee eo KI A ele Te 286 Refere NCES ula aided estes adie KI K a patata ATA Ae 286 20 FAR FIELD VIEWER TUTORIAL 1 esse eee ee NNN 287 Creating an Antenna Pattern File 288 Running the Far Field Viewer 0 0000s 289 Calculating the Response 222 eee eee 290 Selecting Phi Values ooo 291 Selecting Frequencies sous 291 Selecting the Response 2 ee eee ee eee 292 ZOOMING os ood Wa eI ota eee Rea a Re Bede ace oie 295 11 Sonnet User s Guide Probing the Plot snk KKK Kn 296 Re Normalizing the Plot 00 ee eee 297 Changing to a Polar Plot 0 0000 299 Turning Off the Legend 2 2 2 ee eee 299 Changing the Radius Axis essee 300 Selecting a Frequency Plot oss 303 Viewing a Surface Plot 2 0 0 ee ee eee 305 Saving the Far Field Viewer File 24 306 Exiting the Far Field Viewer Program 306 References ava aus Tan k aA NN Ekana a eed 307 21 SPICE MODEL SYNTHESIS 1 e20 ain kas PR be BS anaes 309 PI Spice Model sos se K eee eee eee eee 311 Using The PI Model Spice Option 312 A Simple
2. 173 Running an Optimization sus 178 Observing your Optimization Data 178 Accepting the Optimized Values use 181 12 CONFORMAL MESH ta exes lsie eee wane AKT eee se aa 185 INCFODUCCION Ss nens bye a wih wl Bal TN ae ee Se eel alan 185 Use Conformal Meshing for Transmission Lines Not Patches 187 Applying Conformal Meshing 220 187 Conformal Meshing Rules 00 20 ee eee 188 Memory Save Option 22 eee eee 191 Using Conformal Meshing Effectively 191 Use Conformal Meshing for Non Manhattan Polygons 191 Boundaries Should Be Vertical or Horizontal 193 Cell Size and Processing Time 193 Current Density Viewing era eee ee eee 194 13 NETLIST PROJECT ANALYSIS x s 0 6 6 woe aiv ne et Kalan 197 N LWOPKS i os iui nni acd cies acta edie sa Sotaan igs wyded tend ound Rasa 198 Netlist Project Analyses oss eee eens 199 Creating a Netlist oss 199 Netlist Example Files seen 200 Cascading S Y and Z Parameter Data Files 200 A Network File with Geometry Project 202 Inserting Modeled Elements into a Geometry 204 Using Ungrounded Internal Ports 207 14 CIRCUIT SUBDIVISION 5 sas0nan maana a m 600 erate wae ee wg ae 211 Introduction lt iie vala eee aye ek eed bd atte ee EE 211 Circuit Subdivision in Sonnet 000
3. 21 Click on the OK command button Zooming EU 23 The dialog box disappears and the far field viewer plot is updated It should appear as below Kaas 8 Pietover fme infpole jxy Gain dB n Freguency 5 1 0 GHZ z G a IS 5 Phi 20 0 0 Degrees o dB 25 30 E Field 35 E Total 40 100 860 60 40 20 0 20 40 60 80 100 Theta Click mouse to readout data values Pointer The zoom button located on the tool bar may be used to magnify a specific area in the plot Click on the Zoom In button on the Tool bar For this example zoom in on the area from 0 to 10 dB in Gain where Theta ranges from 20 to 50 You may also use View gt Zoom In or the Space Bar for the zoom function Click on the point in the plot corresponding to 0 dB Gain and Theta 20 then drag the mouse to the point in the plot corresponding to 10 dB Gain and Theta 50 A rubber band surrounding the area to be magnified follows the mouse 295 Sonnet User s Guide When the mouse is released the plot is updated with a magnified view of the se lected area as shown below jnfpole son BARAHA Plot Over Theta infpole son Gain dB Frequency GHz 1 0 GHZ Phi 0 0 Degrees 10 20 30 40 50 60 70 Theta Click mouse to readout data values Pointer Fn 24 Click on the Full View button on the Tool bar The full plot once again appears on yo
4. 10 11 12 You will now enter the linked dimension parameter A linked dimension parame ter is another dimension parameter identified in the circuit that has the same nom inal value and assigned variable Select Tools gt Add Dimension Parameter gt Add Anchored from the project editors main menu This places the project editor in Add an Anchored Parameter mode indicated by the change in cursor To specify the Anchor point for the parameter click the mouse on the corner of the lower stub as shown in the picture below The anchor point is indicated by a small sguare which appears at the point you clicked The next step is to select the reference point Click on the top right end of the bottom stub to add the reference point Reference Point The reference point is indicated by a small sguare which appears at the point you clicked In the next step you select the rest of the adjustable point set Points may be se lected using the any of the edit commands available in the project editor 159 Sonnet User s Guide 160 13 14 15 Drag the mouse until both points on the end of the stub are selected Lstub 220 OA SN Ss NNN Selected Points SS These points will be added to the adjustable point set When the reference point moves these points move relative to the reference point Once all the desired points are selected press Enter This completes the dimensi
5. A ABS caching level 118 subsectioning 119 ABS see adaptive band synthesis absolute power 285 adaptive band synthesis 115 127 ABS caching level 118 analysis issues 124 126 current density data 125 de embedding 125 multiple box resonances 124 optional files 126 ripple in S Parameters 126 transmission line parameters 125 find maximum 121 find minimum 121 parameter sweep 122 resolution 116 running an adaptive sweep 117 viewing the response 126 adaptive sweep 117 add ports auto grounded 78 standard 69 via ports 76 Add Subdivider 229 adjacent polygons 190 191 adjustable point set 139 140 142 ADS interface 17 Agilent ADS Interface 17 air bridges 241 analysis limitations 281 starting 168 analysis frequencies 165 Index analysis monitor 168 Analysis Setup dialog box 118 165 173 analyze 168 anchored dimension parameters 136 137 adding 157 anchor point 138 144 reference point 138 144 Angle Axis 283 anisotropic dielectric bricks 264 269 anisotropic dielectrics 26 antennas 273 280 microstrip 279 pattern 288 surface wave 281 wire 281 att 200 209 att_cascade son 200 attenuator 206 auto grounded ports 76 77 205 autoscale 301 AWR interface 17 axes 301 axis Z 282 Axis Properties dialog box 301 B balanced ports 66 bandpass filter 156 batch file 345 benchmark 339 343 residual error 341 best iteration 179 boundaries 193 box resonance 124 334 box wall ports 69 361 Sonnet User s Guide bri
6. Level 1 Metal 264 an MAN Dielectric Brick a Side View of Circuit shown above All realizable values for the dielectric constant loss tangent and bulk conductivity can be used Furthermore it is possible to set these parameters independently in each dimension to create anisotropic dielectric bricks Em is appropriate for simple structures using very localized dielectric bricks however when your design reguires large areas of brick material you may need a full 3 D electromagnetic analysis tool You should also be aware that the use of dielectric bricks can dramatically in crease the memory reguirements and thus the simulation time for your circuit Bricks should only be used where strictly necessary for the accuracy of your sim ulation Care should be taken when using dielectric bricks since improper modeling of your dielectric brick can yield highly inaccurate data We recommend that you run a convergence test by doubling or halving the number of your Z partitions re Chapter 18 Dielectric Bricks analyzing your circuit and comparing the two results to ensure that you are using a sufficient number of Z partitions For more information on Z partitioning see Z Partitioning page 270 Applications of Dielectric Bricks The use of dielectric bricks is appropriate for applications where the effects of di electric discontinuities or anisotropic dielectric materials are important Examples o
7. 4 Insert a 67 11 ohm resistor between nodes 7 and 8 5 Calculate an overall set of S parameters for the T attenuator The two projects att_lgeo son and att_lumped son are available in the Att exam ple for this chapter The listing below is the analysis output as it appears in the analysis monitor Note that these results are similar to the results given above for distributed elements Frequency 200 MHz 50 0hm S Params Mag Ang Touchstone Format S11 S21 S12 S22 200 000000 0 007889 66 619 0 500390 4 888 0 500390 4 888 0 007889 66 619 Frequency 300 MHz 50 0hm S Params Mag Ang Touchstone Format S11 S21 S12 22 300 000000 0 011495 69 396 0 500788 7 336 0 500788 7 336 0 011495 69 396 Frequency 400 MHz 50 0hm S Params Mag Ang Touchstone Format S11 S21 S12 22 400 000000 0 015119 69 443 0 501342 9 787 0 501342 9 787 0 015119 69 443 Using Ungrounded Internal Ports In the example presented above a pair of auto grounded ports was placed at each location in the em circuit layout where a modeled element would eventually be in serted It is also possible to perform the same analysis using ungrounded internal ports because each resistor in this example is a series modeled element without access to ground Any time access to ground is not required for a modeled ele ment you can replace the pair of auto grounded ports with a single ungrounded internal port 207 Sonnet User s Guide 20
8. I Optimization Parameters par dstub son X Cell Size 10 0 mils Y Cell Size 10 0 mils Optimize Min Max Nominal Granularity Opt Result F Lstub 220 0 F Sstub 220 0 Update nominal settings with optimization results Cancel Help Only one variable Lstub is used for this optimization The range for Lstub is 100 mils to 300 mils Click on the Optimize checkbox next to Lstub This selects the Lstub variable to be used in the optimization Note that the nominal value appears in the Nominal text entry box If you wish to change the nominal value you may do so by entering a new value The circuit will be redrawn Chapter 11 Parameter Sweep and Optimization Tutorial 33 34 35 using the new nominal value Since this is the first optimization run on this project file the Min and Max entries are blank If a previous optimization had been run the last entered values would remain WARNING Editing parameter settings or optimization goals causes any pre existing optimization iterations to be deleted from the project file Enter 100 in the Min text entry box in the Lstub row This sets the minimum value for the Lstub variable to 100 mils for the optimization Enter 300 in the Max text entry box in the Lstub row This sets the maximum value for Lstub to 300 mils for the optimization Click on the OK button to apply the changes and close the dialog box When the dialog
9. Simple Removal 336 In the preceding section we have described several ways to detect box resonances within a structure We would now like to offer some advice as to how to remove them when they are undesirable By this we mean the case when you simply do not wish to consider their effect and would like them removed from the data This can occur when you analyze a portion of your overall circuit in Sonnet and the boxwalls artificially introduce resonances Removal is actually probably not the best term to describe this approach It is more of an attempt to push the resonances out of the desired frequency band or attenuate their levels The best way to remove a box resonance is to change the size of the box either larger or smaller to move the resonant frequency out of band If the problem oc curs in de embedding you may be able to change the length of the calibration standard in the project editor to move the box resonance out of the band of interest Another simple way to remove or at least attenuate the effect of a box resonance is to take off the top cover We can create an approximation of this condition by setting the top cover resistivity to 377 ohms square the impedance of free space To do this open the Box Settings dialog window Circuit gt Box Settings and change top cover to Free Space This is an accurate approximation provided the cover is not so close that it interacts with the evanescent fringing fields surround i
10. gt l Remember settings Print Close Help 5 Select the desired file format from the Format drop list 1 1 1 1 If you select Spectre as the Format PSpice is the default the contents of the output window is updated 6 To change the parameters for the SPICE data click on the Model Options button The PI Model Options dialog box appears on your display To reduce the number of lumped elements in the model open circuit limits can be specified here as shown below EN PI Model Options steps Rmax Cmin L max Kmin Rzero ohms pF nH ohms Separation 10 0 l Remember settings Factory Defaults Cancel Help The values are defined as follows RMAX Maximum allowed resistance ohms The default value is 1000 0 ohms 314 Chapter 21 SPICE Model Synthesis CMIN Minimum allowed capacitance pF The default value is 0 01 pF LMAX Maximum allowed inductance nH The default value is 100 0 nH KMIN Minimum allowed mutual inductance dimensionless ratio The default value is 0 01 RZERO Resistor to go in series with all lossless inductors resistance in ohms Needed for some versions of SPICE The default value is 0 0 Separation This is the calculation interval between the two frequencies used to generate the SPICE model specified as a percentage The second frequency is ob tained by adding the specified percentage of the first frequency to the second fre quency All calculated compone
11. lected by clicking on individual points or by lassoing a set of points with your mouse You do not need to select the reference point since it is automatically in cluded in the adjustable point set 157 Sonnet User s Guide 6 Drag the mouse until both points on the end of the stub are selected Selected Points These points will be added to the adjustable point set When the reference point moves in response to a change in the parameter value these points move relative to the reference point 7 Once all the desired points are selected press Enter This completes the dimension parameter creation The Parameter Properties dialog box appears on your display NN Parameter Properties par_dstub son PR Variable Name Variable Name text entry box Nominal Move points the same distance Global View Options M Show Nominals M Evaluate Equations Cancel Help 8 Enter the variable Lstub in the Variable Name text entry box in the Parameter Properties dialog box and click on the OK button This assigns the variable Lstub to the dimension parameter When you click on the OK button an arrow indicating the length and the name appear on your display 9 Move the mouse until the name is positioned above the stub When the name is in the desired position click on the mouse The dimension parameter should now appear as shown below 158 Chapter 11 Parameter Sweep and Optimization Tutorial
12. rs where Target f Target value of measurement at frequency f Simulation f Simulated value of measurement at frequency f N Number of frequencies in optimization goal Target f MIN Simulation f Target f GreaterThanOperatorError N where Target f Target value of measurement at freguency f Simulation f Simulated value of measurement at frequency f MIN Determines minimum value of the specified arguments N Number of freguencies in optimization goal Simulation f MINISimulation f T arget f LessThanOperatorError lt where Target f Target value of measurement at freguency f Simulation f Simulated value of measurement at frequency f MIN Determines minimum value of the specified arguments N Number of freguencies in optimization goal Setting up an optimization consists of five parts e Specifying optimization frequencies e Specifying your goals e Choosing which variables to vary e Specifying data ranges for the chosen variables e Specifying the maximum number of iterations Care should be taken when setting the nominal values for the variables to be opti mized The optimizer starts at the nominal values and converges to the minima which is closest to those nominal values Thus it is highly recommended that you perform some pre analysis prior to doing the optimization to ensure that the nom 152 Chapter 10 Parameterizing your Project inal values are in
13. scs 321 Sonnet User s Guide 322 Enter the desired name for the Spice model file in the Model File text entry box A default filename is provided which places the Broadband Spice model file in the same directory as your source project If you have selected multiple parameter combinations a file is produced for each combination If you wish to use another name or save the file in another location you may edit the text entry box Enter the desired error threshold The lower the error threshold you set the more processing time is required to calculate the model The error threshold is the error present between the source data and the fitted curve and is defined as follows N ISA source 5P Fid Error a ona 100 where f the number of the frequency point N the total number of frequency points S f source the value of the S parameter at the frequency point fin the project source response S s the value of the S parameter at the frequency point f in the fit curve data The calculation of the Broadband Spice model stops when this error threshold is reached or when it proves impossible to improve the error We recommend using the default value of 0 5 initially and not setting the threshold below 0 1 Select the Generate Predicted S Parameter data file if it is not already selected This option is selected by default When this option is selected the Predicted S Parameter data upon which the model is
14. three types of plots are shown below The cartesian plot allows the magnitude in dB to be plotted on a rectangular graph with your choice of theta 0 phi b or frequency for the X axis as shown in the figure below The polar plot allows you to select either theta 0 or phi for the angle axis The surface plot shows all the calculated values of theta and phi plotted against the gain for a single frequency 283 Sonnet User s Guide Magnitude dB theta 0 phi or frequency The far field viewer allows you to sweep theta a Cartesian 0 phi 6 or frequency 8 or b he Radius Axes Angle Axes b Polar 284 Chapter 19 Antennas and Radiation oA s a U W i i iy At N A EN c Surface Plot Normalization There are three types of normalization to chose from in the far field viewer By default the far field viewer displays the power gain The far field viewer can also provide directive gain and absolute values The three types of normalization are discussed below The power gain is defined as the radiation intensity divided by the uniform radia tion intensity that would exist if the total power supplied to the antenna were ra diated isotropically Directive gain is defined as the radiation intensity from an antenna in a given di rection divided by the uniform radiation intensity for an isotropic radiator with the
15. View W S Parameters 7 Parameters Run 1 Tue Feb 13 10 55 22 2001 Frequency Sweep Zi Response Data Errors Warnings Timing Info Batch List SLU N The project legend indicates that subdivide net s1 sonis being analyzed Em will perform an adaptive sweep on each of the five subprojects and then use the result ing data to analyze the network Status messages are output under the progress bar Chapter 15 Circuit Subdivision Tutorial There are two results that are significant to observe A comparison of the netlist analysis data with the analysis data from the source circuit and a comparison of the amount of time and memory each analysis used We have provided the source project file including analysis data under the example sub_whole son available in the Sonnet Examples The graph below shows the results of the netlist analysis versus the results of a full analysis of the source project fi subdivide net son subdivide_whole son RES ae Cartesian Plot Z0 50 0 Left Axis M subdivide net O a DB S11 O a subdivide whole O i DB S11 i t u d Right Axis e empty dB 23 2 35 24 2 45 25 Sonnet Software Inc Freguency GHz Click mouse to readout data values Pointer As you can see there is very good agreement between the two analysis results Both files were analyzed on the same computer The time reguired for the netlist was actually longer than the time reguir
16. When you select user defined your terminal width is defined based on the location of the Component port The point at which the port is placed on the polygon edge becomes the center of the terminal width extending an equal distance on either side This ability to limit the terminal width size is important in cases where more than one Component port needs to connect to the same polygon edge or the polygon edge is extremely large The next two images demonstrate these concepts ee T a E han A The component has two terminals connected to a single polygon edge The cell size is 2 mils and the user defined terminal width is 8 mils as shown Terminal Width pcos User Defined ALLRA mo mis TTL Po A coplanar waveguide that uses a two port component To the right is shown the entry in the Component Properties dialog box Chapter 6 Components Reference Planes NOTE Components require their ports to be on open polygon edges Reference Planes can be used to effectively move your port position away from the polygon edge To accomplish this em uses circuit theory to cascade a negative length of the line with the analysis results Ifno reference plane is specified then de embedding the Component removes none of the feedline metal but the port s are still de embed ded The use of reference planes is illustrated below Measurement Reference Planes Reference Planes Reference planes
17. if the results are not desirable If you wish to contin ue viewing data as the optimization runs use the Freshen Files command in the Response Viewer Observing your Optimization Data Plotting the best iteration will allow you to judge whether or not to use the opti mized values of the parameters Chapter 11 Parameter Sweep and Optimization Tutorial 47 48 49 50 51 Select Project gt View Response gt New Graph from the main menu of the analysis monitor The response viewer menu appears on your display with the DB S11 response for the nominal values parameter combination displayed There may be some delay while the project loads into the response viewer due to the amount of response data now included Click on the DB S11 curve group in the legend to select it and select Curve gt Edit Curve Group from the main menu of the response viewer The Edit Curve Group dialog box appears on your display Select Optimized from the Data Collection drop list in the Edit Curve Group dialog box Notice that this drop list is now enabled since the project file now contains both parameter sweep data and optimized data Move DBISI1 to the Unselected list by double clicking on the entry Move DB S21 to the Selected list by double clicking on the entry Since your optimization goals were set in reference to the DB S21 response you want to plot this response Notice that when you selected Optimized data that the paramet
18. is added up through the dielectric layer to the level of metalization above it For example if you draw a via on level 2 with the direction set to Up One Level Tools Add Via Up One Level the via extends from level 2 up through the dielec tric to level 1 of your circuit A via which goes down one level extends from the level of metalization to which it is added down through the dielectric layer to the next level of metalization For example you draw a via on level 0 with the direction set to Down One Level Tools Add Vias gt Down One Level The via extends from level 0 through the dielectric layer to metalization level 1 A via which goes down to ground extends from the level of metalization to which it is added through all intervening levels until it reaches the ground bottom of the enclosing box For example a circuit with 5 dielectric layers has four metalization levels 3 0 If you add a via on metalization level 1 with the direction set to down to ground Tools Add Vias gt Down to Ground the via extends from level 1 down through the intervening dielectric layers and metalization levels to the bot tom of the enclosing box which is ground This via is drawn on levels 1 2 3 and ground The ground level is completely metalized but the via is drawn here to rep resent the connection from upper levels Chapter 16 Vias and 3 D Structures Via Types There are basically two types of vias edge and polygon The via pol
19. value This is the reason we suggest you run a convergence test discussed earlier in the chapter on your circuit to determine the best value for the Z parti tioning To set this parameter in the project editor do the following Select Circuit gt Dielectric Layers from the project editor main menu The Dielectric Layers dialog box shown below is displayed Dielectric Layers bridge son Thickness Mat Erel Dielectric Diel Cond mils Name Loss Tan Sim q fo 0 Unnamed N foo Unnamed 1 0 0 0 0 0 fo 0 Unnamed 1 0 0 0 0 0 4 gt cancel Help MES Library Z Parts 2 Click on the Z Parts button in the Dielectric Layers dialog box The Z Partitions dialog box appears on your display Z Partitions bridge son HEI Level Num Mat Name Unnamed Unnamed Unnamed Cancel 271 Sonnet User s Guide 272 Enter the number of z partitions to be used for each dielectric layer in the appropriate Z Parts text entry box Note that changing this value for a particular layer will have absolutely no affect on the analysis if there are no bricks on the layer If there are multiple bricks on the layer the Z subsectioning for all of those bricks will be identical It is not pos sible to apply different Z partitions to brick polygons which appear on the same layer Chapter 19 Antennas and Radiation Chapter 19 Antennas and Radiation To th
20. 0000 125 Ripple in ABS S Parameters 04 126 OUTPUT FILES ua aa Va SUSI wrt are Na ma Sas 126 Viewing the Adaptive Response 6 126 10 PARAMETERIZING YOUR PROJECT 0 solo ee eeeee 129 Variables cates Eeka TKT KETK wee 130 How to Create a Variable nn 131 EQUALIONS e so sed ie aise ara alee e EAN AIN he le ale a 133 Dependent Variables 2 2 0 cee eee 135 Dimension Parameters kk e eee 136 Anchored Dimension Parameters 137 Symmetrical Dimension Parameters 139 Radial Dimension Parameters 000 144 Reference Planes 0 e eee eee eens 146 Dependent Dimension Parameters 146 Circular Dependencies in Parameters 147 Parameter SWEEP s assa k en Sis sha a dara hers wee 148 OPUMIZALION fie see eons Ej es ws a ee ae eae ASS 151 11 PARAMETER SWEEP AND OPTIMIZATION TUTORIAL 0 155 Setting Up Dimension Parameters 156 Anchored Parameters 20ee eee 157 Symmetric Parameters 20 00000 161 Table of Contents Parameter Sweep eee ee ee ee ee ee S 164 Setting Up a Parameter Sweep 4 165 Executing the Parameter Sweep 168 Observing the Parameter Sweep Data 168 OPTIMIZATION 566 5 S25 da sa ana WG GEG GR 172 Entering New Nominal Values 173 Setting Up an Optimization
21. 102 Single Feed Line 0 cece ee ee ee eee 103 Coupled Transmission Lines 4 104 De embedding Results 0 00 e ee eens 105 De embedding Error Codes 000000 106 DE EMBEDDING GUIDELINES 2 2 2 2 22 e eee ee eens 107 Calibration Standards 20 ee eee eee 107 Defining Reference Planes 2 00 eeeeee 108 De embedding Without Reference Planes 108 Reference Plane Length Minimums 109 Reference Plane Lengths at Multiples of a Half Wavelength 110 Reference Plane Lengths Greater than One Wavelength 110 Non Physical S Parameters 2200005 110 Box Resonances sl ou aa ce eee eee eee ee ee eens 113 Higher Order Transmission Line Modes 113 Sonnet User s Guide 9 ADAPTIVE BAND SYNTHESIS ABS 200000 115 ABS RESOLUUION 074 4 dere a ha as eel a Rk eee bee A 116 Q Factor Accuracy cc eee ee eee eee eee 116 Running an Adaptive Sweep 222000 117 ABS Caching Level 0 2 0 0 cece eee eee ee eens 118 Multiple ABS Sweeps and Subsectioning 119 Multi Sweep Caching Scenarios 120 Find Minimum and Find Maximum 66 121 Parameter Sweep ssa KKK 122 Analysis Issues 0 1 ee ee eens 124 Multiple Box Resonances 000000e 124 De embedding loss eee ee ee ens 125 Transmission Line Parameters 125 Current Density Data
22. 15 GHz This circuit consists of eight sections making up the filter metalization two ports and two transmission lines connecting the ports to the filter metalization Reference planes have been defined for port 1 and port 2 at the left and right edges Chapter 7 De embedding of the filter metalization respectively These reference planes instruct em to re move the effects of the transmission lines up to the filter metalization when de embedding is enabled Filter Metalization DUT Port 1 Transmission Line Transmission Line 2 Port 2 Port discontinuities and transmission lines at the upper left and lower right are removed from the em analysis results by enabling de embedding NOTE Adding reference planes to a circuit in the project editor does not automatically enable de embedding in em However the De embed run option is set by default You select the de embed option in the Advanced Options dialog box in the project editor This run option is set by default To open the Advanced Options dialog box select Analysis gt Setup from the project editor main menu Then click on the Advanced button in the Analysis Setup dialog box which appears An analysis was performed on the filter starting at 3 95 GHz to 4 2 GHz in 0 002 GHz steps with the de embedding option on 99 Sonnet User s Guide As em performs the analysis messages are output to the status section of the anal ysis monitor detailing the v
23. Axis par_dstub DB S21 0 ace 30 o Oo 1 2 3 4 5 6 Sonnet Software Inc Frequency GHz Click mouse to readout data values Pointer As you can see the optimized circuit is producing the desired response of a stop band from 5 6 GHz and the passbands from 1 4 GHZ and 7 10 GHz Accepting the Optimized Values 53 54 Since the desired responses have been achieved by the optimization you return to the project editor to update the nominal value of your parameters with the opti mized values If the project par dstub is still open in the project editor continue at step 55 Click on the curve group par_dstub in the Curve Group legend in the response viewer This selects a project file and thereby enables the project menu Select Project gt Edit from the main menu of the response viewer The project editor appears on your display with par_dstub open 181 Sonnet User s Guide 182 55 56 57 Select Analysis gt Optimization Results from project editor main menu The Optimization Parameters dialog box appears on your display IN Optimization Parameters par_dstub son X Cell Size 10 0 mils Y Cell Size 10 0 mils Parameter i Nominal Granularity Opt Result 191 806973 200 0 Update Update nominal settings with optimization results Cancel Help Notice that the nominal value of both variables is still the value input at the begin ning of the optimization
24. Broadband Spice Model You use the response data created as the result of an em analysis to create a Broad band Spice model For the best results use an Adaptive sweep ABS to analyze your circuit and produce response data spread evenly over the frequency band The following procedure demonstrates the method to be used in the response viewer For detailed instructions for setting up a Broadband Model file in the proj ect editor please refer to Help Once you have completed the em analysis of your circuit do the following to cre ate a Broadband Spice model Open your project in the response viewer Select Output gt Broadband Model File from the main menu of the response viewer If you have more than one project open in the response viewer a window appears which allows you to select the desired project Select the desired project from the project drop list You may only create a Broadband Spice Model for one project at a time Click on the OK button to select the project and close the dialog box The Output Broadband Model File dialog box appears on your display You may access Help by clicking on the Help button or use context sensitive help for an explanation of a particular control or entry Select the file format of the Broadband Model PSpice or Spectre from the Format drop list PSpice and Spectre are the two formats of Spice file supported A PSpice file uses the extension lib and a Spectre file uses the extension
25. But the optimization results for both variables are dis played in the last column Since Sstub was not used in the optimization its optimization result is the same as the nominal value Click on the Update button to replace the present nominal values with the optimization results Note that the entries in the Nominal text entry boxes are updated with the optimized values Click on OK to close the dialog box and apply the changes Notice that the circuit has been redrawn with the new nominal values for the dimension parameters Since the parameter lengths are not integer multiples of the cell size the polygons are no longer exactly on the grid You can see this by pressing Ctrl M to turn off the cell fill and looking at the actual polygons The cell fill represents the actual metal em analyzes The actual metalization analyzed by em is not the same as the optimized values Em actually interpolated from data created from analyzing on grid versions of the circuit If your optimization goals did not include a full frequency sweep it is a good idea to perform a full sweep across your frequency band to ensure that your entire band shows reasonable results Running a full frequency sweep is detailed below Chapter 11 Parameter Sweep and Optimization Tutorial 58 59 60 61 62 63 In order for em to use previously calculated response data you should edit your variable value s such that they are the closest on grid
26. GHz An adap tive sweep provides approximately 300 data points For more information on the Adaptive Band Synthesis technigue see Chapter 10 231 Sonnet User s Guide 8 Select Analysis gt Setup from the main menu The Analysis Setup dialog box appears on your display Analysis Setup subdivide son a x Adaptive Sweep ABS mu muu x Cancel 9 Select Adaptive Sweep ABS from the Analysis Control drop list if it is not already selected This selects the Adaptive Sweep as your type of analysis The adaptive sweep provides a fine resolution of response data over the given freguency band Note that the text entry boxes are updated to reflect your choice of analysis 10 Enter 2 3 in the Start box and 2 5 in the Stop box This sets up the analysis freguency band This analysis setup is duplicated in all of the geometry subprojects when the subdivide is executed as well as in the main netlist The Analysis Setup dialog box should appears as shown below Analysis Setup subdivide son a a Adaptive Sweep ABS ks Mu x Cancel 232 Chapter 15 Circuit Subdivision Tutorial 11 12 Click on the OK button to save the analysis setup and close the dialog box Select File gt Save from the main menu The file must be saved before executing the subdivide The position of the subdivision lines are saved as part of your source project Subdividing Your Circuit 13 14
27. GHz The ge ometry projects have the subsectioning set so the lines are 16 cells wide and 128 cells long To evaluate DMAC do an analysis of the line at 15 GHz with de embedding en abled For the error in characteristic impedance take the percent difference be tween the calculated value and the exact value above For the error in propagation velocity take the percent difference between the calculated S phase and 90 de grees Total error in percent is the sum of the two errors Some types of analyses do not calculate characteristic impedance A detailed error analysis shows that to first order for a 1 4 wavelength long 50 ohm line the value of S is equal to the error in characteristic impedance For example an S 1 0 02 means that there is about 2 error in characteristic impedance To use this approximation for say a 25 ohm line the S parameters must be converted to 25 ohm S parameters This may be done by adding transformers in a circuit theory program Error Evaluation We have performed a detailed analysis of the relationship between subsectioning and residual error DMAC The simplest way to subsection a line is to use sub sections the same width as the line In Sonnet and in many other analyses this re sults in a uniform current distribution across the width of the line In reality the current distribution is singular at the edges of the line Since the current distribution is symmetrical about the center
28. Guide User Defined This allows you to enter any value desired for the terminal width This type of Terminal Width is shown below Current Flow User Defined Terminal Width Adding Co calibrated Ports You add co calibrated ports to your circuit by selecting the command Tools gt Add Ports and clicking on an open polygon edge where you wish to place the port Once the ports have been added to the circuit you select the ports then use the Modify Port Properties command which allows you to select the co calibrated port type and assign each port to a calibration group For detailed instructions on this process please refer to co calibrated internal port in Help s index Ref Planes and Cal Lengths for Co calibrated Ports You may specify both a reference plane and a calibration length for co calibrated ports For a detailed discussion of how reference lengths and calibration lengths are used during the de embedding process please refer to Chapter 7 De embed ding on page 97 and Chapter 8 De embedding Guidelines on page 107 For di rections on how to set a reference plane and or calibration length for a co calibrated port please refer to calibration group Help s index 74 Chapter 5 Ports Use in Components Co calibrated ports are used to implement the Component feature Many of the considerations which apply to the property setup of a Component also apply to the property setup for a calibration gro
29. If 257 Sonnet User s Guide the thick metal is the same thickness as the dielectric layer above it appears on both the metal level where it was drawn and on the metal level above Examples of both instances are shown below Level 2 Level 1 Level 0 A 3 mil thick metal polygon is drawn on level 2 below a 5 mil thick dielectric layer The polygon is visible on level 2 where it was drawn but only the outline is visible on level 1 above since the thick metal does not pierce the dielectric Level 2 Level 1 Level 0 A 5 mil thick metal polygon is drawn on level 2 below a 5 mil thick dielectric layer The polygon is visible on level 2 where it was drawn and also on level 1 above since it is the same thickness as the dielectric layer Note that on level 1 the border of the polygon is drawn with a dashed line to indicate that the origin of this polygon is not on this level If the thick metal is thicker than the dielectric above but not thick enough to pierce the next dielectric layer the polygon appears on the level where it was drawn and on the metal level above However note that the top of the thick metal does not appear in the project editor because it is embedded in a dielectric layer You will be able to view the top sheet of metal in the current density viewer which is dis cussed later in the chapter 258 Chapter 17 Thick Metal A side view of a circuit with three 50 mil dielectric layers A B and C and a 75 mil
30. Microwave Example 315 Topology Used for PI Model Output 316 N Coupled Line Option sssusa 317 Broadband SPICE Model 0 022 eee eee 319 Class of Problems 22 e eee eee 320 Creating a Broadband Spice Model 321 Checking the Accuracy of the Broadband Spice Model 323 Improving the Accuracy of the Broadband Spice Model 326 Broadband Spice Extractor Stability Factor 327 22 PACKAGE RESONANCES 2 as aran ies isossa ie Ew ge ww aI 329 Box Resonances 2 eee eee ee eee ee eee 330 Runtime Warning Messages 20 330 Observations of Simulated Results 332 A Box Resonance Example 0 0c eee eee 333 The Box Resonance Estimator 0000 334 Box Resonances Simple Removal 336 The Capability to Ask What if 337 23 ACCURACY BENCHMARKING 00 02 cece eecee 339 An Exact Benchmark lollis 339 Residual Error Evaluation 2220 eee 341 Using the Error Estimates 220 000 343 12 Table of Contents APPENDIX m AND XGEOM COMMAND LINE FOR BATCH 345 em Command Line 00 cc ee eee ee eee 345 Causal Dielectrics 02 e eee eee 348 xgeom Command Line 2 0 ee ee ee ee 349 Example of xgeom Command Line 351 APPENDIX SONNET REFERENCES c22ccccecccees 353 13 Sonnet Us
31. Processing on a Single computer In Release 12 Son net s electromagnetic EM simulations are performed more quickly by utilizing multiple CPU cores on the same computer in parallel making complete use of the latest CPU technology from Intel and AMD The new EM analysis engine creates multiple processes or threads each of which solves a different part of the solution matrix on a different CPU core all at the same time The result is a dramatic de crease in overall simulation time There are two new solver engine products available e Desktop Solver 2 parallel processing threads e High Performance Solver up to 8 parallel processing threads The maximum number of cores enabled by your license and supported by your hardware capability is automatically used on your system If you wish to use few er cores on your computer than the maximum possible you may limit the number of cores available using the Admin gt Thread Control command on the Sonnet task bar Variables for Material Properties and Thicknesses You may now control your materials parametrically using variables to control material properties and thick nesses as well as for lumped element values in ideal Components With this new feature comes the ability to parametrically control e Dielectric thickness e Dielectric loss properties e Metal Thickness e Metal loss properties e Ideal Component properties Diel Cond Thickness Mat Dielectric mil
32. Sonnet box all co calibrated ports in the group are globally grounded to the Sonnet box To do this a via is automatically created which connects to the top or bottom of the Son net box You should choose this option if the element model or measured data to be connected to these ports includes shunt elements Examples are e parameter data that includes pads or other coupling to ground e Transistor data that includes a via in the model measurement 1 Deembedding the Effect of a Local Ground Plane in Electromagnetic Analysis by James C Rautio president and founder of Sonnet Software Inc 70 The article is available in PDF format in the Support section of our web site Chapter 5 Ports This type of co calibrated port is illustrated below The positive terminal is at tached to a polygon edge of a feedline and the negative terminal is attached to a via to ground which is removed during de embedding Via to Ground Via to Ground When the Sonnet box is selected as the ground node connection the analysis en gine automatically determines the most efficient direction the ground via extends taking into consideration both the distance and the loss of the box top or bottom When using this type of ground you must make sure that there is a clear path with no metal on other levels interfering with the path to the box top and bottom In addition either the box top or bottom must have loss less than 50 ohms sq For
33. Sweep ABS Start Stop GHz GHz fio 25 X Cell Size 10 0 mils Y Cell Size 10 0 mils Sweep Start Stop Step Nominal 9 Width 30 so 10 40 0 cont This completes setting up an ABS freguency sweep for the parameter sweep You would also need to select the parameters which you want to use in the parameter sweep and enter their data ranges before closing this dialog box Analysis Issues There are several issues you should be aware of before using the ABS technigue these are covered below Multiple Box Resonances You should be aware that circuits with multiple box resonances make it difficult for an ABS analysis to converge The freguency band for an adaptive sweep should not contain multiple box resonances If multiple box resonances are pres ent the number of discrete full analysis points goes up dramatically and synthesis of the data becomes very difficult If you do not know how to identify box reso nances see Chapter 22 Package Resonances for a detailed discussion of box resonances 124 Chapter 9 Adaptive Band Synthesis ABS De embedding Adaptive data resulting from an ABS analysis is either de embedded or non de embedded With other analysis types when the de embedding option is enabled default then both de embedded and non de embedded response data is calculat ed and available for display and output This is not true for an adaptive sweep In an adaptive s
34. Using Adaptive Band Synthesis Interpolation Workshop WFA IEEE MTT Symposium Digest Philadelphia June 8 13 2003 James C Rautio Conformal Subsections for Accurate EM Analysis Microwave Journal Vol 46 No 6 June 2003 pp 116 120 James C Rautio and Veysel Demir Microstrip Conductor Loss Models for Electromagnetic Analysis IEEE Transactions on Microwave Theory and Techniques Vol 51 No 3 March 2003 pp 915 921 James C Rautio Electromagnetic Analysis Speeds RFID Design Microwaves amp RF Vol 42 No 2 February 2003 pp 55 62 James C Rautio EM Approach Sets New Speed Records Microwaves amp RF Vol 41 No 5 May 2002 pp 81 96 James C Rautio Shawn Carpenter et al CAD EDA virtual panel discussion Microwave Engineering May 2002 pp 15 25 Shawn Carpenter Analysis and Optimization of a Compact CPW Filter Using Planar EM Software MIcrowave Product Digest October 2001 pp 10 14 28 50 James C Rautio Making Practical High Freguency Electromagnetic Simulators Past Present and Future IEICE Transactions on Electronics Vol E84 c No 7 July 2001 pp 855 860 J C Rautio An Investigation of Microstrip Conductor Loss IEEE Microwave Magazine Volume 1 Number 4 December 2000 pp 60 67 Appendix II Sonnet References 20 21 22 23 24 25 26 27 28 29 30 31 32 Sha
35. Values 50 Creating Metal Types loose ee eee ee eee 50 Metal Libraries cee ee eee eee ERN G 56 Sonnet User s Guide VIA LOSS 5 5 ayoo ae Woe ek BR AS BHP is ed Ae 56 Setting Losses for the Box Top and Bottom Ground Plane 56 Dielectric Layer Loss loss NNN 57 Dielectric Layer Parameters 2200 0005 58 Dielectric Layer Loss oloon sans 59 How to Create a New Dielectric Layer 59 Dielectric Libraries oss es sn e eee 59 5 PORTS tis Gila ek ab Plate Saa Klee Ge es a IISA E 61 Port Type Overview saanen 61 Port Normalizing Impedances 085 63 Changing Port Impedance 06 64 Special Port Numbering 00 ee ee eee 65 Ports with Duplicate Numbers 00 65 Ports with Negative Numbers onnen 66 Changing Port Numbering 04 67 Port Placement with Symmetry ON 06 67 Standard Box Wall Port 0 0c eee eens 69 Adding Box wall Ports 2 022200 eee 69 Ref Planes and Cal Lengths for Box Wall Ports 69 Co calibrated Internal Ports 200000e 70 Ground Node Connection 00 000s 70 Terminal Width 2 0 eee ee ee eee 73 Adding Co calibrated Ports 2000 74 Ref Planes and Cal Lengths for Co calibrated Ports 74 Use in Components 2 eee ee ee ee eee 75 Via POES a aae r gn ee ee 75 Adding Via Ports 2 2 ce
36. a circuit which is symmetrical about the midline of the substrate When symmetry is turned on in the Box Settings dialog box Circuit gt Box everything below the line of symmetry is ignored and all metal above the line of symmetry is reflected about the symmetry line Special care should be given to ports when using symmetry 67 Sonnet User s Guide 68 Normally if you are using symmetry ports are placed on the line of symmetry as pictured below Ports are placed on the line of symmetry Line of Symmetry Ports can be placed off the line of symmetry but the port placed above the line of symmetry must have another port equidistant from and below the line of symme try These two ports must also have the same port type port number and proper ties The basic premise of symmetry is that the voltage at any give point above the line of symmetry must be equal to the voltage at the corresponding location below the line of symmetry Using the same number port port type and properties en sures that the voltage is the same at both required points since all ports with the same number as pictured below are electrically connected together This circuit has two sets of ports placed equidistant from the line of symmetry Note that the corresponding ports above and below the line of symmetry have the same number Port Pair Port Pair This circuit violates port usage with symmetry The ports are equidista
37. an error message and stops Edge of Metal Polygon is Lossless Auto grounded ports can attach to the edge of any metal polygon in the interior of a circuit There are no restrictions on the loss parameters of the metal used in the polygon However along the edge of the metal polygon where the port is attached 77 Sonnet User s Guide em does force the cells to be lossless For most circuits this should have little or no effect on the results If however the port is attached to a highly lossy metal polygon such as a thin film resistor the edge cell s of that polygon will be made lossless and the output results may be affected Adding Auto grounded Ports You add an auto grounded port to your circuit by selecting the command Tools gt Add Ports and clicking on the open polygon edge where you wish to place the port Once the port has been added to the circuit you select the port then Modify gt Port Properties In the Port Properties dialog box which appears you select the auto grounded type For detailed instructions on this process please refer to au to grounded ports in Help s index Ref Plane and Cal Length for Autogrounded Ports To set a reference plane or calibration length for an auto grounded port use the Modify Port Properties command You enter the desired Reference Plane and or Calibration Length in the appropriate field For detailed instructions please re fer to Help Note that if you enter a r
38. and generates the desired far field antenna pattern information This pattern information is viewed in one of three ways Cartesian polar or surface plot A default set of values for directions port excitations and terminations are used to calculate plots for the first frequency upon start up of the far field viewer Thereafter the user specifies the frequencies directions for the radiation pattern and the desired port excitations and terminations Chapter 19 Antennas and Radiation Since the far field viewer uses the current density data generated by em it can an alyze the same types of circuits as em These include microstrip coplanar struc tures patch antennas arrays of patches and any other multi layer circuit As with em the far field viewer can analyze any number of ports metal types and fre guencies The far field viewer cannot analyze circuits which radiate sideways structures with radiation due to vertical components coaxial structures wire an tennas surface wave antennas ferrite components or structures that reguire mul tiple dielectric constants on a single layer Be aware that although the current data is calculated in em with a metal box the metal box is removed in the far field viewer calculations The modeling consider ations discussed earlier in the chapter are important however for the accuracy of the far field viewer data relies on the accuracy of the em simulation By default the far field viewer a
39. are set to a large Xmin Ymin and edge mesh is set to off This yields the fastest analy sis but is also the least accurate Shown below is the subsectioning of a typical circuit using this option Setting the Maximum Subsection Size Parameter The parameter Max Subsection Size allows the specification of a maximum sub section size in terms of subsections per wavelength where the wavelength is ap proximated at the beginning of the analysis The highest analysis freguency is used in the calculation of the wavelength This value is a global setting and is ap plied to the subsectioning of all polygons in your circuit The default of 20 subsections A is fine for most work This means that the maxi mum size of a subsection is 18 degrees at the highest freguency of analysis In creasing this number decreases the maximum subsection size until the limit of 1 subsection 1 cell is reached You might want to increase this parameter for a more accurate solution For ex ample changing it from 20 to 40 decreases the size of the largest subsections by a factor of 2 resulting in a more accurate but slower solution Keep in mind that using smaller subsections in non critical areas may have very little effect on the accuracy of the analysis while increasing analysis time Another reason for using this parameter is when you reguire extremely smooth current distributions using for the current density viewer With the default value o
40. at an angle The three dimension parameter types are described in detail in the following sec tions Nominal Value 90 mils Nominal Value 120 mils Symmetric gt Symmetric Nominal Value 40 mils Nominal Value 80 mils Radial 60 Nominal Value 60 mils Nominal Value 80 mils Anchored Dimension Parameters An anchored parameter defines a dimension using an anchor point a reference point and an adjustable point set The nominal value of the parameter is defined by the distance between the anchor point and the reference point When the dimen sion is varied each point moves relative to the anchor point When defining your dimension parameter you perform the following steps 137 Sonnet User s Guide You select the anchor first This is the fixed starting point for the parameter You select the reference point The reference is the first point in the adjustable point set which is the set of points moved relative to the anchor point when the value of the dimension parameter is changed The distance from the anchor point to the reference point is the value of the dimension parameter When the value of the dimension parameter is changed the anchor retains the same position but the reference point moves to a new position Third you select any additional points in your circuit you wish to move when the reference point moves this is the adjustable point set As the value o
41. axis depend ing on the orientation of the parameter Each point in the adjustable point set is moved by an amount based on its relative distance from the anchor Points closer to the anchor are moved a smaller distance then points further away from the an chor For symmetric parameters the anchor is the center point between the two reference points The scaling factor used is the ratio of the new nominal value to the present nomi nal value Each point is moved by a delta calculated by multiplying its present dis tance from the anchor point by the scaling factor Scale Points in x and y When using this setting the geometry controlled by the parameter is scaled or stretched along both the x and y axis keeping the pro portions of the geometry the same Each point in the adjustable point set is moved by an amount based on its relative distance from the anchor Points closer to the anchor are moved a smaller distance then points further away from the anchor For symmetric parameters the anchor is the center point between the two reference points The scaling factor used is the ratio of the new nominal value to the present nomi nal value Each point is moved by a delta calculated by multiplying its present dis tance from the anchor point by the scaling factor An anchored dimension parameter being scaled in both directions is shown below The scaling factor is 1 5 since the new nominal value is 120 mils and the present value is 80 mils A
42. below Chapter 12 Conformal Mesh Current stripes For a tutorial on using conformal meshing please see the Conformal Mesh topic under Tips and App notes in Help You may access Help by selecting Help gt Contents from the menu of any Sonnet application or by clicking on the Help but ton in any dialog box 195 Sonnet User s Guide 196 Chapter 13 Netlist Project Analysis Chapter 13 Netlist Project Analysis Netlist projects provide you with a powerful circuit analysis tool Examples of ways in which the netlist may be used include Cascading Sonnet projects You can analyze and combine multiple proj ects using previously existing data for the subprojects if it is available This is particularly useful when analyzing large complex circuits which require circuit subdivision for an em analysis When analyzing a netlist project em will automatically interpolate between frequencies if there are differences be tween the frequency sweeps used in the subprojects It is also possible to im pose the same frequency sweep on all the subprojects in a netlist For more information about circuit subdivision see Chapter 14 Circuit Subdivision Cascading S Y and Z parameter data files You can read and com bine multiple sets of S Y and Z parameter data files This is particularly useful if you wish to combine results from another vendor s software for use in an analysis by em When analyzing a netlist
43. bottom 56 creating metal types 50 dielectric layer 57 dielectric layer library 59 dielectric layer parameters 58 general metal type 53 low frequency 52 366 metal libraries 56 microstrip 49 51 normal metal type 50 problems in determining 49 properties of commonly used metals 53 Rdc Rrf metal type 52 related to frequency 52 resistor metal type 51 sense metal type 55 Sonnet model 48 thick metal type 55 vias 56 251 LRGC 309 317 lumped elements 204 capacitors 197 inductors 197 inserting 197 inserting in a geometry 204 resistors 197 transmission lines 197 M main netlist 214 default name 233 Max 298 maximum frequency 30 maximum response 122 maximum subsection size 43 measurement data importing 81 memory save using with conformal mesh 191 Metal Editor dialog box 256 metal libraries 56 metal library 56 metal loss Sonnet model 48 Metal Properties dialog box 187 metal type creating 50 general 53 instructions for creating 55 59 libraries 56 normal 50 Index properties of commonly used metals 53 Rdc Rrf 52 resistor 51 sense 55 thick metal 55 253 metalization commonly used metals 53 loss 22 47 metalization levels visibility 245 metallization loss 47 metallization thickness 52 microstrip 156 281 patch antennas 279 microstrip loss 49 51 Microwave Office Interface 17 minima 154 minimum response 122 Mixed Sweep Combinations 25 mixed sweep combinations 148 modeled elements 197 insertin
44. box Conductivity E meee roerty field drop list lt Add Variable gt 131 Sonnet User s Guide 132 When you select lt Add Variable gt the Add Edit dialog box is opened so you can define the variable Hm Add Edit Variable par ds opt son Available Variables Value or Eguation Substrate Eguation Syntax Help Description Units Other v Insert into Egn To learn how to use variables to vary things like dielectric constant press Help OK Cancel Help Enter the desired variable name in the Name text entry box If you opened this dialog box by entering an undefined variable in another dialog box this field will already contain that name Enter a constant value another variable or an eguation that defines the value of the variable in the Value or Eguation text entry box For information about the functions available and eguation syntax click on the Eguation Syntax Help button If you wish to use another variable in the eguation you may select it from the list of Available Variables and click on the Insert into Egn button See the next section for more information on Eguations The variable name will be entered at the present location of the cursor in the Value text entry box Enter a brief description of the variable if desired in the Description text entry box This description appears in the Variable list dialog box and allows you to identify the purpose of the variable or which property it i
45. box To accomplish this a via is automatically created which connects to the top or bottom of the Sonnet box This option should be used if your component model or measured data includes shunt elements and you want the Component s ground reference to be connected to the Sonnet box GONN Sonnet Box Examples of this are e S Parameter data that includes pads or other coupling to ground e Transistor data that includes a via to ground in the model measure ment The analysis engine determines the most efficient direction the ground via extends taking into consideration both the distance and the loss of the box top or bottom When using this type of ground you must make sure that there is a clear path with no metal on other levels interfering with the path to either the box top or bottom If you are using a Component whose ground node connection is to the Sonnet box either the box top or bottom must have loss less than 50 ohms sg For example you should not use Free Space as your box top and bottom definition If the loss is too high on both the box top and bottom for a ground via from the Component to be attached the analysis engine will issue an error message 87 Sonnet User s Guide Polygon Edge s When your ground node connection is set to Polygon Edge s the ground refer ence of your Component is connected to a polygon edge s selected by you when adding the Component You may specify as many ground termin
46. box is closed the Analysis Setup dialog box is updated with an entry for the optimization variables that you just defined H Analysis Setup par_dstub son Options l Compute Current Density Speed Memory Memory Save Advanced Analysis Control Max Iterations 100 Optimization Parameters Lstub 100 0 to 300 0 start at 220 0 Sstub 200 0 fixed Optimization Goals one Now that you have identified which variable to vary and its range you must spec ify the optimization goals Since this is the first optimization for this project there are no previously defined optimization goals and the list is empty Having no goals present disables the Edit and Delete buttons The Edit button allows you to modify an existing goal and the delete button removes the goal from the list 175 Sonnet User s Guide 176 36 37 38 39 As mentioned earlier in the example our goal for the filter is to have passbands at 1 4 GHz and 7 10 GHz with a stopband at 5 6 GHz The optimization goals are set up accordingly Since all three goals in this case are equally important each uses the default Weight of 1 0 In cases where one goal is more essential assigning it a higher weight than other goals tells em to concentrate more on reaching that particular goal Click on the Add button to the right of the Optimization Goals list The Optimization Goal Entry dialog box appears
47. box resonance detected in a calibration standard Sonnet Warning EG2680 Circuit has potential box resonances Filename C Program Files sonnet package son Second de embedding standard left box wall First few ideal resonant frequencies are 30 0871 GHz TE Mode 0 1 1 31 7625 GHz TE Mode 0 1 2 Note that the warning message defines which calibration standard is causing the problem The observant reader will notice that these resonant frequency values are different than with the primary structure This occurs because Sonnet actually cre ates and analyzes two calibration standard as a part of the de embedding proce 331 Sonnet User s Guide dure These standards may have a different box size than the primary structure which causes the change in the resonant frequencies For more information on the calibration standards and de embedding please refer to Chapter 7 and Chapter 8 Observations of Simulated Results A second way to detect box resonances is with a manual review of the simulated data Typically box resonances appear as sharp changes glitches or spikes in S parameter magnitude and phase data They can also be evident in E p and Zo data This is because there is a resonance in at least one of the standards that em creates for de embedding Box resonances can also corrupt de embedding results Be cause em s de embedding feature is based on circuit theory it possesses the same limitation that all de embe
48. button This option may only be used when the Circles option is used CircleSize lt float gt lt float gt is a floating string number Manual text entry box This option is only used if CircleType is set to manual KeepMetals lt boolean gt Metal Polygons checkbox DXF amp Gerber KeepVias lt boolean gt Via Polygons checkbox DXF amp Gerber KeepBricks lt boolean gt Brick Polygons checkbox DXF amp Gerber KeepEdgeVias lt boolean gt Edge Vias convert to one cell wide vias checkbox DXF amp Gerber KeepParent lt boolean gt Output as Metal checkbox This is only applicable if the KeepEdgeVias option is on ConvertParent lt boolean gt Convert to Vias checkbox This is only applicable if the KeepEdgeVias option is on GbrUnits lt unit gt lt unit gt is either inch or mm Gerber Only GbrWholeDigits lt num gt lt num gt is an integer number from 2 to 6 Whole digits drop list GbrDecimalDigits lt num gt lt num gt is an integer number from 2 to 6 Decimal digits drop list GbrFilenameType lt type gt lt type gt is default custom or project Default corresponds to the default radio button Custom corresponds to the Custom Prefix radio button Project corresponds to the Project name radio button Gerber Only 350 Appendix Em and xgeom Command Line for Batch Entry Definition GbrFilenamePrefix l
49. by an equation that uses another variable As the value of the variable in the equation is changed so is the dependent variable If a variable is dependent you may not di rectly edit its nominal value instead you change its value by changing the value of the variable on which it is dependent You may not delete a dependent variable If you wish to delete it you must first remove the dependency by changing the def inition of the dependent variable Variables which do not depend on another variable for their value are independent variables Only independent variables may be selected for a parameter sweep To vary a dependent variable in a parameter sweep you must select the variable on which it depends For more details on parameter sweeps see Parameter Sweep on page 148 Circular Dependencies in Variables Care should be taken when adding dependent variables to your circuit that they do not form a circular dependency A circular dependency is formed when two vari ables are dependent on each other This can happen for two variables or multiple variables In the case of multiple variables the dependency extends from the first variable through all the variables until the first variable is dependent upon the last 135 Sonnet User s Guide An example of a circuit dependency would be the two equations A 2 B and B sin A For variables if the project editor detects a circular dependency an er ror message appears and you are force
50. cell The current density changes most rapidly here thus the smallest possible subsection size is used 35 Sonnet User s Guide Subsection size is 1 cell by 1 cell on corner Subsection size is 1 cell p wide along edge Interior subsections are wide and long Cell Size A portion of circuit metal showing how em combines cells into subsections In this case the subsectioning parameters are set to their default values X Min 1 Y Min 1 X Max 100 and Y Max 100 As we go away from the corner along the edge the subsections become longer For example the next subsection is two cells long the next one is four cells long etc If the edge is long enough the subsection length increases until it reaches X Max 100 cells or the maximum subsection size parameter whichever comes first and then remains at that length until it gets close to another corner disconti nuity etc Notice however that no matter how long the edge subsection is it is always one cell wide This is because the current density changes very rapidly as we move from the edge toward the interior of the metal this is called the edge singularity In order to allow an accurate representation of the very high edge current the edge subsections are allowed to be only one cell wide However the current density be comes smooth as we approach the interior of the metal Thus wider subsections are allowed there
51. compromise between accuracy and speed In the case pictured above X Min and Y Min are set to be very large and the fre quency is low enough so that the Max Subsection size parameter corresponds to a subsection size that is larger than the polygon Using X Max and Y Max for an Individual Polygon NOTE 40 You may control the maximum subsection size of individual polygons by using the X Max and Y Max parameters For example if X Max and Y Max are de creased to 1 then all subsections will be one cell This results in a much larger number of subsections and a very large matrix which are the cause of increased analysis time Thus this should be done only on small circuits where extremely high accuracy is required or you need a really smooth current density plot If the maximum subsection size specified by X Max or Y Max is larger than the size calculated by the Max Subsection Size parameter the Max Subsection Size parameter takes priority The Max Subsection Size is discussed in Setting the Maximum Subsection Size Parameter page 43 Chapter 3 Subsectioning Using the Speed Memory Control The Speed Memory Control allows you to control the memory usage for an anal ysis by controlling the subsectioning of your circuit The high memory settings produce a more accurate answer and usually increase processing time Converse ly low memory settings run faster but do not yield as accurate an answer
52. data each time you analyze your circuit But be aware that in order to maintain the va lidity of the caching data the subsectioning of the circuit must remain the same To control the subsectioning you must use the Advanced Subsectioning Controls which you open by selecting Analysis Advanced Subsectioning from the main menu of the project editor TIP The most efficient way to obtain response data for your circuit is to run a single ABS sweep over the entire desired frequency band The analysis engine em uses the subsectioning frequency to calculate the wave length which is used in setting the Maximum subsection size The default setting used to determine the subsectioning frequency is to use the highest frequency from the present analysis job If you perform multiple sweeps over different frequency bands then the cache data from one run will be invalid for the next since the sub sectioning frequency would be different In order to avoid this you should select the Previous Analysis Only option which will use the highest frequency from all previous analysis jobs run on the project In this case you should analyze the fre quency band with the highest upper limit first and take care to ensure that the sub sectioning frequency being used provides accurate subsectioning for your circuit For details on subsectioning see Chapter 3 Subsectioning on page 29 119 Sonnet User s Guide Another way to keep the subsectioning frequency c
53. data values Pointer 183 Sonnet User s Guide 184 The results conform closely enough to the design criteria that this optimization is considered a success As was stressed at the beginning of this tutorial a simple ex ample was chosen in order to clearly demonstrate the optimization process You should be aware however that most optimization problems are much more complicated and less straightforward The designer needs to make decisions about parameters the parameter sweeps and optimization goals based on knowledge of the circuit and design experience Often you must observe an optimization while in progress judge its viability and as necessary stop the optimization and start a new one with new nominal values and data ranges Chapter 12 Conformal Mesh Chapter 12 Conformal Mesh Introduction Analyzing circuits which have non rectangular polygons can require extensive memory and processing time since the number of subsections needed to model the non rectangular shapes is significantly higher than the number of subsections re quired for a rectangular polygon Conformal meshing is a technique which can dramatically reduce the memory and time required for analysis of a circuit with diagonal or curved polygon edges This technique groups together strings of cells following diagonal and curved met al contours Whereas staircase fill results in numerous small X and Y directed subsections conformal mesh results in a
54. dimensions in the X direction and your Y cell size based on just your dimensions in the Y direction 31 Sonnet User s Guide 32 For example if you have a spiral inductor with widths of 3 microns and spacings of 8 microns modify the 3 microns to 4 microns You may now use 2 cells instead of 8 speeding up the analysis by several orders of magnitude with little impact on circuit performance This concept is illustrated below Circuit 1 Requires 80 cells Runs slow uses more memory More accurate 8 um 3 um 1 um cell size 1 cell Circuit 2 1 cell Reguires only 6 cells i Runs fast uses less memory Less accurate 8 4um 4 um cell size Circuit 1 takes more time and memory to analyze than circuit 2 even though they have approximately the same amount of metal This is because the dimensions in circuit 2 are divisible by 4 so a 4 um cell size may be used Circuit 1 requires a 1 um cell size Think about the sensitivity of your circuit to these dimensions and your fabrication tolerances If your circuit is not sensitive to a 1 micron change or can be made with only a 1 micron tolerance you can easily round off the 3 mi cron dimension in circuit 1 to the 4 micron dimension in circuit 2 Chapter 3 Subsectioning Cell Size Calculator Sonnet also provides a cell size calculator which you may use to calculate the op ti
55. dimensions which are much greater than the London depth of penetra tion The second approach is a model which is still valid at moderate frequencies but includes effects due to kinetic inductance The kinetic inductance is a function of temperature and can be approximated in the following manner 0 Ri 0 L ALIN Roc rf where uo 47 10 7 H m AL hel T T London depth of penetration at temp Xo London depth at T 0 meters T Critical Transition Temperature in degrees Kelvin The third model should be used to account for high frequency effects or effects due to small circuit dimensions In these cases the surface resistances proportion ality to begins to dominate and the following model is suggested The resistiv ity is a function of freguency sguared and Sonnet presently does not have a method to do this Therefore if you are analyzing over a broad band you need to have a separate project for each freguency using the following eguations af F i 2 2 eee 3 Roc 5 Ly A T ON M n L HAT 1 Shen Z Y High Temperature Superconducting Microwave Circuits Boston 1994 Artech House 54 Chapter 4 Metalization and Dielectric Layer Loss where 2nf radians sec O Conductivity of the superconductor in its normal state Mhos m Ny Normal state carrier density 1 m3 Ny Superconducting state carrier density 1 m gt and are as defined above Po d A T The Surf
56. during analysis A variable s value may be defined using e A constant or nominal value e Another variable e An equation Any of these definitions may be directly entered into a property field For a more detailed discussion of eguations please see Eguations on page 133 Chapter 10 Parameterizing your Project How to Create a Variable You may use two basic approaches to creating variables in your project The first approach is to define all the desired variables and then enter these variables as property values The second approach is to enter a variable in the desired property field as needed If the variable has not been previously defined you are prompted to enter a definition Using the second approach allows you to define variables as needed rather than defining them all ahead of time To define a variable do the following 1 Open the Add Edit Variable dialog box This dialog box may be opened one of four ways e By selecting Circuit gt Add Variable from the project editor main menu e Select Circuit gt Variable List from the project editor main menu then click on the Add or Edit button in the Variable List window which appears e By entering an undefined variable in a property field in another dialog box When the dialog box is closed the Add Edit Variable dialog box is opened so you can define the variable e By selecting lt Add Variable gt from a drop list of a property field in another dialog
57. example you should not use Free Space for both your box top and bottom def inition If the loss is too high on both the box top and bottom for a ground via from the Component to be attached the analysis engine will issue an error message Floating When the ground node connection is defined as Floating all co cali brated ports in the group are connected to a common ground but not to the Sonnet box Instead the ground node is left unconnected to the rest of your circuit You should choose this option if the element model or measurement data that will be connected to these ports does not have a ground reference or does not have shunt elements Examples of this are e A series RL equivalent circuit e S Parameter data that was measured without any pads This type of co calibrated port is illustrated below Sonnet automatically adds ex tra metal which connects the co calibrated ports in a calibration group This extra metal is defined as Generalized Local Ground GLG metal since it acts as a local 71 Sonnet User s Guide ground for the ports in the calibration group This metal is removed during the de embedding process The positive terminal of a co calibrated port is attached to a polygon edge of a feedline and the negative terminal is attached to GLG metal WCE n To observe the GLG metal for either type of ground node connection you may se lect the View gt View Subsections command in the project edit
58. few long conformal subsections Fewer subsections yields faster processing times with lower memory requirements for your analysis In older meshing techniques large non rectangular subsections did not include the high concentration of current on the edge of the lines required by Maxwell s equa tions The results could significantly under estimate loss and inductance In con trast the Sonnet conformal meshing automatically includes the high edge current 185 Sonnet User s Guide 186 in each conformal section In conformal meshing Sonnet can achieve the speed of using large subsections and at the same time enjoy the accuracy of using small cells This patented Sonnet capability is unique Pictured above is a typical circuit which would be appropriate for Conformal Meshing The left picture shows the rectangular subsections created by using staircase fill This results in approximately 800 subsections unknowns The right picture shows the conformal sections created by using conformal fill resulting in only about 130 subsections Note that each conformal section shown represents multiple subsections Conformal sections like standard subsections are comprised of cells so that the actual metalization still shows a jagged edge when the polygon has a smooth edge as pictured below However the sections can be much larger due to confor mal meshing You may now make the underlying grid sufficiently small to accu ratel
59. is shown in the graph below Est steps_sweep son EERE Cartesian Plot Parameter Sweep of Steps Z0 50 0 Left Axis steps_sweep_width_20 DB S21 ne steps_sweep_width_40 DB S21 steps_sweep_width_60 DB S21 lt gt D AC 50 0 Z Q W dB Right Axis r 7 empty Sonnet Software Inc Frequency GHz Click mouse to readout data values Pointer You may also plot your response data against the parameter values by selecting the Graph gt Plot Over gt Parameter command in the response viewer Shown below is the plot of the magnitude in dB of S21 versus the variable Width at 10 Hz Data markers have been added to the plot for clarity Graph gt Marker gt Add gt Data Marker 2 steps son Cartesian Plot Z0 50 0 Left Axis steps DB S21 mi m m3 O Width 20 0 0 3494 d8 i m2 Width 40 0 1 332 dB Width 60 0 2 091 dB m3 Width 60 0 2 091 dB 35 40 45 50 55 60 Sonnet Software Inc Parameter Click mouse to readout data values Pointer Chapter 10 Parameterizing your Project Since an analysis of the circuit at each combination of variable values is executed for each specified analysis frequency care should be taken when choosing data ranges The higher the number of analysis frequencies and variable values the higher the number of analyses that must be computed by em The number of com binations specified is displayed in the projec
60. is the usual case for resistors The above equation for Rgp assumes that all of the current travels on just one side of the conductor This is a good approximation for some microstrip circuits How ever if the current really travels on both sides this gives a pessimistic value for the loss The equation should be modified for other structures Stripline for exam ple has current of equal amplitude on both the top and bottom of the conductor In this case you should divide the Rgp value by two while maintaining Rpc As an example the conductivity O for copper is 5 8E 7 Mhos m giving Rpc 0 006 Ohms square t 3 um and a microstrip Rpr 2 6E 7 In reality the bulk conductivity of copper or any other given metal may not equal the laboratory val ue so the figures as calculated above are likely to be lower than actual results The table below provides calculated results of commonly used metals using the equa tions above Chapter 4 Metalization and Dielectric Layer Loss Properties of Commonly Used Metals RRF a RDC RDC OH Metal my sa sg ha Nela t 1uM t 1mil Kin Effect microstrip Aluminum 3 72e7 0 027 1 1e 3 3 3e 7 Brass 1 57e7 0 070 2 5e 3 5 0e 7 Copper 5 80e7 0 017 6 8e 4 2 6e 7 Gold 4 09e7 0 024 9 6e 4 3 1e 7 Nichrome 1 00e6 1 000 3 9e 2 2 0e 6 Silver 6 17e7 0 016 6 4e 4 2 5e 7 Tantalum 6 45e6 0 155 6 le 3 7 8e 7 Tin 8 70e6 0 115 4 5e 3 6 7e 7 General
61. m NN b N w e E _ KIR Zo Jer TKO TW 2 124 No 376 7303136 k tanh The expression for K k cited above provides an accuracy of about 1 x 108 When programmed on a computer the following values are obtained for three different transmission line impedances unity dielectric constant Table 1 Stripline Benchmark Dimensions Zo ohms w b 25 0 3 3260319 50 0 1 4423896 100 0 0 50396767 For a length of stripline there are two parameters of interest characteristic imped ance and propagation velocity With the w b given above we know the exact an swer to within 1 x 109 for Zo With a dielectric constant of 1 0 we also know the exact answer for the propagation velocity It is the speed of light known to about 1 x 107 Any difference from these values is error or DMAC 340 Chapter 23 Accuracy Benchmarking Residual Each of the above three benchmarks is available in the Sonnet examples To get the 50 ohm line get the example S50 The other benchmark circuits are in S25 and S100 For directions on obtaining a Sonnet example select Help gt Examples from the menu of any Sonnet program then click on the Instructions button The b dimension is exactly 1 0 mm the w dimension is given by the above table and the length of each line is 4 99654097 mm with a dielectric constant of 1 0 Each of these lines is precisely 0 25 wavelengths long at 15 0
62. not used in the em simulation but are there to provide a graphic in both the 2D and 3D view which represent the actual size of the Component This is especially useful for design presentations and re views Shown below is a 3D view of the example Component pictured above Component Types Data File 84 There are three types of Component model Data File Ideal and Ports Only All three models are described below The Data File Component allows you to add a Component to your geometry that is modeled with a user specified S Y or Z Parameter file Touchstone format The data file used for your Component can be the result of another simulation or measured data from an actual component There is no limit to the number of ports you may use for a data file Component You add a data file type Component by selecting the command Tools gt Add Com ponent gt Data File This command opens the Components Properties dialog box as well as the Component Assistant Chapter 6 Components Ideal Component The Ideal component allows you to add a single 2 port ideal component There are three types of ideal components available resistor capacitor or inductor All ideal components use a series element with two ports as shown below Resistor EW Capacitor 4 Inductor jp You add an Ideal component by selecting the command Tools gt Add Component gt Ideal This command opens the Components Properties dialog box as well as the Compo
63. pending on the direction of the via A via post has a horizontal cross sectional area equal to one cell and a height equal to the thickness of the dielectric layer If you change the cell size then the via is resubsectioned into via posts with the new cell size The project editor places enough via posts to cover the entire length of the polygon edge for an edge via and the complete perimeter of a via polygon A via with the via posts detailed is illustrated on page 247 To view vias as they are being captured it is convenient to be able to change the viewed level in the project editor quickly To do so just type Ctrl U to go up one level towards the box top or Ctrl D to go down one level You may also click on the Up One Level or Down One Level button on the tool bar in the project editor Most keyboards also support the up and down arrow keys If you want a level to be displayed as a ghost outline whenever you are not on that level make the level visible in the Levels dialog box which appears in re sponse to selecting View Metalization Levels Then you can see how different levels of metalization line up You may also use the Levels dialog box to turn off the visibility of any given level By default the project editor starts with all levels visible 245 Sonnet User s Guide 246 Adding a Via to Ground A via to ground can be added from any metalization level To add a via to ground go to the level from which you wi
64. project em will automatically interpolate between freguencies if there are differences in the freguencies be tween the data files Inserting modeled elements into a circuit Modeled elements such as resistors capacitors inductors and transmission lines can be combined with geometry subprojects and S Y and Z parameter data files 197 Sonnet User s Guide Networks 198 A netlist project contains a netlist which consists of one or more networks with elements connected together The netlist provides a map in which the ports of in dividual elements in the netlist are connected to the ports of other elements by the use of nodes Nodes represent a connection between netlist elements example_net example_net son ox MACRI I ts eee oS B PRJ 1 2 steps son Hierarchy Sweep RES 23 R 25 0 CAP 3 C 0 2 PRJ 4 3 steps son Hierarchy Sweep DEF2P 1 4 example_net Main Network Use buttons or menus to modify netlist Network None Line None The picture above shows the network represented by the netlist shown in the proj ect editor below it The nodes are represented by the numbered black dots The ge ometry project steps son is connected between nodes 1 and 2 with node 1 corresponding to Port 1 in the geometry project and node 2 corresponding to Port 2 A resistor is connected between nodes 2 and 3 A capacitor is connected be tween node 3 and ground The project steps son is also connected between
65. see Standard Box Wall Port page 69 Co calibrated internal port Used in the interior of a circuit Identified as part of a calibration group with a common ground node connection The ground node connection can be defined as floating or the Sonnet box When em performs the electromagnetic analysis the co calibrated ports within a group are simultaneously de embedded Highly accurate de embedding Often used by a circuit simulation tool to connect some type of ele ment into your geometry at a later time outside the Sonnet environ ment Reference planes may be used For more information on co calibrated internal ports see Co calibrated Internal Ports page 70 Via port Used in the interior of a circuit Negative terminal is connected to a polygon on a given level and the positive terminal is connected to a second polygon on another level above Cannot be de embedded Most commonly used to attach a port between two adjacent levels in your circuit or when you want a port to go up to the box cover rather than down to ground Reference planes cannot be used For more information on via ports see Via Ports page 75 Auto grounded port Used in the interior of a circuit The positive terminal is attached to the edge of a metal polygon and the negative terminal is attached to the ground plane through all intervening dielectric layers Used in place of a co calibrated port to reduce the de embedding pr
66. spherical coordinate system shown below The X Y and Z coordinates are those used in the analysis engine and the project editor The XY plane is the plane of your project editor window with the Z axis pointing toward the top of the box The spherical coordinate sys tem uses theta O and phi b as shown in the figure below Z Toward Lossy Top This edge is the left side of the project editor window This edge is the top of t project editor window The far field viewer allows values for theta from 0 to 180 degrees However val ues of theta greater than 90 degrees are below the horizon and are only useful for antennas without infinite ground planes To view just the top hemisphere sweep theta from 0 to 90 degrees and sweep phi from 180 to 180 degrees The X and Y axes in the figure above correspond to the X and Y axes in the project editor The origin is always in the lower left corner of the project editor window To look at an E plane cut or an H plane cut set phi p to 0 or 90 degrees and sweep theta 0 from 0 to 90 degrees To view an azimuthal plot set O and sweep Chapter 19 Antennas and Radiation NOTE The far field viewer will allow the user to analyze the same space twice with the user determining the appropriate angle ranges for each analysis For details see Graph Select in the far field viewer s help The far field viewer displays three plot types cartesian polar and surface All
67. the Fill Type Enter the desired Maximum Length in the text entry box Click on the OK button to close the dialog box and apply the changes For a more detailed discussion of Conformal Mesh please refer to Chapter 12 Conformal Mesh on page 185 There is also an application note on conformal mesh available in Help Chapter 4 Metalization and Dielectric Layer Loss Chapter 4 Metalization and Dielectric Layer Loss This chapter is composed of two parts metalization loss and dielectric layer loss For information on dielectric brick loss see Chapter 18 Dielectric Bricks on page 263 Both the theoretical aspect of how Sonnet models loss and the practical how to s of assigning loss in your circuit are covered including the use of metal and dielectric material libraries The discussion of metalization loss begins below For the discussion of dielectric loss see Dielectric Layer Loss page 57 There is also a paper available by the president and founder of Sonnet Software Dr James Rautio which contains a detailed discussion of metal losses You may find this paper at www sonnetsoftware com support publications asp Metalization Loss Metalization loss is specified in the project editor in the Metal Types dialog box which is opened by selecting Circuit gt Metal Types Losses may be assigned to circuit metal top cover and ground plane Sidewalls are always assumed to be per fect conductors 47 Sonnet
68. the MTLINE model in Cadence Spectre Moreover modal characteristic imped ances Zp and propagation constants a jf are provided along with their cor responding excitation vectors For more information see N Coupled Line Option on page 317 Variable Granularity for Optimizations There is a new Granularity entry box available in the Optimization Parameters dialog box The granularity defines the finest resolution the smallest interval between values of a variable for which em will do a full electromagnetic simulation during optimization For values which occur between those set by this resolution em performs an interpolation to pro duce the analysis data Please see Help for the details look under granularity in the index Anisotropic Dielectrics Standard dielectric layers in the simulation environment may now be modeled with uniaxial anisotropy The properties of a given dielectric layer in the X Y direction view in the project editor may have different dielec tric magnetic and or conductivity properties from the Z directed properties Click on the Help button in the Dielectric Editor dialog box Circuit gt Dielectric Layers for details Measuring Tape Tool There is a new measuring tool available in the project ed itor that allows you to quickly measure distances in your geometry The measuring tape can provide distance measurement between vertices and shortest distance to an adjacent line in the circuit Th
69. the Sonnet Electromagnetic Analysis Proceedings of the 1994 IEICE Fall Conference Tokyo pp 325 326 J C Rautio An Ultra High Precision Benchmark For Validation Of Planar Electromagnetic Analyses IEEE Tran Microwave Theory Tech Vol 42 No 11 Nov 1994 pp 2046 2050 J C Rautio A Precise Benchmark for Numerical Validation IEEE International Microwave Symposium Workshop WSMK Digest Atlanta June 1993 Comparison of Strategies for Analysis of Diagonal Structures Sonnet Application Note 51 02 J C Rautio MIC Simulation Column A Standard Stripline Benchmark International Journal of Microwave amp Millimeter Wave Computer Aided Engineering Vol 4 No 2 April 1994 pp 209 212 J C Rautio Response 3 Standard Stripline Benchmark MIC Simulation Column International Journal of Microwave and Millimeter Wave Computer Aided Engineering Vol 5 No 5 September 1995 pp 365 367 J C Rautio Some Comments on Approximating Radiation International Journal of Microwave and Millimeter Wave Computer Aided Engineering Vol 4 No 2 1994 pp 454 457 J C Rautio Synthesis of Lumped Models from N Port Scattering Parameter Data IEEE Tran Microwave Theory Tech Vol 42 No 3 March 1994 pp 535 537 J C Rautio Educational Use of a Microwave Electromagnetic Analysis of 3 D Planar Structures Computer Applications in Engineering Education Vol 1 No 3 19
70. the far field viewer tool bar REAREA Plot Over rreguencu v Plot Over drop list Select Graph gt Select gt Theta from the far field viewer main menu The Select Theta s dialog box appears on your display 303 Sonnet User s Guide 304 40 41 42 43 44 Double click on 90 0 degrees in the Plotted list This value moves to the Calculated list which removes it from the display Double click on 0 0 degrees in the Calculated list This value moves to the Plotted list which adds it to the display Click on the OK command button The display is updated with a frequency plot as shown below Note that the gain is now calculated relative to 7 55049 dB since the Normalization is relative to Max and this value is the maximum value of radiation for this plot infpole son FAMA Plot Over Frequency v infpole son Gain dB Relative To 7 55049 dB Theta 0 0 Degrees EEEE Phi 0 0 Degrees dB 30 3 40 08 0 85 09 095 1 1 05 1 1 1 15 1 2 1 25 Freguency GHz Click mouse to readout data values Pointer Select Graph gt Select gt Phi from the far field viewer main menu The Select Phi s dialog box appears on your display TIP You may also invoke the Select Phi s dialog box by right clicking on the Phi box in legend and selecting Select from the pop up window Double click on 0 0 degrees in the Plotted list This value moves to the
71. the number of inde pendent variables selected for the parameter sweep e A Sensitivity Sweep allows you to see how sensitive your circuit is to changes in any given variable The nominal value of each variable is combined with the maximum and minimum values of the other variables as well as the nominal values For a sensitivity sweep the number of combinations which are analyzed is N 2eN 1 where N is the number of combinations and N is the number of inde pendent variables selected for the parameter sweep e Mixed Sweep Combinations allows you to define a range of values for each variable then perform an analysis at each possible combination of variable values There are four types of sweeps available Fixed Linear Linear steps and Exponential Parameter Sweep Example For example the graphics below illustrate a linear parameter sweep of the circuit steps with a single dimension parameter whose value is defined as the variable Width The parameter sweep starts with a value of 20 mils for the variable and increases in steps of 20 until the variable s value is 60 Em automatically performs an analysis at each specified frequency for each circuit shown below when the pa rameter sweep is executed Width 20 mils Width 40 mils Width 60 mils 149 Sonnet User s Guide 150 In the case of this sweep an ABS analysis from 10 20 GHz was performed The response data for the parameterization
72. the parameter Width in your circuit For more information on inputting a parameter please re fer to Variables page 130 To select ABS for a parameter sweep do the following Select Analysis gt Setup from the project editor main menu The Analysis Setup dialog box appears on your display Chapter 9 Adaptive Band Synthesis ABS Select Parameter Sweep from the Analysis Control drop list The dialog box is updated to allow you to specify the parameter sweep M Analysis Setup untitled Options E p Speed Memory l Memory Save Advanced Analysis Control Parameter Sweep si Parameter Sweeps Click on the Add button to the right of the Parameter Sweep list box The Parameter Sweep Entry dialog box appears on your display The default frequency specification is a linear sweep H Parameter Sweep Entry untitled Freguency Specification Sweep Type Adaptive Sweep ABS Start Stop GHz GHz X Cell Size 10 0 mils Y Cell Size 10 0 mils Sweep Stop Step Nominal F Width 4 40 0 40 0 Select Adaptive Sweep ABS from the Sweep Type drop list to select an adaptive freguency sweep The dialog box changes so that there are only Start and Stop text entry boxes 123 Sonnet User s Guide 5 Enter the frequency band for the ABS in the Start and Stop text entry boxes M Parameter Sweep Entry untitled Frequency Specification Sweep Type Adaptive
73. the port attached to it Sonnet then builds and analyzes two through lines based on this geometry If there is more than one port on a box wall then the calibration standard is a multiple coupled line The lengths of these two through lines can determine the accuracy of the de em bedding see below for a discussion of the problems which can occur with improp er lengths By default Sonnet chooses calibration lengths for you If the port 107 Sonnet User s Guide Defining contains a reference plane then the first calibration length is the same length as the reference plane and the second length is double the first If no reference plane exists Sonnet chooses one for you If you are having trouble with de embedding you may want to change this cali bration length using the following sections as a guide If you are using reference planes you can simply change your reference plane length and the calibration lengths will change accordingly If you are not using reference planes then you can set the calibration length using Circuit gt Ref Plane Cal Length This allows you to set the first calibration length The second is always twice as long as the first Reference Planes Sonnet places very few restrictions on the reference planes which may be defined for a given circuit This is done intentionally so as to provide maximum flexibility for all users However there are some basic guidelines concerning reference planes th
74. they are attached to and via polygons have their own loss properties To assign loss to a via polygon select the via polygon and choose Modify gt Via Properties In the Via Properties dialog box select a metal type in the Via Loss drop list for the via polygon For extremely precise loss anal ysis of vias you should use the same measurement approach as discussed earlier for polygon loss Setting Losses for the Box Top and Bottom Ground Plane You set the loss for the box top or bottom by assigning a metal type to the box top or bottom The box top and bottom use the same metal types which are used for the metalization in your circuit i e the polygons and via polygons In addition Chapter 4 Metalization and Dielectric Layer Loss there are two special metal types available in Sonnet for the Top and Bottom met als Free Space and Waveguide Load See Chapter 19 Antennas and Radiation for a discussion of how and why you would use these types To assign a metal type to the Box Top or Bottom metal select Circuit gt Box Set tings from the project editor main menu In the Box Settings dialog box which ap pears on your display select the desired metal type for the top metal from the Top Metal drop list and the desired metal type for the bottom metal from the Bottom Metal drop list Dielectric Layer Loss The dielectric layer loss calculations in Sonnet are virtually exact given the sub strate really has a frequency ind
75. unstable structures need a higher value to maintain their stability You input the stability factor in the Advanced Broadband Model Options dialog box opened when you click on the Advanced button in the Broadband Model En try dialog box in the project editor or response viewer You enter the stability fac tor in the Additional Options text entry box using the following format Stability lt factor gt 327 Sonnet User s Guide where lt factor gt is the desired stability factor An example of the entry of a stability factor of 0 1 is pictured below MN Advanced Broadband Model Options _ Add to Predicted S Parameter File Start Stop Step GHZ GHZ GHZ l DC Point Stability Factor Max Total Order 200 Additional Options 328 Chapter 22 Package Resonances Chapter 22 Package Resonances Simply stated the Sonnet analysis is a solution of Maxwell s equations These general equations are not limited to a purely TEM or Quasi TEM analysis For a given structure if a higher order mode TE or TM can propagate or an evanescent mode can exist it will be included in the results The strongest evidence of the presence of a waveguide mode occurs when the 6 conducting sides of the Son net box create a resonant cavity As most microwave designers can attest to these box resonances occur in practice as well The designer can use Sonnet to predict unwanted box resonances in the package or module housing th
76. wish to attach a port between two adjacent levels in your cir cuit Another application is when you wish to connect a port to the interior of a polygon which is not allowed for co calibrated ports which must be added to an open polygon edge You can not apply reference planes to via ports since it is not possible for em to de embed them Adding Via Ports NOTE To add a via port you must first create a via The via can be an edge via or a via polygon For more details on how to create vias see vias in Help s index Once the via is in place click on the Add a Port button in the tool box and click on the via to add a port The via port only appears in the project editor on the bottom level of the via if you are adding the port to any other level of the via the port is not displayed in the project editor To see the port go to the metal level on which the bottom of the via is placed Automatic Grounded Ports 76 An automatic grounded port is a special type of port used in the interior of a circuit similar to a co calibrated internal port This port type has the positive terminal at tached to the edge of a metal polygon located inside the box and the negative ter Chapter 5 Ports minal attached to the ground plane through all intervening dielectric layers An auto grounded port with a reference plane is shown below Auto grounded ports can be de embedded by the analysis engine In most circuits the add
77. xgeom from a command line in order to perform an export of a project file in DXF GDSII or Gerber format The syntax of the command line is as follows xgeom lt project gt Export lt type gt RWOut lt file gt ExpRegistry ExpOptions lt exfile gt lt project gt lt type gt lt file gt ExpRegistry ExpOptions lt exfile gt The name of the project which you wish to export If there is no extension then the extension son is assumed This field is required This identifies the format of the output file Choices are DXF GDS or GERBER This field is required For DXF and GDSII this is the filename to which you wish to write your output For Gerber this is the folder to which you wish to write your output files This woe field is required Use as the folder name if you wish to use the present folder This option instructs xgeom to use the export options from the registry This field is optional If neither Exp option is included then the default export options are used If both Exp options are included in the command the export options are read first from the registry and then from the specified lt exfile gt Any options set in the file will overide those in the registry Any options in the regristry overides the default setting The export options in the registry are what was used the last time you performed an export from the project editor This option instructs xgeom to use the export options fro
78. you open the response viewer to look at your results Observing the Parameter Sweep Data 14 15 16 17 18 You want to see the data for the S response at Lstub 120 mils and Lstub 280 mils Select Project gt View Response gt New Graph from the main menu of the analysis monitor output window The response viewer window appears on your display with Sj displayed Right click on par dstub in the Curve Group legend A pop up menu appears on your display Select Edit Curve Group from the pop up menu The Edit Curve Group dialog box appears on your display Double click on DB S11 in the Selected list This moves the Sj response to the Unselected list It will no longer appear in your plot Double click on DB S21 in the Unselected list This moves the S gt response to the Selected list so that it appears in your plot Chapter 11 Parameter Sweep and Optimization Tutorial 19 20 21 22 23 Click on the Select Combinations button in the Edit Curve Group dialog box The Select Parameters dialog box appears on your display Note that by default only variables which are varied during the parameter sweep are displayed so only Lstub appears If you wish to also display variables which were not varied in this case Sstub click on the Configure Columns button and select the Static checkbox in the Configure Columns dialog box Click on the Select All button above the Selected Parameter Combi
79. 0 20 0 20 40 60 80 100 Theta Click mouse to readout data values Pointer 289 Sonnet User s Guide The far field viewer display defaults to a cartesian plot with theta selected on the X axis The polarization defaults to Theta Phi The Y axis is set to display the Gain in dB of the pattern response and is normalized to power gain of the ideal isotropic antenna To change the calculation and display defaults see File Preferences in the far field viewer s help Calculating the Response 290 As mentioned above when the far field viewer is invoked the response data is cal culated for only the first frequency in the current response file To calculate data for the other frequencies at additional angles perform the following Select Graph gt Calculate from the far field viewer main menu The Calculation Setup dialog box appears on your display with the Angles tab se lected as shown below M Calculation Setup infpole son Review settings in all categories before pressing Calculate Angles Ports Frequencies Start Stop Step New Theta Degrees Degrees Degrees Theta 1 90 000 300 Bo phit foo 900 oo Calculate Chapter 20 Far Field Viewer Tutorial Selecting Phi Values 6 Enter 0 in Start text entry box 90 in the Stop text entry box and 5 in the Step text entry box of the Phi line This analyzes data points from phi 0 to 90 in intervals of 5 Selec
80. 0 213 Choosing Subdivision Line Placement 216 Sonnet User s Guide 10 Good and Bad Placements of Subdivision Lines 217 Subdivision Line Orientation 00 221 Setting Up Circuit Properties 04 223 Setting Up the Coarse Step Size Frequency Sweep 224 Subdividing Your Circuit 0 oss 2 eee eee ee ee 225 Analyzing Your Subdivided Circuit 225 15 CIRCUIT SUBDIVISION TUTORIAL eee ee ee ee eee ees 227 Obtaining the Example File 06 228 Adding the Subdivision Lines 228 Setting Up Circuit Properties 000 231 Subdividing Your Circuit 0 oss kesk 233 Analysis of the Network File sos 236 Additional Improvements sossun 238 16 VIAS AND 3 D STRUCTURES eee wesc ee eeee 241 INCFOUUCHION sissi wt Siete Rew Baw avd eee Wawel AE 818 241 Restrictions on Vias 0 2 eee ee ee ee eee 241 Creating the Vias ooe k ce ee eens 242 Via Direction lt soks KKK KK ee ee ee 242 Via TYPOS aa eda aa ad EA Wes 243 Via Posts is shai seats SPR ans Be eave le Gee Poh elena safe ws 245 Adding a Via to Ground 2005 246 Multi layer Vias 6 ee ens 248 Deleting Vias 2 1 ee ee ens 250 Vid LOSS saat aasien Wa ee alee stele Bee goer ae ter ate 251 Mia POUS 350203 ok ae ea Sed ee day ais A fa 251 Simple Via Example 0 2 cee eee eee 252 A Coni al Vidi 13 ana dS asd ede
81. 0 017788 69 364 200 MHz 300 MHz 400 MHz 209 Sonnet User s Guide 210 Chapter 14 Circuit Subdivision Chapter 14 Circuit Subdivision Introduction Sonnet provides the capability to take a large circuit and split it into any number of smaller projects then connect the results in a netlist project to produce a re sponse for the whole circuit This method can significantly reduce the required processing time and memory necessary to analyze the circuit while still obtaining an accurate answer The number of subsections in a circuit is one of the most important factors in de termining processing time since the matrix solve time is proportional to N To il lustrate how circuit subdivision reduces processing time consider two subprojects each with half as many subsections as the source project The total matrix solve time is now four times faster 2 N 2 3 N 4 Circuit subdivision allows you to take advantage of this technique by breaking your circuit into smaller parts with fewer subsections hence requiring less pro cessing time and memory to analyze The trade off is that you introduce some er ror into the analysis However by subdividing the circuit appropriately you can minimize the error while still obtaining the reduction in processing time 211 Sonnet User s Guide 212 The circuit should be split where there is no coupling across the subdivision line Areas where significant coupl
82. 000000000 0 70711620654 0 00000000000j 0 7070844351 5 7766439e 7 2000000000 0 6 15674302e 7 4 81156085e 7 6 15695041e 7 RLGC Data Matrix values extracted from structure of length 1 25e 4 meters Z0 Matrix Eigenvectors Modal Excitation Vector 0 70709973181 1 01204653e 7 0 70710975084 0 00000000000 From Z Matrix Odd Mode 0 70711383049 0 00000000000 0 7071038115 4 2771946e 8 Modal Excitation Vector ZO Matrix Eigenvalues From Zo Matrix Even Mode Zoe Even Mode Zoo Odd Mode Modal Excitation Vector Gamma Matrix Eigenvectors From Yy Matrix Odd Mode Modal Excitation Vector From y Matrix Even Mode Gamma Matrix Eigenvalues 0 28101510488 189 350366291 0 97887215574 102 080263771 Y Even Mode Y Odd Mode 36 6622803867 4 23884026037 36 6646940705 3 4873268e 10 1 417338e 10 3 4873269e 10 1 33833238e 6 4 375153le 7 1 33785617e 6 After the Sonnet header the format of the RLGC data is provided This is followed by RLGC data and comments for each analysis freguency Each comment line be gins with the character Though the comment lines can be ignored they con tain useful modal information Each value in the comment session has both a real and imaginary part Characteristic impedance Z0 propagation constant y and the modal excitation vectors are provided for each mode Broadband SPICE Model NOTE The Broadband Spice Extractor feature is only available
83. 07 for details Modeled Elements KI Modeled Element 67 11 Q Eee Geometry Project metalization The two port T attenuator will be re analyzed to demonstrate the use of modeled elements 205 Sonnet User s Guide The geometry file att_lgeo son contains three sets of auto grounded ports placed at locations where modeled elements will eventually be inserted This file is available as part of the Att example used for this chapter Below is the netlist att_lumped son that will be used for this example T att_lumped son 01 x ojee x see os we ew ela PRJ 123456 7 8 att_Igeo son Hierarchy Sweep RES 34 R 16 77 RES 56 R 16 77 RES 7 8 R 67 11 DEF2P 1 2 ATTEN Main Network Use buttons or menus to modify netlist Network None Line None The netlist above instructs em to perform the following steps 1 Perform an electromagnetic analysis on the geometry file att 1geo son using the Freguency sweep and run options defined for this netlist Note that according to the PRJ line Ports 1 8 correspond to nodes 1 8 respec tively in the main network atten The node numbers are listed after the PRJ keyword in the order of ports in the circuit 206 Chapter 13 Netlist Project Analysis 2 Insert a 16 77 ohm resistor between nodes 3 and 4 which is the equiva lent of inserting the resistor between autogrounded ports 3 and 4 in the geometry project 3 Insert a 16 77 ohm resistor between nodes 5 and 6
84. 1 0 26 Click or drag mouse to readout data values 1 0x Pointer Moves up one level Up Arrow 1 0 Pointer The current density viewer creates as many sublevels as are needed A thick metal which is defined as having 4 sheets placed on level 2 would appear in the current density viewer as 2a 2b 2c and 2d with 2a being the top of the thick metal structure and 2d being the bottom drawn on level 2 262 Chapter 18 Dielectric Bricks Chapter 18 Dielectric Bricks Although em is primarily a planar electromagnetic simulator it also has the capa bility to add dielectric brick material anywhere in your circuit A dielectric brick is a solid volume of dielectric material embedded within a circuit layer See the illustration below Dielectric bricks can be made from any dielectric material in cluding air and can be placed in circuit layers made from any other dielectric ma terial including air For example dielectric bricks can be used to simulate structures such as an embedded capacitor in an air circuit layer or an air hole in a dielectric substrate circuit layer A WARNING Misuse of dielectric bricks can lead to significantly inaccurate results It is highly recommended that you read this entire chapter before attempting to use dielectric bricks 263 Sonnet User s Guide Level 1 Level 0 yx Dielectric Layer Level 0 Metal Dielectric Layer
85. 1 Deembedding the Effect of a Local Ground Plane in Electromagnetic Analysis by James C Rautio president and founder of Sonnet Software Inc The article is available in PDF format in the Support section of our web site 81 Sonnet User s Guide In cases where the data file or ideal component types are used the Sonnet solver uses a circuit simulation technique to produce the combined results Since this is a post EM analysis step the user can change the ideal component value or asso ciated S parameter data file without requiring a new EM analysis only the circuit simulation part of the analysis is performed by the analysis engine Please note that the coupling from the inside of the component to the rest of the circuit is not considered in the Sonnet analysis Only the coupling from the com ponent s terminals is considered When connecting external parts to your EM structure we highly recommend that you use either the co calibrated ports or the Component feature This novel ap proach provides greatly enhanced accuracy for this application by perfectly de embedding the ports thus completely removing all coupling between them Auto grounded Ports have the limitation of not removing any port to port coupling Before proceeding to use the Component feature it would be helpful to become familiar with the related co calibrated internal ports discussed in Co calibrated Internal Ports page 70 in the Ports chapter C
86. 130 circular dependencies 135 dependent 135 independent 135 vertical components 281 vertical orientation 221 setting 229 via 252 via loss 56 via ports 76 251 via posts 245 vias 241 conical 252 deleting 250 example 252 ground 252 inside dielectric bricks 265 loss 56 251 restrictions 241 subsections 245 symbol 244 to ground 246 via posts 245 view legend 300 303 metalization levels 245 zoom in 295 viewing the response 168 W warnings 208 waveguide simulator 274 wavelength 30 what s new 23 wire antennas 281 wire bonds 241 X xgeom 16 XMAX 40 XMIN 37 39 Y YMAX 40 YMIN 37 39 371 Sonnet User s Guide Z Z current 241 ZO 110 125 Z axis 282 zoom in 295 zoom in button 295 Zooming 295 Z partitioning 264 265 270 272 372
87. 8 The figure below shows a geometry project for the T attenuator with ungrounded internal ports at each modeled element location Note that the gaps between poly gons at these locations have been removed This is because you must attach un grounded internal ports between two abutted polygons This slightly impacts the overall performance of the attenuator The geometry project att_lgeo2 son uses ungrounded internal ports at locations where modeled elements will eventually be inserted The network file shown below connects the desired resistors across the unground ed internal ports of the network shown on page 208 Since ungrounded internal ports do not have access to ground only a single node is specified when connect ing an element across them WARNING Ungrounded internal ports have one terminal connected to an edge of a polygon and the second terminal connected to an abutted edge of a second polygon Ungrounded internal ports do not have access to ground Therefore only 1 port elements or 1 port networks may be connected across ungrounded internal ports Resistors capacitors and inductors are technically one port elements and therefore may be inserted in place of an ungrounded internal port in a netlist Chapter 13 Netlist Project Analysis The netlist for this circuit att lumped2 son is shown below Both the geometry project att 1geo2 son and this netlist are available in the Att example prov
88. 93 pp 243 254 J C Rautio Characterization of Electromagnetic Software 42nd ARFTG Conference Digest San Jose CA Dec 1993 pp 81 86 J C Rautio Some Comments on Electromagnetic De Embedding and Microstrip Characteristic Impedance International Journal of Microwave amp Millimeter Wave Computer Aided Engineering Vol 3 No 2 April 1993 pp 151 153 J C Rautio Some Comments on Electromagnetic Dimensionality IEEE MTT S Newsletter Winter 1992 pg 23 357 Sonnet User s Guide 358 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 J C Rautio Sonnet Software Reveals Tangential Fields EEsof Wavelengths Vol 9 No 1 March 1993 pg 12 J C Rautio Sonnet Introduces Antenna Pattern Visualization in New Release EEsof Wavelengths Vol 9 No 2 June 1993 pg 21 J C Rautio EEsof Joins Forces With Sonnet Software EEsof Wavelengths Vol 8 No 3 Sept 1992 pg 14 J C Rautio Electromagnetic Design of Passive Structures Emerging Technology in Microwave CAD IEEE MTT S Newsletter Fall 1990 pp 21 22 J C Rautio Electromagnetic Microwave Design RF Microwave Applications Conference Santa Clara CA March 1992 pp 105 109 J C Rautio Experimental Validation of Microwave Software IEEE International Microwave Symposium Panel Session PSB Digest Albuq
89. 98 gds 17 GDSII translator 16 17 general metal type 53 Generalized Local Ground 71 geometry project 202 geometry subprojects 213 Gerber Translator 17 GLG metal 71 global ground 87 goal 153 goals 176 Granularity 26 granularity 153 graph axes 301 calculate 281 290 normalization 285 298 select frequencies 292 phi 293 294 304 theta 303 305 type cartesian 303 polar 299 surface 306 ground node connection 86 floating 71 86 polygon edge s 88 Sonnet box 70 87 ground plane 287 303 ground reference 86 ground terminals 88 ground via 241 252 H highest frequency 30 High Performance Solver 24 horizontal orientation 221 hot key mapping 26 H plane 282 ideal component 85 ideal element 81 impedance 64 65 67 surface 55 importing measurement data 81 365 Sonnet User s Guide independent variable 135 inductor 85 inductors 197 infinite array 274 infinitesimal dipole 287 288 303 infpole 302 interdigital 156 interface basics 23 interpolation 212 isotropic 285 iteration 179 iterations 153 selecting for display 179 K keyboard shortcuts custom 26 kinetic inductance 53 L lateral dimensions 281 legend selecting frequencies 292 selecting phi s 294 304 turning off 299 view 300 303 Levels dialog box 245 libraries metal 56 library dielectric 59 metal 56 limitations 281 linear sweep 148 Lite 23 local ground de embedding 70 81 98 local origin 26 loss 22 47 60 box top and
90. As before the width goes from one cell to two cells then four etc 36 Chapter 3 Subsectioning TIP If two polygons butt up against each other or have a small overlap the modeling of the edge singularity will require a larger number of subsections at the boundary between the two polygons Using the Merge command Edit gt Merge Polygons to join the two polygons into one will reduce the number of required subsections and speed up your analysis Conversely if you have an area of your circuit at which you desire greater accu racy using the Divide Edit gt Divide Polygons command at the point of interest to create two polygons forces the analysis to use smaller subsections in order to model the edge singularities X Min and Y Min with Edge Mesh Off Having the edge mesh option on is the default state for Sonnet projects howev er examining the case where edge mesh is off first makes understanding the concept easier This part of the discussion only applies to Manhattan polygons which is a polygon that has no diagonal edges Turning edge mesh off for non manhattan polygons has no effect On occasion you may wish to change the default subsectioning for a given poly gon You can do this using the subsectioning parameters X Min Y Min X Max and Y Max For Manhattan polygons with edge mesh off X Min and Y Min set the size of the edge subsections By default X Min and Y Min are 1 This means the edge sub sect
91. Calculated list which removes it from the display Chapter 20 Far Field Viewer Tutorial 45 Double click on 90 0 degrees in the Calculated list This value moves to the Plotted list which adds it to the display 46 Click on the OK command button The dialog box disappears and the display window is updated 47 Select Graph gt Select gt Theta from the far field viewer main menu The Select Theta s dialog box appears on your display 48 Double click on 45 0 degrees and 90 0 degrees in the Calculated list These values move to the Plotted list which adds these values to the display 49 Click on the OK command button The dialog box disappears and the display is updated as shown below infpole son MIEIEVEIEI Plot Over Frequency v infpole son Gain dB Relative To 8 23633 dB Theta 0 0 Degrees 45 0 Degrees 90 0 Degrees Phi 90 0 Degrees 08 085 09 095 1 105 11 115 12 1 26 Freguency GHz Click mouse to readout data values Pointer Notice that E Total at Theta 90 is shown in the legends but does not appear on the graph This occurs because the magnitude is too small to show on the plot Viewing a Surface Plot The surface plot shows all the calculated values of theta and phi plotted against the gain for a single frequency 305 Sonnet User s Guide 50 Select Graph gt Type gt Surface from the main menu Your display is updated with a surface plot with the first fr
92. Click on the OK button to close the Metal Editor dialog box and apply the changes The Metal Types dialog box is updated with the new metal type Metal Types thick_metal son BEI WN as a Metal for New Polygons Gold Cnd 4 09e7 T 50 NS 2 Jlossiess F Edit Remove Library Apply Cancel Help 7 Click on the OK button to close the Metal Types dialog box The thick metal is now available to use in your project 8 Enter the desired polygon then double click on the polygon to open the Metalization Properties dialog box 9 Select the thick metal model metal type from the Metal drop list in the Metalization Properties dialog box This will apply the metal type which uses thick metal to the selected polygon The thick metal extends upwards from the level on which the polygon was drawn 10 Click on the OK button to close the Metalization Properties dialog box and apply the changes The fill pattern of the polygon changes to the fill pattern used by the thick metal If the thick metal polygon is thicker than the dielectric layer s above it the polygon also appears on metal levels above Viewing Thick Metal in the Project Editor The thick metal extends upward through the dielectric layer from the level on which the polygon is drawn If the thick metal is not as thick as the dielectric layer above it then the polygon only appears on the lower level where it was drawn
93. Compute Current Density option must be selected in the Analysis Set up dialog box in the project editor Infpole was analyzed at a linear frequency sweep from 0 8 GHz to 1 2 GHz in in tervals of 0 1 GHz Chapter 20 Far Field Viewer Tutorial Running the Far Field Viewer EY Click on the View Far Field button on the Sonnet task bar to invoke the far field viewer A pop up menu appears on your display Select Browse for Project from the pop up menu A browse window appears on your display Using the browse window select your saved copy of inpole son The far field viewer window opens on the project file infpole son After the initial calculation is complete a plot appears on your display as shown below When a new file is opened the far field viewer performs an analysis on the first freguency based on a default set of values for directions port excitations and terminations and displays the Gain dB versus theta for the first value of phi The calculation defaults are as follows e There are two values of phi 0 and 90 e Theta ranges from 90 to 90 in 5 intervals e Port 1 is set to a 1 0 V source magnitude with a 50 0 Q load amp infpole jxy nd JAJA s l a Plot Over Theta F infpole jxy Gain dB 10 Frequency 0 8 GHZ 5 5 9 0 f 1 Phi 0 0 Degrees o dB n 1 on L E Field E Total D 1 a O O N N S i L 100 80 60 4
94. Curve Group dialog box appears This curve group uses the default name of par_dstub_2 Following the same steps you used for par_dstub above set up this curve group to display the S response for Lstub 280 mils Sstub 220 mils Your plot should now look like the one below Ee par_dstub son EERE Cartesian Plot Z0 50 0 Left Axis par_dstub DB S21 par dstub 2 O DB S21 O oc 50 9 o 5 6 7 Frequency GHz Sonnet Software Inc Click mouse to readout data values Pointer You could also have right clicked the curve group par_dstub in the Left Axis pane of the legend and selected Edit Curve Group from the pop up menu Using the Edit Curve group dialog box you could have added this parameter combination to this curve group This would result in one curve group with one symbol represent ing both parameter combinations This is useful if you want multiple measure 171 Sonnet User s Guide ments Sj and S for example Each measurement would use a different symbol but each parameter combination with a measurement would use the same symbol An example is pictured below ES par dstub son EARMA Cartesian Plot Z0 50 0 Left Axis par_dstub DBIS21 par_dstub 2 O DB S11 2 ace 50 v o 5 6 7 Sonnet Software Inc Freguency GHz Click mouse to readout data values Pointer In the beginning the goal of the filter
95. Ga a a a a 252 THICK METAL 3 50 20 soar he ese Ee Ow SoS EA anata SE 253 Thick Metal Type oloon 253 Creating a Thick Metal Polygon 255 Viewing Thick Metal in the Project Editor 257 Restrictions with Thick Metal Polygons 259 Modeling an Arbitrary Cross Section 260 Thick Metal in the Current Density Viewer 261 Table of Contents 18 DIELEGPRIC BRICKS 3015 oat ie varie vans ties ats eta E a 263 Applications of Dielectric Bricks 00 265 Guidelines for Using Dielectric Bricks 265 Subsectioning Dielectric Bricks 265 Using Vias Inside a Dielectric Brick 265 Air Dielectric Bricks oss 266 Limitations of Dielectric Bricks 000 266 Diagonal Fille feito ws aia esl Bl es teak ite Geos 266 Antennas and Radiation 0 0000 266 INLEFFACES n aa bad SoA a i de eer gee eee did a 266 Dielectric Brick Concepts 0 20 ee eee 267 Creating a Dielectric Brick 267 Viewing Dielectric Bricks 006 267 Defining Dielectric Brick Materials 268 Changing Brick Materials 000 269 Z PArtitiOning inssi ele ahaa ee ie he KISA J a alae 270 19 ANTENNAS AND RADIATION 2 ce eee cere eres 273 Background o 666 ananasta Me dew we wo ea esa ees 274 Modeling Infinite Arrays oss ee ee ee 274 Modeling an Open Environment
96. High Frequency Electromagnetic Software SONNET Suites ri y Gc NS s This page intentionally left blank SONNET USER S GUIDE Published April 2009 Release 12 Sonnet Software Inc 100 Elwood Davis Road North Syracuse NY 13212 Phone 315 453 3096 Fax 315 451 1694 Technical Support support sonnetsoftware com Sales Information sales sonnetsoftware com www sonnetsoftware com Copyright 1989 1991 1993 1995 2009 Sonnet Software Inc All Rights Reserved Registration numbers TX 2 723 907 TX 2 760 739 Copyright Notice Reproduction of this document in whole or in part without the prior express written authorization of Sonnet Software Inc is prohibited Documentation and all authorized copies of documentation must remain solely in the possession of the customer at all times and must remain at the software designated site The customer shall not under any circumstances provide the documentation to any third party without prior written approval from Sonnet Software Inc This publication is subject to change at any time and without notice Any suggestions for improvements in this publication or in the software it describes are welcome Trademarks The program names xgeom emstatus emvu patvu dxfgeo ebridge emgraph gds emserver emclient sonntcds and sonntawr lower case bold italics Co calibrated Lite LitePlus Level2 Basic Level2 Silver and Level3 Gold are trademarks of Sonn
97. It is not designed for optimum VSWR Top view of a triple patch antenna courtesy of Matra Defense The central patch is fed with a coaxial probe indicated by a down pointing triangle Each patch is resonant at a different frequency to increase the overall antenna bandwidth Good results are also regularly obtained on single microstrip patch antennas We cite this example as one of the more sophisticated antennas analyzed using the Open Waveguide Simulator technique In this antenna each patch has a slightly different resonant frequency resulting in an increased bandwidth The antenna is fed from below with a coax probe attached to the central patch The feed point is indicated with a triangle The substrate is 3 04 mm thick with a dielectric constant of 2 94 The drawing is to scale with substrate dimensions of 200 mm x 100 mm The top cover is 200 mm above the substrate surface Cell size is 0 78125 mm square A loss tangent of 0 001 is used in both air and substrate The small air loss helps terminate the prop agating modes The antenna project Tripat is available in the Sonnet examples For directions on obtaining a Sonnet example select Help gt Examples from the menu of any Son net program then click on the Instructions button The chart below shows the result We see that the low VSWR points of each patch have differences between measured and calculated of about 1 This is typical of most analyses of patch antennas
98. Parent OFF 351 Sonnet User s Guide 352 Appendix II Sonnet References Appendix II Sonnet References 1 2 3 4 5 6 This appendix contains articles written by Sonnet authors or articles which directly impacted the analysis theory used by Sonnet An extensive list of articles in which Sonnet was used as the analysis tool is available on Sonnet s website at www sonnetsoftware com Search for References James C Rautio In Search of Maxwell Microwave Journal Vol 49 No 7 July 2006 pp 76 88 Heng Tung Hsu James C Rautio and San Wen Chang Novel Planar Wideband Omni directional Quasi Log Periodic Antenna Asia Pacific Microwave Conference 2005 Suzhou China December 4 7 2005 James C Rautio and Vladimir I Okhmatovski Unification of Double Delay and SOC Electromagnetic Deembedding IEEE Transactions on Microwave Theory and Techniques Vol 53 No 9 September 2005 pp 2892 2898 James C Rautio Applied numerical electromagnetic analysis for planar high frequency circuits Encyclopedia of RF and Microwave Design Wiley New York Vol 1 2005 pp 397 413 James C Rautio Deembedding the Effect of a Local Ground Plane in Electromagnetic Analysis IEEE Transactions on Microwave Theory and Techniques Vol 53 No 2 February 2005 pp 770 776 James C Rautio Comments on On Deembedding of Port Discontinuities in Full Wave CAD Models of Multiport Circui
99. Simple Via Example A simple via is stored in the example Via and is shown in the figure on page 252 For directions on obtaining a Sonnet example select Help gt Examples from the menu of any Sonnet program then click on the Instructions button Note that the top end of the via shown below is a pad which is larger than the via itself There are no restrictions on the polygons at the top of a via Em s sub sectioning algorithm handles the subsectioning accurately A simple via to ground On the left as it would appear in the project editor On the right a view in perspective A Conical Via 252 One may simulate a conical ground via with a staircase approximation Simply di vide say a 100 uM GaAs substrate into four 25 uM substrates Then put vias at appropriate places to form a step approximation to the conical via sides For an example see Cvia in the Sonnet examples This circuit is a conical via to ground placed in the center of a through line the purpose being to measure the via induc tance For directions on obtaining a Sonnet example select Help gt Examples from the menu of any Sonnet program then click on the Instructions button The cvia son file is a very detailed model of a conical via If you are modeling a large circuit say an inter stage matching network with multiple vias you may want to use a simpler model for faster analysis Another approach would be to use circuit subdivision where you s
100. Summary for matchnet Maximum error was for S12 Error 2 98411 Total model time 25 minutes 43 seconds Model matchnet finished with no errors 5 warnings W Indicates that a fit was found for all S parameters but for some the error exceeded the error Improving the Accuracy of the Broadband Spice Model If you need to increase the accuracy of your Broadband Spice model there are several strategies you may use e Ifthe Broadband model met your error threshold criteria but is still not acceptable you may decrease the error threshold to increase the accuracy of the model Be aware however that the processing time may be significantly increased by lowering the error threshold Typically values below 0 1 result in unacceptably long analysis times e If there are more than 200 frequency points in your response data try decreasing the number of freguencies in your response data To do so use the Analysis gt Clean Data command in the project editor to remove the response data then run another Adaptive sweep ABS Chapter 21 SPICE Model Synthesis using a coarser resolution to produce less data points but still more than 50 data points You may change the resolution of an adaptive sweep in the Advanced Options dialog box in the project editor Select Analysis gt Setup then click on the Advanced button in the Analysis Setup dialog box which appears e Increase the number of data points in the critical freque
101. The Sonnet Design Suite skn ee ee ee 15 The Analysis Engine em oloon KNN 20 A Simple Outline of the Theory 21 Em OGBIN 3 a fa eee J ae ot atlas ae HIS INN 22 2 WHAT S NEW IN RELEASE 12 20 20 ee eee ee eeee 23 Sonnet LITO iina ise gs a Ae aks wee eek ene Bele 8 ee 23 New Features a uimari ansaa BAG See bok ee 24 Changes oo si saama ee ee ENON wl eed ate ae are ees 27 Bc SUBSECTIONING 10 01 stow eds eh ht eee kee ewe ee 29 Tips for Selecting A Good Cell Size 4 30 Cell Size Calculator 2 2 ee ee eee 33 Viewing the Subsections 00 eee eee 33 Subsectioning and Simulation Error 34 Changing the Subsectioning of a Polygon 34 Default Subsectioning of a Polygon 34 X Min and Y Min with Edge Mesh Off 37 X Min and Y Min with Edge Mesh On 39 Using X Max and Y Max for an Individual Polygon 40 Using the Speed Memory Control 0000 41 Setting the Maximum Subsection Size Parameter 43 Defining the Subsectioning Frequency 44 Conformal Mesh Subsectioning 2000 44 Conformal Mesh Subsectioning Control 46 4 METALIZATION AND DIELECTRIC LAYER Loss 47 Metalization Loss 0 oloon KKK ee ee eee 47 Sonnet s Loss Model loss oksan KK 48 Problems In Determining Metal Loss 49 Determining Good Input
102. The actual subdivision of the project is executed by the software but you must en ter names for the resulting main netlist file and subproject files produced as well as optionally defining a feedline length to be added to the subprojects Feedlines should be added to the subprojects if you feel it necessary to move dis continuities in the various sections of the circuit further away from the boxwalls to prevent any interaction between the discontinuities and boxwalls This can pro vide a more accurate analysis result for each section of the circuit Any added feedlines are of lossless metal regardless of the metal type to which they are at tached Sonnet software provides a default recommended value for the feedline or you may enter your own value Select Tools gt Subdivide Circuit from the project editor main menu The Circuit Subdivision dialog box appears on your display Circuit Subdivision subdivide son This feature may be used to divide your whole geometry project into subprojects A main netlist project for connecting the subprojects together is also generated Main Netlist Project subdivide_net son Browse Cancel Help The name subdivide_net son is provided by default in the Main Netlist Project text entry box This name is used for the main netlist which connects the geometry projects resulting from the subdivide The default name is the basename of the source project with a _net added
103. This loss model includes the metalization resistivity described above in Rdc Rrf The General loss definition also includes the metalization reactance composed of the surface reactance X4 and the kinetic inductance L Surface reactance X o is specified in Ohms square Em uses the same reactance at all frequencies Until recently the only surface resistivities of practical interest were pure real i e pure loss With the growing application of superconductors in high frequency work surface reactance reaches significant levels A superconductive effect known as kinetic inductance slows the velocity of the electrons with no loss of energy This can be modeled as a surface inductance The effect of surface inductance is to make g larger or the velocity of propaga tion slower For normal conductors ge can never be larger than Ee In a super conductor this is no longer true This unusual effect becomes significant for very thin substrates Surface inductance L is specified in the project editor in the Metal Types dialog box accessed by selecting Circuits gt Metal Types This parameter takes into ac count the surface reactance at higher freguencies 53 Sonnet User s Guide There are three recommended approaches to obtaining a value for Ls A first order approximation is to assume the metal is a perfect conductor This model works well for moderate frequencies less then 150 GHz and moder ate circuit
104. To access the Speed Memory Control follow the instructions below 1 Select Analysis gt Setup from the project editor main menu 2 In the Analysis Setup dialog box which appears click on the Speed Memory button 3 Inthe Analysis Speed Memory Control dialog box which appears select the desired setting Analysis speed memory control dcblock son 12 xi More Accurate Faster Analysis More Memory _ _ Less Memory j J J Mesh Coarse Edge Meshing 41 Sonnet User s Guide There are three settings for the Speed Memory Control Fine Edge Meshing Coarse Edge Mesh Coarse No Edge Meshing Fine Edge Meshing is the default setting and is described in Default Subsectioning of a Polygon page 34 An ex ample is shown below Again note that this setting provides the most accurate an swer but demands the highest memory and processing time The second option is Coarse Edge Mesh This setting is often a good compromise between speed and accuracy When this setting is used the Xmin and Ymin of all polygons are set to a large number typically the value of 50 is used and edge mesh is on Shown below is a typical circuit with this setting Notice the edges of the polygons have small subsections but the inner portions of the polygons have very large subsections because of the large Xmin and Ymin 42 Chapter 3 Subsectioning The last option is Coarse No Edge Meshing For this setting all polygons
105. User s Guide 48 Sonnet s A common misconception is that only one type of metalization is allowed on any given level In fact different metalizations i e different losses can be mixed to gether on any and all levels For example it is possible to have a thin film resistor next to a gold trace on the same level Sonnet allows you to use pre defined metals such as gold and copper using the global library The global library allows you to define your own metal types as well There is also a local metal library which can be created for an individual or to share between users Loss Model The Sonnet model of metal loss uses the concept of surface impedance measured in Ohms sq This concept allows planar EM Simulators such as Sonnet em to model real 3 dimensional metal in two dimensions Real Metal Modeled Zero Thickness Metal Substrate If you are unfamiliar with this concept please refer to any classic textbook such as Fields and Waves in Communication Electronics by Simon Ramo John R Whinnery and Theodore Van Duzer John Wiley amp Sons New York 1965 It is important to note that this technique models the loss of the true 3 dimensional metal fairly accurately but does not model any change in field distribution due to the metal thickness This approximation is valid if the metal thickness is small with respect to the width of the line the separation between lines and the thick ness of th
106. a batch file which runs multiple analyses is shown below em v steps son em v filter son filter eff em v airbridge son filter eff em v airbridge son To execute a batch file on the PC you should create a text file containing the command lines with a bat extension Then open a DOS prompt window and type the filename at the prompt and press return 347 Sonnet User s Guide To execute a batch file on UNIX create a text file containing the command lines The filename does not need any extension Then change the permissions mode of the file to allow you to execute it For example chmod a x lt filename gt where lt filename gt is the name of the batch file you wish to execute Then type the name of the file at the UNIX prompt and press return On UNIX systems there are several additions to the command line which are useful to know Placing nice before the command runs it at lower priority Placing amp at the end of the command runs it in background so you get your cursor back Entering nohup before the command line allows you to log off while the em job s keep running If you are using the amp or the nohup you might want to consider redirecting the output using gt outfile See your system administrator for details on any of these options Causal Dielectrics If you wish to export data from a Sonnet analysis to be used in a time domain tool you may wish to use causa
107. accuracy when using frequency do main data To address these problems Sonnet provides the capability to output your frequen cy domain data into a SPICE compatible file You may choose from three differ ent models depending on your needs This chapter discusses three solutions provided by Sonnet e PI Lumped Element Spice Model e N Coupled Line RLGC matrices e Broadband Spice Model using rational polynomial fit requires a separate Broadband Spice Extractor license The first model is a lumped element fit to the S parameter data For this type of model the circuit often resembles the symbol 7 therefore this type of model is referred to as a PI Model Sonnet creates this type of model when you specify a PI Model output file in the PSpice or Spectre format Analysis gt Output Files in the 309 Sonnet User s Guide project editor or Output gt PI Model File in the response viewer The PI model is only applicable for a narrow band The model that is output is usually one which is intuitive and easily understood by a user as shown below o o Za This figure shows a 2 port model but the PI model may be used for any Zb Ze number of ports O O The second output is an N coupled line Multiple Transmission Line model Son net creates this model when you specify an N Coupled Line Model output file in the Spectre format Analysis gt Output Files in the pr
108. accurate 224 Chapter 14 Circuit Subdivision Subdividing Your Circuit The actual subdividing of your circuit into separate geometry subprojects and a master netlist project is performed by the software You enter the desired names for the master netlist and geometry subprojects You may also automatically add feedlines of lossless metal to any ports generated in the subprojects Feedlines should be added when discontinuities contained in sections of your source circuit need to be moved away from the boxwall to prevent interaction be tween the boxwalls and the discontinuity The use of feedlines are optional if you choose to add a feedline you may use the suggested length calculated by the soft ware or input your own value By default the software creates feedlines using the suggested length When the subdivide is executed Sonnet creates a geometry subproject for each section of the circuit in which you placed the subdividers It also creates a master netlist that connects the geometry subprojects together to produce an equivalent circuit for the original geometry project that you subdivided Each of the geometry subprojects uses the properties of the original circuit cell size dielectric layers dielectric and metal materials analysis setup etc There fore all the geometry subprojects contain the same analysis setup with the same analysis frequencies specified Analyzing Your Subdivided Circuit To obtain the desired res
109. ace Impedance Z for superconductors is modeled in Sonnet using the following equation Z Rocti L Xpc for L gt 0 0 Sense Em solves for the current distribution however on occasion you may want to view the fields not the current You do this with what is called a sense metal The sense metal is a rectangular patch of conductor placed where you want to see the tangential electric field You cannot view the normal direction of the field with Sonnet For further discussion of sense metal see View Tangential Electric Fields under Tips and App notes in Help You may access help by selecting Help gt Contents from any Sonnet application Thick Metal For thick metal you input two parameters the bulk conductivity and the metal thickness The loss is calculated in the same manner as for the Normal metal type except that the thickness in this case represents a physical thickness which elimi nates the need to enter the current ratio For a detailed discussion of thick metal see Chapter 17 Thick Metal on page 260 How to Create a Metal Type For detailed instructions on creating a metal type please refer to metal types add ing in the Index of Help You may access help by selecting Help gt Contents from the main menu of any Sonnet application or by clicking on the Help button in any dialog box 55 Sonnet User s Guide 56 Metal Libraries Via Loss There are two types of me
110. ach conformal section This patented Sonnet capability is unique U S Patent No 6 163 762 issued December 19 2000 An example of a circuit using both standard subsectioning and conformal mesh is shown below The circuit shown at the left is displayed using standard subsection ing staircase fill Conformal meshing for the curved part of the circuit is shown on the right Note that for the curved part of the geometry conformal mesh uses substantially fewer subsections than the number used in the standard subsection ing 45 Sonnet User s Guide 46 Conformal Mesh Subsectioning Control When you apply conformal mesh to a polygon it is possible to limit the maximum length of a conformal section in order to provide a more accurate simulation The default length of a conformal section is 1 20 of the wavelength at the subsection ing frequency For more information on the subsectioning frequency see Defin ing the Subsectioning Frequency page 44 To set the maximum length for a conformal section do the following Select the desired polygon s The selected polygons are highlighted Select Modify gt Metal Properties This opens the Metalization Properties dialog box Click on the Maximum Length checkbox in the Conformal Mesh Subsectioning Controls section of the dialog box This will enable the Length text entry box to the right Note that this checkbox is only enabled when Conformal is chosen as
111. ad Placements of Subdivision Lines This section contains a series of illustrations each showing the good placement of a subdivision line in a circuit and its counterpart showing a bad and in some cases illegal placement of a subdivision line Setting a subdivision line perpendicular to one or more transmission lines provides a good general guideline for line place ment The first example is a pair of coupled lines As explained above when you split coupled lines as on the left very little loss of accuracy results However on the right you have split the coupled pair along the axis where significant interaction takes place The subprojects have no way to account for this coupling and will pro duce bad data SSS Bad 217 Sonnet User s Guide 218 The second example shows how to split a series of resonators In this type of struc ture there is strong coupling at the gaps between adjacent resonators The exam ple on the left is good since the subdivision lines do not prevent this inter resonator coupling The example on the right is incorrect since the resulting sub projects do not contain the inter resonator coupling sl s2 s3 s4 s1 s2 s3 Good Bad The third example shows a square spiral The example on the left is a good place ment since the location where the spiral is divided is essentially a group of coupled transmission lines and the subdivision line is perpendicula
112. ain area of your metal Or you may have chosen a small cell size because you have a small dimension in your circuit but 29 Sonnet User s Guide do not need the accuracy ofa small cell size in larger structures within your circuit In these cases you can change the method by which em combines cells into sub sections This chapter explains how em combines cells into subsections and how you can control this process to obtain an analysis time or the level of accuracy you require There is also a discussion of selecting the cell size and how that may affect the em analysis Conformal Mesh is a special case of subsectioning used to model polygons with long diagonal or curved edges For more information on subsectioning when using conformal mesh see Conformal Mesh Subsectioning page 44 Tips for Selecting A Good Cell Size 30 As you know em subdivides the circuit into subsections which are made up of cells the building block in the project editor The following discussion de scribes how to select a cell size You may also use the Sonnet Cell Size Calculator which allows you to enter important dimensions to calculate the most efficient cell size which provides the required accuracy To access the Cell Size calculator click on the Cell Size Calculator button in the Box Settings dialog box which is invoked when you select Circuit gt Box from the project editor menu TIP Select a cell size that is smaller than 1 20
113. als as you need I Z Examples of this are e Transistor data without parasitics to ground but with a ground path included in the Sonnet structure e A multi pin module with one or more ground pins NOTE The Polygon Edge s ground node connection is only available for Data File type Components Terminal Width The terminal width is the electrical contact width of the Component Entering a terminal width allows you to accurately model the current flow from the circuit geometry into the Component There are three types of terminal width feedline one cell and user defined Each type of terminal width is illustrated and explained below 88 Chapter 6 Components Feedline Width Choosing Feedline Width sets your terminal width to match the length of the poly gon edge to which the Component is attached This option should be used when the polygon edge is about the same size as the width of the Component An exam ple is pictured below Feedline Width Terminal Width Current Flow One Cell One Cell sets your terminal width to the smallest possible size of one cell wide as pictured below One Cell Terminal Width One Cell Current Flow User Defined This option allows you to enter a known electrical contact width An illustration of a Component with User Defined terminal widths is shown below User defined uneni Row Terminal Width 89 Sonnet User s Guide 90
114. alyses are performed on modeled elements To demonstrate the use of modeled elements we will again analyze the T attenu ator However instead of the attenuator being the result of connecting the results of electromagnetic analyses as shown previously in the chapter in this case the geometry project att_lgeo son has the full attenuator with cutouts where the mod eled elements need to be inserted The three resistors will not be analyzed as part of the geometry project but will be inserted as modeled elements in the netlist The figure below shows the circuit layout with the modeled resistor elements A Chapter 13 Netlist Project Analysis geometry project for the transmission line structures are created first A netlist project will then be used to insert the three resistors and calculate two port S pa rameters for the overall circuit To accomplish this task it is necessary to create a geometry project with the trans mission line structure and three holes where modeled elements will eventually be inserted The figure on page 206 shows such a geometry project Here pairs of auto grounded ports have been placed on the edges of each modeled element hole When the modeled elements are inserted later on each is connected across the corresponding pair of auto grounded ports Note that under certain conditions ungrounded internal ports can be used instead of auto grounded ports See Using Ungrounded Internal Ports page 2
115. ameter combinations Each com bination is analyzed at each analysis frequency For example you have two variables the first has seven values and the second has eleven values In that case there would be 77 variable combinations for the anal ysis M Analysis Setup par_dstub son Options Compute Current Density Speed Memory l Memory Save Advanced Analysis Control Parameter Sweep v Parameter Sweeps 2 0 to 10 0 GHz ABS Lstub 120 0 to 260 0 step of 160 0 11 Click on the OK button of the Analysis Setup dialog box This completes the entry of the parameter sweep Next you run the analysis and use the analysis monitor to observe the progress 167 Sonnet User s Guide 168 Executing the Parameter Sweep 12 13 Select Project gt Analyze from the project editor s main menu to invoke the analysis engine em and start the analysis If you are prompted save the file The output window of the analysis monitor appears on your display Click on the Response Data button in the analysis monitor output window This allows you to observe the analysis as it progresses There is a progress bar at the top of the window which shows what percentage of the total analysis is complete with the number of frequencies analyzed appearing above it The response data is output in the bottom of the window The analysis could take a few minutes to run depending on your computer Once the analysis is complete
116. ameter sweep A parameter sweep allows you to run through a set of analyses with different variable values all in one step This allows you to see how changes in your circuit affect the response of your circuit You set up the parameter sweep in the Analysis Setup dialog box in the project editor To access this dialog box select Analysis gt Setup from the main menu of the project editor In the dialog box which appears select Parameter Sweep from the Analysis Control drop list For details on using this dialog box please refer to Help All frequency sweep types are available for a parameter sweep You may allow one or multiple variables to change when running a parameter sweep Sweep modes allow you to control what variable combinations are analyzed for a parameter sweep Sweep modes for a parameter sweep include Linear Sweep Corner Sweep Sensitivity Sweep and Mixed Sweep Combinations e A linear sweep analyzes your circuit at every available combination of variable values e A corner sweep allows you to analyze the extremes of your variables by analyzing at all the combinations of the minimum and maximum Chapter 10 Parameterizing your Project values of the variables as well as at the nominal values This allows you to see how your circuit varies over the data range of your variable For a corner sweep the number of combinations which are analyzed is N N 2 1 where N is the number of combinations and N is
117. ample the spiral conductor shown below contains Manhattan sections in the feed lines and non Manhattan sections in the circular spiral It should be di vided up such that the feedlines are represented by polygons set to staircase fill and the circular spiral is another polygon set to Conformal fill Conformal Staircase Fill The exception to this rule is when relatively small Manhattan polygons are be tween conformal mesh polygons In that case the inefficiency of switching so fre quently between staircase and conformal mesh outweighs the gain of using Manhattan polygons In that case conformal mesh should be applied to all the polygons An example is shown below Normally these polygons would use staircase fill but because they are relatively small areas and in between polygons on which you would use conformal mesh it is more efficient to apply conformal meshing to these Manhattan polygons Chapter 12 Conformal Mesh Boundaries Should Be Vertical or Horizontal For the most efficient results the boundaries between polygons using conformal meshing and rectangular subsectioning should be vertical or horizontal as shown in the first picture below Diagonal boundaries as shown in the second picture make the analysis less efficient Polygon with rectangular subsections Polygon with conformal subsections Vertical Boundary Polygon with rectangular subsections Polygon with conformal subsections Dia
118. anging the value of the variable changes the length of both For a detailed discussion of variables and their definitions please refer to Vari ables on page 130 Chapter 11 Parameter Sweep and Optimization Tutorial Anchored Parameters The linked anchored parameters are input first followed by the symmetric Select Tools gt Add Dimension Parameter gt Add Anchored from the project editor s main menu This places the project editor in Add an Anchored Parameter mode indicated by the change in cursor Note that the message Click Mouse to Specify the Anchor Point appears in the status bar at the bottom of the project editor window As you add a parameter directions for each step appear in the status bar To specify the Anchor point for the parameter click the mouse on the corner of the upper stub as shown in the picture below Anchor Point The anchor point is indicated by a small square which appears at the point you clicked The next step is to select the reference point TIP If you select the wrong point for either the anchor or reference point press the Es cape key to exit without adding a parameter You may then start over Click on the top left end of the top stub to add the reference point Reference Point The reference point is indicated by a small square which appears at the point you clicked In the next step you select the rest of the adjustable point set Points may be se
119. ar waveguide probes 90 The technigue expresses the fields in side the box as a sum of waveguide modes and is thus closely related to the spec tral domain approach The complete theory has been published in detail in peer reviewed journals A full list of relevant papers is presented in Appendix II Sonnet References on page 353 Chapter 2 What s New in Release 12 Chapter 2 What s New in Release 12 This chapter summarizes new capabilities and changes in release 12 of Sonnet If you are not yet familiar with Sonnet you may want to just skim this chapter skip ping any terms that are unfamiliar If you are an experienced user this chapter merits detailed reading Sonnet User s Manuals are only updated with each full release However our Help is also available at our web site and will periodically be updated with new material To access this help go to www sonnetsoftware com support and click on the Knowledge Base link for the most recent updates Sonnet Lite If you are looking for what s new and changed in the Sonnet Lite release please refer to the What s New topic in Help in either the Sonnet task bar or the project editor For what s new in the full release see the sections below 23 Sonnet User s Guide New Features 24 Below is a summation of the major new features in release 12 of Sonnet For changes from release 11 refer to Changes page 27 Multi core CPU Parallel
120. ard is too short Port 1 interacts with port 2 Box Wall gt Metal Box Poor de embedding results may be obtained when very short but non zero reference plane lengths are used e The port is too close to the device under test DUT There are fringing fields associated with the port and separate fringing fields associated with the DUT If the port and DUT are too close the fringing fields interact The de embedding algorithm which is virtually identical to algorithms used in de embedding measured data is based on circuit theory and cannot handle fringing field interaction See reference 66 in Appendix II Sonnet Refer ences for a detailed description of the problem e The first calibration standard is too short In this situation the dis continuity associated with port 1 interacts with the discontinuity associated with port 2 As a result the first calibration standard does not behave like a transmission line and its S parameters are invalid There is no precise rule as to how long a reference plane or calibration standard must be made in order to prevent the above effects from corrupting the de embed ded results The required reference plane or calibration standard length is depen dent upon the circuit geometry and the nature of the analysis However we recommend that you use reference plane or calibration standard lengths equal to or greater than one substrate thickness This is sufficie
121. arious tasks in the process The actual response data is shown in the output window when the Response Data button is pressed Below is the output response data for the filter as it appeared in the analysis monitor Frequency Run 1 Sat Apr 07 15 18 18 2001 Frequency Sweep De embedded 50 Ohm S Params Mag Ang Touchstone Format S11 S21 S12 S22 3 95000000 0 999998 149 22 0 001765 113 1 0 001765 113 1 0 999998 164 55 lt Pl F 3 95 Eeff 2 93154529 0 0 Z0 52 0732019 0 0 R 0 0 C 0 0748436 lt P2 F 3 95 Eeff 2 93105773 0 0 Z0 52 0687952 0 0 R 0 0 C 0 07484847 3 95 GHz De embedded S parameter transmission parameter and port discontinuity results The analysis monitor displays the de embedded S parameter results along with the feed transmission line parameters Eg rand Zp and calculated discontinuity R and C for each de embedded port P1 and P2 stand for port 1 and port 2 respectively A detailed discussion concerning the port discontinuities R and C is presented in the next section De embedding Port Discontinuities 100 All ports in em introduce a discontinuity into the analysis results Sometimes this is desirable For example when analyzing a circuit fabricated with box walls the effects introduced by a box wall port discontinuity are real Under this circum stance the discontinuity should not be removed However in analyses where only the behavior of the DUT is of int
122. at should almost always be followed These guidelines are discussed below De embedding Without Reference Planes 108 De embedding does not require reference planes Reference planes are optional for all box wall co calibrated and auto grounded ports If you do not specify a reference plane for a particular port in the project editor em will assume a zero length reference plane for that port This means that de embedding will remove the discontinuity associated with that particular port but will not shift the refer ence plane for it As discussed in the next section em may generate bad de embedded results if you attempt to remove a very short but greater than zero reference plane However if you de embed without a reference plane em will not attempt to remove any length of transmission line at all As a result de embedding without a reference plane does not lead to any error Therefore we recommend that you de embed without reference planes rather than specify very short non zero reference plane lengths Chapter 8 De embedding Guidelines Reference Plane Length Minimums If the reference plane or calibration standard is very short relative to the substrate thickness or the width of the transmission line em may generate poor de embed ded results This is due to one or both of the following reasons which are illustrat ed below Fringing fields from DUT interact with fringing fields from port First calibration stand
123. aware that analyzing a thick metal of 3 or more sheets at low frequencies may in troduce error into the DC loss To avoid this problem use only 2 sheets for your thick metal when analyzing at very low frequencies 259 Sonnet User s Guide Modeling an Arbitrary Cross Section In this section we use a combination of thick metal and Normal zero thickness metal to approximate thick metal lines where the vertical cross section has an ar bitrary geometry To demonstrate this capability we use a simple trapezoidal ge ometry the cross section shown in the figure below Thick metal polygon placed on top of zero thickness polygon Zero thickness polygon as the wide bottom of the trapezoid A trapezoidal cross section transmission line viewed in perspective If the line has no current going around the edge it can be modeled as shown as two infinitely thin sheets of current one at the top and the other at the bottom of the actual metal To create the thick metal trapezoid set up the dielectrics so that there is one layer of dielectric with the same thickness as the thick metal Then place a polygon rep resenting the wider bottom side of the thick metal on the bottom side of that di electric layer This polygon should use the Normal model for the metal type which is modeled as a zero thickness metal To get the proper loss you should set the thickness of this metal type to one half the total thickness of the metal T
124. ayer There are two methods you may use to do this The first is to de 133 Sonnet User s Guide fine another variable die_thick which you define as 5 sub and the second is to simply enter the equation 5 sub as the thickness of the dielectric layer You may enter an equation in any field in which you may enter a variable CE Xt In this case only one variable Thickness Mat Ere halen Ada mils Name Loss Tan S m Above sub is defined and the equation 5 sub is entered directly in the Dielectric Layers dialog box as the thickness of the dielectric layer The only variable which appears in the Variable List opened using the command Circuit gt Variable List is sub sub v Unnamed fub z Unnamed 1 0 ai Below Edit Delete Library ZParts W Dielectric Layers untitled In this case two variables are Thickness Mat Erel Dielectric Diel Cond defined sub and die thick mils Name Loss Tan S m Above 5 Below The value entered for the 7 aie thick CEES L a variable die_thick is the sub Z Unnamed 10 0 0 0 0 Edit equation 5 sub Both variables appear in the Variable List ere Library 4 TE Z Parts cance Available functions for eguations include Help U Add e Operators such as addition subtraction multiplication etc e Logarithmi
125. based is also output to a file The name of the file appears below the checkbox and may not be changed The file is created in the same directory in which your model file is created Once the creation of the model is completed you may use the response viewer to compare your original response data to the Predicted S Parameter data to evaluate the accuracy of the Broadband model Chapter 21 SPICE Model Synthesis 9 Click on the Create button to create the Broadband Spice model A progress window appears on your display Be aware that the processing time needed to create your models can be significant The processing time is proportional to the number of analysis frequencies times the square of the number of ports in your circuit If you wish to stop the process before it is complete click on the Cancel button in the progress window 10 Once the calculation is complete the Broadband Spice details dialog box appears on your display A log of the creation process appears in this dialog box The log contains information on the error for each parameter which parameter had the greatest error and the filename of the predicted S Parameter data It will also indicate whether the model achieved the error threshold Use this information to determine which parameters to examine in the response viewer You should look at the S parameter with the greatest error as well as any critical S parameters whose error was greater than 0 1 For a detailed exp
126. been calculated the cache data is deleted from the project This setting provides for the circumstance in which the analysis is stopped or interrupt ed before the adaptive data is synthesized you will not lose the internal data pro duced so far Multi Sweep with Stop Restart retains all calculated cache data in your project for every analysis job run In addition cache data is calculated and saved for even non ABS types of sweeps This option can reduce processing time on subsequent ABS analyses of your project but increases project size on non ABS sweeps In Chapter 9 Adaptive Band Synthesis ABS A order for the cache data to remain useful there are also subsectioning issues of which you must be aware For a detailed discussion of the Multi Sweep cache op tion please refer to Multiple ABS Sweeps and Subsectioning page 119 The third setting for ABS caching level is None In this setting cache data is not retained This option should only be selected if you have constraints on disk space WARNING If you select None for the ABS caching level and an ABS sweep is stopped before the adaptive data has been calculated you will have to start the analysis over from the beginning Any processing time invested in the analysis is lost Multiple ABS Sweeps and Subsectioning If you will need to run multiple ABS sweeps on a project it is important to set your ABS caching to Multi sweep to avoid having to re calculate your caching
127. better chance of exciting both X directed and Y directed modes To excite Z directed modes connect a via to the end of the probe Make sure you don t place the probe precisely in the middle of the box wall You want to make sure you excite both even and odd modes 333 Sonnet User s Guide Then create another probe on an adjoining box wall We do this in order to mea sure the coupling between the two probes During a resonant situation the cou pling will increase Sweep the frequency in fine steps and look for resonances You should run the analysis without de embedding since de embedding assumes there are no box resonances which can cause erroneous results When the box resonates there should be stronger coupling between your two probes This can easily be seen by plotting the magnitude of S21 Box Resonances 40 m oc 50 0 X 50 dB so Frequency GHZ The peaks represent box resonances The Box Resonance Estimator 334 The best way to understand the box resonance situation within your package is to use the Box Resonance Estimator BEFORE running an analysis It is recommend ed that this tool be routinely used to prevent wasted simulation time It is an ex tremely useful tool because it allows the user to make modifications to the structure and gauge its impact on box resonances It can also be used after a sim ulation is complete to help determine which characteristics of a comp
128. ble click on 90 0 Degrees to move this value to the Plotted column Values in this column are displayed in the far field viewer 293 Sonnet User s Guide 294 18 Click on the OK command button 19 20 The dialog box disappears and the far field viewer display is updated It should appear similar to the figure below Patvu infpole jxy EERE Plot Over Theta v infpole jxy Gain dB 10 5 4 0 4 Frequency 1 0 GHZ n 5 G a 104 i n 154 Phi 0 0 Degrees O dB 20 90 0 Degrees o 254 304 E Field 354 E Total 40 7 T 1 T T T T T 1 T 1 100 80 60 40 20 0 20 40 60 80 100 Theta Click mouse to readout data values Pointer The plot is drawn showing two curves Epa at phi 0 and 90 degrees The upper curve is the radiation pattern at phi 90 degrees The lower curve is the radiation at phi 0 degrees The far field viewer automatically selects an appropriate scale for the plot Select Graph gt Select gt Phi from the far field viewer main menu The Select Phi s dialog box appears on your display TIP You may also access the Select Phi s dialog box by right clicking in the Phi box in the legend and selecting Select from the pop up menu which appears Double click on 90 0 degrees in the Plotted column to move it from the Plot ted column to the Calculated column This removes 90 0 degrees from the plot Chapter 20 Far Field Viewer Tutorial
129. c Analysis of Shielded Microstrip Circuits IEEE Trans Microwave Theory Tech Vol MTT 35 pp 726 730 Aug 1987 J C Rautio and R F Harrington An Efficient Electromagnetic Analysis of Arbitrary Microstrip Circuits MTT International Microwave Symposium Digest Las Vegas June 1987 pp 295 298 J C Rautio and R F Harrington Results and Experimental Verification of an Electromagnetic Analysis of Microstrip Circuits Trans of The Society for Computer Simulation Vol 4 No 2 pp 125 156 Apr 1987 J C Rautio A Time Harmonic Electromagnetic Analysis of Shielded Microstrip Circuits Ph D Dissertation Syracuse University Syracuse NY 1986 J C Rautio Preliminary Results of a Time Harmonic Electromagnetic Analysis of Shielded Microstrip Circuits ARFTG Conference Digest Baltimore pp 121 134 June 1986 Voted best paper at the conference J C Rautio Techniques for Correcting Scattering Parameter Data of an Imperfectly Terminated Multiport When Measured with a Two Port Network Analyzer IEEE Trans Microwave Theory Tech Vol MTT 31 May 1983 pp 407 412 359 Sonnet User s Guide 91 R Horton B Easter A Gopinath Variation of Microstrip Losses with Thickness of Strip Electronics Letters 26th August 1971 Vol 7 No 17 pp 490 481 92 R F Harrington Time Harmonic Electromagnetic Fields New York McGraw Hill 1961 section 8 11 pg 8 360 Index
130. c Diel Cond add bricks Loss Tan S m foo f ir v E Tn Air A 0 0 0 0 iin SiN 0 0 0 0 AYA BERRA Alumina 0 0 0 0 Edit Remove If the brick type is isotropic only one set of parameters X will be set Conversely if the brick material is set to anisotropic each parameter is defined separately for the X Y and Z dimensions If you wish to make a brick material anisotropic click on the Ani checkbox The default material used when new dielectric bricks are created can also be set in the Brick Materials dialog box Select a brick type from the Default for add bricks drop list Once the default material has been set all bricks created thereafter will be made of that material Changing Brick Materials The material type for bricks that already exist in a circuit can be changed by fol lowing the procedure given below 1 Select the brick s by clicking on it or lassoing it The brick is highlighted 269 Sonnet User s Guide 270 Select Modify gt Brick Materials from the main menu of the project editor This will open the Dielectric Brick attributes dialog box shown below E Brick Properties par dstub son Brick Hn Subsectioning Controls X Min 1 YMin 1 X Max fo Y Max 100 Edge Mesh On z 1 polygon selected Apply Cancel Help Select the brick material you desire from the drop list labeled Brick This drop list contains all the types defined for diele
131. c functions e Complex Math functions e Trigonometric functions e General Mathematical functions such as maximum or minimum e Conversion functions for converting units e Table function to use for data lookup There are also constants available for equations including project constants such as the cell size and box size and the frequency which is discussed more below Chapter 10 Parameterizing your Project For complete details on all the functions and constants available for equations and their syntax please refer to the equation syntax help topics in Help You may ac cess these topics by clicking on the Equation Syntax Help button in the Add Edit Variable dialog box If you enter an equation which uses a variable as the definition of another variable then the variable defined by the equation is dependent on the variable used in the equation This is discussed later in the chapter in Dependent Variables on page 135 Frequency Dependency There is a frequency constant FREQ available for use in Sonnet equations This allows you to model properties whose characteristics are frequency dependent such as a dielectric It is important to be aware that if a variable uses the FREQ constant in its definition that the value of the variable changes during the analysis even if the variable is NOT selected for the parameter sweep or optimization Dependent Variables One variable is dependent upon another if the value of a variable is defined
132. changed the anchor retains the same position but the reference point along with the adjustable point set moves to a new position e Third you select any additional points in your circuit you wish to move when the reference point moves this is the adjustable point set As the value of the dimension parameter is varied the reference point as well as the rest of the adjustable point set is moved accordingly Each of the 144 lt sr SN SI SN arameter Radial Sonnet User s Guide 146 Reference Planes Linking your reference plane to a dimension parameter moves the reference plane in response to a change in the dimension parameter helping to ensure correct placement of your reference plane In order to do this link your reference plane to a point in the adjustable point set for the desired dimension parameter as illustrat ed below In the circuit shown at the top the reference planes are a fixed length When the dimension parameter changes the reference plane lengths do not change resulting in incorrectly placed Link point for the reference planes left reference plane On the bottom the reference planes are linked to points in the adjustable point set When the dimension parameter is changed the reference planes move with it keeping Link point for the the reference planes in right reference plane the correct place Dependent Dimension Parameters One dimensi
133. checkbox or the All Objects radio button Occasionally when a circuit contains many layers with overlapping metal poly gons and dielectric bricks it may be somewhat difficult to distinguish the metal polygons and dielectric bricks from one another The ability to turn dielectric bricks off usually makes it easier to view such circuits Defining Dielectric Brick Materials Just as it is possible to define a variety of metal types each with different proper ties it is also possible to define a variety of dielectric brick materials each with different values for the dielectric constant loss tangent and bulk conductivity Chapter 18 Dielectric Bricks To define a new dielectric brick material or to modify the characteristics of an ex isting material you use the Brick Materials dialog box which is opened by select ing Circuit gt Brick Materials from the main menu of the project editor The Brick Materials dialog box shown on page 269 shows all the dielectric brick materials previously defined the color fill pattern assigned to each brick material and whether the material is isotropic or anisotropic To modify the settings for a particular dielectric brick material edit that materials text entry boxes Note that for anisotropic materials all the parameters do not fit in the dialog box simultaneously so that it is necessary to use the scroll bars to access all settings Brick Materials 2 x Default for Dielectri
134. circuit to move the discontinuities in the subprojects far enough from the boxwalls to pre vent interaction In the case of this example either discontinuities were not present or they were already far enough from the box wall that additional feedlines were unnecessary If you leave the feedlines out by selecting None in the Subprojects Specifications dialog box the netlist analysis runs 1 5X faster than previously The last method that would allow you to decrease the processing time would be to use fewer subprojects in the netlist to create the circuit Observation of the circuit geometry and response data shows that subdivide_net_sl son and subdivide net s5 son are virtually identical The same is true for Chapter 15 Circuit Subdivision Tutorial subdivide_net_s2 son and subdivide_net_s4 son You could edit the main netlist subdivide net son so that you only use three files subdivide_s1 son subidivide_net_s2 son and subdivide net s3 son to create the whole circuit This eliminates the need to calculate data for two out of five subprojects This analysis is 2X faster than the analysis using feedlines and all five subprojects 239 Sonnet User s Guide 240 Chapter 16 Vias and 3 D Structures Chapter 16 Vias and 3 D Structures Introduction Em can handle full 3 D current as well as 2 5 D structures The third Z dimen sion of current is handled by a special kind of subsection called a via The term via co
135. ck a particular data point in an ABS anal ysis and wish to ensure that a full calculation is done at a particular frequency point you should select a Linear Sweep This analysis will calculate caching data if Multi sweep is selected for ABS caching data but will not use the caching data in producing analysis results Find Minimum and Find Maximum Find Minimum determines the frequency where the circuit response reaches a minimum Find Maximum determines the frequency where the circuit response 121 Sonnet User s Guide reaches a maximum You enter a starting and ending frequency in the Start and Stop text entry boxes respectively and select the parameter for which you wish to determine the minimum or maximum value Em performs an ABS analysis for the frequency band then uses the adaptive data to determine the frequency where the response reaches a minimum or a maximum The Find Minimum and Find Maximum commands are both available in the Fre quency Sweep Combinations analysis controls For more details see the Fre quency Sweep Combinations topic in Help in the project editor Parameter Sweep 122 You may choose either a linear sweep or an adaptive sweep for a parameter sweep Selecting an adaptive sweep for a parameter sweep is done in the Parameter Sweep Entry dialog box For more information about parameter sweeps please see Parameter Sweep page 122 The following example assumes that you have already defined
136. cks see dielectric bricks broadband spice 319 checking accuracy of model 323 class of problems 320 creating a model 321 improving accuracy of model 326 stability factor 327 C Cadence Virtuoso Interface 17 310 CAE software 22 calculate 281 290 calculating the response 290 Calculation Setup dialog box 290 calculations defaults 289 status of 292 calibration lengths 107 for co calibrated internal ports 74 for Components 91 capacitor 85 capacitors 197 265 cartesian plot 273 280 283 290 303 cascading data files 197 200 causal dielectrics 348 cell size 29 266 determining error 342 processing time 193 selecting 30 32 subsectioning 29 38 wavelength 30 circuit analyses 197 199 circuit properties 223 circuit subdivision 211 225 additional improvements 237 analysis 225 coarse frequency sweep 224 comparison of results 237 executing 225 233 feedlines 234 illegal conditions for subdivision lines 222 main netlist 214 placement of subdivision lines 216 220 procedure 214 362 reference planes 234 subdivision line orientation 221 subproject naming conventions 234 tutorial 227 239 using parameters 215 Circuit Subdivision dialog box 233 circular dependencies 135 147 CKT 203 coarse frequency sweep 224 coaxial structures 281 co calibrated internal ports 70 75 adding 74 calibration lengths 74 de embedding coupling 70 GLG metal 71 ground node connection 70 reference planes 74 terminal width 73 use in Compon
137. click on the Help button on the Keyboard dialog box New Stability Factor for Broadband Spice Extraction A new stability factor has been added to the Broadband Spice Extractor feature which forces the poles of your model to be stable For more information see Broadband Spice Extractor Stability Factor on page 327 New Append Feature for the DXF and GDSII Translators You may now im port a DXF or GDSII file into an existing project and add the translated objects to your existing geometry This feature enables you build up a Sonnet project from two or more separate DXF or GDSII files For information about the DXF and GDSII translators see the Translators Manual available in PDF format by select ing Help gt Manuals from any Sonnet Application Information about the Append feature is available in Help Hover Over A new feature in the project editor displays information about ob jects in your geometry when the cursor is placed over them This feature is off by default If you wish to turn this on select View Info Hover Over in the project editor menu X axis Logarithmic Scale A new feature in the response viewer allows you to apply a logarithmic scale to the x axis of your plots For details please refer to Help for the Axis Setup dialog box This dialog box is opened when you select the command Graph gt Set Axes from the response viewer main menu Parameters in Current Density Viewer and Far Field Viewer There is new functionali
138. croll bar 293 second reference point 140 sections 213 select phi 294 304 theta 303 305 select dependents 147 Select Freguencies dialog box 292 Select Normalization dialog box 298 Select Phi s dialog box 293 304 selecting the response 292 sense metal type 55 Sensitivity Sweep 25 sensitivity sweep 148 series RL eguivalent circuit 71 shunt elements 71 86 SMD 81 Sonnet suite 15 369 Sonnet User s Guide Sonnet Lite 23 space bar 295 S parameter data importing 81 S Parameters ripple in 126 Spectre 17 310 spherical coordinate system 282 spiral inductors 241 stability factor 327 steps 198 steradian 285 Stop Restart caching 118 stripline benchmark 339 sub_whole 237 subdivide 228 Subdivide Circuit command 233 Subdivider Orientation dialog box 229 subdividing 225 subdivision 211 225 procedure 214 subdivision lines 213 adding 228 coupling across 212 illegal conditions 222 orientation 221 229 placement 212 216 223 placement examples 217 Subproject Specifications dialog box 234 subprojects 213 naming conventions 234 subs lambda 43 subsectional vias 245 subsectioning 20 ABS caching level 119 cell size 29 38 frequency 119 subsections 29 43 of polygon 34 vias 245 XMIN 39 YMIN 37 superconductor 53 surface impedance 55 surface impedance 55 370 surface plot 273 280 283 305 selecting 306 surface reactance 53 surface resistance 58 surface wave antennas 281 sweep corner 148 linear 148 mixed combina
139. ctric bricks including the default type air Click on the OK button to apply your selection and close the dialog box Z Partitioning A dielectric brick simulates a volume of dielectric material Because a brick sim ulates a volume it must be subsectioned in the X Y and Z dimensions The more subsections finer resolution used in each dimension the more accurate the anal ysis X Y subsectioning of dielectric bricks is identical to X Y subsectioning of metal polygons You can control the X Y subsectioning of both through your choice of grid size XMIN YMIN XMAX YMAX and subsections per lambda Z subsectioning of dielectric bricks is controlled by the Z Partitions dialog box which is opened when you click on the Z Parts button in the Dielectric Layers di alog box Circuit gt Dielectric Layers You may enter a Z Parts value for each dielectric layer in your circuit This parameter specifies the number of Z partitions for all dielectric bricks on a particular circuit layer The default for this parameter is zero so that you are forced to enter a value for this field If you use a dielectric brick in a layer and do not set the z partitions em re ports an error and exits the analysis You must enter a non zero integer value for this parameter in order to run an analysis The value of this parameter is highly Chapter 18 Dielectric Bricks dependent on your circuit design therefore Sonnet cannot determine a reason able
140. d even mode or push push ports and have 65 Sonnet User s Guide 66 many uses including simulating the even mode response of a circuit See Mod eling an Arbitrary Cross Section page 260 for an example of using push push ports Ports with identical port numbers are electrically connected together Ports with Negative Numbers Ports may also have negative numbers as shown in the figure below This feature can be used to redefine ground Strictly speaking em sums the total current going into all the positive ports with the same port number and sets that equal to the total current going out of all the ports with that same negative port number For exam ple for a circuit with a 1 port and a 1 port em sets current flowing into port 1 to be equal to the current flowing out of port 1 Thus they are sometimes called balanced push pull or odd mode ports Coplanar lines can be represented with balanced ports See below for an example of push pull ports o a SARA Emmaa PAN ES N X K RKI er lt XK AN 7 Mxx xx xxzx4 OOGOCOF POS RS ewww S An example of a coplanar waveguide cross junction S SKERRY RRR E esse 280 SRI lt N AA Nono 0 IOA pe a X K KKAKKK n ZEIZ ORO arate oen SEES poke 13 ALS an R T lt Ree Ports are required to be in sequential order with no numbers missing If the ports are not in seque
141. d Both eguations are eguivalent Each describes how em uses the input dielectric pa rameters to compute loss in the dielectric material See Circuit gt Dielectric Layers in the project editor s Help for information on setting these parameters How to Create a New Dielectric Layer For detailed instructions on creating a new dielectric layer please refer to dielec tric layers adding in the Index of Help You may access help by selecting Help gt Contents from the main menu of any Sonnet application or by clicking on the Help button in any dialog box Dielectric Libraries NOTE The dielectric libraries contain standard definitions of dielectric materials which may be used for your dielectric layers There are two types of dielectric libraries available in Sonnet global and local There is no real difference between the two libraries The names refer to the way in which they are used The Dielectric Libraries materials may not be used for dielectric bricks but only for dielectric layers 59 Sonnet User s Guide 60 The global library would usually be used as a group wide library of standard di electrics for a group of designers There is a default global library supplied by Son net which contains definitions for dielectric materials The default location for the global library is in lt Sonnet Directory gt data library where lt Sonnet Directory gt is the directory in which your Sonnet software is install
142. d at 990 mils from the left box wall Move the cursor until the X coordinate is 990 0 in the status bar and click to place the second subdivision line The subdivision line appears on your circuit and the sections are relabeled as shown below s2 ALLLLLLLLELLLLLLLA a a a AAA AA APA A C2222 277 7277277 Z7Z AZZ Chapter 15 Circuit Subdivision Tutorial 7 Add subdividers at 1585 mils and 2180 mils from the left box wall Once you have completed adding all the subdivision lines press the Escape key to return to pointer mode Your circuit should now appear like this sl s2 s3 s4 s5 Setting Up Circuit Properties For this example the circuit properties such as box size dielectric layers metal materials etc have already been input in the example circuit It is important to have the circuit properties input before performing the subdivide since these are the properties used for all the subprojects created as the result of the subdivide If you do not enter all the desired properties you will need to enter them individually in each subproject or modify the original source project and execute the subdivide again For this example you will analyze the netlist using an adaptive sweep ABS with Hierarchy Sweep turned on When the Hierarchy Sweep option is used the anal ysis control settings for the netlist are used to analyze all the subprojects in the netlist The desired freguency band for the circuit is 2 3 GHz to 2 5
143. d to correct the problem before proceed ing You need to redefine one of the variables such that it is no longer dependent on the other A correction of the example would be A 2 B and B sin C Dimension Parameters 136 A dimension parameter allows you to identify dimensions in a geometry project and assign a variable to the dimension which allows you to vary those dimensions within an analysis The initial value of the dimension parameter is the length that appears in your circuit This is the nominal value of the variable assigned to the dimension parameter If you change the nominal value of the variable then the cir cuit is redrawn with that length Anchored Dimension Parameter There are three types of dimension parameters anchored symmetric and radial For brevity we refer to anchored dimension parameters as anchored parameters symmetric dimension parameters as symmetric parameters and radial dimension parameters as radial parameters for the remainder of this discussion An anchored parameter allows you to fix one end of a parameter then vary its length extending from that point A symmetric parameter allows you to fix the center point of a di mension parameter and vary the distance it extends on each side A radial param eter allows you to fix one end of a parameter then radiate out from that fixed point Chapter 10 Parameterizing your Project the direction is not restricted to the x or y direction but may extend
144. d values for the loss parameters Creating Metal Types To assign loss to a polygon in Sonnet you first define a metal type by inputting its loss parameters and then assign that metal type to the polygon drawn in your circuit The previous section s described how to determine values for the Sonnet loss model This section provides instructions for creating a metal type and dis cusses the loss models used in the Metal Editor dialog box The Metal Editor dialog box allows you to enter a loss definition for the metal type There are five different methods for entering loss Normal Resistor Rd Ref General and Sense The different loss models are discussed below followed with a procedure for entering new metal types The discussions assume simple single conductor microstrip and stripline geometries where mentioned You do not need to read the details of each loss model Instead you should make yourself familiar with the loss models you are likely to use Most users only need concem themselves with Normal All the methods use the same loss model in Sonnet which model you choose depends on the parameters you know about your real metal type Normal For the Normal metal type you determine the loss using the bulk conductivity the metal thickness and the current ratio Chapter 4 Metalization and Dielectric Layer Loss NOTE Metal thickness is used only in calculating loss it does not change the physical thickness of metalizat
145. dding algorithms share It is unable to de embed a struc ture contained inside a resonant cavity box This means that if a box resonance exists for a de embedding calibration standard the final S parameters will be sus pect Below is an S parameter S21 curve for the example project package son No tice that at 31 76 GHz there is a sharp change in the data and it approaches unity This indicates a strong package resonance induced coupling between the input and output at this frequency package son DB S21 mace 350 59 g 1 No O 1 31 7 31 71 31 72 31 73 31 74 31 75 31 76 31 77 31 78 31 79 318 Sonnet Software Inc Freguency GHz Results of a search for package resonances shows strong coupling between input and output at 31 7625 GHz 332 Chapter 22 Package Resonances A Box Resonance Example This example describes how to create a simple geometry file you can use to deter mine box resonance frequencies before you fabricate the wrong enclosure Errors of less than 0 1 can be achieved with no limit on the number of dielectric layers used The basic idea is to re create the box parameters of your real circuit using the same substrate size dielectric layers etc but without the metalization Once the box parameter setup is complete you should create a small probe which is used to excite the modes This is just a small less than 1 8 wavelength open stub with a port on it If you bend the stub you have a
146. ddition it is not a very good filter design This circuit was chosen for the purposes of clarity in explaining cir cuit subdivision You will use four vertical subdivision lines to split the circuit into five sections as shown below 227 Sonnet User s Guide Obtaining the Example File You use the example file subdivide son for this example You can obtain a copy of this file from the Sonnet Examples If you do not know how to obtain a Sonnet example select Help gt Examples from any program menu then click on the In structions button If you are reading this in PDF format click on the link above Open the project subdivide son in the project editor The circuit appears as shown below T subdivide son DER al 41818 LARREA SS Click or drag to selectobje 1 0x 1320 684 0 mils Pointer Adding the Subdivision Lines 228 The first step in subdividing a circuit as discussed in Choosing Subdivision Line Placement on page 216 is to place the subdivision lines that indicate where you wish to split your circuit Subdivision lines should be placed in locations where there is negligible coupling across the lines The best place to put subdivision lines in the example used here is at points in the circuit on the coupled lines as far from the discontinuities as possible Therefore a vertical subdivision line will be placed in the middle of each coupled pair of polygons Each coupled pair of pol
147. de 3 of the network Node 3 of the network is Port 2 of the network RESNET 201 Sonnet User s Guide The S Parameters for an analysis of the netlist are shown below Frequency 200 MHz 50 0hm S Params Mag Ang Touchstone Format S11 S21 S12 S22 200 000000 0 250782 5 309 0 748778 6 263 0 748778 6 263 0 250782 5 309 Frequency 300 MHz 50 Ohm S Params Mag Ang Touchstone Format S11 S21 S12 22 300 000000 0 250310 7 963 0 748702 9 395 0 748702 9 395 0 250310 7 963 Frequency 400 MHz 50 Ohm S Params Mag Ang Touchstone Format S11 S21 S12 S22 400 000000 0 249650 10 62 0 748595 12 53 0 748595 12 53 0 249650 10 62 A Network File with Geometry Project The next example demonstrates a netlist project analysis which invokes a geome try project analysis in conjunction with using previously generated data To demonstrate a netlist with a geometry project the two port T attenuator shown below will be analyzed S parameter S parameter Node 3 file att_res16 s2p7 file att res16 s2p geometry project att res67 son The two port T attenuator will be analyzed with em to demonstrate a combined electromagnetic circuit analysis 202 Chapter 13 Netlist Project Analysis Pictured below is the geometry project att_res67 son which is a 67 ohm thin film resistor This project is read by em and analyzed during the netlist analysis The results of the pro
148. de simulator of that infinite array just by setting the top cover impedance to the impedance of the ex cited waveguide mode Modeling an Open Environment If we can use a closed i e terminated waveguide to model an infinite array we can also model radiation from a finite array although it must be done under cer tain conditions It is important to keep in mind that unless the analysis is carefully prepared these conditions are easily violated yielding incorrect results When the conditions are met useful results can be obtained as shall be demonstrated 275 Sonnet User s Guide 276 First Condition Make both of the lateral substrate dimensions greater than one or two wavelengths When using the Open Waveguide Simulator we view the sidewalls of the shield ing box as forming a waveguide whose tube extends in the vertical direction prop agating energy from the antenna toward the Termination as shown on page 275 Radiation is then approximated as a sum of many waveguide modes If the tube is too small there are few if any propagating modes violating the First Condition There is an easily made mistake when modeling radiation from small discontinu ities Discontinuities are usually small with respect to wavelength For a disconti nuity analysis the sidewalls are usually placed one or two substrate thicknesses from the discontinuity In this case the substrate dimensions are unlikely to meet the First Conditio
149. depicts a via going from the single metalization level to ground The same via is shown in the top of the figure as it appears in the project editor The rectangular via is subsectioned into via posts which are rectangular cylinders of current extending between level 0 and the ground plane A via post has a horizontal cross sectional area equal to one cell and a height egual to the thickness of the dielectric layer The via polygon is made up of a single cell wide fence which forms the border of the polygon The center of the via polygon does not contain metal it is filled with the dielectric material used in the dielectric layer If you change the cell size then the via is resubsectioned into via posts with the new cell size 247 Sonnet User s Guide If the via to ground is added when there are multiple intervening metal levels be tween the present level and ground the via polygon can be seen on each level The intervening levels have via arrows pointing in both directions to indicate that the via extends both upward and downward Below is shown a rectangular via poly gon extending from metal level 0 to ground in a three level circuit Level 1 Level 2 Gnd The via shown above extends from level 0 the highest metal level in the circuit down to the ground level The via arrows on the rectangular via on level 0 point only in the downward direction The via polygon appears on levels 1 and 2 in the sam
150. design was stated as a stopband between 5 0 and 6 0 GHz By looking at the graph of Lstub 120 as compared to Lstub 280 you can see that a filter with the required stopband would fall approximately in the middle of the two curves So a value of 220 mils is chosen for the nominal value for Lstub for the optimization A nominal value of 220 mils is chosen for Sstub Optimization 172 This next section of the tutorial shows how to set up and execute an optimization For a detailed discussion of optimization please refer to Optimization on page 172 If par_dstub son is not still open in the project editor open the file in the project editor Chapter 11 Parameter Sweep and Optimization Tutorial Entering New Nominal Values Usually for this type of circuit you would optimize using both of the defined pa rameters Lstub and Sstub but for the sake of processing time the optimization only uses one parameter Lstub The nominal value used for Sstub will be 220 mils This was arrived at by actually executing the optimization using both parameters and using the closest value on the grid of the optimized parameter 26 Double click on the parameter Sstub in the circuit The Parameter Properties dialog box for Sstub appears on your display 27 Change the nominal value in the Nominal text entry box to 200 28 Click on the OK button to close the dialog box and apply the new nominal value The circuit is redrawn using the new nomina
151. dots in the project editor screen The small dots are placed at the corners of a cell One or more cells are automatically combined together to create subsections Cells may be square or rectangular any aspect ratio but must be the same over your entire circuit The cell size is specified in the project editor in the Box Settings di alog box which is opened by selecting Circuit gt Box The analysis solves for the current on each subsection Since multiple cells are combined together into a sin gle subsection the number of subsections is usually considerably smaller than the number of cells This is important because the analysis solves an N x N matrix where N is the number of subsections A small reduction in the value of N results in a large reduction in analysis time and memory Care must be taken in combining the cells into subsections so that accuracy is not sacrificed Em automatically places small subsections in critical areas where cur rent density is changing rapidly but allows larger subsections in less critical areas where current density is smooth or changing slowly However in some cases you may wish to modify the automatic algorithm because you want a faster less accurate solution or a slower more accurate solution than is provided by the automatic algorithm Also in some cases you may have knowl edge about your circuit that the software does not For example you may know that there is very little current on a cert
152. ds pF The inductive and capacitive parts modify only the reactive portion of the load they are included so you do not have to man ually re calculate the reactive part at each frequency R jX E Eguivalent circuit of an em port The normalizing impedances are ignored if Y or Z parameters are specified for output Y and Z parameters are always normalized to one ohm This capability should be used only by the most advanced user This feature should never be applied to data which is to be used in a standard circuit theory pro gram other than Sonnet s Many programs assume S parameters normalized to ex actly 50 ohms S parameters normalized to another value would introduce error into the analysis Changing Port Impedance 64 There are two methods for changing the impedance of a port If you wish to change the impedance of a given port and do not need to see the impedance values of other ports take the following steps using the project editor 1 Select the desired port s This will enable the Modify menu option 2 Select Modify gt Port Properties to open the Port Properties dialog box 3 The impedance values can be changed by typing the desired values in the Resistance Reactance Inductance and Capacitance text boxes in the dialog box This changes the parameters on all ports selected and all ports with the same number as the ports selected Chapter 5 Ports If you wish to change the impedance of a given port and wis
153. e length of 5 degrees However em has some smarts built in If a non physical re sult is seen em increases the calculated phase length by 360 degrees at a time until physical i e Er gt 1 0 results are obtained This usually corrects the problem Thus it takes a particularly long reference plane or calibration standard before the E ogg calculation fails When it does fail it suddenly jumps down to a value just above 1 0 Zo and the de embedded S parameter data still have full validity This failure mode is rarely seen Non Physical S Parameters Generally reference planes should not be set in the project editor such that they extend beyond a discontinuity in the circuit Doing so may result in non physical S parameters 110 Chapter 8 De embedding Guidelines To illustrate this problem consider the circuit shown below In this circuit the ref erence planes do not extend beyond any discontinuities When de embedding is enabled the port 1 discontinuity is removed along with a transmission line of width W1 and length L1 Similarly the port 2 discontinuity is removed along with a transmission line of width W2 and length L2 The de embedded result is a set of 2 port S parameters for the block in the middle of the circuit Now consider the figure on page 112 This circuit is identical to the circuit shown above except that the length of the reference plane originating on the left box wall has been increa
154. e Parameter Properties Variable dialog box in which you select the Name Width moving option from the drop list shown to the left This dialog box Nominal 15 0 x appears when you are entering a dimension parameter or when you Move points the same distance v select the command Modify F Move points the same distance Parameter Properties when a Scale points in one direction dimension parameter is selected Scale points in X and Y 0W WO a Moving option drop list Evaluate Equations Apply Cancel Help Move Points the Same Distance This setting moves the adjustable point set the same distance as the reference point is moved and all the points in the adjust able point set maintain their relative position This is the default setting An exam ple using an anchored dimension parameter is shown below Note that the adjustable point sets are highlighted The anchored dimension parameter is increased by 10 mils so each point in the adjustable point set is moved away from the anchor point by 10 mils As shown in the illustration the original distance from the anchor to the circled point was 40 mils when the value of the parameter is increased the point was moved by 10 mils so that it is now 50 mils away from the anchor point Chapter 10 Parameterizing your Project Scale Points in one direction When using this setting the geometry con trolled by the parameter is scaled or stretched along either the x or y
155. e Sonnet loss model The effect is small but potentially significant in certain cases Keep in mind that a circuit running with lossless metal and dielectrics requires about one half the amount of memory and runs about twice as fast Therefore the simplest approximation is to run a lossless simulation This can be quite useful in the initial design phase Problems In Determining Metal Loss Sonnet s loss model is very accurate if accurate values are used In practice how ever there are many aspects of metal loss that cannot easily be accounted for For example surface roughness metal purity metal porosity etc cannot easily be measured and included in an all encompassing loss model In addition most soft ware programs Sonnet included do not allow you to enter all of the parameters that determine metal loss Many users like to use the ideal values as a starting point and add a little of their own real world loss But how much should be added to the ideal models This question is not easily answered but is addressed in the next section An additional loss problem exists with planar EM analysis tools such as Sonnet The problem stems from the fact that planar EM tools treat the metal conductor as zero thickness This means that there is no difference between the top of the con ductor and the bottom of the conductor In some circuits stripline for example the current is symmetrical with half of the current flowing on the top of th
156. e circuit In this chapter we will outline several ways to detect package resonances within the Sonnet simulation based on an example project As you will see this is a great way to prove a package design early in the design cycle We will also outline the use of the Box Resonance Estimator and give some advice as to how to remove box resonances from a structure 329 Sonnet User s Guide To obtain the example file package son used in this chapter get the example folder Package_resonances from the Sonnet examples For directions on obtaining a Sonnet example select Help gt Examples from the menu of any Sonnet pro gram then click on the Instructions button The file package son is a model of an amplifier used to check for package resonances The entire width of the box is not shown Box Resonances The purpose of this section is to give the user a basic understanding of how to de tect box resonances in a Sonnet project or simulated data There are three ways to do so 1 Runtime warning messages 2 Observations of simulated results 3 The Box Resonance Estimator Runtime Warning Messages If the proper selection is made during the analysis setup Sonnet will detect box resonances and output warning messages in the analysis monitor while the simu lation is being performed The steps to enable this feature are 1 Select Analysis gt Setup from the project editor menu 330 Chapter 22 Package Resonanc
157. e conductor and half flowing on the bottom of the conductor The zero thickness model works well in these cases In other circuits such as microstrip the current can be unequally distributed re sulting in higher loss than the equivalent stripline circuit If you know the ratio be tween the top and the bottom currents you can obtain a better loss model All planar solvers must either estimate this value in order to calculate metal loss or the information must be input by the user For this class of circuits it is difficult for the user to know an exact value of the current ratio without obtaining measured data on the circuit For these cases assuming all the current flows on one side of 49 Sonnet User s Guide 50 the conductor gives a worst case loss result This tends to compensate for the best case loss caused by ignoring the other aspects of loss metal porosity etc mentioned earlier Determining Good Input Values The best method to determine proper loss values is to build and measure a simple structure of the desired metalization The structure should be sensitive enough to loss so that measurement errors do not significantly affect the results Then ana lyze the same structure on Sonnet and adjust the loss values until the calculated loss matches the measured loss This may take several iterations before success but then you can use these values for similar circuits You are now effectively us ing measure
158. e design features have been optimized is to add an absorbing material in the housing cavity The material is normally iron or carbon loaded so it can provide a fairly high magnetic or electric loss tangent It comes in various forms such as liquid or sheet and is usually placed at a position such that it has a minimal effect on the circuit performance and a great effect on the box resonance The user can easily model this material in Sonnet by adding a dielectric layer to the stackup 338 Chapter 23 Accuracy Benchmarking Chapter 23 Accuracy Benchmarking Electromagnetic analyses are often described as providing what is called Good Agreement Between Measured And Calculated GABMAC However in the past there has been little effort to decide just what good means The more useful result is the Difference Between Measured And Calculated DMAC There is an example of a coupled stripline benchmark available in Help under Ap plications An Exact Benchmark What we need to calculate DMAC is an exact benchmark One source of an exact benchmark is stripline The characteristic impedance of a stripline has an exact theoretical expression K k and is the complete elliptical integral of the first kind 339 Sonnet User s Guide For evaluation on a computer a polynomial for K k is available in Abramowitz and Stegun Handbook of Mathematical Functions pp 590 592 Be sure to note the errata ml 1 m2 not 1
159. e dielectric If the true 3 dimensional affect of the metal is important then you should consider using the Thick Metal Model metal type as discussed in Chapter 17 Thick Metal on page 253 Some electromagnetic analyses use a perturbational approach for loss This means that they assume the current flowing everywhere is the same as the lossless case This approximation works for low loss metals good conductors However for thin film resistors high loss the lossless current is not the same as the lossy current and a perturbational approach fails Em s loss analysis is not perturbation al It works just as well for a 100 Ohms square resistor as it does for a 0 004 Ohms square good conductor The Sonnet loss analysis also properly models the transi tion between electrically thin low frequency and electrically thick high frequen Chapter 4 Metalization and Dielectric Layer Loss cy conductors See reference 24 in reference Appendix II listed on page 353 for a detailed description of the theory used by Sonnet See reference 91 listed on page 360 for the equations actually used in the Sonnet model Another aspect of loss is that the surface impedance of a good conductor has an imaginary part which is equal to the real part This reactive surface impedance is physically due to the increased surface inductance caused by the current being confined closer to the surface of the conductor This surface reactance is included in th
160. e eee ee ee ee e 76 Automatic Grounded Ports 76 Special Considerations for Auto Grounded Ports 77 Adding Auto grounded Ports 0088 78 Ref Plane and Cal Length for Autogrounded Ports 78 Ungrounded Internal Ports 2250000 78 6 COMPONENTS tux i sie oas ey hws diate eae aie Ala te 81 IMEFOCUCLION ee e e taiten sata Tha TL Dupre Sod Sb ee mae ae a 81 Component Assistant onn ee ee eee 82 7 8 Table of Contents Anatomy of aComponent 20020 ee eee 82 Component Types samaan 84 Data FIle mme aa ena a Soin a Beat arte de Dodd ail vei ina 84 Ideal Component soks KNN 85 PoS OMY iii e5 225 nd Amala eran Goats Modan j 20 EIR Gs See Ars 85 Component Properties kokak a eee eee eee 85 Ground Node Connection 020 005 86 Terminal Width lesken 88 Reference Planes 1 2 2 ee eee ee ee ee eens 91 Calibration Lengths lt loss 2002020 91 Physical SiE ananas echoed ee SA ek ANAR oie R k 92 Rules for Using Components 20020 eee 92 Analysis of aComponent knn 95 Data File Frequencies 02 eee eee 95 Rerunning an Analysis 0000 eee eee 95 DE EMBEDDING s sii deg a stupa Dareia re ana a eer aad alt 97 Enabling the De embedding Algorithm 98 De embedding Port Discontinuities 100 Box Wall Ports look eee eee eee eee 101 Shifting Reference Planes 00 20 eee
161. e of its importance In general any surface wave is both reflected and refracted when it encounters the edge of the substrate This boundary condition is different from either the conduct ing wall of Sonnet or the infinite substrate provided by a true open space analysis 277 Sonnet User s Guide A dual patch antenna is illustrated conceptually below Free Space Top Cover Double Patch Antenna Feed point Radiation can be simulated by including a lossy top cover a lossy dielectric layer optional and by placing the sidewalls far from the radiator drawing not to scale Place the top cover one half wavelengths from the radiator The feed point is created in the project editor by creating a via to ground at the feed point Then the ground end of that via is specified as a port just as one would specify a more typical port on the edge of the substrate at a box sidewall A file showing an antenna similar to this one is named dual_patch son and is available in the Sonnet examples 278 Chapter 19 Antennas and Radiation Validation Example For validation we offer work performed by E Ongareau of Matra Defense An tennas amp Stealthness Dept France as presented at the 1993 EEsof User s Group meeting at HYPER in Paris Reprinted with permission The antenna is a triple patch structure with a top view shown below The antenna is a test realization in tended only for validation
162. e position but with via arrows pointing in both the upward and downward po sition indicating that the via extends in both directions from these levels Only the outline of the via polygon is drawn on the ground plane to indicate its position with the via arrows pointing upward indicating that the via extends upward Since the complete ground plane is metalization the via polygon is drawn simply as a reference for the user Note that the center of the via polygon is not metalization but is a rectangular cylinder of dielectric material Multi layer Vias 248 It is possible to have a via which traverses more than one dielectric layer You may insert a via in your circuit originating on any level and ending on any level The via is automatically drawn on each level it traverses To create a multi layer via Chapter 16 Vias and 3 D Structures first create a via in your circuit then modify its properties For example you have a four level circuit with an existing via polygon which extends from level 1 to lev el 0 as shown below Level 0 Level 1 Level 2 If you want to modify this via such that it extends from level 0 to level 2 you would do the following 1 Right click on the via polygon on any level on which it appears A pop up menu appears on your display 2 Select Properties from the pop up menu The Via Properties dialog box appears on your display Via Properties multi layer son 2 x Via Levels Via Metal From Le
163. e resonances 329 338 par_dstub 155 Parameter Properties dialog box 158 parameter sweep 122 148 155 analysis frequencies 165 data 179 setting up 165 viewing the response 168 Parameter Sweep Entry dialog box 165 parameterization 129 154 tutorial 155 parameters adding 157 161 adjustable point set 138 139 140 144 adjusting point set 142 anchor point 138 144 anchored 136 137 circular dependencies 135 147 data range for optimization 175 example 155 first reference point 161 in a subproject 215 nominal value 136 137 173 ports 65 67 radial 136 144 reference planes 146 reference point 138 144 second reference point 162 select dependents 147 selecting for optimization 174 symmetric 136 139 patch antenna 273 patch antennas 281 pattern 280 288 368 pattern response 296 patvu 17 phased arrays 273 phi 282 283 default values 289 selecting values to plot 293 294 304 specifying range for calculation 283 291 physical size of Component 84 pin number 83 plot cartesian 273 280 283 290 303 frequency 303 polar 273 280 283 299 probing 296 selecting type 299 surface 273 280 283 305 title area 299 types 283 Plot Over drop list 303 polar 283 299 polar plot 273 280 polarization 286 default 290 polygon edges 217 polygon overlap 189 Port Impedance dialog box 65 ports 61 79 auto grounded 76 77 78 205 balanced 66 box wall 69 101 103 co calibrated internal 70 component 83 discontinuitie
164. ed You may choose to use this location or can save this library in another location The local library would usually be used as the user s own library of dielectric ma terial definitions This library may be stored in a location of the user s choice You use the Dielectric Editor dialog box to add edit and delete entries to these librar ies Chapter 5 Ports Chapter 5 Ports This chapter describes the five different types of ports used in Sonnet how they are modeled and how to place or delete them in your circuit The five types of ports used in Sonnet are the standard box wall port the co cali brated internal port the via port the auto grounded port and the ungrounded in ternal port Port Type Overview As mentioned above the five types of ports available in Sonnet are the standard box wall co calibrated internal port via port autogrounded port and internal un grounded port All ports in Sonnet are two terminal devices The box wall and co calibrated port types are those used the majority of the time Each type of port is described below Box wall e Most common type of port e Positive terminal is attached to a metal polygon and the negative terminal is attached to the box wall ground e De embedding is the most accurate for this type e Used for connections to the periphery of your geometry 61 Sonnet User s Guide 62 Reference planes may be used For more information on box wall ports
165. ed isotropically 297 Sonnet User s Guide 298 We shall now normalize the plot to the maximum value 27 Select Graph gt Normalization to change the normalization 28 29 The Select Normalization dialog box appears on your display E Select Normalization infpole son EI Gain dB C PowerJEMC Relative To isotropic v Reference Value 5 dB Cancel Help Select Max from the Relative To drop list This selects the maximum value of radiation for the plot to be the 0 dB point of the plot Click on the OK command button The dialog box is closed and the display is updated with the data normalized to the maximum value which in this case is 5 6026 dB infpole son DER Ja Re E Piot over fne infpole son Gain dB Relative To 5 6026 dB Frequency GHz 1 0 GHZ Phi 0 0 Degrees 00 80 60 40 20 0 20 40 60 80 100 Theta 1 0GHZ Theta 45 0 Phi 0 0 0 96019 dB Pointer Chapter 20 Far Field Viewer Tutorial Changing to a Polar Plot 30 Select Graph gt Type gt Polar to select a polar plot for the display A polar plot is chosen since the theoretical data for an infinitesimal dipole is shown in a polar plot The display is updated using the polar coordinate system Phi is held constant and theta is swept infpole son 13 AJA 522 29 Plot over Theta E infpole son Gain dB Relative To 5 6026 dB Phi 0 0 D
166. ed to analyze the circuit as a whole be cause this was a simple example chosen for clarity and the benefits of circuit sub division are only seen for larger circuits Using circuit subdivision reduces your memory reguirements for analysis of a large circuit Each of the subprojects reguires less subsections to analyze than the complete circuit This improvement comes as a result of reducing the number of subsections for any given analysis since both computation time and memory re guirements rise sharply as the subsections go up as shown on the chart below For 237 Sonnet User s Guide this example the entire filter circuit used 2006 subsections while the largest indi vidual piece only required 1400 subsections and the smallest only required 854 subsections Time amp A Full Filter Memory Piece wise Analysis Number of Subsections On many larger circuits the use of the automatic circuit subdivision features in Sonnet can greatly improve the efficiency of your em usage Additional Improvements 238 There are two other ways this circuit could have been made even more efficient You could have refrained from adding the automatic feedlines and you could have taken advantage of the fact that some of the subprojects were virtually identical For the purpose of illustration this tutorial added feedlines to all ports generated in the subdivide using the recommended length Feedlines are added to a
167. ed to your circuit There are three types of ground node connections Sonnet Box Floating and Polygon Edge s The Ideal Component does not use a ground node connection by definition The ground node connection needs to be specified for the Data File and Ports Only Component types Sonnet uses a common ground for all the Component ports associated with a given Component This common ground should model as closely as possible how your component was measured or modeled Vendors who supply components often have measured S parameters or a model which may be used to create S parame ters In either case information about how these values were obtained should also be available Use this information to guide your choice of ground node connec tion The three types of ground node connection are discussed below Floating When your ground node connection is set to Floating all the Component ports ref erence a common local ground as pictured below This option should be used if your Component does not have a ground reference or if there are no shunt ele ments in your component model or measured data Any shunt admittance is re moved by em GORIN Floating No ground reference Chapter 6 Components Examples of this are e A series RL equivalent circuit e S Parameter data that was measured without pads Sonnet Box When your ground node connection is set to Sonnet box all the Component ports are globally grounded to the Sonnet
168. eference plane it applies only to the selected port s For details on how reference planes and calibration lengths are used in the de embedding process please refer to Chapter 7 De embedding on page 97 and Chapter 8 De embedding Guidelines on page 107 TIP Changing a port to an autoground type and setting up a reference plane or calibra tion length for the port can be accomplished at the same time in the Port Properties dialog box It is also possible to set calibration lengths for multiple ports by select ing the desired ports selecting Modify gt Port Properties and inputting a value in the calibration length text entry box in the Port Attributes dialog box Ungrounded Internal Ports 78 An ungrounded internal port is located in the interior of a circuit and has its two terminals connected between abutted metal polygons An ungrounded internal port is illustrated below Note that internal ports have their negative terminals on Chapter 5 Ports the left or top side of the port depending on how the port is oriented Ungrounded internal ports can be de embedded by em however you may not set a reference plane or calibration length Ungrounded internal ports are not as accurately de em bedded as co calibrated internal ports but they do not require any space between the two polygons as is required for a co calibrated port TES D SSI WSS SS OYN Unground internal ports are not allowed on the edge
169. egrees 135 135 1 0GHZ Theta 45 0 Phi 0 0 0 96019 dB Pointer q TP You may select another type of plot by right clicking in the plot title area of the far field viewer display and selecting Type from the pop up menu which appears Turning Off the Legend Since the legends take up a lot of space on the display you may turn them off al lowing the plot to fill the extra space 299 Sonnet User s Guide 31 To turn off the legend select View gt Legend This turns off the legend and the far field viewer redraws the plot without the legends The menu item toggles the display state of the legend so that selecting View gt Legend again displays the legend infpole son BAMA Plot Over Theta v 1 0GHZ Theta 45 0 Phi 0 0 0 96019 dB Pointer Changing the Radius Axis You can change the radius axis limits of the plot to another value For this exam ple you will change the intervals from 20 dB to 10 dB 300 Chapter 20 Far Field Viewer Tutorial 32 Select Graph Axes from the main the far field viewer menu The Axes Properties dialog box appears on your display Axis Radius Axis z Label M Tick Labels Min 40 0 Max 20 0 Interval Number Divisions 20 0 fb Apply Cancel Help 33 Click on the AutoScale checkbox to turn it off This enables the Min and Max text entry boxes under Autoscale and the Interval and Number text e
170. en box wall The coupling between transmission lines is removed by the de embedding process De embedding Results The listing below shows the de embedded results obtained earlier in the chapter from the analysis of the example filter circuit see page 99 This example illus trates the format of the de embedded data is output in the analysis monitor and saved as part of your project If you wish to also have a separate file containing your response data you may specify that one be output from an analysis using the Analysis gt Output Files command in the project editor See Analysis Output Files in the project editor s Help for details on specifying a file Run 1 Wed Oct 11 18 38 10 2000 Frequency Sweep Freguency 10 GHz De embedded 50 0hm S Params Mag Ang Touchstone Format S11 S21 S12 S22 10 0000000 1 000000 72 59 6 414e 4 17 050 6 414e 4 17 050 1 000000 73 31 lt Pl F 10 0 Eeff 6 45562325 0 0 Z0 51 7880826 0 0 R 0 0 C 0 04163932 lt P2 F 10 0 Eeff 6 47619184 0 0 Z0 51 8822385 0 0 R 0 0 C 0 04165009 Analysis successfully completed Example showing format of results obtained when de embedding is enabled in em 105 Sonnet User s Guide You should notice the following about the results in above e The line which starts with De embedded is a comment line which describes the analysis results on the line below In this example the results are de embedded 50 ohm S parameters in Touc
171. ent it first per forms an electromagnetic analysis of the geometry then uses circuit theory to con nect the Component to the geometry If you change the data file used for a Component or the value and or type of an ideal component in subsequent analy ses em only needs to perform the circuit theory part of the analysis significantly reducing processing time Please note that any graphs of the response are not au tomatically updated Instead you need to select Graph Freshen Files to update your graph in the response viewer 95 Sonnet User s Guide 96 Chapter 7 De embedding Chapter 7 De embedding Each port in a circuit analyzed by em introduces a discontinuity into the analysis results In addition any transmission lines that might be present introduce phase shift and possibly impedance mismatch and loss Depending upon the nature of your analysis this may or may not be desirable De embedding is the process by which the port discontinuity and transmission line effects are removed from the analysis results The figure on page 98 illustrates the general layout of a circuit to be analyzed with em The device under test DUT shown as a box in the figure is the circuitry for which we wish to obtain analysis results The DUT is located inside the metal box and is connected to one or more ports The ports may be located on box walls as in the figure or in the interior of the metal box see Chapter 5 for a description o
172. ents 82 83 85 combined circuit analyses 199 combining data files 197 command line 345 components 81 analysis 95 anatomy of 82 calibration lengths 91 Component Assistant 82 component symbol 83 Data File type 84 defining physical size 92 definition 82 ground node connection 86 Ideal component 85 label 83 physical size 84 ports 83 Ports Only type 85 properties of 85 reference planes 91 94 restricted space 93 restrictions 92 settings 85 terminal number 83 terminal width 88 types of 84 Index use rules 92 conformal mesh 185 195 adjacent polygons 190 adjacent polygons with interior vertex 191 applying 187 cell size 193 current density viewer 194 current striping 194 figure eight polygons 190 Manhattan polygons 191 memory save 191 polygon boundaries 193 polygon overlap 189 processing time 193 rules of use 188 transmission lines 187 using effectively 191 conjugate gradient optimizer 151 convergence test dielectric bricks 264 coordinate system spherical 282 coplanar 66 281 corner sweep 25 148 coupled line 317 coupling 212 217 cross talk 311 current density data 125 current density file 281 current density viewer 16 43 current striping 194 custom keyboard commands 26 cut 250 cvia 252 D data blocks CKT 203 Data File 84 data files 197 cascading 200 de embedding 97 114 281 box wall ports 101 103 components 70 81 98 coupled transmission lines 104 enabling 98 example 98 gu
173. ep the current density data is only calculated for the discrete data points therefore your plot in the current density viewer shows a coarse resolution of your frequency band 125 Sonnet User s Guide If you wish to calculate the current density data at more points in your band run anon ABS sweep for the points in question with the Compute Current Density op tion enabled For more information about the Compute Current Density option see the help top ic Analysis gt Setup in Help for the project editor Ripple in ABS S Parameters Please note that when the value of the S parameters is close to 1 0 dB over the entire band you may have small ripples or oscillations in the S parameter values This is due to the rational fitting model having too many degrees of freedom when trying to fit a straight line If this is a problem it is recommended that you analyze the frequency band in which this occurs with another type of sweep Output Files You specify additional output files in the Output Files dialog box which appears on your display when you select Analysis gt Output Files from the project editor menu You click on the appropriate button to open the corresponding file entry di alog box Each entry dialog box has an option pertinent to ABS Response File When you specify an optional output file for your project you may select which type of data to output from an adaptive sweep The data selection is controlled b
174. ependent conductivity and or loss tangent Our web site has a lossy conductivity benchmark you can perform on any electromag netic solver or measurement system See Benchmarking on the Products section of our web site www sonnetsoftware com The dielectric loss is calculated in Sonnet at the beginning stages of the analysis The method Sonnet uses starts with the calculation of a sum of waveguide modes The exact solution requires an infinite sum of modes but Sonnet truncates this sum to some reasonable value the truncation has never been a source of error So for each mode if there is a lossy dielectric the calculation involves complex numbers instead of just real numbers This is NOT a discretized function it is a continuous function Therefore the dielectric loss calculation can be thought of as exact only limited to the precision of the machine A more reasonable source of error is in the assumption that the conductivity is constant with frequency All real dielectrics have frequency dependant loss some smaller than others Sonnet supplies you with two parameters Loss Tan and Diel Cond to control this frequency dependency The equation Sonnet uses to calcu late the TOTAL loss is given in Dielectric Layer Loss page 59 There are some dielectrics with more complicated frequency dependencies but this equation works for most dielectrics Of course this requires that you know the frequency dependency of your dielectric If y
175. equency 0 8 GHz se lected for display infpole son DEK a SA A a 9 Plotting osez gt infpole son Gain dB Relative To Gain dB E Total 0 8 GHZ 7 42044 dB Freguency 0 8 GHZ Pu Use scroll bars to rotate plot Pointer Saving the Far Field Viewer File 51 Select File gt Save from the far field viewer main menu The file is saved to the same filename with a pat extension i e infpole pat This saves any data calculated during this the far field viewer session Exiting the Far Field Viewer Program This is the end of the first example of using the far field viewer 52 To stop the program select File gt Exit The far field viewer window disappears from your display 306 Chapter 20 Far Field Viewer Tutorial References 1 Simon Ramo John R Whinnery and Theodore Van Duzer Fields and Waves in Communication Electronics John Wiley amp Sons Inc 1994 pg 601 2 Constantine A Balanis Antenna Theory Analysis and Design New York Harper amp Row 1982 section 4 7 3 307 Sonnet User s Guide 308 Chapter 21 SPICE Model Synthesis Chapter 21 SPICE Model Synthesis Sonnet s analysis engine em provides a frequency domain solution in the form of S Y and Z parameters Many time domain simulators such as traditional SPICE engines do not have the capability to import frequency domain data or have problems with efficiency stability or
176. er s Guide 14 Chapter 1 Introduction Chapter 1 Introduction The Sonnet User s Guide is intended to provide in depth discussions of features of Sonnet s software There is a short exposition of the theory behind Sonnet s analysis engine em followed by discussions of geometry elements and features available in Sonnet This manual also contains tutorials demonstrating how to use some features in Sonnet The tutorials follow chapters discussing that topic Please refer to the Zable of Contents to see what tutorials are available For installation instructions and the basics of using Sonnet please refer to the Get ting Started manual To learn about new features in this release please refer to Chapter 2 What s New in Release 12 on page 23 The Sonnet Design Suite The suite of Sonnet analysis tools is shown on page 19 Using these tools Sonnet provides an open environment to many other design and layout programs The following is a brief description of all of the Sonnet tools Check with your system administrator to find out if you are licensed for these products 15 Sonnet User s Guide Project Editor Analysis Engine Analysis Monitor Response Viewer Current Density Viewer 16 The project editor is a user friendly graphical interface that enables you to input your circuit geometry or circuit netlist for subsequent em analysis If you have purchased the DXF GDSII and or the Gerber t
177. er combination was updated to read Best Error Iteration 13 Error 0 098536 Lstub 191 807 Sstub 200 0 The best iteration is plotted by default when you select optimized data If the op timization was still running this provides a useful way of always plotting the best iteration calculated thus far Pressing the Freshen Files button on the tool bar of the response viewer will always show the best iteration If you were to click on the Select Iterations button the dialog box would appear with all the variable values used in all 25 iterations available to plot Since you wish to see the response at the best iteration you do not need to change the param eter value for this curve group 179 Sonnet User s Guide NN Edit Curve Group par_dstub son Project 53 dstub son Data Collection Optimized v De Embedded Y Group Name par_dstub Y Axis Measurements Left Data Type s Params C Right Data Format Magnitude dB v Unselected Selected D Optimization Iterations F Graph All Iterations Best Error Iteration 13 Error 0 098536 Lstub 191 807 Sstub 200 0 Select Iterations Cancel Help 52 Click on the OK button to close the dialog box and apply the changes The plot is updated showing DB S21 for the best iteration It should appear similar to the plot pictured below 180 Chapter 11 Parameter Sweep and Optimization Tutorial RS par dstub son EARE Cartesian Plot Z0 50 0 Left
178. ere are no more frequencies For example for a frequency sweep from 10 40 GHz with a 0 1 GHz resolution using a sepa ration of 10 the first few frequencies used would be 10 11 12 1 and 13 3 GHz After completing the analysis always do a reality check for reasonable values If you have bad data the frequency may be too high or too low If the frequency is too low the solution may have unity S parameters causing a strange SPICE model To be absolutely sure your results are good select a different frequency band and re analyze the circuit You should obtain similar results between the two analyses Chapter 21 SPICE Model Synthesis You may obtain PI Model Spice data in two different ways The first is to specify an optional output file before executing your analysis The second is to generate a PI model from the response viewer The second method has the advantage of al lowing you to perform the data check mentioned above before creating the SPICE data file To specify a PI Model Spice output file from the response viewer perform the fol lowing Analyze the circuit at the desired frequencies The analysis monitor appears on your display to show the progress of the analysis It is important to note that if your results contain more than two analysis frequen cies then multiple Spice models one for each pair of frequencies will be created in one file When the analysis is complete click on the View Response button on
179. ere is a button shown to the left in the tool bar for this tool For details about the measuring tape please refer to Tools gt Mea suring Tape in Help To access help select Help gt Contents from the project ed itor menu Local Origin The default origin in the project editor is the lower left hand corner of the substrate Local origin allows you to move an origin anchor to any location in your circuit The origin can be moved in a number of ways including selecting and dragging it to the desired position All the measurements which appear in the status bar at the bottom of the project editor window are given relative to the lo cation of the origin anchor For more information please refer to the command Tools gt Local Origin in Help The location of the origin is represented in the proj ect editor with this symbol L Hot Key Mapping In this release you may create custom hot keys for your com monly used commands in the project editor response viewer current density viewer and far field viewer For example you may set a Hot Key so that whenever the letter d is pressed on the keyboard the project editor automatically enters Chapter 2 What s New in Release 12 Changes the add dimension mode To access this feature select File gt Preferences in the desired program In the Preferences dialog box which appears click on the General tab then click on the Keyboard button For details about creating hot keys
180. erest all port discontinuities should be removed by de embedding When enabled em s de embedding algorithm automatically removes the discon tinuities for box wall co calibrated auto grounded and ungrounded internal ports see Port Type Overview page 61 for a description of port types available in em A via port is the only type of port that cannot be de embedded by em The port discontinuity for box wall ports is described in the section that follows The discontinuity for the other types of ports is similar in nature Chapter 7 De embedding Box Wall Ports Box wall ports have one port terminal connected to a polygon inside the metal box and the second port terminal connected to ground see the figure on page 69 The port discontinuity is modeled as a series resistor R and capacitor C shunted to ground as shown below If the circuit being analyzed is completely lossless the resistor value R is zero Even with loss in the circuit the capacitive reactance is normally very large compared to the resistance S parameters from em without de embedding A Device O Under Test R Box wall port a C discontinuity Port discontinuity associated with a box wall port When enabled em s de embedding feature automatically calculates the values of R and C for each box wall port present in the circuit The port discontinuities are then removed by cascading a negative R and C as il
181. es In the Analysis Setup dialog box which appears click on the Advanced button In the Advanced Options dialog box which appears click on the Box Resonance Info check box Click on the OK button to close the Advanced Options dialog box Click on the OK button to close the Analysis Setup dialog box The warning symbol shown to the left appears in the analysis monitor when a box resonance is detected If you click on the Errors Warning button on the analysis monitor you can view all of the warning messages associated with that particular analysis Below is an example of the first type of box resonance warning message When this message appears there is a box resonance detected in the primary structure Sonnet Warning EG2680 Circuit has potential box resonances Filename C Program Files sonnet project package9 son Primary structure First few ideal resonant frequencies are 30 0866 GHz TE Mode 0 1 1 31 7587 GHz TE Mode 0 1 2 Note that the warning message is describing box resonances which appear in the primary structure The term primary refers to the actual structure being ana lyzed By ideal resonant frequency we mean a theoretical value based on an empty Sonnet box The specified dielectric stackup is considered but the effect of any circuit metallization and loss parameters are not Below is an example of the second type of box resonance warning message When this message appears there is a
182. ese lines are used to create the subprojects A geometry project is created for each segment of your circuit These geometry projects contain significantly smaller geometries that may be analyzed faster using less memory 4 If you plan to take advantage of the netlist interpolation feature set up the analysis frequency controls as a coarse resolution of the entire desired frequency band in the project before subdividing Both the netlist and geometry subprojects all inherit these frequency specifica tions Entering these frequency controls now in the Analysis Setup dia log box saves having to enter them in each individual subproject 5 Subdivide the circuit in the project editor to create the subprojects and netlist project which connects the individual subprojects in a network equivalent to the circuit as a whole Ports and reference planes are added to the subprojects as needed to connect to the larger circuit 6 Edit the subprojects to fine tune the geometries if needed Possible adjustments would include the use of a binary box adjusting the grid size setting z partitions for bricks changing the frequency sweep speci fication and adding parameters TIP If you add parameters to a subproject in a netlist the parameters are not automat ically displayed in the netlist You must save the main netlist and re open it to dis play the parameters and make them available for editing 7 Set up the analysis controls in the netlist to use t
183. esh option 41 edit cut 250 editing a circuit 16 Eeff 110 125 electrically thick conductors 52 em batch file 345 command line 345 description 20 364 theory 21 22 emgraph 16 emstatus 16 emvu 16 E plane 282 eguivalent circuit 71 error codes de embedding 106 nl 110 error function 151 error residual 341 E Total 305 example files att 209 att cascade son 200 benchmark s100 341 s25 341 s50 341 cvia 252 dual patch 75 278 infpole 302 par dstub 155 steps 198 sub whole 237 subdivide 228 Thkthru 261 Tripat 279 via example 252 examples att 200 excitations 280 default values 289 exit 306 exiting 306 F far field 273 280 303 Far Field Viewer exiting 306 saving a file 306 tool bar 303 tutorial 287 far field viewer 280 286 dielectric bricks 266 Index normalization 285 polarization 286 spherical coordinate system 282 feedlines 234 ferrite components 281 figure eight polygons 190 file exit 306 save 306 filter 156 Find Maximum 122 find maximum 121 Find Minimum 122 find minimum 121 FINDMAX 122 FINDMIN 122 first frequency 281 first reference point 140 floating ground 86 frequencies 284 default value 281 selecting to calculate 291 selecting to plot 292 303 frequency maximum 30 frequency interpolation 212 frequency plot 303 frequency specification 165 frequency sweep coarse 224 fringing fields 114 full view button 296 G GABMAC 339 gain directive 285 power 285 relative to 285 max 2
184. et Software Inc Sonnet em and emCluster are registered trademarks of Sonnet Software Inc UNIX is a trademark of Unix Systems Labs Windows NT Windows2000 Windows ME Windows XP and Windows Vista are trademarks of Microsoft Inc AutoCAD and Drawing Interchange file DXF are trademarks of Auto Desk Inc SPARCsystem Open Windows SUN SUN 4 SunOS Solaris SunView and SPARCstation are trademarks of Sun Microsystems Inc HP HP UX Hewlett Packard are trademarks of Hewlett Packard Company ADS Touchstone and Libra are trademarks of Agilent Technologies Cadence and Virtuoso are trademarks of Cadence Design Systems Inc AWR and Microwave Office are registered trademarks and EM Socket is a trademark of Applied Wave Research Inc GDSII is a trademark of Calma Company Acresso FLEXIm and FLEXnet are registered trademarks of Acresso Software OSF Motif is a trademark of the Open Software Foundation IBM is a registered trademark of International Business Machines Corporation Linux is a registered trademark of Linus Torvalds Redhat is a registered trademark of Red Hat Inc SuSE is a trademark of Novell Inc Adobe and Acrobat are registered trademarks of Adobe Inc AWR and Microwave Office are trademarks of Applied Wave Research Inc Platform is a trademark and LSF is a registered trademark of Platform Computing Table of Contents TABLE OF CONTENTS T INTRODUCTION 15 oie Se on Oe See Ree Be OS 15
185. ete or move a polygon from which an edge via originates the via is moved or deleted from your circuit as well 250 Chapter 16 Vias and 3 D Structures Via Loss Via Ports The loss for the via post is determined by the metal type of via polygons and the metalization of the polygon that the via is associated with for edge vias See Met alization Loss page 47 for an explanation on how to set the metalization loss for a metal polygon When a via polygon is created it s metal type is set to the default metal used for new metalization This is controlled in the Metal Types dialog box accessed by se lecting Circuit gt Metal Types from the project editor s menu You may also change the metal type of the via polygon after it has been added to the circuit You may use any metal type defined in your circuit for a via polygon To change the metal type of a via polygon Right click on the via polygon and select Properties from the pop up menu which appears on your display The Via Properties dialog box appears on your display Select the desired metal type from the Via Metal drop list Via Properties multi layer son Via Levels Via Metal From Level o v Lossless Lossless Via Metal C Up Cooper drop list Aluminum Down 3 s Level s To Level 3 gt Cancel Help For a detailed discussion of via ports please see Via Ports on page 75 251 Sonnet User s Guide
186. etic analysis with the S parameter results from att_res16 s2p to obtain an overall set of S parameters for the T attenuator TIP Before executing a PRJ statement em checks for the existence of data at the spec ified control frequencies If the data already exists and the project has not changed since the data was generated em does not execute an electromagnetic analysis but uses the available data The listing below shows the output of the netlist analysis as it appears in the anal ysis monitor which contains the overall set of S parameters for the T attenuator 200 MHz 50 Ohm S Params Mag Ang Touchstone Format S11 S21 S12 22 200 000000 0 008924 67 700 0 500516 5 758 0 500516 5 758 0 008924 67 700 Frequency 300 MHz 50 Ohm S Params Mag Ang Touchstone Format S11 S21 S12 S22 300 000000 0 013072 68 918 0 501160 8 647 0 501160 8 647 0 013072 68 918 Frequency 400 MHz 50 0hm S Params Mag Ang Touchstone Format S11 S21 S12 S22 400 000000 0 017177 67 763 0 502055 11 54 0 502055 11 54 0 017177 67 763 Inserting Modeled Elements into a Geometry 204 Another very useful feature of the netlist project is the ability to insert modeled elements into a geometry project after an electromagnetic analysis has been per formed on that circuit A modeled element is an ideal element such as a resistor inductor capacitor or transmission line which has a closed form solution No electromagnetic an
187. ewer main menu The Select Freguencies dialog box appears on your display Patvu Select Freguencies infpole jxy Calculated Calculate More Plotted 0 8 GHZ BE C e The Calculated column displays the freguencies for which data has been calculat ed but is not presently displayed The Plotted Column shows those freguencies which are presently displayed In this case 0 8 GHz TIP You may also open the Select Freguencies dialog box by right clicking in the Freguency area of the legend and selecting Select from the menu which appears on your display Chapter 20 Far Field Viewer Tutorial 12 13 14 15 16 17 Double click on 0 8 in the Plotted column This moves 0 8 to the calculated column i e this frequency is not displayed Double click on 1 0 in the Calculated column This moves the value 1 0 to the Plotted column Click on the OK command button This closes the dialog box and updates the display with the data for 1 0 GHz at Phi 0 Select Graph gt Select gt Phi from the far field viewer main menu The Select Phi s dialog box appears on your display Select Phi s x Calculated Calculate More Plotted 9 0 Degrees mms 0 0 Degrees 90 0 Degrees 45 0 Degrees a E Select All Select All Apply Cancel Help Use the scroll bar on the Calculated Column to move down the list until 90 0 Degrees is displayed Dou
188. f port types available in em Typically transmission lines are necessary to connect the ports to the DUT When de embedding is enabled em performs the following seguence of steps 1 Calculates port discontinuities 2 Removes effects of port discontinuities from analysis results 3 Optionally shifts reference planes removes effects of feed transmission lines from analysis results 4 Calculates transmission line parameters Earp and Zo 97 Sonnet User s Guide Metal Box Walls Transmission Line Transmission Line General layout of a circuit to be analyzed with em Upon completion of the de embedding process em outputs de embedded S pa rameter results transmission line parameters and the calculated port discontinui ties An abbreviated summary of the de embedding algorithm used is presented in ref erence 76 and the complete theory is presented in reference 77 in Appendix II Sonnet References on page 353 For a discussion of the de embedding tech nique used for co calibrated ports see Deembedding the Effect ofa Local Ground Plane in Electromagnetic Analysis by James C Rautio The article is available in PDF format in the Support section of our web site Enabling the De embedding Algorithm 98 To demonstrate de embedding with em we will analyze the filter shown below This is an example of a hairpin filter with a passband of approximately 4 0 to 4
189. f 20 large interior subsections may make the current distribution look choppy 43 Sonnet User s Guide Defining Setting this value to a large number forces all subsections to be only 1 cell wide providing smooth current distribution Again analysis time is impacted signifi cantly The Max Subsection Size parameter is specified in the Advanced Subsectioning Controls which are opened by selecting Analysis gt Advanced Subsectioning from the project editor main menu the Subsectioning Frequency The subsectioning parameter Max Subsection Size applies to the subsectioning of all polygons in your circuit and is defined as subsections per wavelength Nor mally the highest analysis frequency is used to determine the wavelength How ever this may be changed by using the Subsectioning Frequency options in the Advanced Subsectioning Control dialog box in the project editor This dialog box is opened by selecting Analysis gt Advanced Subsectioning from the project editor main window For details on what options are available to define the subsection ing frequency click on the Help button in the Advanced Subsectioning Control di alog box The frequency defined by the selected option is now used to determine the maxi mum subsection size instead of the highest frequency of analysis Thus the same subsectioning can be used for several analyses which differ in the highest frequen cy being analyzed Conformal Mesh Subsec
190. f such applications include dielectric resonators dielectric overlays airbridges microstrip to stripline transitions dielectric bridges and crossovers microslab transmission lines capacitors and module walls Guidelines for Using Dielectric Bricks Subsectioning Dielectric Bricks A dielectric brick simulates a volume of dielectric material Because a brick sim ulates a volume it must be subsectioned in the X Y and Z dimensions The more subsections finer resolution used in each dimension the more accurate the anal ysis X Y subsectioning of dielectric bricks is identical to X Y subsectioning of metal polygons You can control the X Y subsectioning of both through your choice of grid size XMIN YMIN XMAX YMAX and subsections per wavelength See Chapter 3 Subsectioning for details Z subsectioning of dielectric bricks is controlled by the number of Z partitions parameter This parameter specifies the number of Z subsections for all dielectric bricks on a particular dielectric layer See the Z Partitions dialog box topic in the project editor s Help for information on setting this parameter Using Vias Inside a Dielectric Brick Vias through dielectric bricks are treated the same as vias through the standard di electric layers Note that via ports inside dielectric bricks are not allowed 265 Sonnet User s Guide Air Dielectric Bricks Dielectric bricks can be made of any dielectric material a
191. f the dimension parameter varies and the reference point is moved the positions of the points in the adjustable point set also move There is a setting associated with each dimension parameter that determines how the adjustable point set is moved With the default and simplest option each point in the adjustable point set retains its relative distance from the reference point For a discussion of all the options controlling moving the adjustable point set see Moving Adjustable Point Sets on page 142 Note that the anchored parameter is always defined as the distance between the an chor and the reference point in either the X direction or the Y direction never as a diagonal distance between them Two examples of anchored parameters each at two different nominal values are illustrated below This example uses the default setting for how the adjustable point set moves 138 Chapter 10 Parameterizing your Project Anchor Point Adjustable Point Set Dwidth nominal value 40 mils Dwidth nominal value 60 mils Notice that although the top and bottom examples have identical anchor and reference points and starting and ending nominal values that the resulting polygon on the top differs from that on the bottom due to a different adjustable point set the point set is highlighted by the oval Anchor Point Reference Point Adjustable Point Set Dtop nominal value 60 mils ge TP Once you have finished addi
192. file which contains all the Broadband Spice Models or multiple files one for each specified combination Class of Problems Be aware that there are several types of responses for which an accurate Broad band Spice Model may not be produced e If your response data contains a data point which sharply deviates from the data curve such as you would see for a box resonance or a narrow band spike the Broadband Spice model may not accu rately model that response e The Broadband Spice model is generally not accurate for response data below 60 dB e A gentle curve may sometimes get fitted with a straight line e Broadband Spice Extractor has only been tested for passive circuits e Broadband Spice Extractor has only been tested using S parameters produced by em However you should be able to use S parameters produced by other sources such as other simulators or measured data to create a Broadband Spice model If you are concerned with the accuracy of the model you should visually inspect the predicted S Parameter data produced by the same rational polynomial which was used to create the Broadband model to determine the usefulness of the Broad band Spice model Chapter 21 SPICE Model Synthesis NOTE Be aware that the processing time needed to create your models can be significant The processing time is proportional to the number of analysis frequencies times the square of the number of ports in your circuit Creating a
193. g 204 inserting in a geometry 204 modeling assumptions 281 modes higher order 113 TEM 113 modify attributes ports 64 78 moving adjustable point set 142 MTL 317 MTL coupled line 309 multi conductor transmission line 309 317 multi core processing 24 multi sweep plus Stop Restart caching 118 multi threaded processing 24 N n coupled line 309 netlist creating 199 invoking an analysis of a subproject 202 netlist editor 197 netlist project 197 analysis 199 network file analysis 236 networks 198 new features 23 nl error code 110 nominal value 136 137 changing 173 nominal values update with results 182 non Manhattan polygons 191 normal metal type 50 normalization 285 297 changing 285 default 285 290 directive gain 285 power gain 285 number of iterations 153 O open environment 281 opening a graph 168 optimization 129 154 best iteration 179 conjugate gradient method 151 data 179 data range for parameters 175 example 155 172 executing 178 methodology 151 number of iterations 153 process 152 results 154 181 selecting parameters for 174 setting up 173 specifying goals 153 176 tutorial 155 172 Optimization Goal Entry dialog box 176 Optimization Parameters dialog box 174 optimization results 367 Sonnet User s Guide update 182 Optimization Results dialog box 182 optimized values 181 optional files 126 orientation of subdivision lines 221 origin 282 output files lumped rsp 207 P packag
194. g two sheets is illustrated below Two Sheet Default Thick Metal Top Sheet This is a cross section of thick metal modeled using two sheets note that the sidewalls are vias Bottom Sheet For two sheets the current travels on only the top and bottom surface of the thick metal Current on the sides of the thick conductor can be approximated by using three or more sheets The two sheet model Current flows in the x y plane on the top and bottom of the thick metal polygon shown here Current is also allowed to flow between the top and bottom sheets but only in the z direction No current flows in the zy or zx plane Chapter 17 Thick Metal For most cases using the default of two sheets provides a high accuracy solution However for very tightly coupled lines where the gap between the lines is much less than the metal thickness the coupling between them may be underestimated In these cases you may need to increase the number of sheets However increas ing the number of sheets increases the memory requirements and processing time Increasing the number of sheets adds more layers of infinitely thin metal between the top and bottom metal sheet A cross section of a four sheet model is shown be low Four Sheet Thick Metal Top Metal Interior Sheet Interior Sheet Bottom Metal im Metal Sheet Vias This is a cross section of thick metal modeled using four sheets note that the sidewalls are via
195. gain this dialog box appears Click on the OK button to apply your selections and close the dialog box The cursor changes to indicate that you are adding subdivision lines and a line appears which moves with your cursor 229 Sonnet User s Guide 230 Move your cursor until the X coordinate of the cursor position in the status bar is 395 0 and click A line representing the subdivider appears in the vertical plane running through the point at which you clicked The sections of the circuit are now labeled s1 and s2 Subdivision sections are labeled from left to right or top to bottom depending upon orientation These labels are always sequential and are non editable 1 VWVAALLZIZ2ZZZEZZZZZZZ Subdivision lines are always snapped to the grid and may not be placed on top of each other Once a subdivider has been added to your circuit you may edit the sub divider as you would any other object in your geometry You may click on the sub divider and move it You may also control the display of the subdivider lines and labels in the Object Visibility dialog box invoked by selecting View gt Object Visibility from the project editor s main menu Since each of the coupled line segments are 595 mils long and you wish to place the subdivision lines at the halfway point each subsequent subdivision line should be placed 595 mils further to the right in the circuit So the second subdivision line should be place
196. gonal Boundary Cell Size and Processing Time Care should be taken when choosing your cell size when using conformal mesh Many users especially experienced Sonnet users will estimate processing time based on the amount of memory required to analyze a circuit The amount of memory used for conformal mesh can be deceptive Using a smaller cell size in a circuit which uses conformal mesh may not increase the required memory but will have a noticeable effect on processing time The significant factor in determining processing time with conformal meshing is the number of metalized cells needed to construct a conformal section The number of conformal mesh cells displayed as the result of the Estimate Memory command may be more reliably used as a guideline 193 Sonnet User s Guide Current Density Viewing 194 You may view the current of circuits using conformal mesh just like any other cir cuit However the current density of conformal mesh polygons might show un usual striping These stripes do not represent real current but are a by product of the conformal meshing algorithm There are two types of current striping 1 A single stripe of current can appear on the junction between two con formal sections as shown below a Current Stripe Current stripe with section boundaries shown 2 Horizontal or vertical stripes may appear within a curved conformal sec tion producing a ripple effect as shown
197. gt from the Operand drop list The display is updated with gt Select Value from the Goal Type drop list This choice allows you to put in a specific value This is the default you may also specify another project file or another network in your project if the project is a Netlist project In those cases you may select a response for that circuit to which you wish to match your selected response Enter 1 0 in the Value text entry box This sets your goal of DB S21 gt 1 0 dB Click on OK to apply the changes and close the dialog box The Analysis Setup dialog box is updated An entry for this optimization goal now appears in the Optimization Goals list The other two goals should be entered in a similar manner The second goal is a adaptive sweep from 5 0 GHz to 6 0 GHz with a desired response of DB S21 lt 30 0 dB This is the stopband The third goal is an adaptive sweep from 7 0 GHz to 10 0 GHz with a desired response of DB S21 gt 1 0 When you have complet ed entering these goals the Optimization Goals list should appear as shown below Analysis Control Max Iterations Optimization Parameters 100 Lstub 100 0 to 300 0 start at 220 0 Edit Sstub 200 0 fixed Optimization Goals 1 0 to 4 0 GHz ABS a es Add par_dstub DB S21 gt 1 0 weight 1 0 Aid Edit par_dstub DB S21 lt 30 0 weight 1 0 7 0 to 10 0 GHz ABS _ Delete 4 5 0 to 6 0 GHz ABS Thi
198. h the Component is connected to the circuit metal and must be attached to an open polygon edge This point also serves as a reference plane for de embedding the Component unless a reference plane is added for the port There is one Component port for each terminal on the Compo nent Component ports are modeled using co calibrated internal ports For more information on co calibrated ports please see Co calibrated Internal Ports page 70 Terminal numbers identify the physical pin on your Component connected to the corresponding Component port Components may have an unlimited number of terminals with the exception of those Components which use the Ideal Component model since the available ide al components are limited to two terminals Terminals and or ports are numbered in the order in which they are added to your circuit and may be modified after the Component is added to your circuit The label is user defined text which identifies the Component in your circuit Each Component label in a project must be unique Component ports may be placed only on open polygon edges You may use a ref erence plane to control how much if any of your circuit metal is also de embed ded in addition to the Component For more information see Reference Planes page 91 83 Sonnet User s Guide Physical Size You may also optionally enter a physical package size for your Component These measurements height width and length are
199. h to see the imped ance values of other ports while doing so proceed as follows 1 Select Circuit gt Ports from the main menu to open the Port Impedance dialog box 2 The impedance values for any port can be changed by typing the desired values in the Resistance Reactance Inductance and Capacitance fields in the row labeled with the desired port number GTP Note that the impedance of multiple ports may be changed at the same time through the first method by selecting multiple ports before selecting Modify gt Port Properties and by the second method by modifying all the desired port val ues while the Port Impedance dialog box is open Special Port Numbering All ports are assigned a number at the time they are created in the project editor There is no limit on the number of ports and the number of ports has a minimal impact on the analysis time needed for de embedding By default the ports are numbered by the order in which they are created i e first port created is assigned the number 1 second port created is assigned the number 2 etc With this default method all ports are positive and unique However there are some applications that require the ports to have duplicate or even negative numbers Ports with Duplicate Numbers All ports with the same number as pictured below are electrically connected to gether As many physical ports as desired may be given the same numeric label Such ports are sometimes calle
200. he 30 cell wide lines give about 0 5 error In non resonant situations you can expect the total error to be somewhere between 5 and 0 5 If most of the circuit is the low impedance line the error is closer to 0 5 etc However let s say that our circuit has resonant structures Let s say it is a low pass filter It is easy to verify by means of circuit theory that the low pass filter is very sensitive to the high impedance lines This means we can expect about 5 error even though the high impedance lines only make up half the filter Given this information there are several courses of action First if 5 error is ac ceptable no further effort is needed More likely we wish to analyze the filter with less error Since we now know the error in the characteristic impedance is 5 we can physically widen the line so that the characteristic impedance is 5 lower to compensate for the known in crease in characteristic impedance due to subsectioning the line only one cell wide Very precise analyses are possible using this compensation technique 343 Sonnet User s Guide 344 Appendix Em and xgeom Command Line for Batch Appendix Em and xgeom Command Line for Batch em Command Line If you wish to set up batch or script files to run your analyses overnight or at times of the day when the processing load is lighter it is possible to use command lines to run em from a batch file You should also be aware that i
201. he complete set of desired analysis frequencies if the subprojects are already set to analyze the coarse frequency sweep When the analysis is performed on the master netlist project em interpolates between the frequency points in the subprojects saving processing time You may also use a Hierarchy Sweep in which the frequency band set up in the master netlist is imposed on the analyses of all the subprojects This is useful when additional accuracy is needed in the data and you do not wish to use interpolation This is accomplished by setting the Hier archy Sweep option in the Analysis Setup dialog box in the project edi tor 8 Analyze the netlist project The data response for the netlist project pro vides analysis results that may be used for the whole circuit 215 Sonnet User s Guide 9 It is often a good idea after analyses are complete on the resultant sub projects to check the response data to verify that data was calculated for enough frequency points to provide accurate interpolated data Since it is possible for a netlist project to include a netlist subproject it is possible to use double subdivision After subdividing your initial circuit you then may use subdivision on one of the resulting geometry subprojects In this case you would need to change the name on the appropriate PRJ line from the old geometry subproject to the new netlist subproject Choosing Subdivision Line Placement 216 As mentioned ab
202. he subdi vide but not port 1 which is contained in the source project All the ports in subdivide_net_s2 have feedlines since all were created in the subdivide Note that the feedlines are all of lossless metal Original Port subdivide_net_s1 son subdivide_net_s2 son 235 Sonnet User s Guide Analysis of the Network File 236 17 18 The last step to complete the analysis of the filter is to analyze the netlist project created by the subdivide The analysis controls you entered in the original project are the ones you wish to use to analyze the netlist so the analysis setup is already complete An adaptive sweep from 2 3 GHz to 2 5 GHz will be performed on the netlist Click on the project editor window containing the netlist to make this the active file This is indicated by the title bar on the netlist being highlighted TIP You can switch the active file in the project editor by clicking on the title bar of the project window or by selecting the project from the Windows menu on the main menu Click on the Analyze button to launch the netlist analysis The analysis monitor appears on your display 2ff subdivide net son Running on TINA Mi E3 File Edit View Run Project Help omae gt NE s13 6 subdivide net s1 0 of 101 Frequencies Done Subs 854 Memory 9 MB Analyzing 2 3 GHz Loading matrix source level 0 field level 0 SO MUS
203. he variable Sstub to the dimension parameter When you click on the OK button an arrow indicating the length and the variable name appear on your display Note that since there is a difference between the reference points in both the x horizontal and y vertical direction you may move the parameter name so that the parameter is defined in either the x or y direction If you were to choose the y direction moving the mouse to the left orright of both reference points to define your parameter it would appear like this However for this example you define the parameter in the x direction moving your mouse up or down above or below both reference points 163 Sonnet User s Guide 24 Move the mouse until the name is positioned in the middle of the thru line 25 When the name is in the desired position click on the mouse This sets the dimension parameter in the x direction The dimension parameter should now appear as shown below eee Oo pisos NNN DO Lstub 220 This completes entering the dimension parameters Note that Lstub is affected by Sstub As Sstub increases although it does not directly affect the value of Lstub the two stubs do get further apart The dimension parameter to which Lstub is as signed is dependent on the dimension parameter to which Sstub is assigned How ever the variable Lstub is NOT dependent on the variable Sstub so that both are available to be selected for the parameter s
204. his compensates for the fact that current is now flowing through two conductors in stead of the usual single conductor SSG The wide bottom of the trapezoidal line is made up of a polygon using the Normal model for the metal type This is a zero thickness 260 Chapter 17 Thick Metal Then place a polygon representing the top side of the thick metal on the bottom side of that dielectric layer using the Thick Metal metal type Make this polygon as thick as the dielectric layer Thick metal polygon on level 1 where it is drawn and placed on top of the wider zero thickness The same polygon shown on level 0 Since the thick polygon is the same thickness as the dielectric layer the metal also appears on this level Only the outline of the zero thickness metal is shown on this level Next place any desired ports on the thick metal polygon not on the thin metal polygon Since the thick metal polygon is placed on top of the zero thickness poly gon the two are connected electrically and the port is across both polygons A circuit implementing the above transmission line is stored in Thkthru and an ex ample of a thick step junction is stored in a project called Thkstep Copies of these projects can be obtained from the Sonnet examples For directions on obtaining a Sonnet example select Help gt Examples from the menu of any Sonnet program then click on the Instructions button Thick Metal in the Current Densi
205. hstone magnitude angle format e The second line gives the analysis results e The remaining two lines give de embedding information for each port in the circuit The various fields are defined as follows P Port number F Frequency in units defined earlier in the results file Eeff Effective dielectric constant of the transmission line connected to the port Z0 TEM equivalent characteristic impedance of the transmission line in ohms R Equivalent series resistance of port discontinuity in ohms C Equivalent series capacitance of port discontinuity in pF De embedding Error Codes Please see De embedding Error Codes in Help for explanations of the error code messages To access Help select Help gt Contents from any Sonnet application 106 Chapter 8 De embedding Guidelines Chapter 8 De embedding Guidelines The previous chapter describes the basics of de embedding what it is how it is enabled and what it does when enabled This chapter presents guidelines for ob taining good de embedded results Calibration Standards In order to determine the port discontinuity as described on page 100 Sonnet must electromagnetically analyze several calibration standards which include the same port discontinuity as the primary circuit For a single box wall port the calibration standards are two through lines which have the same geometry width dielectrics distance to box wall etc as the polygon which has
206. ich you wish to perform the ABS analysis The step size is automatically set by em during the analysis See page 116 for a description of how the ABS resolution is determined 117 Sonnet User s Guide Click on the OK button to close the dialog box and apply the changes Save the project by selecting File gt Save from the menu or by clicking on the Save button on the tool bar You need to save the file before analyzing it Select Project gt Analyze from the menu or click on the Analyze button on the tool bar Em performs an adaptive sweep on your project The analysis monitor appears on your display and indicates the progress of the adaptive sweep The Adaptive Sweep is also available within the Frequency Sweep Combinations analysis controls This allows you to mix adaptive sweeps with other types of sweeps For more details see the Frequency Sweep Combinations topic in Help in the project editor ABS Caching Level 118 There are three levels of ABS caching available None Stop Restart and Multi Sweep plus Stop Restart The options for ABS caching level are found in the Ad vanced Options dialog box To access the Advanced Options dialog box select Analysis gt Setup from the project editor main menu then click on the Advanced button in the Analysis Setup dialog box which appears The default is Stop Re start Stop Restart retains the cache data while the analysis is proceeding Once the adaptive data has
207. ided for this chapter Deja xee os eee ae PRJ 12345 att_Ilgeo2 son Hierarchy Sweep RES 3 R Z3 RES 4 R 74 RES 5 R Z5 DEF2P 1 2 ATTEN Main Network Use buttons or menus to modify netlist Network None Line None An important feature to notice in this netlist is the use of parameters Three param eters Z3 Z4 and Z5 have been defined in the netlist project and their values used for the three resistor modeled elements Parameters are defined in a netlist by se lecting Circuit gt Parameters from the main menu then entering the parameter name and nominal value in the Parameters dialog box which appears Z3 and Z4 are equal to 16 77 and Z5 is equal to 67 11 The listing below shows the S parameter results obtained from the analysis with ungrounded internal ports These results are very similar but not identical to the results for auto grounded ports The differences are primarily due to the change in the gap size between polygons at the points where lumped elements are inserted Frequency 50 Ohm S Params Mag Ang Touchstone Format S11 S21 S12 S22 200 000000 0 009217 68 496 0 500482 5 785 0 500482 5 785 0 009217 68 496 Frequency 50 Ohm S Params Mag Ang Touchstone Format S11 S21 S12 S22 300 000000 0 013510 70 114 0 500994 8 683 0 500994 8 683 0 013510 70 114 Frequency 50 Ohm S Params Mag Ang Touchstone Format S11 S21 S12 S22 400 000000 0 017788 69 364 0 501707 11 59 0 501707 11 59
208. idelines 107 higher order modes 113 port discontinuities 100 reference planes 102 108 110 de embedding error codes 106 deleting vias 250 dependent variable 135 design suite 15 Desktop Solver 24 diagonal fill 266 dialog box Parameter Properties 158 dialog boxes Analysis Setup 118 165 173 Axis Properties 301 Calculation Setup 290 Circuit Subdivision 233 Dielectric Layers 58 Levels 245 Metal Editor 256 Metal Properties 187 Optimization Goal Entry 176 Optimization Parameters 174 Optimization Results 182 Parameter Sweep Entry 165 Port Impedance 65 Select Frequencies 292 Select Normalization 298 Select Phi s 293 304 Subdivider Orientation 229 Subproject Specifications 234 dielectric 281 anisotropic 26 causal 348 multiple constants 281 dielectric bricks 263 272 air 266 anisotropic 269 applications 265 363 Sonnet User s Guide convergence test 264 far field viewer 266 limitations 266 materials 268 269 subsectioning 265 vias 265 visibility 268 Z partitions 270 dielectric layers creating new 59 loss 47 57 loss parameters 58 Dielectric Layers dialog box 58 dielectric library 59 digital interconnect 311 dimension parameter adjusting point set 142 anchored 136 137 radial 136 144 symmetric 136 139 dipole infinitesimal 287 288 303 directions 280 directive gain 285 discontinuity lumped models 311 port 113 dual_patch 75 278 DUT 97 DXF Translator 17 dxfgeo 17 E E total 294 ebridge 17 edge m
209. if you have purchased a Broadband Spice Extractor license from Sonnet Please see your system administrator if you are unsure of the availability of this feature In order to create a Spice model which is valid across a broad band the Sonnet broadband SPICE Extractor feature finds a rational polynomial which fits the S Parameter data This polynomial is used to generate the equivalent lumped ele 319 Sonnet User s Guide 320 ment circuits in either PSpice or Spectre format Since the S Parameters are fitted over a wide frequency band the generated models can be used in circuit simula tors for AC sweeps and transient simulations To create a Broadband Spice file you open your project in the response viewer and select Output gt Broadband Model File from the main menu You may also create a Broadband Model by using the Analysis gt Output Files command in the project editor See Help for Details This opens the Output Broadband Model File window which allows you to calculate a broadband SPICE file based on the anal ysis data for your project You need a minimum of 50 frequency points in order to generate a Broadband Spice file therefore we highly recommend that you use an ABS sweep when analyzing your circuit to ensure the correct number of analysis frequencies If your circuit contains parameterization or optimization data and you select more than one parameter or iteration combination then you may choose to create one
210. ign without leaving the ADS environment Program module ebridge The AWR Microwave Office Interface provides a seamless incorporation of Son net s world class EM simulation engine em into the Microwave Office environ ment using Microwave Office s EM Socket You can take advantage of Sonnets accuracy without having to learn the Sonnet interface Although for advanced us ers who wish to take advantage of powerful advanced features not presently sup ported in the integrated environment the partnership of AWR and Sonnet has simplified the process of moving EM projects between Microwave Office and Sonnet Program Module sonntawr This Sonnet plug in for the Cadence Virtuoso suite enables the RFIC designer to configure and run the EM analysis from a layout cell extract accurate electrical models and create a schematic symbol for Analog Artist and RFDE simulation Program Module sonntcds A Broadband Spice extraction module is available that provides high order Spice models In order to create a Spice model which is valid across a broad band the Sonnet broadband SPICE Extractor feature finds a rational polynomial which fits the S Parameter data This polynomial is used to generate the equivalent 17 Sonnet User s Guide lumped element circuits which may be used as an input to either PSpice or Spec tre Since the S Parameters are fitted over a wide frequency band the generated models can be used in circuit simulators fo
211. in ohms sq in the Rdc text entry box which appears when you select this metal type To use this loss model the resistivity should be constant over the frequency range of interest 51 Sonnet User s Guide 52 Rdc Rrf This method allows you to enter two values Rpc and Rpg The first parameter Rpc determines loss at low frequency where the conductor is much thinner than the skin depth Surprisingly other electromagnetic analyses often predict zero loss at low frequency because they assume Rp is zero The second parameter is the skin effect coefficient Rrp Em multiplies this num ber by the square root of the frequency in Hertz to yield the Ohms square value at high frequency The equations for Rpc and Rpg are Roc 1 ot Rrp Skin effect coefficient Tu o where o is the bulk conductivity in mhos meter t is the metalization thickness in meters and u 47 x 107 H m Typical values for Rpc and Rpg are 0 004 and 3e 7 If you start getting very strange loss results check Rgp paying special atten tion to the exponent Em also properly models the transition between electrically thin low freguency and electrically thick high freguency conductors The transition freguency from Rpc to Reg is the square of Rpc Rpr At this frequency and a relatively narrow band around it both coefficients are important If the skin effect coefficient Rgp is set to 0 0 then the value of Rpc is used over all frequencies This
212. ing occurs must be contained within a subproject In this way all the significant coupling in the circuit is accounted for If care is taken when subdividing the circuit the accuracy of the results is very high Circuit subdivision is not appropriate for every design but in the cases of large circuits 5 10 minutes processing time per frequency where it is applicable you can obtain marked increases in processing efficiency Another advantage of circuit subdivision is the use of frequency interpolation in the master netlist analysis A netlist is used to connect the response data of the sub projects of the circuit to simulate the full circuit If the subprojects are chosen in such a way that their response data does not vary significantly over the frequency band very few frequency points need to be calculated for the subproject So not only do the smaller files require less time and memory because of their smaller size but you can also analyze these smaller circuits at fewer frequency points In terpolating in the netlist file requires much less processing than calculating data for a frequency point in a geometry project Shown below is an example showing the typical advantages of using this ap proach 30 minutes frequency Large Circuit 4 n g X 25 freguencies 750 minutes total Netlist Subdivided Large Circuit Small Circuit Small Circuit Small Circuit 4 mins freg 3 mins freg 4 mins freg X 5 freg X 5 freq X 5 fre
213. ing their own analysis controls Netlist subprojects always inherit their analysis controls from the present netlist 4 Once the analysis of geometry subprojects is complete em performs the circuit analysis specified in the netlist 5 Em combines the electromagnetic results with the circuit results to obtain the desired output results Note that the above sequence of steps is generalized for analyses which include both electromagnetic and circuit analysis In cases where the overall analysis is re stricted to either electromagnetic analysis or circuit analysis some of the steps are omitted Creating a Netlist You create a netlist using the project editor To create a new netlist select File gt New Netlist from the main menu of the project editor The project editor tool bar and menus change for the netlist editor to allow you to add elements and networks to your netlist The initial netlist file contains a default two port network named Net The last net work in the netlist is the main network The main network is the network whose solution you are solving for in this netlist When you analyze the netlist the re sponse data produced in the analysis is for the main network 199 Sonnet User s Guide You can edit the name and attributes of this network including the number of ports by double clicking on the entry This is true of all entries made in the netlist you must double click on them to open the dialog box which allo
214. ion in your circuit The metalization in your circuit is still modeled as zero thickness Sonnet models your circuit using zero thickness metal but your real circuit pos sesses a metal thickness At higher frequencies current flows in a thin skin around the edge of the metal as pictured below The current ratio is the ratio of the current flowing on the top of the metal to the current flowing on the bottom of the metal Current KS GI AUS GS eas BOTTOM Cross section of metalization There are no sides in a zero thickness model therefore when translating from these parameters the current which flows on the sides is ignored In some cir cuits stripline for example the current is symmetrical with half of the current flowing on the top of the metal and half flowing on the bottom of the metal In this instance the current ratio is 1 If you had twice as much current flowing on the top as on the bottom the current ratio is 2 This could occur for some microstrip circuits for example It is difficult to know an exact value of the cur rent ratio without obtaining measured data on your circuit All planar solvers must estimate this value in order to calculate metal loss this particular model in Sonnet allows you to enter the value Note that reciprocal values have the same effect i e 0 5 results in the same loss as 2 0 Resistor To define a metal which you wish to use as a resistor enter the DC resistance
215. ion parameters in a cir cuit set up and execute a parameter sweep set up and execute an optimization and view the results of both a parameter sweep and an optimization For a detailed dis cussion of parameterization and optimization please refer to Chapter 10 This tutorial presumes that you are familiar with Sonnet Software especially the project editor and the analysis monitor If you are new to Sonnet please review the tutorials in Chapter 4 and Chapter 5 of the Getting Started manual before per forming this tutorial This example uses the Sonnet example Par dstub If you do not know how to ob tain a Sonnet example select Help gt Examples from any program menu then click on the Instructions button TIP If you are using the PDF manuals to read this section click on the blue link above to take you to the Par dstub example 155 Sonnet User s Guide This is an example of a microstrip interdigital bandstop filter This circuit is used to perform a parameter sweep and optimization Most parameter sweeps and op timizations will present more of a challenge but we have deliberately chosen a simple example to more clearly demonstrate Sonnet s methodology Our goal is to design the bandstop filter such that a stopband exists from 5 6 GHz and the passbands are from 1 4 GHZ and 7 10 GHz Open Par_dstub in the project editor Select File gt Save As from the project editor main menu Since this file is a Sonnet exa
216. ions are cell wide When X Min is set to 2 the subsections along vertical edges are now 2 cells wide in the X direction see the figure on page 38 This re duces the number of subsections and reduces the matrix size for a faster analysis However accuracy may also be reduced due to the coarser modeling of the current density near the structure edge or a discontinuity 37 Sonnet User s Guide 2 Cells Wide X Min 2 4 Cells 1 Cell Wide g Y Min 1 p 2 Cells v Cell Size x A portion of circuit metal showing how em combines cells into subsections for Manhattan polygons when X Min 2 and Y Min 1 IfX min or Y min are greater than your polygon size em uses subsections as large as possible to fill the polygon NOTE The subsection parameters X Min Y Min X Max and Y Max are specified in cells not mils mm microns etc For example X Min 5 means that the minimum subsection size is 5 cells Although the X Min and Y Min parameters are very useful options it is not a sub stitute for using a larger cell size For example a circuit with a cell size of 10 mi crons by 10 microns with X Min 1 and Y Min 1 runs faster than the same circuit with a cell size of 5 microns by 5 microns with X Min 2 and Y Min 2 Even though the total number of subsections for each circuit may be the same em must spend extra time calculating the value for each subsection for the circuit wi
217. irst point set is indicated by small open squares on all the points in the set The message Click Mouse to Specify Second Reference Point appears on your display Next you will specify the second reference point and its point set To specify the second reference point for the parameter click the mouse on the intersection of the inside of the bottom stub to the transmission line as shown in the picture below lt lt lt fe stub 229 _______ Second Reference Point The second reference point is indicated by a small square which appears at the point you clicked Note that the first point set continues to be identified by small squares on all its points The next step is to select the point set you want attached to the second reference point Chapter 11 Parameter Sweep and Optimization Tutorial 21 22 23 Drag the mouse until all points on the lower stub are selected Selected Points These points will be added to the second adjustable point set When the second reference point moves these points move in the same direction and distance as the reference point Once all the desired points are selected press Enter This completes the second point set and the symmetrical parameter The Parameter Properties dialog box appears on your display Enter the name Sstub in the Variable Name text entry box in the Parameter Properties dialog box and click on the OK button This assigns t
218. is point this manual has been focused on using Sonnet for the analysis of high frequency circuits and transmission structures However there is a large class of radiating structures for which Sonnet has proven very useful This chapter de scribes how to use Sonnet to analyze 3 D planar radiating structures such as mi crostrip patch arrays and microstrip discontinuities using the Open Waveguide Simulator technique The underlying assumptions of this technique are described in detail Common modeling mistakes are also pointed out Examples are provided to illustrate the correct use of the modeling technique This chapter also discusses the far field viewer an analysis and viewing tool which calculates far field antenna patterns for arbitrary 3 D planar geometries The far field viewer uses the current distribution data in the project as input and creates a pattern The pattern may be viewed as a cartesian polar or surface plot 273 Sonnet User s Guide Background Since em is an analysis of 3 D planar circuits in a completely enclosing shielding rectangular box the analysis of radiating structures is not an appli cation which immediately comes to mind However em can be used to simulate infinite arrays using a waveguide simulator In this technique as shown in on page 275 a portion of the array is placed within a waveguide The waveguide tube is vertical connecting the radiating patches to the termination which is a ma
219. ition of co calibrated ports has little influence on the total analysis time of the em job However for some circuits co calibrated ports may require more time in the de embedding phase of the analysis In these cases you may wish to use auto grounded ports which are more efficient but less accurate than co calibrated ports since the de embedding for auto grounded ports does not take into account the coupling between the auto grounded ports Special Considerations for Auto Grounded Ports Metal Under Auto Grounded Ports Similar to co calibrated ports which use the Sonnet box as the ground node con nection you cannot have metal directly beneath an auto grounded port in a multi layer circuit Auto grounded ports are two terminal devices with the positive ter minal connected to an edge of a metal polygon and the negative terminal connect ed to the ground plane When em detects the presence of an auto grounded port it automatically connects the two terminals in this manner This includes circuits which have multiple dielectric layers between the polygon and the ground plane However in order for em to accomplish this there must be a direct path from the edge of the metal polygon to the ground plane When an auto grounded port is used in a circuit where there is more than one dielectric layer between the port and the ground plane em checks to make sure that there is no metal directly beneath the auto grounded port If metal is found em prints
220. ject Chapter 10 Parameterizing your Project Sonnet allows you to assign variables and equations to many properties in order to parameterize your project Below are some of the reasons you might wish to pa rameterize your project Avoid creating multiple projects Parameter Sweep of a project allows you to vary a circuit property during an analysis Optimization of a project Easier construction and maintenance of a project Using equations to establish relationships between circuit proper ties Variables may be used for the following properties in your project Geometry dimensions Metal Properties Dielectric Properties Ideal Component Values Layer Thicknesses The value of a variable may be changed either by you or by the analysis engine during a parameter sweep or optimization During a parameter sweep em sweeps the variable values through a user defined range therefore changing the properties of your circuit In an optimization the analysis engine controls the variable value 129 Sonnet User s Guide within a user defined range in an attempt to reach a user defined goal Both pa rameter sweeps and optimization of a project may be performed over a range of analysis frequencies For a tutorial which details how to add variables to your circuit and perform an optimization please refer to Chapter 11 Parameter Sweep and Optimization Tutorial on page 155 For most circuit properties you simply defi
221. ject analysis are used to compute the results for the netlist Transmission Line co A YKI SRS O xI O 3 SSC 2805 A gt TI ADT X sec KN k Resistor x RRS SOR gt Transmission Line The netlist project att_combine son is shown below The project att_combine son is available as part of the Att example for this chapter Dee x x 8 8 2 we ee 8 va S S2P 1 2 att res16 s2p S2P 2 3 att_res16 s2p PRJ 2 0 att res67 son Hierarchy Sweep DEF2P 1 3 ATTEN Main Network Messages and Prompts Network None Line None The primary distinction between the netlist shown above and the previous netlist is that this netlist contains an instruction to perform a project analysis The PRJ keyword instructs em to run an electromagnetic analysis on the project att_res67 son using the analysis controls from the netlist The analysis control use is indicated by Hierarchy Sweep in the PRJ statement When control is set to Hierarchy Sweep em automatically analyzes the subproject at the same fre quency sweep and run options as the netlist During the analysis em performs the following steps 1 Reads S parameter data from the file att_res16 s2p 2 Performs an electromagnetic analysis of the geometry project att_res67 son a 67 ohm thin film resistor 203 Sonnet User s Guide Frequency 3 Combines the S parameter results from the electromagn
222. l dielectrics Using a causal dielectric will vary the properties of the dielectric layer the relative dielectric constant the dielectric loss tangent and the dielectric conductivity slightly over a frequency band The variations are modeled using Debye functions based on a reference freguency The reference frequency is the frequency at which the values entered for the properties are known to be accurate based on obtained measurements or given by the manufacturer The options to use causal dielectrics are provided below Meaning CausalDielectrics lt freq gt where lt freq gt is the reference frequency in Hz at which you know the values for the dielectric properties are accurate For example if your reference frequency is 3 0e9 Hz than the option you enter would be CausalDielectrics3 0e9 CausalDielectrics Use this option if you do not know the reference frequency In this case the analysis engine uses the average of the minimum and maxi mum analysis freguencies to obtain a reference freguency 348 For a detailed technical discussion of Causal Dielectrics and the use of Debye functions in modeling them please see the following article Morgan Chad Solutions for Causal Modeling and A Technique for Measuring Causal Broadband Dielectric Properties DesignCon 2008 February 4 7 2008 Appendix Em and xgeom Command Line for Batch xgeom Command Line You may also run the project editor
223. l stop the analysis job Two examples of this type of polygon are shown below In the polygon shown on the left the vertices have been labelled in the order in which they were added Adjacent Polygons Should Have No Gap Any polygon which is adjacent to another polygon using conformal meshing should have its edges exactly touching with no gap existing between the two poly gons Extremely tiny gaps are automatically removed but should be avoided Tiny gaps can be easily avoided by using any of the following methods e Using a snap grid while drawing your circuit Tools gt Snap Setup e Creating a larger polygon then dividing the polygon Edit gt Divide Polygons and applying conformal meshing to one of the resulting polygons The resultant polygons are adjacent with no space in between e Adding a small polygon which bridges the gap and overlaps the two polygons on either side of the gap then using the Merge Polygon command Edit gt Merge Polygons e Snapping the existing polygons to the grid Modify gt Snap To command using the Preserve shape and spacing option WARNING If you are snapping a circuit with curved edges use the Preserve shape and spacing option in the Snap Objects dialog box Otherwise curved edges can become distorted and are difficult to restore in the project editor Chapter 12 Conformal Mesh Rule 4 Adjacent Polygons Should Not Have an Interior Vertex When three polygons are adjacent a ver
224. l value for Sstub N WARNING It is recommended that you change the nominal value of dimension parameters by using the properties dialog box since changing your nominal value this way does not affect any previous response data in your project file If you change the nominal value of the dimension parameter by changing the circuit through editing commands such as a reshape all previous response data is deleted from the project file when you save Setting Up an Optimization 29 Select Analysis gt Setup from the main menu of the project editor The Analysis Setup dialog box appears on your display 173 Sonnet User s Guide 30 Select Optimization from the Analysis Control drop list This selects a optimization as the type of analysis The dialog box s appearance changes to accommodate the input needed for an optimization Note that initially the nominal values are listed for the variables since no range has yet been specified H Analysis Setup par_dstub son Options I Compute Current Density Speed Memory l Memory Save Advanced Analysis Control Sana Main Analysis Control drop list Optimization Parameters Lstub 220 0 fixed Sstub 200 0 fixed Variables list Optimization Goals Optimization Goals one 31 Click on the Edit button on the right side of the Variables list 32 174 The Optimization Parameters dialog box appears on your display
225. l you will see a bright polygon Only the outline of the dielectric brick is visible from levels other than the origi nation and termination of the dielectric brick Note that while it is possible to see a brick from two different circuit levels se lecting a brick for cutting copying moving changing attributes etc can only be done from the circuit level where the base of the brick is located if you are in Single layer edit mode The polygon can be selected on either level if you are in multilayer select 267 Sonnet User s Guide 268 Finally it is possible to turn the display of dielectric bricks on or off in the project editor You select View gt Object Visibility from the main menu of the project editor which opens the Object Visibility dialog box shown below Visibilty 21x Make Visible All Objects Only Objects Checked Below W Metalization B M Ports W Parallel Subsections W Vias W Reference Planes M Dimensions W Parameters M Subdividers Click on the Only Objects Checked Below radio button to enable the object choic es then click on the Dielectric Bricks checkbox to turn off the display of the bricks This will make any bricks present in the circuit invisible and unselectable but does not remove them from the circuit The dielectric bricks can be turned back on by once again selecting View gt Object Visibility and clicking the Dielectric Bricks
226. lanation of the log see Broadband Spice Extractor Log page 324 11 Click on the Plot button to open a plot of your response data versus the predicted S Parameter data The Predicted S Parameter data is opened in the response viewer along with the original response data You should view the S parameter with the greatest error and any other critical response data whose error was greater than 0 1 to judge if the fit or accuracy of the model is sufficient for your needs If the model is not accurate enough see Improving the Accuracy of the Broad band Spice Model page 326 for suggestions on improving your Broadband Spice model Checking the Accuracy of the Broadband Spice Model It is possible to save the predicted S parameter data created while calculating your Broadband Spice model so that you may visually check the accuracy of your mod el when it is complete To save the predicted S parameter data you should select the Generate Predicted S Parameter data file checkbox in the Output Broad band Model File dialog box when you create your model The predicted S param eter data file is created in the same directory as your Broadband Spice model file 323 Sonnet User s Guide 324 Upon the completion of creating your Broadband model you should open the original project in the response viewer then add the predicted S parameter data file to your graph and compare the two responses If you are creating your Broad ba
227. lex data curve are related to box resonances As with the runtime warning message these Chapter 22 Package Resonances NOTE are theoretical values based on an empty Sonnet box The specified dielectric lay ers are considered but the effect of any circuit metallization and loss parameters are not To access the Box Resonance Estimator select Analysis gt Estimate Box Reso nances from the project editor main menu The Box Resonances dialog box ap pears on your display An example is shown below Box Resonances package son x Box resonances estimated for package son Calculation based on lossless empty cavity Only lowest order modes considered 30 09 GHz TE Mode 0 1 2 31 76 GHz TE Mode 0 1 3 The Box Resonance Estimator displays not only the resonant freguencies con tained in the simulation freguency range but also tells the user the particular mode type It is sophisticated enough to realize that when Symmetry is enabled for a cir cuit that Even Y modes will not exist In this particular instance two Transverse Electric TE modes exist in or around the desired freguency range The Box Resonance Estimator will detect Trans verse Magnetic TM modes as well For a complete description of propagation modes please refer to any classic field theory textbook The Box Resonance Estimator only checks the primary structure not the de embedding calibration standards 335 Sonnet User s Guide Box Resonances
228. line using either one or two subsections across the width of the line gives the same amount of error We find that a one or two subsection wide line gives 5 to 6 error If there is not much stray coupling circuit theory can often give a better result When the line is 16 cells wide we see about 1 error much more reasonable We have found and you can verify that convergence is very strong Double the number of cells per line width and the error is cut in half 341 Sonnet User s Guide 342 When we vary the number of cells per wavelength along the length of the line we see an inverse square relationship Double the number of cells per wavelength along the length of the line and the percent error decreases by a factor of four An equation which expresses the error as a function of subsectioning is _ 16 16 where Nw Number of cells per line width Ny Number of cells per wavelength along line length Er Total Error DMAC This eguation estimates subsectioning error only For example any de embedding errors are added to the above error This error estimate should be valid for any electromagnetic analysis which uses roof top subsectioning Notice that the guantities used for the error estimate are in terms of cells not sub sections Cells are the smallest possible subsections size In Sonnet subsections in the corners of polygons are one cell on a side Subsections along the edge of polygons are one ce
229. list The desired output network is the series combination of resistors The S Parameter data file att_res16 s2p as well as the geometry project att_res16 son used to generate the data file are included in the examples for this chapter Chapter 13 Netlist Project Analysis 1 6 S parameter N a 2 S parameter Node 3 file att res16 s2p fileatt res16 s2p i o 2 The two port S parameters contained in file att_res16 s2p are cascaded to obtain an overall set of two port S parameters The netlist att_cascade son for the circuit is pictured below 2P 1 2 att_res16 s2p 2P 2 3 att_res16 s2p DEF2P 13 RESNET Main Network Use buttons or menus to modify netlist Network None Line None The main network Resnet has two ports indicated by the 2 in DEF2P Port 1 corresponds to node 1 in the network Port 2 corresponds to node 3 There are two data file elements in the network The first entry is the response file att_res16 s2p with 2 ports Port 1 corresponds to node 1 of the network which as mentioned above is port 1 of the whole circuit Port 2 for the data file corresponds to node 2 of the network The other entry is also for the data file att_res16 s2p except that port 1 ofthe data file goes to node 2 of the network which means that port 1 of the second data file is connected to port 2 of the first data file Port 2 of the second data file corresponds to no
230. ll wide and can be many cells long Interior subsections can be many cells in both dimensions We have found that for most cases the cell size is the important parameter in de termining error Or in other words the smallest subsection size is important For example the stripline benchmark geometry projects mentioned before are set to make the lines 16 cells wide even though those 16 cells may be merged into only 4 or 5 subsections It is the 16 cells which determine the level of error not the 4 or 5 subsections In performing this error evaluation we also found that the error in characteristic impedance due to Nw is always high never low Also there is very little variation in the error for different impedance lines The above eguation can be very accurate in evaluating error And finally for Ny above about 40 cells per wavelength all the error is in the characteristic impedance The error in velocity of propagation is essentially zero The above eguation can be very accurate in evaluating error With this precise knowledge of the error we can now do something about it Chapter 23 Accuracy Benchmarking Using the Error Estimates The above error estimate can be used to estimate the error for an overall circuit Let s say that a cell size is used that makes some high impedance transmission lines only 1 cell wide Other low impedance transmission lines are say 30 cells wide The 1 cell wide lines give us about 5 error T
231. llowing Right click on a dimension parameter in your circuit The variable name and the dimension parameter point set is highlighted and a pop up menu appears on your display Select Select Dependents from the pop up menu If any dependent dimension parameters are present in your geometry the dependent dimension parameter is highlighted Circular Dependencies in Parameters Care should be taken when adding dimension parameters to your circuit that they do not form a circular dependency A circular dependency is formed when two di mension parameters are dependent on each other This can happen for two dimen sion parameters or multiple dimension parameters In the case of multiple dimension parameters the dependency extends from the first dimension parame ter through all the dimension parameters until the first dimension parameter is de pendent upon the last 147 Sonnet User s Guide If the project editor detects a circular dependency of dimension parameters all the involved dimension parameters are shown in red An example of two dimension parameters in a circular dependency is shown below A circular dependency is an error condition and must be corrected before you can analyze your circuit You need to redefine one of the dimension parameters such that it is no longer dependent on the other Parameter Sweep 148 Once you have defined variables in your circuit you may use the variables to per form a par
232. lustrated above 101 Sonnet User s Guide La ra a a a a a eA eee SO I S Parameters S parameters from em from em with l without TA I de embedding l I Device I O Under I I Test I I R R I I CC C I I I I K I I I L m m J Block cascaded to negate Box wall port box wall port discontinuity discontinuity De embedding automatically cancels the discontinuity associated with a box wall port Shifting Reference Planes Transmission lines are reguired in many circuits to connect ports to the device un der test DUT If the length of a transmission line is more than a few degrees rel ative to a wavelength unwanted phase and possibly loss will be added to the S parameter results If the impedance of the transmission line differs from the nor malizing impedance of the S parameters usually 50 ohms an additional error in the S parameters results Thus if we are only interested in the behavior of the DUT any long transmission lines connecting the ports to the DUT should be re moved during de embedding The process of removing lengths of transmission line during de embedding is known as shifting reference planes Reference planes may be specified in the project editor for box wall co calibrat ed and auto grounded ports but not ungrounded internal and via ports When em detects a reference plane and de embedding is enabled it aut
233. m the specified file lt exfile gt This field is optional If neither Exp option is included then the default export options are used This option is not applicable for a GDSII export Any options set in this file override any default options or options set in the registry Options which can be entered in the Export Options file lt exfile gt are in the following table The lt boolean gt field can use any of the following entries yes no true false on off Each option should be entered on a separate line Not all options need to be specified 349 Sonnet User s Guide Each entry corresponds to a control in the DXF or Gerber Export Options dialog box Each entry provides syntax and the control to which it corresponds Please refer to Help in the project editor for details about the control You may access Help by opening the appropriate Export Options dialog box and clicking on the Help button in the dialog box Entry Definition SepObj lt boolean gt Separate By Object Types checkbox DXF amp Gerber SepMat lt boolean gt Separate By Material Types checkbox DXF amp Gerber DivideMulti lt boolean gt Divide Multi layer Vias checkbox DXF amp Gerber Circles lt boolean gt Convert Vias to Circles checkbox DXF amp Gerber CircleType lt type gt lt type gt is inscribed or manual Inscribed corresponds to the Auto radio button Manual corresponds to the Manual radio
234. mal cell size based on your critical circuit parameters You access the Cell Size Calculator in the Box Settings dialog box Circuit gt Box Using the Cell Size Calculator is detailed in Chapter 6 Determining Cell Size of the Getting Start ed manual A detailed discussion of all the entries in the cell size calculator may be found in Help Viewing the Subsections You can see the subsections used by Sonnet by following the instructions below Be aware that your dielectric layers must be defined and at least one port must be added to your circuit before you may use the Estimate Memory command To view the subsectioning do the following 1 From the project editor select Analysis gt Estimate Memory This calculates the amount of memory required for your analysis 2 Click the View Subsections button A picture of your circuit will appear The metal will show up as red and the sub section borders will show up as black lines as shown in the illustration below Metalization Note the use of smaller subsections in an area where current density is changing rapidly Subsection Borders 33 Sonnet User s Guide Subsectioning and Simulation Error As discussed above Sonnet uses a fixed resolution grid and discretely meshes a given metallization pattern based on that underlying grid The edges of metal pat terns in a design do not necessarily have to be aligned to the grid even though Sonnet only simulate
235. may only be used when the ground node connection is defined as the Sonnet box All the Component ports on a side of a Component use the same reference plane For a detailed discussion of reference planes and de embedding please see Chap ter 7 De embedding on page 97 As with all Sonnet reference planes the Component reference planes are snapped to the grid It is important that you are working with a fine enough cell size to en sure the accurate placement of your reference planes If the length is set to less than one half the cell size then the reference plane will not be displayed in the project editor window Calibration Lengths The analysis engine will automatically determine appropriate lengths for the cali bration standards used in the de embedding algorithm Normally the Auto setting default produces efficient and highly accurate simulation results In rare cases you may wish to manually override the automatic lengths Before manually over riding these settings please be sure to read Chapter 8 De embedding Guide lines on page 107 91 Sonnet User s Guide Physical Size You may enter a physical size for your Component for display purposes The physical dimensions length width and height are not used in the simulation but do affect how your Component is displayed in the project editor You may enter the precise dimensions or choose Auto to have the software choose approximate dimensions based on you
236. mmonly refers to a connection from metal on the substrate sur face to the ground plate beneath the substrate However as used in Sonnet a via can be used to connect metalization between any substrate or dielectric layer not just bottom layer to ground Thus em s vias can be used in modeling airbridges spiral inductors wire bonds and probes as well as the standard ground via Restrictions on Vias Em s vias use a uniform distribution of current along their height and thus are not intended to be used to model resonant length vertical structures The height of the via should be a small fraction of a wavelength The via height is the same as the thickness of the substrate or dielectric layer it penetrates 241 Sonnet User s Guide If a microstrip substrate is a significant fraction of a wavelength thick over mod ing also becomes a major problem If vias are used to form for example a septum or an interior wall you may need to model it with multiple layers to achieve an accurate analysis Creating the Vias 242 Vias may be added to your circuit in a number of ways Both the direction and type of via is chosen in the Tools gt Add Via menu The default may be set to go up one level down one level or down to ground through multiple layers if necessary Vias may be edge vias rectangular vias via polygons or circular vias Via Direction A via which goes up one level extends from the level of metalization to which it
237. mple it is a read only project In order to be able to edit the circuit and save those changes you must save a copy to your working directory Use the Save As browse window to save a copy of par_dstub son to your working directory Setting Up Dimension Parameters 156 Before executing either a parameter sweep or optimization it is first necessary to to add your variables and dimension parameters Variables should be used for the properties most critical to the circuit s response Dimension parameters should be added to those dimensions you deem critical to the circuit s response These prop erties and dimensions are the most likely to change as the design progresses For this example you will enter three dimension parameters two anchored di mension parameters which are linked and one symmetric dimension parameter Anchored dimension parameters are referred to as anchored parameters and sym metric dimension parameters are referred to as symmetric parameters for the rest of the tutorial An anchored parameter is one in which one end of the dimension parameter is a fixed point with a point set which moves in reference to that fixed or anchored point A symmetric parameter is one with two reference points and two point sets which move relative to the center point between the reference points Dimension parameters which appear in more than one place in a circuit but are of the same length and assigned the same variable are linked Ch
238. n Currently Sonnet can export the RLGC parameters in a format compatible with the MTLINE component in Cadence Virtuoso Spectre 317 Sonnet User s Guide 318 Shown below is an example of a project composed of four transmission lines R NNN Ni s s s wn ASX GSS MM BRYSSSSSAQGWFI AHS As in the circuit shown above the input ports of your project must be numbered 1 through N and the output ports N 1 through 2N The input of line M should be port M and its output should be port M N The software does not check for this condition but issues a warning message if the number of ports is not an even num ber You may generate RLGC parameters automatically by setting up an output file in the project editor To setup an output file in the project editor select Analysis gt Output Files from the project editor main menu then click on the N coupled Line Model button in the Output Files dialog box which appears You may also gener ate an output file of RLGC parameters from previously generated response data in the response viewer To do so open your project in the response viewer and select Output gt N coupled Line Model from the response viewer s main menu RLGC parameters are generated for each analysis frequency Chapter 21 SPICE Model Synthesis FORMAT Freq Shown below are the RLGC parameters in Spectre format for a two line project F 0 70709735571 2 43871317e 7 0 70712912656 0 00
239. n If the sidewalls form below a cut off waveguide there is no radiation Second Condition Make sure the sidewalls are far enough from the radiating structure that the sidewalls have no affect Another way to look at this condition is to consider the image of the structure dis continuity or antenna created by the sidewall Position the sidewall so that the im age it forms has no significant coupling with the desired structure Usually two to three wavelengths from the sidewall is sufficient for discontinui ties For single patch antennas one to three wavelengths is suggested Require ments for specific structures can easily be greater than these guidelines If the First Condition requires a larger substrate dimension than the Second Condition it is very important that the larger dimension is used If you are using the far field viewer the larger the box the better The far field viewer assumes that S parameters from em are from a perfect open environment If some of the power is reflected due to a box that is too small the input power calculated by the far field viewer will be slightly incorrect The far field viewer then calculates antenna efficiencies greater then 100 If this occurs the box size should be increased Third Condition Place the top cover outside the fringing fields i e near field of the radiating structure preferably a half wavelength If this condition is violated the resistive top cover becomes involved i
240. n the Object Visibility dialog box and the Selection Filter dialog box The following are illegal conditions for subdivision lines e May not be off grid e Should not be placed where there is coupling across the subdivision line e May not be colinear with polygon edges e May not split a diagonal polygon edge e May not split a port e May not be below the line of symmetry e May not split a polygon at a box wall See the picture below Chapter 14 Circuit Subdivision Illegal Subdivision Lines Illegal Subdivision Lines Once you have completed adding all the desired subdividers to your circuit you must save the project before performing the subdivision Setting Up Circuit Properties Since the geometry subprojects created by the subdivide inherit their properties from the source project you should complete entering all the desired attributes for your circuit before performing the subdivide This includes such things as defin 223 Sonnet User s Guide ing the dielectric layers which includes the height of the box top top and bottom box metals metal and dielectric brick materials cell size and box size This saves the effort of having to enter these values in each of the subprojects Setting Up the Coarse Step Size Frequency Sweep If you plan to use interpolation to obtain response data when analyzing the master netlist project you should input the coarse frequency sweep at which yo
241. n the reac tive fringing fields which form the near field of the radiator This changes what would have been reactive input impedance into resistive input impedance overes timating the radiation loss Chapter 19 Antennas and Radiation Do not place the top cover thousands of wavelengths away from the radiator Ex treme aspect ratios of the box should be avoided Empirical data for patch anten nas has shown that a distance of about 1 2 wavelength works best Fourth Condition Set the top cover to Free Space This value is a compromise As shown by the equations on the previous page all TE modes have a characteristic impedance larger than 377 ohms Q while all TM modes are lower Thus while a 377 Ohms square top cover does not perfectly ter minate any mode it forms an excellent compromise termination for many modes This approximates removing the top cover of the box If the box is large it in turn approximates radiation as shall be demonstrated Fifth Condition The radiating structure can not generate a significant surface wave If there is a significant compared to required accuracy surface wave it is reflect ed by the sidewalls of the box Unless this is the actual situation such antennas are inappropriate for this technique Actually the Fifth Condition is a special case of the Second Condition since if there is significant surface wave the Second Con dition cannot be met This condition is stated explicitly becaus
242. nal of Microwave amp Millimeter Wave Computer Aided Engineering Vol 1 No 3 July 1991 pp 282 287 Appendix II Sonnet References 78 79 80 81 82 83 84 85 86 87 88 89 90 J C Rautio Triangle Cells in an Electromagnetic Analysis of Arbitrary Microstrip Circuits MTT International Microwave Symposium Digest Dallas June 1990 pp 701 704 J C Rautio Experimental Validation of Microwave Software 35th ARFTG Conference Digest Dallas May 1990 pp 58 68 Voted best paper at the conference J C Rautio Preliminary Results of a Time Harmonic Electromagnetic Analysis of Shielded Microstrip Circuits 27th ARFTG Conference Digest Dallas Dec 1986 Voted best paper at the conference J C Rautio An Experimental Investigation of the Microstrip Step Discontinuity IEEE Tran Microwave Theory Tech Vol MTT 37 Nov 1989 pp 1816 1818 J C Rautio A Possible Source of Error in On Wafer Calibration 34th ARFTG Conference Ft Lauderdale FL Dec 1989 pp 118 126 J C Rautio Microstrip Program Improves Accuracy of Circuit Models Microwaves amp RF Vol 27 No 12 pp 89 96 Nov 1988 J C Rautio Reflection Coefficient Analysis of the Effect of Ground on Antenna Patterns IEEE Antennas and Propagation Society Newsletter Feb 87 pp 5 11 J C Rautio and R F Harrington An Electromagnetic Time Harmoni
243. nalyzes the first freguency in the current density data stored in the project at a default set of angles and port excitations when the file is opened To obtain the antenna pattern for other than the first freguency you must select Graph Calculate from the far field viewer main menu The Calculate dialog box allows you to set up all the parameters for the data you desire to calculate The far field viewer calculates the fields radiated by the current that is stored in the project The analysis is performed in an open environment with a substrate of in finite extent For details on the Calculate dialog box please refer to the Help in the far field viewer program Please refer to Far Field Viewer Tutorial page 287 for a tutorial on using the far field viewer Analysis Limitations The analysis of the far field viewer has the following limitations e The plotted antenna patterns do not represent de embedded data Therefore the effect of the port discontinuity is still included even if you specify de embedding when running em e Radiation from triangular subsections i e diagonal fill is not included e The far field viewer patterns are for a substrate which extends to infinity in the lateral dimensions 281 Sonnet User s Guide 282 Spherical Coordinate System You view your antenna plot using the spherical coordinate system which is de scribed below To view an antenna plot the far field viewer uses the
244. nations list There should be only one entry in this list the Select All button was used to demonstrate its function This selects all the parameters in the Selected List Click on the Up Arrow button to move all the parameter combinations to the Unselected list Double click on Lstub 120 mils in the Unselected List This moves this parameter combination to the selected list so that the data for this combination appears in your plot Click on the OK button in the Select Parameters dialog box to apply the changes and close the dialog box The entry Lstub 120 0 Sstub 220 0 appears in the Parameter Combinations section of the Edit Curve Group dialog box 169 Sonnet User s Guide 24 Click on the OK button in the Edit Curve Group dialog box to apply the changes and close the dialog box The plot is updated with the S21 response for Sstub 220 mils Lstub 120 mils The entry for the curve group par_dstub appears in the Curve Group Legend The graph should be similar to the one shown below E par dstub son RESCUES EIE Cartesian Plot Z0 50 0 Left Axis par dstub DB S21 M a g n i t u d e N as 5 6 7 Sonnet Software Inc Freguency GHz Click mouse to readout data values Pointer 170 Chapter 11 Parameter Sweep and Optimization Tutorial 25 To add the response at Lstub 280 mils select Curve gt Add Curve Group from the response viewer main menu The Add
245. nclude modeling cross talk and propaga tion delay in digital interconnect circuits and multiple spectrum circuits that com bine digital analog and RF functions The Broadband Spice model is fitted over a wide frequency band and can be used in circuit simulators for AC sweeps and tran sient simulations Broadband Spice Extractor is only available if you have purchased a license from Sonnet which includes the Broadband Spice Extractor feature Please see your system administrator if you are unsure of the availability of this option PI Spice Model Specifying an optional PI Model Spice output file automatically takes the results of the electromagnetic analysis of a circuit and synthesizes a model using induc tors capacitors resistors and mutual inductors This information is then formatted and saved in one of two SPICE formats PSpice or Spectre 311 Sonnet User s Guide 312 The PI model Spice generation capabilities are intended for any circuit which is small with respect to the wavelength at the highest frequency of excitation Typi cally 1 20th wavelength is an appropriate limit If a circuit is too large you can often split it into two or more circuits and analyze each separately This limitation is due to the circuit theory limitations of modeling a circuit with just a few lumped elements The Sonnet electromagnetic analysis is not intrinsically limited in this fashion The model generated by the analysis i
246. ncludes any lumped elements including mutual inductors between any ports of the circuit layout Lumped elements from any port to ground are also included The synthesis capability does not allow in ternal nodes nodes which are not connected to a port in the layout with the single exception of the internal node required to specify a resistor in series with an in ductor Any circuit which requires internal nodes for an accurate model should be split into several parts so that the required points become nodes Internal ports without ground reference give incorrect results Any internal ports should be carefully specified and checked for reasonable results Using The PI Model Spice Option The PI Model synthesis needs electromagnetic results for at least two frequencies to accomplish its work It is not possible to create a PI model if the circuit is ana lyzed at only one frequency A PI model is created for pairs of frequencies The second frequency is determined by taking the first frequency and adding a percent age specified by the user The second frequency then becomes the first frequency for the next pair of frequencies for which a SPICE model is generated The syn thesis continues in this way until all the frequencies have been used The default value for the separation percentage is 10 In this case a SPICE mod el is generated using the first frequency and the next highest frequency which pro vides a 10 gap This continues until th
247. ncy band in which you are concerned and decrease the number of data points in frequency ranges which are not as important e You may be able to increase the accuracy of your model by using the Stability factor Please see Broadband Spice Extractor Stability Factor in the next section Broadband Spice Extractor Stability Factor Although the extracted model may be a good fit to the S parameters a transient analysis which uses the model may be unstable To help with this problem Sonnet provides a control which pushes the poles away from the unstable region Howev er pushing the poles too far could result in a less accurate fit usually by causing a decrease in the Q of the circuit Therefore you should only use this control if you are having stability problems with the model The Broadband Spice stability factor allows you to control the amount by which the model fitting forces the poles of your model away from the unstable region The factor represents a magnitude ratio for which the real part of a pole cannot be less than the magnitude of the pole The higher the stability factor the greater the effect on the model Reasonable val ues for the stability factor are between 0 5 to 1 0e 5 the default value is 1 0e 3 If you are having stability problems raising this value may result in a stable model The forcing done using the stability factor could result in a decrease in Q such that strongly resonant structures need a lower value but
248. nd Model in the response viewer you may do this automatically by clicking on the Plot button in the Broadband Spice Details dialog box which appears upon completion of your model Use the log information in the Details window which is detailed in the next section to determine which parameter had the highest error and any critical parameters whose error was greater than 0 1 Check these pa rameters to see how much the curve fit data varies from your circuit response If your Broadband Spice Model is to be used for a transient analysis be aware that the frequency response of the model up to 1 T where T is the minimum time step of the transient analysis is important You should use the Advanced Broadband Model options dialog box to specify additional predicted data up to 1 T You ac cess this dialog box by clicking on the Advanced button in the Broadband Model File entry dialog box in the project editor or in the Output Broadband Model dia log box in the response viewer This allows you to view the frequency response of your model at data points not included in your em analysis You should look for anomalies in the response that indicate a problem with the model such as S pa rameters greater than one or unexpected sharp resonances You may also use the stability factor in order to ensure a stable transient analysis Please see Broadband Spice Extractor Stability Factor on page 327 If the model is not accurate enough see Improving the Accu
249. nd can be placed in any circuit layer This allows for instance alumina bricks to be created in an air circuit layer However it is also possible to reverse this scenario Dielectric bricks made of air can also be created in alumina circuit layers This is an important consideration to remember Depending upon the circuit geometry for a given ap plication this ability to reverse the dielectric characteristics may simplify the cir cuit and make it faster to analyze Limitations of Dielectric Bricks Diagonal Fill Diagonal fill is not allowed for dielectric bricks All dielectric bricks must use staircase fill Thus dielectric bricks with curved or rounded edges must be stairstep approximated Note that the error caused by such an approximation de creases as the X and Y cell sizes are decreased Thus it is possible to make this error arbitrarily small by choosing sufficiently small X and Y cell sizes Antennas and Radiation The far field viewer does not support dielectric bricks Circuits containing dielec tric bricks can be analyzed with the far field viewer but the radiation effects of the dielectric bricks are not accounted for in the analysis Interfaces The Agilent ADS Interface Cadence Virtuoso Interface and AWR MWOffice do not create dielectric bricks 266 Chapter 18 Dielectric Bricks Dielectric Brick Concepts Creating a Dielectric Brick To create a dielectric brick in the project edit
250. ne a variable and enter that variable in a property field However if you wish to vary the size of your geometry for ex ample changing the width of a feed line or the length of a polygon you define a dimension parameter which identifies the dimension you wish to change Once the dimension parameter is defined you assign a variable to the dimension parameter The first step in performing a parameter sweep or optimization is defining the variables and dimension parameters in the project editor Variables NOTE 130 Variables are user defined circuit attributes that allow the analysis engine to mod ify the circuit in order to perform parameter sweeps and optimization Variables also provide a quick way for the user to change dimensions in the project editor or multiple elements in a circuit For example the length of a transmission line can be assigned the variable L To change the length of the transmission line you edit the value for L Another example would be a circuit which contains 10 re sistors all of which have the same value Entering a variable R for the resistance of these ideal components allows you to change the value of all 10 resistors by changing the value in only one place Just because it is possible to use a variable in any given property field does NOT make it necessary to do so You may enter a nominal value for the field instead of a variable if you do not wish to change that particular property
251. nent Assistant Ports Only The Ports Only Component allows you to insert internal ports in your circuit which may be used later in a circuit design program All of the ports associated with this Component have a common ground and are simultaneously de embed ded during the electromagnetic analysis There is no limit to the number of ports your Component may have This Component type is functionally equivalent to us ing co calibrated internal ports For a detailed discussion of co calibrated ports see Co calibrated Internal Ports page 70 You add a Ports Only type Component by selecting the command Tools gt Add Component Ports Only This command opens the Components Properties dia log box as well as the Component Assistant Component Properties An important part of modeling a Component in Sonnet is to consider the condi tions under which the measured data or model for your Component was obtained These conditions should be used to determine 85 Sonnet User s Guide e The type of ground node connection e The terminal width e Ifreference planes are used for the Component ports and if so of what length The em environment should be set up to use the Component in the same manner that the component was measured The correct setting of the Component proper ties is discussed in detail below Ground Node Connection NOTE 86 The ground node connection defines how the ground of your Component is con nect
252. ng a dimension parameter double clicking on the variable name and entering a new nominal value allows you to check whether the dimension parameter was defined correctly Symmetrical Dimension Parameters A symmetric parameter defines a dimension using two reference points and their respective adjustable point sets The nominal value of the parameter is the distance between the two reference points The anchor is defined as the midpoint between 139 Sonnet User s Guide the two reference points the user does not define an anchor point for a symmetric parameter When the dimension is varied each point moves relative to the anchor point When defining your dimension parameter you perform the following steps e Select the first reference point e Select the adjustable point set that moves with the first reference point e Select the second reference point The value of the parameter is the distance between the two reference points e Select the adjustable point set that moves with the second reference point There is a setting associated with each dimension parameter that determines how the adjustable point sets are moved With the default and simplest option each point set moves one half the distance of the difference between the present value and the previous value out from the middle point maintaining its relative positive to the reference point with which it is associated For a discussion ofall the options contr
253. ng the circuit Please note that it is inaccurate to place the top cover directly on top of the circuit without an intervening dielectric layer Using either technique will entail changing basic project parameters making it necessary to analyze the project again Chapter 22 Package Resonances Below is the resulting S parameter S21 curve with the top cover set to free space Please note that while the resonance is still evident its level has been greatly atten uated Again the data is from a simulation of the example project package son package notop son ssa no E25 E 8 Cartesian Plot Z0 50 0 0 Left Axis 54 package_notop M 10 4 DB s21 a 154 g 204 Right Axis n 25 4 empty 30 4 t 35 4 u 404 d 454 e 504 55 4 dB 60 65 4 70 20 25 30 35 40 45 50 55 60 Sonnet Software Inc Frequency GHz Click mouse to readout data values Pointer The package resonances disappear when the top cover is removed Taking the top cover off works provided the sidewalls of the box are large enough to form a propagating waveguide up to the top cover or you can place the top cov er close enough to the substrate surface to catch the fields in the box mode High order box modes tend to be confined primarily to the substrate and can be diffi cult to remove in this manner As you make the box bigger by increasing the sub strate surface area the modes loosen up so that the
254. nodes 3 and 4 with Port 1 corresponding to node 4 and Port 2 corresponding to node 3 Port 1 ofthe network example_net corresponds to node 1 and port 2 of the network corresponds to node 4 A netlist project is simply a list of these elements as you can see in the netlist pic tured above Notice that the first number after the name of the element is the net work node which corresponds to port 1 of the element the second number is the network node which corresponds to port 2 of the element and so on for all the ports in an element Chapter 13 Netlist Project Analysis Netlist Project Analyses The sequence of steps for a netlist project analysis may be summarized as follows 1 You input the netlist using the project editor in netlist mode The project editor allows you to create and edit networks network elements project elements modeled elements and data file elements in your netlist You also input the analysis controls which may include defining parameters in the netlist 2 Em reads the netlist project which contains circuit and analysis control information This includes S Y and Z parameter data files modeled elements geometry subprojects project elements and network ele ments 3 Em uses the analysis controls input as part of the netlist project to run each electromagnetic analysis invoked by the network file It is possible to configure the analysis controls in such a way that geometry subproj ects are analyzed us
255. nt for most types of analy sis 109 Sonnet User s Guide Reference Plane Lengths at Multiples of a Half Wavelength Eee and Zo cannot be calculated when the length of the reference plane or calibra tion standard is an integral multiple of a half wavelength For example at an ex tremely low frequency the electrical length of the reference plane or calibration standard may be a fraction of a degree i e zero half wavelengths In this case the analysis is unable to accurately evaluate the electrical length and especially the characteristic impedance At some point as the length of the reference plane or calibration standard ap proaches a multiple of a half wavelength em is able to determine that the calcu lated values of E grand Zp are becoming corrupt When this occurs em outputs the error message undefined nl in place of the E and Zo values see De em bedding Error Codes in Help Note however that while em is unable to deter mine E grand Zo the de embedded S parameter results are still perfectly valid Reference Plane Lengths Greater than One Wavelength If the length of the reference plane or calibration standard is more than one wave length incorrect E p results might be seen However the S parameters are still completely valid Em s calculation of E gr is based on phase length If the reference plane or calibra tion standard is say 365 degrees long em first calculates E based on a phas
256. nt from the line of symmetry but have different port numbers so that the voltage is not equal Chapter 5 Ports Standard Box Wall Port A standard box wall port is a grounded port with the positive terminal attached to a polygon edge coincident with a box wall and the negative terminal attached to ground An example of a standard box wall port is shown below Standard box wall ports can be de embedded and can also have reference planes This type of port is the most commonly used Adding Box wall Ports You add a standard box wall port to your circuit by selecting the command Tools Add Ports and clicking on the polygon edge on the box wall where you wish to place the port Ports are numbered automatically in the order in which they are added to your circuit starting at the number one You may change the properties of a port after it has been added to the circuit by selecting the port and using the Modify Port Properties command For detailed instructions for these tasks please click on the Help button in the Modify Port Properties dialog box which ap pears when you select the command Ref Planes and Cal Lengths for Box Wall Ports Reference planes and calibration lengths are both used during the de embedding process in which the analysis engine removes the port discontinuity and a desired length of transmission line For details of how these values are used during the de embedding process please
257. nt values which fall outside the allowed range specified by the user in the model options are excluded from the resulting lumped model The RZERO entry is provided for those versions of SPICE which need inductors to have some small loss to avoid numerical difficulties The default value of 0 0 dis ables this capability Enter the desired values for the parameters in the PI Model Options dialog box 7 Click on the OK button in the PI Model Options dialog box to apply the changes and close the dialog box 8 Click on the Save button in the Output PI Model dialog box A browse window appears which allows you to save the data displayed in the output window The file extension depends on which type of SPICE format you have selected A Simple Microwave Example Shown below is the Ste sym example a simple step discontinuity followed by the PI model produced when you set up an optional PI Model Spice output file 315 Sonnet User s Guide Limits C gt 0 01pF L lt 100 0nH R lt 1000 00hms K gt 0 01 Analysis frequencies 1000 0 1100 0 MHz subckt SonData 1 2 GND C_C1 1 GND 0 273341pf C C2 2 GND 0 232451pf LI1 1 2 0 310155nh ends SonData There are two capacitors to ground node GND and one inductor connected be tween node 1 and node 2 in the lumped element model Topology Used for PI Model Output 316 The topology of the lumped element model generated by em depends on the cir cuit being analyzed In gene
258. ntial order you will receive an error message when you attempt an analysis The port order for the S Y or Z parameters will be listed in increasing numeric order For the example of a two port the output would be S11 S21 12 and S22 For a four port it would be 11 S12 S13 S14 S21 S22 etc Chapter 5 Ports NOTE For a discussion of using ports to model coplanar waveguides CPW please see Modeling Co Planar Waveguide CPW in Sonnet under Tips and App Notes in Help You can find this topic by selecting CPW in the help Index When you are referred to Sonnet s Help you may access Help by selecting Help gt Contents from the menu of any Sonnet application or by clicking on the Help button in any dialog box Changing Port Numbering You can change the port number of any port after it has been added to your circuit Any nonzero integer negative or positive is valid To change the number on a port or ports do the following 1 Select the port s whose number you wish to change 2 Select Modify gt Port Properties from the main menu to open the Port Properties dialog box 3 The number for the selected port s can be changed by typing the desired port number in the dialog box Note that if multiple ports are selected all are set to the number input in the dialog box Port Placement with Symmetry On Symmetry can be used to considerably reduce the amount of memory and process ing time required to analyze
259. ntrol section of the dialog box The Parameter Sweep Entry dialog box appears This dialog box allows you to add a parameter sweep The first step is to specify the analysis frequencies you wish to use for the param eter sweep For this example you wish to perform an ABS sweep from 2 0 GHZ to 10 0 GHz Since Adaptive Sweep ABS is the default sweep type you do not need to take any action to select it 4 Enter 2 0 in the Start text entry box in the Frequency Specification section of the Parameter Sweep Entry dialog box This is the starting frequency 5 Enter 10 0 in the Stop text entry box This is the highest frequency This defines a band of 2 GHz to 10 GHz for the adaptive sweep Next you will select the variables you wish to sweep 165 Sonnet User s Guide 166 6 Click on the checkbox in the Sweep column of the entry for the Lstub variable M Parameter Sweep Entry par dstub son x Freguency Specification Sweep Type Adaptive Sweep ABS Start Stop GHz GHz 2 10 j Cell Size 10 0 mils Linear Sweeps v j Y Cell Size 10 0 mils Sweep Start Stop Step Nominal W Lstub 120 0 280 0 160 220 0 M Sstub 220 0 Cancel Help It is possible to select multiple variables for a parameter sweep however for this example only one variable is used If you wished to deselect the variable you would simply click on the checkbox again Unchecked variables are simulated at thei
260. ntry boxes under Tick Labels 34 Enter 10 in the Interval text entry box This sets the intervals on the plot grid to 10 dB 301 Sonnet User s Guide 35 Click on the OK command button The dialog box disappears and the far field viewer display is updated with the new interval value for the axes Your display should be similar to the one shown below infpole son 3 E S ALS e 2 Plot over theta a 1 0GHZ Theta 45 0 Phi 0 0 0 96019 dB Pointer Shown above is the far field viewer calculated far field antenna pattern for the very short dipole in the file infpole son The result should be compared with theoretical result in the next figure 302 Chapter 20 Far Field Viewer Tutorial Exact far field antenna pattern from reference 2 of an infinitesimal dipole antenna one wavelength above a ground plane Selecting a Frequency Plot 36 37 38 39 To see how the antenna pattern changes with frequency you use a frequency plot Before you can select a frequency plot you must return to a cartesian plot Select Graph gt Type gt Cartesian from the far field viewer main menu Your display is updated with a cartesian plot Note that the autoscale is automati cally turned back on when you switch plot types Select View gt Legend from the far field viewer main menu The legend once again appears in your display Select Frequency from the Plot Over drop list on
261. o be attached the analysis engine issues an error message 93 Sonnet User s Guide 3 Nearby objects should be placed so that coupling between the Component and the object does not occur Metal polygons vias or dielectric bricks which couple to the Component ports may decrease the ac curacy of the analysis as shown below 4 All ports must be on a single metal level Sonnet does not support multi level Components 5 Multiple ports on the same side of a Component should be aligned In the illustration below the ports on Comp are placed incorrectly and will produce an error during an analysis The ports on comp2 are placed correctly P E s 7 COMP1 ITB cone jo T NNN Hi RANN n s i UU Wrong Correct The dashed lines represent the alignment plane 6 Reference planes must be the same length for each side of a Component However reference planes can be set independently for each side of the port rectangle as shown below 94 Chapter 6 Components Analysis of a Component Data File Frequencies When using a data file Component type frequencies in your data file do not need to precisely match the Sonnet analysis frequencies The analysis engine will inter polate between data file frequencies if necessary but it will not extrapolate outside the frequency range of the data file Rerunning an Analysis When the analysis engine analyzes your circuit with a Compon
262. ocessing time at the cost of less accuracy Reference planes may be used Chapter 5 Ports NOTE When using auto grounded ports be aware than any coupling between auto grounded ports is not accounted for when performing the de embedding For more information on auto grounded ports see Automatic Grounded Ports page 76 Ungrounded Internal Ports e Used in the interior of a circuit e Each terminal is attached to one of two adjacent polygons e Used in place of a co calibrated port when you do not want any space between the two polygons e Will have a different ground reference from the other ports in the circuit e Commonly used to add a series element in post em processing e Reference planes cannot be used For more information on ungrounded internal ports see Ungrounded Internal Ports page 78 Port Normalizing Impedances The default normalizing impedance for a port is 50 ohms This is done since 50 ohms is an industry standard some analysis tools only accept the value of 50 ohms as the normalizing impedance In rare cases you may wish to have S parameters normalized to some other im pedance The normalizing impedance in Sonnet is represented by four numbers as shown in the diagram below First is the real part in ohms Next comes the reactive part in ohms Third is the inductive part in nanohenries nH The last number is 63 Sonnet User s Guide NOTE the capacitive part in picofara
263. of a single polygon because this would leave one terminal of the port unattached Also care should be taken in interpreting the results for circuits which use these ports since the ports do not all access a common ground You add an ungrounded internal port in the same manner that you add a standard box wall port for details see Adding Box wall Ports page 69 79 Sonnet User s Guide 80 Chapter 6 Components Chapter 6 Components Introduction The Component feature is built upon the high accuracy de embedding technique used for Sonnet co calibrated internal ports technology Using this technique the user can insert an ideal element measurement of a physical component or even results from another Sonnet project In addition using the Component feature in conjunction with the Agilent ADS Interface AWR Microwave Office Interface or the Cadence Virtuoso Interface provides a powerful tool to model complex cir cuits The Components features allows for a high level of flexibility by using three dif ferent Component types e Data File type If you would like to insert an S parameter data file of your component into your Sonnet model e Ideal type If you would like to insert an ideal component R L or C into your Sonnet model e Ports Only type If you would like to use a separate circuit simulation tool for the final combined simulation you may insert only ports within the Sonnet model
264. of a wavelength Before calculating a cell size it is important to calculate the wavelength at your highest frequency of analysis An exact number is not important If you know the approximate effective dielectric constant of your circuit use this in the wave length calculation otherwise use the highest dielectric constant in your structure Most circuits require that your cell size be smaller than 1 20 of a wavelength Larger cell sizes usually result in unacceptable errors due to incorrect modeling of the distributed effects across the cell Cell sizes smaller than 4 20 may increase the accuracy slightly but usually increases the total number of subsections which increases the analysis time and memory requirements Chapter 3 Subsectioning TIP When possible round off dimensions of your circuit so that they have a larger common multiple Since your circuit geometry is snapped to the nearest cell you must find a cell size such that all of the dimensions of the circuit are a multiple of this cell size For example if your circuit has dimensions of 30 microns 40 microns and 60 microns possible cell sizes are 10 microns 5 microns 2 5 microns 2 microns etc Large cell sizes result in more efficient analyses so choosing 10 microns is probably best TIP Calculate the X cell size and the Y cell size independently The X cell size and Y cell size do not have to be the same number Calculate the X cell size based on just your
265. of magnitude of speed increase over volume meshing and other non FFT based surface meshing techniques Em is a complete electromagnetic analysis all electromagnetic effects such as dispersion loss stray coupling etc are included There are only two approxima tions used by em First the finite numerical precision inherent in digital comput ers Second em subdivides the metalization into small subsections made up of cells Chapter 1 Introduction A Simple Outline of the Theory Em performs an electromagnetic analysis of a microstrip stripline coplanar waveguide or any other 3 D planar circuit by solving for the current distribution on the circuit metalization using the Method of Moments The metalization is modeled as zero thickness metal between dielectric layers Metal Box Top Lee Metal Side Walls Em analyzes planar structures inside a shielding box Port connections are usually made at the box sidewalls Subsectioning the Circuit Em evaluates the electric field everywhere due to the current in a single subsec tion Em then repeats the calculation for every subsection in the circuit one at a time In so doing em effectively calculates the coupling between each possible pair of subsections in the circuit The picture on the left shows the circuit as viewed in the project editor On the right is shown the subsectioning used in analyzing the circuit 21 Sonnet User s Guide Zero Voltage Acro
266. oject editor or Output gt N Coupled Line Model in the response viewer This model produces a RLGC matrix which can be used in Cadence Virtuoso Spectre The equivalent circuit is shown below for four lossless transmission lines Reis series R R and Lm are mutual Rand L Lg is series L they are not drawn e Cs is shunt C Cm is mutual C Gsis shunt G Ghpmis mutual G 310 Chapter 21 SPICE Model Synthesis NOTE A third way to bridge the gap between the frequency domain and the time domain is to fit the frequency domain data with a rational polynomial Sonnet s Broadband Spice Extractor feature uses this method to provide a circuit model which is valid over a broad band This model unlike the lumped element model described above does not yield an intuitive understanding of a design Instead the Broadband Spice Extractor feature generates a model that can be used in Spice as a black box rep resenting the broad band behavior of your circuit as shown below This type of model will be referred to as the Broadband Spice model filter olb This chapter describes how to use Sonnet to automatically synthesize PI Model N Coupled Line Model and Broadband Spice Model files The PI capability is useful for circuits which are small with respect to the wavelength at the highest frequency of interest This includes structures such as discontinuities like step tee and cross junctions Other applications i
267. olling moving adjustable point sets see Moving Adjustable Point Sets on page 142 Note that the symmetric parameter is always defined as the distance between the reference points in either the X direction or the Y direction never as a diagonal distance between them 140 Chapter 10 Parameterizing your Project Two examples of symmetric parameters each at two different nominal values are illustrated below This example uses the default setting for how the adjustable point set moves Reference ERAN an a AASS justable N FANS justable nse J at pate o 9 Width nominal value 40 mils Width nominal value 80 mils Notice that although the top and bottom examples have identical reference points and starting and ending nominal values that the resulting polygon on the top differs from that on the bottom due to a different adjustable point set the point set is highlighted by the oval Reference i Reference Point 1 Point 2 Adjustable Point Set 2 Adjustable Point Set 1 Bwidth nominal value 40 mils Bwidth nominal value 80 mils 141 Sonnet User s Guide 142 Moving Adjustable Point Sets Anchored and symmetric parameters have a setting which controls how the adjust able point sets are moved There are three settings Move points the same distance Scale points in one direction and Scale points in X and Y Each type is explained below m Parameter Properties moving control son x This is th
268. omatically builds and analyzes the calibration standards necessary to de embed the port and shift the reference plane by the specified length 102 Chapter 7 De embedding NOTE Reference planes are not necessary for de embedding If you do not specify a reference plane in the project editor for a box wall or auto grounded port the reference plane length defaults to zero This means that em will not shift the reference plane for that port when de embedding is enabled However em will remove the discontinuity for that port Single Feed Line The figure below shows a circuit with a length of transmission line TRL inserted between a box wall port and the device under test O Transmission line F4 S parameters from em without de embedding TRL R Device Under Test C Box wall port n discontinuity Port discontinuity and transmission line associated with a box wall port 103 Sonnet User s Guide When de embedding is enabled em removes the transmission line in a manner similar to that used to remove the port discontinuity Em calculates S parameters for the TRL alone and then cascades a negative TRL along with negative R and C as illustrated in the next figure Block cascaded to negate transmission line S parameters from em S parameters from em with de embedding with
269. omponent Assistant When you select any of the Add Component commands in the project editor the Component Assistant appears on your display Whenever you select a control in the Component Properties dialog box the assistant provides a description of the field and often an illustration of the principle so that you may select the correct setting and model your Component more accurately If the Component Assistant does not appear you should select the Use Compo nent Calibration Group Assistant checkbox on the Hints tab of the Preferences dialog box in the project editor File gt Preferences Anatomy of a Component 82 The Component is represented in your circuit by a component symbol The label of the Component appears above the component symbol and the terminal numbers are identified there Ports indicating where the terminals of the Component are Chapter 6 Components Component Symbol Port Terminal Numbers Label Open Polygon Edge connected to the metal in your circuit are represented by a small rectangle Com ponent ports are only numbered when the Component model type is Ports Only An example of a Component as it appears in the project editor is shown below Label Metal Polygon COMP1 A Physical Size Port Open Polygon N Edge Terminal Number Component Symbol A This is the symbol which represents your Component in your project The Component port defines the point at whic
270. on You may use any project name you wish but it must be different than the project name of the source file 233 Sonnet User s Guide 234 15 If you wish to change the directory in which the resulting files are created click on the Browse button to open a browse window If you select an existing project file you are prompted if you wish to overwrite the existing file Click on OK to set the name and close the dialog box The Subproject Specifications dialog box appears on your display as shown below This dialog box allows you to enter names for each of the geometry subprojects that result from performing the subdivide Default names consisting of the main netlist project name with the section number added are provided but may be edited For this example use the default names Subproject Specifications subdivide son Section Subproject Name sl subdivide net s1 son s2 subdivide net s2 son s3 subdivide net s3 son Length of feedline with reference plane amp Suggested length 295 0 mil C Fixed length 0 0 mil None Cancel Help The names for the subprojects must be unique and must be different from the source project name and main netlist name The suggested length option is already selected for the feedline length This feed line of lossless metal is added to ports generated when the subdivide is executed To enter your own feedline length you would select the fixed length radio butt
271. on and enter the value in the corresponding text entry box Select the None radio but ton if you do not wish to add a feedline Chapter 15 Circuit Subdivision Tutorial 16 Click on the Subdivide button to execute the subdivide The main netlist and subprojects are created using the names input by you The main netlist project is opened in the project editor expo eal amp 0 8 sy ae ae ame a PRJ 1 3 4 subdivide_net_s1 son Hierarchy Sweep PRJ 345 6 subdivide_net_s2 son Hierarchy Sweep PRJ 5 6 7 8 subdivide_net_s3 son Hierarchy Sweep PRJ7 8910 subdivide_net_s4 son Hierarchy Sweep PRJ 9 10 2 subdivide net s5 son Hierarchy Sweep DEF2P 1 2 subdivide_net Main Network Use buttons or menus to modify netlist Network None Line None The main network is defined as subdivide _net and has two ports This corresponds to the source circuit There is a project PRJ entry line for each of the subprojects The project line includes the setting for the source of the analysis frequencies A Hierarchy sweep in which the netlist frequency sweep is imposed on all the proj ect elements is on by default If you turn this off the project default setting of us ing its own sweep is displayed Pictured below are the geometries for the first two sections subdivide net s1 son and subdivide net s2 son Note that in subdivide net sl son feedlines with a ref erence plane have only been added to ports 2 and 3 the ports created in t
272. on parameter creation The Parameter Properties dialog box appears on your display Select the variable name Lstub from the drop list in the Variable Name text entry box in the Properties dialog box and click on the OK button IN Parameter Properties par_dstub son PR Since you have already created Variable the variable Lstub and this dimension parameter is the same length as the dimension Nominal parameter to which Lstub is already assigned the variable name is available in the drop list Name Move points the same distance z Global View Options M Show Nominals M Evaluate Equations Cancel Help This assigns the variable Lstub to the dimension parameter When you click on the OK button an arrow indicating the length and the variable name appear on your display Use your mouse to move the label to the desired location then click Since this dimension parameter s nominal value is the same as the first parameter you defined the project editor allows you to assign the same variable to both di mension parameters These dimension parameters are now linked A change in value of the variable changes both dimension parameters If the dimension param eters had been of a different length the variable name Lstub would not have ap peared in the list Entering the variable name manually would invoke an error message Chapter 11 Parameter Sweep and Optimization Tutorial Next
273. on parameter is dependent upon another if the anchor point and or the reference point s for the second parameter are part of an adjustable point set for the first parameter This is allowed as long as a circular dependency is not formed see the following section You need to be aware of dependent dimension parame ters so that you can take into consideration the complete impact on your circuit when the value of the primary dimension parameter is changed When the primary dimension parameter is changed a dependent parameter is adjusted i e the an chor point or reference point is moved along with the primary dimension param Chapter 10 Parameterizing your Project Feed Adjustable Pt Set Feed Anchor Point Feed Ref Pt The dimension eter on which they depend A picture of a dependent dimension parameter is shown below with the Anchor and Reference points highlighted as well as the point sets Width Anchor Point width lt s Width Adjustable SE ook ie es Pt Set Width Ref Pt parameter Width is dependent on the dimension parameter Feed Note that the anchor point for the dimension parameter Width shown on the right is part of the adjustable point set for the dimension parameter Feed shown on the left You may use the Select Dependents command in the project editor to determine if there are any dependent dimension parameters With the project open in the project editor do the fo
274. on your display H Optimization Goal Entry par_dstub son a b Sweep Freguency Specification Type Sweep Type Adaptive Sweep ABS k Specification Start Stop Freguency GHz GHz Controls Goal Specification Goal Type Response Type d a t yP Network Operand 1E Value text entry box Response I JA drop list Cancel The first goal corresponds to the first passband therefore you need to set the ABS freguency range to 1 0 GHz to 4 0 GHz There are several different types of fre guency sweeps available you will use the default ABS sweep for this optimiza tion Enter 1 0 in the Start text entry box in the Freguency Specification section of the dialog box This sets the beginning of the freguency band for this optimization goal at 1 0 GHz Enter 4 0 in the Stop text entry box in the Freguency Specification section of the dialog box This sets the end of the freguency band for this optimization goal at 4 0 GHz This completes the specification of the freguency sweep for this optimization goal Since this is the first passband your goal is to have DB S21 be greater than 1 0 dB Select DB from the Response Type drop list on the left side of the eguation This is the default so DB may already be selected Chapter 11 Parameter Sweep and Optimization Tutorial 40 41 42 43 44 Select S21 from the Response drop list The display is updated with S21 Select
275. onformal Meshing Rules Not all conditions which may affect accuracy or processing time are automatically identified in the project editor Below are some basic rules for using conformal meshing you may follow to prevent causing an error in the analysis engine em 188 Chapter 12 Conformal Mesh Rule 1 Polygon Overlap Polygons should be drawn or moved in your circuit such that there is no overlap between polygons if any one of the polygons is using conformal meshing It is possible for two polygons to overlap and not cause an error condition but the most conservative use would be no overlaps See the illustration below Liss The circuit on the left has three overlapping polygons and the polygon on the bot tom is using conformal meshing This would cause em to issue an error message and stop running The circuit shown on the right has no overlap between polygons and would not cause any errors TIP To maintain the same metal in your circuit without any overlap use the Edit gt Merge Polygons command on polygons which use the same metal type Using the Merge command on the example above in which all three polygons are the same metal type is shown below 189 Sonnet User s Guide 190 Rule 2 Rule 3 Figure Eight Polygons A conformal mesh polygon should not wrap back around itself in other words its vertices should not form a figure eight This will result in an error message being issued and em wil
276. onsistent is to select the Use Fixed Frequency option for the subsectioning frequency and enter the desired fre quency This ensures that all analysis runs on the project will use the same subsec tioning frequency Again care should be taken that the subsectioning frequency entered provides the desired accuracy Multi Sweep Caching Scenarios 120 The analysis engine always attempts to use any existing data in the project which is consistent with the present analysis Described below are some common scenar ios describing ABS analyses when the ABS caching level is set to Multi Sweep with Stop Restart and how data consistency is maintained Higher or Lower Resolution over the Same Frequency Band You are running an ABS analysis over the same band as a previous ABS analysis but with higher or lower resolution an example is shown below In order for the caching data to be valid for the second analysis your Advanced Subsectioning controls must be set such that the subsectioning frequency is the same for both runs If the subsec tioning frequency remains the same the second analysis will usually not require any re analysis and the results should be provided very quickly The only excep tion would be if the difference between the resolutions is unusually high Frequency Band 10 40 GHz lst ABS analysis 10 10 1 10 2 10 3 39 8 39 9 40 2nd ABS analysis 10 10 05 10 1 10 15 10 2 39 85 39 9 39 95 40 Zoom In Yo
277. or When the Sub section Viewer appears select View GLG Metal from the subsection viewer s main menu Views of two calibration groups as viewed in the subsection viewer with the GLG metal displayed are shown below A calibration group which is grounded to the Sonnet box is shown on the left and one with a floating ground is shown on the right GLG Metal Via GLG Metal Polygon Sonnet Box Floating Circuit Metal Note that in the case of the Sonnet box ground node connection the GLG metal does not connect the two ports Instead there is a via composed of GLG metal which extends to ground 72 Chapter 5 Ports Terminal Width You must also determine how you will define the terminal width for your calibra tion group Terminal width is the electrical contact width of the component which is to be attached This allows the current flow from the circuit geometry into the component to be accurately modeled There are three settings for terminal width Feed Line Width One Cell and User Defined Please note that the terminal width is not shown in the project editor Feed Line Width This defines the terminal width as equal to the feed line to which the co calibrated port is attached This is illustrated below Feed Line Width Terminal Width Current Flow One Cell This defines the terminal width to the smallest possible size as pictured below Current Flow One Cell Terminal Width 73 Sonnet User s
278. or do the following 1 Move to the circuit level where the base of the dielectric brick is to be located The dielectric brick that is created will rest on this circuit level and will extend upward to the next level Dielectric bricks can be placed on any level including the ground plane If a brick is placed on the highest circuit level level 0 it will extend up to the top cover of the metal box 2 Create a base polygon which defines the cross section of the brick This is done by selecting either Tools gt Add Dielectric Brick gt Draw Rectangle or Tools gt Add Dielectric Brick gt Draw Polygon from the project editor s main menu The first option allows the vertices of arbitrarily shaped base polygons to be entered on a point by point basis This option is used to create dielectric bricks with any cross sectional shape However if the cross section is rectangular in shape it is often quicker to create dielectric bricks using the second option Viewing Dielectric Bricks Once a dielectric brick has been created in the project editor it is possible to see the brick from both the circuit layer where the base of the brick is located and the circuit layer where the top of the brick is located On both levels you will see a polygon which defines the cross sectional shape of the dielectric brick The brightness of the polygon however will vary When you are on the top level you will see a dim polygon on the base leve
279. or Cancellation Mechanism with Respect to Subsectional Electromagnetic Analysis Validation International Journal of Microwave and Millimeter Wave Computer Aided Engineering Vol 6 No 6 November 1996 pp 430 435 J C Rautio The Microwave Point of View on Software Validation IEEE Antennas and Propagation Magazine Vol 38 No 2 April 1996 pp 68 71 J C Rautio and Hiroaki Kogure EMI Applications Of The Electromagnetic Analysis By The Method Of Moments Electromagnetic Analysis Applied To Analog And Digital PCB Design JPCA Show 96 Text Today and Tomorrow of EMI Design pp 11 19 J C Rautio EM Analysis Error Impacts Microwave Designs Microwaves and RF September 1996 pp 134 144 James R Willhite Turning Clean Theory into Reality Wireless Design and Development March 1996 Vol 4 No 3 pp 19 20 Appendix II Sonnet References 47 48 49 50 51 52 53 54 55 56 57 58 59 60 J C Rautio Response 2 Comments on Zeland s Standard Stripline Benchmark Results MIC Simulation Column International Journal of Microwave and Millimeter Wave Computer Aided Engineering Vol 5 No 6 November 1995 pp 415 417 J C Rautio EMI Analysis from a Wireless Telecommunication and RF Perspective Proceedings of the 1995 Nepcon West Conference Anaheim CA USA pp 749 755 J C Rautio and Hiroaki Kogure An Overview of
280. orizontal Subdividers N N N N s5 s6 N N N A N N sf You may use both orientations by using double subdivision mentioned earlier The first time you subdivide your main circuit you choose an orientation for your subdivision lines Then use circuit subdivision on the resulting geometry subproj ects this time using the opposite orientation for your subdivision lines 221 Sonnet User s Guide 222 Before adding subdividers to your geometry project you should ensure that spec ification of your circuit is complete Subprojects created when you execute the subdivision inherit their properties from the source project Such properties as cell size metal types properties of the dielectric layers dielectric bricks metal levels etc are all used in the resultant subprojects When you place a subdivider in your circuit a line representing the subdivider appears in the horizontal or vertical plane running through the point at which you clicked The resultant sections of the circuit are automatically labeled Subdivision sections are labeled from left to right or top to bottom depending upon orientation These labels are always sequential and are non editable Once a subdivider has been added to your circuit you may edit the subdivider as you would any other object in your geometry You may click on the subdivider and move it You may also control the display and selection of the subdivider lines and labels i
281. ory threshold at which 64 bit processing is used If this command is not used the threshold is set to 3600 Mbytes 3 6 Gbytes 64BitForce This option forces the analysis to use 64 bit processing regardless of how much memory is required to analyze your circuit the memory threshold is not used 32BitForce This option forces the analysis to use 32 bit processing regardless of how much memory is required to analyze your circuit the memory threshold is not used NOTE When using 32 bit processing em can only access up to 4 GB of RAM on 64 bit Windows and 2 GB on 32 bit Windows If you try to run problems larger than this limit the analysis will run out of memory even if you have more RAM and stop lt project name gt is the name of the project which you wish to analyze If there is no extension then the extension son is assumed This field is required external frequency file is the name of an optional external frequency control file whose extension is eff This extension must be included when specifying the control file You may create an external frequency control file in the project editor For details see Frequency Sweep Combinations in online help in the project editor The frequencies in this file override the frequencies in the project For example if you wish to analyze the project steps son in a batch file using the v option the command line would be em v steps son An example of
282. ou have a method of measuring the loss as a function of frequency or published data which you can trust and if it is constant over your range of frequencies then dielectric loss is probably not a source of er ror Be careful however of published loss data Verify that the data is valid over your frequency range 57 Sonnet User s Guide 58 Dielectric Layer Parameters You can set the dielectric constant and loss of a dielectric layer by changing the following parameters in the project editor by selecting Circuits gt Dielectric Lay ers then clicking on the Above Below or Edit button in the Dielectric Layers di alog box This opens the Dielectric Editor dialog box which allows you to edit the parameters below rial Erel The relative dielectric constant The ratio e where amp is the real part of the permittivity of the dielectric layer material and is the permittiv ity of free space The ratio is dimensionless Dielectric Loss Tan The dielectric loss tangent The ratio e where amp je and amp is the complex permittivity of the dielectric layer material The ratio is dimensionless Diel Cond The dielectric conductivity o where o is the bulk conductivity in siemens per meter Mrel The relative magnetic permeability 1 of the dielectric layer material Magnetic Loss Tan The magnetic loss tangent of the dielectric layer mate One last parameter that may be
283. out de embeddi F mmm m mM M M mu m m m m mM M m m mu m L I 0333 10 ey 0800 a sd 7 I l Transmission my I I Device I o TRL TRL Under l Test I Block cascaded R R I to negate port c n I l discontinuity Box wall port I m discontinuity I L m eee n n ee J Illustration of how de embedding removes the port discontinuity and transmission line associated with a box wall port Coupled Transmission Lines NOTE 104 The two previous figures illustrated how the reference plane for a single transmis sion line attached to a box wall port is shifted during de embedding In general there may be multiple transmission lines on a given box wall on one or more cir cuit levels This is illustrated in the next figure In this situation em shifts the ref erence plane an egual distance for all transmission lines on the given box wall All coupling between the transmission lines is accounted for and removed When shifting a reference plane for coupled lines em assumes the following a all coupled lines are either horizontal or vertical b the width of each coupled line is constant c the spacing between coupled lines is constant Chapter 7 De embedding SSS Ports N E ja N coupled transmission lines JSN Box Wall De embedding shifts the reference plane an egual distance for all N coupled transmission lines on a giv
284. ove the difficult part in using circuit subdivision is to decide where to place your subdivision lines to split the circuit The subdivision lines should be placed between polygons which have negligible coupling Places on the circuit where a high degree of coupling or rapidly varying currents are present should be kept within an individual subproject The de embedding of the port discontinuity in Sonnet is done by essentially mod eling infinitely long transmission lines at the port This allows transmission lines to be subdivided with very little loss of accuracy This includes microstrip lines stripline and coupled lines including coplanar This point is illustrated below The circuit shown below on the left consists of a coupled transmission line This is too simple a circuit to require subdivision but is very useful in demonstrating the principle When subdivided the circuit is split into two subprojects both of Chapter 14 Circuit Subdivision which would resemble the circuit shown on the right Since the port discontinuity is modeled as an infinite transmission line when the port is de embedded the cou pling between points A and B is accounted for sl s2 Infinite Transmission Line It is important to avoid areas where there is coupling across the subdivision line Subdivision lines should not split any diagonal polygon edges Illustrated below are good placements and bad placements of subdivision lines Good and B
285. pattern which is the video re verse of the metal pattern Since current travels on the surface of a via the middle of the via is hollow filled with the dielectric material of the dielectric layer that in black The actual via metal is shown by the fill the via traverses Tops of Vias Rectangle Via Circle Via The example shown below uses an edge via to connect two polygons on adjacent levels The up via symbol indicates that the via connects this level to the next level above The vias on the upper level are shown with a down via symbol which is a down triangle Via symbols were automatically created on the desti Polygon Via nation level when the via was added to the source level Lower level up triangles Upper level down triangles 244 Chapter 16 Vias and 3 D Structures Via Posts With the metalization turned on default setting by setting View gt Cell Fill to On the via subsections called via posts are also displayed in reverse video as shown below Via posts shown in reverse The via is indicated by video with cell fill on only triangles and an outline when cell fill is When em subsections the circuit it subsections each edge via or via polygon into subsectional vias called via posts Each via post is a rectangular cylinder of cur rent extending between the present level to the next level above or below de
286. ponse data edit the analysis setup for the master netlist so that all of the desired analysis frequencies are specified Each of the geometry subprojects are set up with the coarser resolution of analysis frequencies When the netlist is analyzed em runs the geometry project analyses first to produce re sponse data for each part of the network Then the analysis of the whole network is executed Em interpolates to produce data for frequency points in between those available from the analysis of the geometry subprojects If properly subdivided the results of the netlist analysis should provide an accu rate solution for your difficult to handle circuit using fewer resources The use of circuit subdivision is demonstrated in Chapter 15 Circuit Subdivision Tutorial on page 227 225 Sonnet User s Guide 226 Chapter 15 Circuit Subdivision Tutorial Chapter 15 Circuit Subdivision Tutorial This tutorial walks you through how to add subdivision lines subdivide your cir cuit and analyze the final netlist The results of this subdivision are compared to the analysis of the complete circuit in order to demonstrate the accuracy of the re sults of the subdivision and the savings in memory For a detailed discussion of circuit subdivision and the use of subdividers please refer to Chapter 14 The circuit an edge coupled microstrip bandpass filter is a fairly simple example of a circuit which you might decide to subdivide In a
287. q 20 minutes 15 minutes 20 minutes Netlist Total Analysis Time 55 minutes 14X faster When the netlist analysis is performed em will interpolate to provide simulation data at freguencies not specified in the subprojects Each subproject should be an alyzed at the same minimum and maximum freguency as the overall analysis and at enough points in between to provide for reasonable interpolation of data at fre guencies which fall between these values As you can see from the Smith chart be low while you need many freguency points to obtain reasonable response data for Chapter 14 Circuit Subdivision the whole circuit you need far fewer frequency points to obtain accurate data for the smaller pieces of the whole circuit whose response data does not vary appre ciably Whole Circuit Be aware however that in some cases you may need the added precision of ana lyzing all the pieces at the same resolution of the frequency band Interpolation is best used when the response of a subproject varies little over the frequency band and the analysis time of the subproject is appreciable Circuit Subdivision in Sonnet Circuit subdivision in Sonnet allows you to insert subdivision lines in your geom etry in the project editor These subdivision lines create the sections from which the subdivide command makes geometry subprojects When you select the subdi 213 Sonnet User s Guide vide command the software create
288. r AC sweeps and transient simulations 18 Chapter 1 Introduction DXF amp GDSII Interfaces Agilent s ADS User Entr Gerber Cadence s Virtuoso Y Translators AWR s Microwave Office Project Editor Analysis Engine EI Response Viewer Far Field Viewer Current Density Viewer Broadband Spice Extractor Post Processing 19 Sonnet User s Guide Em performs electromagnetic analysis 85 86 88 for arbitrary 3 D planar 60 e g microstrip coplanar stripline etc geometries maintaining full accuracy at all frequencies Em is a full wave analysis in that it takes into account all pos sible coupling mechanisms The analysis inherently includes dispersion stray coupling discontinuities surface waves moding metalization loss dielectric loss and radiation loss In short it is a complete electromagnetic analysis Since em uses a surface meshing technique i e it meshes only the surface of the circuit met alization em can analyze predominately planar circuits much faster than volume meshing techniques The Analysis Engine em 20 Em analyzes 3 D structures embedded in planar multilayered dielectric on an un derlying fixed grid For this class of circuits em can use the FFT Fast Fourier Transform analysis technique to efficiently calculate the electromagnetic cou pling on and between each dielectric surface This provides em with its several or ders
289. r Component s port placements An example is shown below Physical Size of Component 2D View 3D View Rules for Using Components The following restrictions apply to the placement of Components in your circuit 92 Chapter 6 Components No objects may be placed within the restricted space in the interior of the Component Metal polygons vias or dielectric bricks may be present in the rectangular area defined by the port locations and the terminal width as illustrated below The bottom circuit shows the restricted area in a multiport Component Polygon Right Wrong The dashed boxes identify the restricted space for each Component On the circuit labeled Wrong a metal polygon passes through the middle of the restricted space Restricted Space Components whose ground node connections are defined as the Sonnet box require direct access to the Sonnet top or bottom cover The analysis engine determines the most efficient direction the ground via extends taking into consideration both the distance and the loss of the box top or bottom When using this type of ground you must make sure that there is a clear path with no metal on other levels interfering with the path to either the box top or box bottom In addition the box top or bottom should not have loss greater than 50 ohms sq If the loss is too high on both the box top or bottom for a ground via from the Component t
290. r nominal value so Sstub is a constant fixed at 220 mils for the parameter sweep The nominal value that is the present value of the variable in the circuit appears in the Nominal column of the variable entry In this case the nominal value of Ls tub is 220 mils so the project editor shows the length as 220 mils even though the start value for the variable is different Enter 120 in the Start text entry box in the Lstub row This sets 120 mils as the first variable value used for Lstub Enter 280 in the Stop text entry box in the Lstub row This sets 280 mils as the last variable value used for Lstub Enter 160 in the Step text entry box in the Lstub row The interval between variables is 160 mils therefore this parameter sweep analyzes at two variable values 120 and 280 mils Chapter 11 Parameter Sweep and Optimization Tutorial There is a drop list for the Sweep mode just above the entries for the variables The default mode of Linear Sweep is used for this example so there is no need to take any action For details on sweep modes please refer to Help by clicking on the Help button in this dialog box This completes the setup for the parameter sweep entry 10 Click on the OK button to close the dialog box When the dialog box is closed the Analysis Setup dialog box is updated with an entry for the parameter sweep that you just defined In this case since there are two values for a single variable there are two par
291. r to those lines Here the left side of the spiral is sufficiently far from the right side so that coupling is negligible The example on the right is bad because the lines on the left side of the spiral do couple strongly with the lines on the right side Chapter 14 Circuit Subdivision The meander line on the left is split in such a way that Sonnet provides an accurate answer since the bends on the top are far enough away from the bends on the bot tom that coupling between them is negligible The example on the right provides an inaccurate result because the coupling between two close transmission lines is eliminated by the subdivision A a a N N N N N N N N N N N N 227777 E The circuit shown below has coupled transmission lines on two different layers Once again it is correct to place a subdivision line perpendicular to the transmis sions lines but not parallel to them Subdivision is valid for multi layer structures as long as the coupling across the subdivider is negligible sl s2 ASSAS Good Bad In the double stub circuit shown on the left the subdivision lines split the polygon perpendicular to the direction of current flow and far from any discontinuities The circuit on the right however shows the subdivision line splitting the bases of the two stubs which may be coupled 219 Sonnet User s G
292. racy of the Broad band Spice Model page 326 for suggestions on improving your Broadband Spice model Broadband Spice Extractor Log The Broadband Spice Extractor log displayed in the Broadband Spice details win dow contains detailed information about the creation of your Spice model file You may view a summary of the log or the complete log To view the summary of the log click on the Summary button at the bottom of the window To return to the full log click on the Complete button You use the log to determine which parameters to examine in order to determine if the Spice model is accurate enough for your use Two log files are shown below the first log is for a model which achieved the error threshold and the second log Chapter 21 SPICE Model Synthesis is one in which the error threshold was not achieved on all the parameters A warn ing message is issued for all S parameters whose error is greater than the error threshold Generating files coup_end lib and coup end predict snp Model Log for coup end Data set has 201 points and 4 ports Model Options Error threshold 0 5 Error Threshold Output predicted file C Program Files sonnet proj ect coup_end_predict snp lt a Curve Fit Data File Max order target 200 amp Maximum Order Model Results S11 Order 2 Error 0 03850722 S12 Order 2 Error 0 005954352 S13 Order 2 Error 0 005379771 S14 Order 2 Er
293. ral the model contains an inductor in series with a resistor 1f using loss a capacitor and a resistor when using loss connected in parallel from each port to ground A similar parallel RLC network is also connect ed between each port Therefore a four port circuit can contain more elements than a two port circuit Each inductor may also have a mutual inductance to any Chapter 21 SPICE Model Synthesis other inductor in the network The figure below shows the most complex equiva lent circuit possible for a two port mutual inductances not shown Any values that are outside of the open circuit limits are not included Equivalent circuit of a two port structure using the PI Model Mutual inductances also exist between all inductors but are not shown Any component whose value is outside of the open circuit limits are not printed in the SPICE output file N Coupled Line Option Most circuit design programs provide models for single and multiple coupled transmission lines However it is often desirable to use EM simulated data in cir cuit design programs These programs often provide transmission line models which utilize RLGC parameters R L G and C are the resistance inductance conductance and capacitance per meter of a transmission line The RLGC param eters can be extracted from an EM simulation of a short section of the transmission line They can then be used to model any length of line having the same cross sec tio
294. ral Inductor on Silicon Microwaves amp RF September 1999 pp 165 172 Takashi MIURA Hideki NAKANO Kohji KOSHIJI and Eimei SHU Reduction of time required for electromagnetic analysis by dividing circuit Faculty of Science and Technology Science University of Tokyo Japan Institute of Electronics Packaging pp 79 80 Mar 1999 Article in Japanese James C Rautio Tips and Tricks for Using Sonnet Lite Free EM software will radically change the way you do high frequency design Microwave Product Digest November 1999 pp 30 34 67 70 James C Rautio EM Simulation 1999 IEEE MTT S International Microwave Symposium Microwave and Millimeter Wave Design Tool Applications Workshop Anaheim CA June 13 1999 James C Rautio Application of Electromagnetic Analysis Software to 3 D Planar High Frequency Design International Multilayer Circuits Symposium IMCS March 1999 pp B2 1 B2 17 Shigeki Nakamura Top Interview Electromagnetic Analysis is not Difficult Big Rush to Install PC Version Electronic Products Digest Vol 16 No 1 January 1999 page 48 Japanese Article 355 Sonnet User s Guide 356 33 34 35 36 37 38 39 40 41 42 43 44 45 46 James C Rautio Comments on Revisiting Characteristic Impedance and Its Definition of Microstrip Line with a Self Calibrated 3 D MoM Scheme IEEE Transac
295. ranslator the translator interface is found in the project editor You also set up analysis controls for your project in the project editor Program module xgeom Em is the electromagnetic analysis engine It uses a modified method of moments analysis based on Maxwell s eguations to perform a true three dimensional current analysis of predominantly planar structures Em computes S Y or Z parameters transmission line parameters Zo Eeff VSWR GMax Zin and the Loss Factor and SPICE equivalent lumped element networks Additionally it creates files for further processing by the current density viewer and the far field viewer Em s circuit netlist capability cascades the results of electromagnetic analyses with lumped elements ideal transmission line elements and external S parameter data Program module em The analysis monitor allows you to observe the on going status of analyses being run by em as well as creating and editing batch files to provide a queue for em jobs Program module emstatus The response viewer is the plotting tool This program allows you to plot your response data from em as well as other simulation tools as a Cartesian graph or a Smith chart You may also plot the results of an equation In addition the response viewer may generate Spice lumped models Program module emgraph The current density viewer is a visualization tool which acts as a post processor to em providing you with an immediate qualitati
296. refer to Chapter 7 De embedding on page 97 69 Sonnet User s Guide For a box wall port you may set either a reference plane or a calibration length both values cannot be set at the same time for box wall ports All ports on any giv en box wall use the same reference length To set either of these values for box wall ports use the Circuit gt Ref Planes Cal Length command For details please click on the Help button in the Reference Planes Calibration Lengths dialog box which appears when you select the command Co calibrated Internal Ports Co calibrated ports are used in the interior of a circuit These ports are often used by acircuit simulation tool to connect some type of element into your geometry at a later time outside the Sonnet environment Co calibrated internal ports are iden tified as part ofa calibration group with a common ground node connection When em performs the electromagnetic analysis the co calibrated ports within a group are simultaneously de embedded using a high accuracy de embedding technique thus coupling between all the ports within a calibration group is removed during de embedding This type of port is the most commonly used internal port Ground Node Connection You must define how the common ground of your calibration group is connected to your circuit There are two types of ground node connection Sonnet Box and Floating Sonnet Box When the ground node connection is defined as the
297. ror 0 02510101 22 Order 2 Error 0 001637623 Error values for 23 Order 2 Error 0 0010330191 S parameters 524 Order 2 Error 0 005380005 533 Order 2 Error 0 001635971 534 Order 2 Error 0 005951772 S44 Order 2 Error 0 03853657 Model Summary for coup end S parameter Maximum error was for S44 Error 0 038536 6aq With greatest Total model time 0 391 seconds error Model coup_end successful gq Indicates that the Error Threshold was achieved for all S parameters 325 Sonnet User s Guide 326 Generating files matchnet lib and matchnet predict snp Model Log for matchnet Data set has 1246 points and 2 ports Model Options Error threshold 0 5 lt Error Threshold Curve Fit Output predicted file C Program Files sonnet proj Pata File ect matchnet_predict snp Max order target 200 Warning Messages Model Results p S11 Order 203 Error 1 387911 WARNING Error threshold of 0 5 not achieved S12 Order 208 Error 2 984112 WARNING Error threshold of 0 5 not achieved WARNING Poor figure of merit on S12 parameter Visual inspection of predicted S12 recommended S22 Order 214 Error 1 833756 WARNING Error threshold of 0 5 not achieved WARNING Model prediction is not passive at 112 freguency points Error threshold may need to be decreased or input data may be non passive Model
298. rt Enable ABS stop restart caching overrides setting in project file AbsCacheMultiSweep Enable ABS multi sweep plus stop restart caching overrides project file AbsNoDiscrete Used when running ABS with pre existing cache data Tells the analysis engine not to do any more discrete frequencies If pre existing cache data is sufficient to get converged ABS solution then that solution is written to output Otherwise no processing is performed SubFreqHz value where value is the subsectioning frequency in Hz Note there is no space before the value field This option allows subsectioning frequency to be specified on the command line thereby overriding the settings in the project file ParamFile lt filename gt where lt filename gt is the name of a file which contains the value s which you wish to use for parameter s in the circuit being analyzed These values override the value contained in the geometry project for the analysis but do not change the contents of the geometry project The syntax for the parameter file is lt parname gt fnum where lt parname gt is the name of the parameter and fnum is a floating point number which defines the value of the parameter for the analysis 346 Appendix Em and xgeom Command Line for Batch Option Meaning 64BitThresh lt mem gt Memory threshold in MB to enable the 64 bit solver where lt mem gt contains an integer value identifying the mem
299. s Creating a Thick Metal Polygon To create a thick metal polygon in your circuit you must first define a metal type using the Thick Metal model then apply that metal type to the polygon in your circuit This creates a thick metal polygon which extends upwards toward the box top from the metal level on which it is created To do this perform the following 1 Inthe project editor select Circuit gt Metal Types from the main menu The Metal Types dialog box appears on your display 2 Click on the Add button in the Metal Types dialog box The Metal Editor dialog box appears on your display 255 Sonnet User s Guide 3 Select Thick Metal Model from the type drop list in the Metal Editor dialog box This updates the dialog box with the text entry boxes for the three parameters needed for the thick metal model Conductivity Thickness and Number of Sheets 4 Enter the three parameters in the appropriate text entry boxes 5 Ifyou do not wish to use the default metal name enter the desired name for the metal type in the Name text entry box The Metal Editor dialog box should appear similar to the picture below Metal Editor thick metal son 12 x Select metal from library a Name Gold Pattern Q Type Thick Metal Model v Conductivity 40900000 0 Sim Thickness po mils Num Sheets B Thickness is simulated at the expense of analysis time Cancel Help 256 Chapter 17 Thick Metal 6
300. s Name Name Metan Pattern Type TERE gt Conductivity INF Sim Thickness Met_thick v mils Sub 5 TNT Sub z Unknown 9 8 Num Sheets 2 Chapter 2 What s New in Release 12 Variables and Equations This release introduces a new variable and equation feature that enables you to control circuit properties using equations based on mathematical functions such as sine cosine natural logarithm etc A circuit property can be a function of one or more independent variables to pro vide advanced capabilities like e Simulating temperature effects on circuit response by defining metal or dielectric loss as a function of a temperature variable e Defining your own frequency dependent properties by using the new FREQ constant in an equation e Enforcing geometry scaling by defining a variable as a multiple of another variable e Controlling a circuit property based on a table of data from an external text file For more information on variables and equations please see Chapter 10 Pa rameterizing your Project on page 129 Radial Dimension Parameters A radial parameter is a new type of dimension parameter that allows you to fix one end of a parameter then radiate out from that fixed point the direction is not restricted to the x or y direction but may extend at an angle See Radial Dimension Parameters page 144 for more information Enhanced Meshing Algorithm Sonne
301. s 100 113 excitations 280 289 impedance 64 65 67 modify attributes 78 numbering 67 69 push pull 66 renumbering 65 standard 69 terminations 280 289 ungrounded internal 76 205 207 using with symmetry 67 via 76 Index via ports 76 251 Ports Only Component 85 power gain 285 probe readout 297 probes 241 probing the plot 296 processing time 193 Product Editor origin 282 Project Editor 288 project editor 16 netlist editor 197 project file circuit geometry 288 properties circuit 223 push pull ports 66 R radial dimension parameters 136 144 radiation 273 273 280 radius axis changing 300 Rdc Rrf metal type 52 reactive surface impedance 49 reference planes 102 108 110 de embedding without 108 for co calibrated internal ports 74 for components 91 parameters 146 short length 109 reference point 138 144 161 162 first in symmetrical 140 second in symmetrical 140 references 286 303 307 reflection boundary 287 release 7 0 new features 23 remove top cover 336 337 residual error 341 resistance 58 resistor 85 resistor metal type 51 resistors 197 thin film 48 200 resonance box 334 response maximum 122 minimum 122 response data calculating 290 selecting 292 response viewer invoking 168 results of optimization accepting 181 right click 147 right clicking 292 299 304 ripple in S parameters 126 RLCG 309 RLGC 317 run options edge mesh 41 S s100 341 s25 341 s50 341 saving a file 306 s
302. s a main netlist file and the geometry subproj ects The main netlist connects the subprojects so that the response data for the netlist may be substituted for the response data of the source project sl s2 s3 1 ees S ISSIS 2 KASSSSSSSS Source Circuit with Subdivision Lines Added PRJ 2 5 6 simple_subdivide_net_s3 son Hierarchy Sweep DEF2P 1 2 simple_subdivide_net Main Network Use buttons or menus to modify netlist Network simple subdivide net Line 22 Generated Main Netlist You should also be aware that if your main circuit contains any parameters or di mensions they are removed during the subdivision process After the subprojects are created you may enter parameters in any of the geometries In fact it is pos sible to run optimizations on the main netlist project using a parameter in one of the subprojects Performing circuit subdivision as a method of analysis should in general be done as follows 1 You should input as many of the circuit properties as possible before subdividing Dielectric layers dielectric brick and metal types grid size top cover height etc are inherited by the created geometry subprojects 214 Chapter 14 Circuit Subdivision 2 Decide where to subdivide your circuit This step often requires exper tise and experience to avoid splitting the circuit at a junction where there is coupling across the subdivision line 3 Create the subdivision lines in the project editor Th
303. s being used to define If the variable is created when editing a dialog box Dielectric Layers Metal Types etc a default description is provided by the software This may be changed by entering a different description here This field is not reguired Select the desired units for the variable from the Units drop list Available units are the length freguency resistance capacitance and inductance units presently set in your project If none of these are suitable then select Other It is important to select the units for your variable so that if you change the units used in your project the value of the variable is converted correctly Chapter 10 Parameterizing your Project Equations As mentioned earlier a variable may be defined by a constant another variable or an equation An equation is composed of constants and or variables Below are some examples of valid equations e 3 3 e 3 pi e 3 H e sin H e sgrt H The last three eguations are ones in which one variable is used to define another This allows you to relate properties in your circuit such that changing one effects the other maintaining a set relationship between them For example you wish to define a dielectric layer which is always five times the thickness of your substrate To do so you define a variable sub which you would enter as the thickness of your substrate Then you would enter 5 sub as the value for the thickness of the dielectric l
304. s completes the setup for the optimization 177 Sonnet User s Guide 178 Running an Optimization 45 46 This optimization took approximately 6 5 minutes on a 2 GHz Pentium 4 Select Project gt Analyze from the main menu of the project editor The output window of the analysis monitor appears on your display TIP You can also click on the Analyze button on the project editor tool bar Click on the Response Data button in the analysis monitor output window if it is not already displaying the response data This allows you to observe the optimization as it progresses The error for the first present and best iteration are displayed and updated as the optimization progresses The response data is output in the bottom of the window You may notice that some iterations complete more quickly than others This is because em can reuse portions of the response data calculated for previous itera tions Once the analysis is complete you open the response viewer to look at your results Be aware that since this optimization took a number of iterations to conclude there may be small delays in opening the response viewer and the Edit Curve Group dialog box TIP You may use the response viewer to observe data produced by the optimization while it is still running The response viewer can chart any data which has been generated This allows you to stop the optimization and start it over using new variable ranges or new goals
305. s metal fill which is on the grid Off grid metalization may be over or under filled depending on the degree of misalignment between grid and metal pattern While misalignment gives the user visual feedback of one potential error source in a Sonnet simulation it is important to keep in mind that every pla nar Method of Moments MoM simulation contains multiple sources of error Unlike Sonnet most EM software vendors speak very little about error sources see Accuracy Benchmarking page 339 The fact that Sonnet shows misalign ment between the desired metal pattern and simulation grid does not necessarily imply that Sonnet simulations will be any less accurate than competitive simula tors that mesh using infinite resolution With all simulation packages the user should investigate every potential error source which will vary depending on the MoM technique used and ensure a good converged data set is achieved Changing the Subsectioning of a Polygon 34 Sonnet allows you to control how cells are combined into subsections for each polygon This is done using the parameters X Min Y Min X Max and Y Max These parameters may be changed for each polygon allowing you to have coarser resolution for some polygons and finer resolution for others See Modify Metal Properties in the project editor s Help for information on how to change these parameters Before discussing how to make use of these parameters
306. s shown in the illustration the original distance from the anchor of the circled point was 36 5 mils along the x axis and 43 5 mils along the y axis 143 Sonnet User s Guide when the value of the parameter is increased the point was moved to 54 75 mils away from the anchor point along the x axis and 65 25 mils along the y axis the original distances multiplied by the scaling factor of 1 5 W NN NNN NNN NNN NN MQ W N NNN NN NN WX vnyn SRY RRA NN Radial Dimension Parameters A radial parameter defines a dimension using an anchor point a reference point and an adjustable point set The nominal value of the parameter is defined by the distance between the anchor point and the reference point When the dimension is varied each point moves along a line extending from the anchor point through it s original position Setting up a radial parameter is identical to setting up an an chored parameter When defining your radial parameter you perform the follow ing steps e You select the anchor first This is the fixed starting point for the parameter e You select the reference point The reference is the first point in the adjustable point set which is the set of points moved relative to the anchor point when the value of the radial parameter is changed The diagonal distance from the anchor point to the reference point is the value of the dimension parameter When the value of the dimension parameter is
307. same total radiation power 7 The Gain and Directive gain may be displayed relative to the isotropic antenna i e 0 dB the maximum value of E for the antenna or an arbitrary value Selecting Absolute for the normalization displays the radiated power in Watts ste radian at a given angle You may change the normalization in the far field viewer using the Select Nor malization dialog box which is opened by selecting Graph gt Normalization from the far field viewer main menu 285 Sonnet User s Guide Polarization The far field viewer displays the magnitude of the electric field vector for a given direction The magnitude may be represented as the vector sum of two polariza tion components E theta Eg and E phi Ey as shown in the figure describing spherical coordinates on page 282 The far field viewer allows you to see the total magnitude or either component of the magnitude Other polarizations are also available in the far field viewer and are discussed in Graph Polarization in the far field viewer help References 1 Simon Ramo John R Whinnery and Theodore Van Duzer Fields and Waves in Communication Electronics John Wiley amp Sons Inc 1994 pg 601 2 Ibid pg 600 286 Chapter 20 Far Field Viewer Tutorial Chapter 20 Far Field Viewer Tutorial This tutorial describes an example of using the far field viewer to display plots The far field viewer displays far field radiation pa
308. sed If em is run with de embedding enabled on this circuit it re 111 Sonnet User s Guide moves a length of transmission line equal to the specified reference plane length This occurs even though the actual port transmission line is shorter than the refer ence plane length As a result the de embedded S parameters are non physical Discontinuity begins here W1 Example circuit for which non physical S parameters will be obtained when em is run with de embedding enabled A second de embedding example leading to non physical S parameter results is shown in the next figure In this example the circuit has two via pads on each side of the port transmission line The via pads are grounded to the box wall 112 Chapter 8 De embedding Guidelines When em is run with de embedding enabled on this circuit it removes three coupled transmission lines with a length equal to the reference plane length Since the reference plane extends from the box wall beyond the vias the de embedded S parameters are again non physical w3 N Fae Box Resonances Because em s de embedding algorithm is based on circuit theory it is unable to de embed a structure contained inside a resonant cavity a limit it shares with all de embedding algorithms Thus whenever you wish to de embed a circuit with box resonances you must take the necessary steps to remo
309. sh the via to extend downwards and perform the following Select Tools gt Add Via gt Down to Ground from the project editor menu Any vias subsequently added to your circuit will extend from the level to which they are added down through all intervening levels to ground Select Tools gt Add Via gt lt Via Type gt to add the desired type of via The command places you in an add via mode the type of via is dependent on the command you selected Draw the desired via The via you input is drawn on the present level and vias are drawn on each level below up to and including the ground plane at the bottom of the box If you wanted to add an edge via you would first have had to drawn a metal polygon to which to attach the edge via An example of a via polygon going from level 0 to ground in a two level circuit is pictured below The via polygon metalization is shown on Level 0 Note that the arrows are point ing down indicating the direction of the via The center of the via does not contain metalization but is filled with the dielectric of the dielectric layer The ground lev Chapter 16 Vias and 3 D Structures elis completely metallized the outline of the via polygon is drawn on ground level simply as a reference with up arrows indicating that there is a via polygon in the level above Ground Level Metalization Via Post S 2 s 6 A pig EN Level 0 The lower part of the figure
310. sis gt Setup then click on the Advanced but ton in the Analysis Setup dialog box Selecting this option forces a higher accu racy for ABS convergence by including the Q factor of your analysis as a criterion for convergence This is done to insure high accuracy in the Q Factor result when ABS is used The Q Factor is defined as follows imag Y teal Y Chapter 9 Adaptive Band Synthesis ABS The result is higher accuracy from the ABS sweep but this accuracy comes at the cost of requiring more discrete frequencies to be analyzed before conversion is reached Running an Adaptive Sweep To run an analysis using the Adaptive Band Synthesis technique you do the fol lowing 1 Open your project in the project editor 2 Select Analysis gt Setup from the main menu of the project editor The Analysis Setup dialog box appears on your display with an adaptive sweep already selected since Adaptive Sweep is the default for analysis control Analysis Setup steps son Options l Compute Current Density I Memory Save Speed Memory Advanced Analysis Control Adaptive Sweep ABS Start Stop GHz GHz fi 0 25 0 Cancel Help 3 Select Adaptive Sweep ABS from the Analysis Control drop list if necessary This selects the ABS technique for the analysis 4 Enter the desired frequency band in the Start and Stop text entry boxes This defines the frequency band on wh
311. solution re sponse for a frequency band requiring only a small number of analysis points Em performs a full analysis at a few points and uses the resulting internal or cache data to synthesize a fine resolution band TIP This technique in most cases provides a considerable reduction in processing time Using the input frequency band em first performs a full analysis of the circuit at the beginning and end frequencies Em continues solving at discrete points stor ing the full analysis data for each point This process continues until enough inter nal or cache data is generated to synthesize a fine resolution response Once the frequency band response is synthesized em outputs approximately 300 data points for the frequency band These data points are a combination of the dis crete analysis points and synthesized points This combined data is referred to as adaptive data 115 Sonnet User s Guide Em dedicates the bulk of the analysis time for an ABS analysis in calculating the response data at the discrete data points Once the adaptive band synthesis is com plete calculating the adaptive data for the entire band uses a relatively small per centage of the processing time ABS Resolution The ABS resolution is the value in frequency units between adaptive data points in your response output from an adaptive sweep Normally the resolution in an adaptive sweep is provided by em such that around 300 data points are outp
312. specified for a dielectric layer is the Z Partitioning This value may be changed in the Z Partitions dialog box which is opened when you click on the Z Parts button in the Dielectric Layers dialog box Z Partitions The z partitioning parameter is the setting which controls the number of partitions which the dielectric layer is divided into in the z direc tion for the dielectric layer While this parameter is specified in the dielectric layer window it only has an effect on the dielectric bricks on that layer Changing this value for a particular layer will have absolutely no affect on the analysis if there are no bricks on the layer If there are multiple bricks on the layer the Z subsectioning for all of those bricks will be identical The more partitions better resolution used in the Z dimension the more ac curate the analysis however analysis time and memory requirements also in crease dramatically Chapter 4 Metalization and Dielectric Layer Loss Dielectric Layer Loss Em uses the above parameters to calculate the total effective tan for the dielectric material as follows tan Loss Tan Diel Cond o Erel e where is the radian frequency 27f where f is frequency in hertz Note that tan has both a frequency dependent term and a frequency independent term The above eguation for tan can also be expressed in terms of conductivity as fol lows Total Effective Cond Loss Tan o Erel z Diel Con
313. ss a Conductor Each subsection generates an electric field everywhere on the surface of the sub strate but we know that the total tangential electric field must be zero on the sur face of any lossless conductor This is the boundary condition no voltage is allowed across a perfect conductor The problem is solved by assuming current on all subsections simultaneously Em adjusts these currents so that the total tangential electric field which is the sum of all the individual electric fields just calculated goes to zero everywhere that there is a conductor The currents that do this form the current distribution on the met alization Once we have the currents the S parameters or Y or Z follow imme diately If there is metalization loss we modify the boundary condition Rather than zero tangential electric field zero voltage we make the tangential electric field the voltage on each subsection proportional to the current in the subsection Follow ing Ohm s Law the constant of proportionality is the metalization surface resis tivity in Ohms sguare Sonnet is designed to work with your existing CAE software Since the output data is in Touchstone or Compact format at your discretion em provides a seamless interface to your CAE tool Em Origins 22 The technigue used in em was developed at Syracuse University in 1986 by Rautio and Harrington 85 86 88 It was originally developed as an extension of an analysis of plan
314. t s default meshing algorithm has been improved for circuits containing large ground planes and planar shields irregular edges and interior via connections Circuits containing these features are accu rately meshed with dramatic reduction in memory usage and analysis time Matrix solve time reduction of 10x or more are not uncommon for such circuits Gerber Translator Release 12 introduces a new Gerber translator which allows you to perform single layer or multi layer import of Gerber files to create a Sonnet project You may also export a Sonnet project and create Gerber formatted output files of your circuit Please refer to Chapter 5 The Gerber Translator in the Translators manual New Parameter Sweep Analysis Definitions The EM Analysis Engine also has new parameter sweep analysis types useful for tolerance studies and design for manufacturing testing The new parameter sweeps include Corner Sweep Analy sis Sensitivity Sweep Analysis and Mixed Sweep Combinations For details about these sweeps please see Help for details by looking up Corner Sweep Sen sitivity Sweep or Mixed Sweep in the Index 25 Sonnet User s Guide 26 Multiconductor Transmission Line MTL modeling Sonnet s MTL modeling N Coupled Line Model has been greatly improved Analytical extraction of RLGC per unit length parameters from the Scattering Parameters of MTLs has been implemented The output format of the RLGC data file is compatible with
315. t editor Optimization You may also use variables to perform an optimization on your circuit An opti mization allows you to specify goals the desired response of your circuit and the data range for the variables s over which you seek the response The software using a conjugate gradient method iterates through multiple variable values searching for the best set which meets your desired goals The conjugate gradient optimizer begins by analyzing the circuit at the nominal variable values It then perturbs each variable individually while holding the oth ers fixed at their nominal values to determine the gradient of the error function for that variable Once it has perturbed each variable it then performs a line search in the direction of decreasing error function for all variables After some iterations on the line search the optimizer again calculates the gradients for all variables by perturbing them from their present best values Following this a new line search is performed This continues until one of three conditions are met 1 the error goes to zero 2 the error after the present line search is no better than the error from the previous line search 3 the maximum number of iterations is reached When one of these three conditions is met the optimizer halts 151 Sonnet User s Guide The equations used to determine the optimization goal error are as follows Simulation f Target f EqualOperatorError
316. t is possible to setup batch files with start and stop times using the analysis monitor For directions on how to do so please see How do I create a batch file to run multiple analysis jobs in online help You should be aware that running from the command line does not provide all of the status information that is provided in the analysis monitor while running an analysis The syntax of the command line is as follows em options lt project name gt external frequency file where 345 Sonnet User s Guide lt options gt is one or more of the run options shown in the table below If you use multiple options they should be typed with no spaces in between after the minus sign Note that other run options may be set in the Analysis Setup dialog box for your project and will be used during the analysis Option Meaning Dlicense Used for debugging em licensing problems Displays all environment information relevant to licensing N Display number of subsections and estimated required memory Em then exits without running a full analysis test Run em ona test circuit Used to verify that em can get a license and run successfully v Display analysis information as the analysis is performed The analysis information is output to the command prompt window or terminal from which the batch was executed AbsCacheNone Disable ABS caching overrides setting in project file AbsCacheStopResta
317. t string gt lt string gt is a character string of alphanumeric characters Custom Prefix text entry box This is only applicable if the GbrFilenameType option is set to custom Gerber Only GbrFilenameExt lt string gt lt string gt is a character string of alphanumeric characters ext text entry box Gerber Only GbrJobFilenameType lt type gt lt type gt is custom or project Custom corresponds to the Custom Prefix radio button in the Netex G Job Filename section of the dialog box Project corresponds to the Project Name radio button Gerber Only GbrJobPrefix lt string gt lt string gt is a character string of alphanumeric characters Custom Prefix text entry box This is only applicable if the GbrJobFilenameType option is set to custom Gerber Only Example of xgeom Command Line An example command line is shown below xgeom test son Export DXF RWOut outfile dxf ExpRegistry ExpOptions expopt txt The above command creates a DXF output file named outfile dxf from the Sonnet project test son using the export options provided in the Export Options file expopt txt this feature creates a DXF file called outfile dxf The programs closes once the export is complete An example of an Export Options file is shown below SepObj yes SepMat no DivideMulti no Circles yes CircleType inscribed CircleSize 5 8 KeepMetals yes KeepVias true KeepBricks no KeepEdgeVias off KeepParent TRUE Convert
318. tal libraries available in Sonnet global and local The metal libraries contain standard definitions for metal types which may be used in your projects There is no real difference between the global and local library The names refer to how they are used The global library would usually be used as a group wide library of standard metals for a group of designers There is a default global library supplied by Sonnet which contains definitions for some common metals The default location for the global library is in lt Sonnet Di rectory gt data library where lt Sonnet Directory gt is the directory in which your Sonnet software is installed You may choose to use this location or can save this library in another location The local library would usually be used as the user s own library of metal defini tions This library may be stored in a location of the user s choice You use the Metal Editor dialog box to add edit and delete entries to these libraries For instructions on adding metals to a metal library editing metals in a metal li brary or using metals defined in a metal library please refer to Sonnet Help avail able from the Help menu in any Sonnet application The loss of a via is accomplished in much the same way as a metal polygon The only difference is that a via is a 3D object and a polygon is only two dimensional Therefore the Sonnet via loss model is only an approximation In general edge vias use the loss of the polygon
319. tched load The images formed by the waveguide walls properly model the entire infinite array scanned to a specific angle The waveguide simulator inspired what we now call the Open Waveguide Simu lator Technique described in the next section Modeling Infinite Arrays 274 The sidewalls of the shielding box in the em analysis easily represent the sidewalls of the waveguide in the infinite array waveguide simulator A side view is shown in the figure on page 275 Providing a termination for the end of the waveguide requires a little more thought Any waveguide mode can be perfectly terminated by making the top cov er resistivity in em equal to the waveguide mode impedance This can be done in the project editor automatically at all frequencies and all modes by selecting WG LOAD from the metals in the Top Metal drop list in the Box Settings dialog box Chapter 19 Antennas and Radiation Waveguide Walls Pete NAINJINANNIN NS Waveguide Termination KS Te c Array Patches a 0 B 4 Substrate The waveguide simulator for infinite arrays inspired the technique described here In this side view the waveguide walls form images of the array of microstrip patches simulating an infinite array Vc is the velocity of light in the medium filling the waveguide In a phased array with the array scanned to a specific direction a single waveguide mode is generated The em software can model the wavegui
320. ted polygons are highlighted 2 Select Modify gt Metal Properties from the main menu The Metal Properties dialog box appears on your display M Metalization Properties conformal son Metal Lossless Fill Type Subsectioning Controls X Min Y Min ies XMax 100 YMax jo Edge Mesh Conformal Mesh Subsectioning Controls Maximum Length mils 1 polygon selected Apply Cancel Help 187 Sonnet User s Guide 3 Select Conformal in the Fill Type drop list 4 Click on the OK button to apply the changes and close the dialog box The polygon does not appear any different in the circuit To see the difference you need to use the Analysis gt Estimate Memory command When the Estimate Memory dialog box appears click on the View Subsections button Shown below is the subsectioning for the same spiral inductor The circuit on the left uses rectangular subsections and the one on the right uses conformal subsections Note that the rectangular subsectioning uses a much higher number of subsections for the spiral inductor than does the conformal meshing Rectangular subsectioning was used for the feed lines in both cases Spiral inductor with rectangular Spiral inductor with conformal subsections Default subsections If you chose Conformal meshing then the subsectioning controls in the Metaliza tion Properties dialog box Xmin Ymin XMax YMax and Edge Mesh are dis abled and ignored C
321. tex where two polygons meet should not occur between two vertices of the third polygon See the illustration below Correct Placement Error Condition Memory Save Option It is recommended that memory save not be enabled when your circuit has poly gons using conformal mesh fill This is because conformal mesh subsections are sensitive to precision error Since using the memory save option involves reducing the required memory at the expense of increasing precision error its use may lead to noisy S parameter results for circuits with conformal mesh fill Using Conformal Meshing Effectively This section discusses some guidelines to use in order to get the most improve ment in processing time and memory use and the most accurate results when using conformal meshing Following these guidelines will help you to use conformal meshing in the most efficient manner Use Conformal Meshing for Non Manhattan Polygons Conformal meshing should be used for non Manhattan polygons Manhattan polygons are polygons which only have vertical and horizontal edges no diago nals or curves For these types of polygons rectangular subsections are more effi cient 191 Sonnet User s Guide 192 You should look at your geometry and if necessary divide it up into Manhattan and non Manhattan polygons using the Edit gt Divide Polygon Then set the Man hattan polygons to staircase fill and the non Manhattan polygons to Conformal fill For ex
322. th the smaller cell size 38 Chapter 3 Subsectioning X Min and Y Min with Edge Mesh On Having the edge mesh option on is the default state for Sonnet projects because it provides a more accurate analysis Having edge mesh on for a polygon chang es how the subsections on the very edge are handled Starting from the left side of the previous example with edge mesh off the subsections were 2 cells 4 cells and 8 cells wide With edge mesh on the subsections for the same polygon would be 1 cell 4 cells and 8 cells as shown in the illustration below Notice only the out ermost edge is affected 1 Cell by 1 Cell on corner D Cell Size x A portion of circuit metal showing how em combines cells into subsections for polygons with edge mesh on with X Min 2 and Y Min 1 Edge mesh polygons always have 1 cell wide edge subsections As mentioned in the previous section the edge mesh setting only affects Manhat tan polygons i e those with no diagonal or curved edges Edge mesh is always on for non Manhattan polygons regardless of the edge mesh setting for that polygon 39 Sonnet User s Guide When used in conjunction with large X Min or Y Min values the edge mesh op tion can be very useful in reducing the number of subsections but still maintaining the edge singularity as shown in a simple example below This is very often a good
323. the analysis monitor s tool bar The response viewer is invoked with a plot of your response data Click on the project name in the response viewer legend to select it An outline appears around the project name to indicate that it is presently selected If you have multiple projects open in the response viewer and have not selected a project before using the extraction command then a window appears which allows you to select the desired project 313 Sonnet User s Guide 4 Select Output gt PI Model File from the response viewer main menu The Output PI Model dialog box appears on your display The contents of the output window in the Output PI Model dialog box displays the Spice data for the PI Model in the PSpice format which is the default F Output PI Model br32 Format Data Type PSpie De Embedded Model Options Include Comments M Include Adaptive Data F High Precision Sonnet Data File From emyraph Version 10 02 0 040 alpha From Emgraph Data br32 Data File Written 09 24 2004 11 38 50 lt HDATE 09 02 2004 17 46 48 lt MDATE 09 02 2004 17 46 48 Spice Data Limits C gt 0 01pF L lt 100 0nH R lt 1000 00hms K gt 0 01 Analysis frequencies 10 0 15 0 MHz Subckt SonData 123456789 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 C C1 1 GND 14 4632pf C C2 12 1 06465pf C C3 1 9 0 044715pf 1 10 0 037854pf 11 0 03433pf 12 0 029809pf 13 0 022267pf 17 0 057935pf ja assus se7 3 l
324. the right value range when the optimizer is started Otherwise the optimizer may converge to a local minima for which the error is not the mini mum achievable value as pictured below Error Function Local Minima Actual Minimum Parameter Values You specify a goal by identifying a particular measurement and what value you desire it to be For example S4 lt 20 dB Keep in mind that the goals you specify may not be possible to satisfy Em finds the solution with the least error You may also specify a goal by equating a measurement in one network to a mea surement in another network or file For example you may set S4 for network Model equal to S4 for network Measured Likewise you may equate S4 for network Model to S4 for data file meas s2p You may select one or multiple variables to optimize For each variable that you select you must specify minimum and maximum bounds The analysis limits the variables to values within the specified bounds Variables that are used in an optimization have a granularity value assigned to them the granularity defines the finest resolution the smallest interval between values of a variable for which em will do a full electromagnetic simulation during optimization For values which occur between those set by this resolution em per forms an interpolation to produce the analysis data By default the software deter mines the granularity but you may enter a val
325. thick metal polygon on level 2 is shown below Note that the top of the thick metal only extends halfway through dielectric layer The top of this thick metal is not visible in the project editor Z direction A 150 mils Level 0O 75 mils i Ta B 100 mils Level 1 m 50 mils Level 2 Dielectric Thick metal Another important thing to note about the modeling of a thick metal which ends in the interior of a dielectric layer is that even though you model the thick metal with 2 sheets the software actually uses three sheets The bottom sheet is on level 2 where the polygon originates The top sheet is in the interior of dielectric layer A The third sheet is on metal level 1 Whenever a thick metal polygon traverses a metal level a sheet is added on that level This adds additional computational time and should be kept in mind when using thick metals which encompass more than one dielectric layer If Single Level select is enabled then you may only select the thick metal polygon on the level where it was drawn Thick metal polygons are connected to thin metal polygons by drawing the thin metal polygon on the same level on which the thick metal was drawn and placing the thin metal polygon adjacent to or overlapping the thick metal This connects the two structures electrically Restrictions with Thick Metal Polygons If you are using the thick metal model with more than two sheets of metal be
326. ting Frequencies 7 Click on the Frequencies tab in the Calculation Setup dialog box The Frequencies tab is now displayed as shown below W Calculation Setup infpole son Review settings in all categories before pressing Calculate Angles Ports Frequencies Available Freguencies Freguencies to Calculate 0 8 GHZ D J Select All Cancel Help 8 Click on the Select All command button under the Available Frequencies All of the frequencies are highlighted 9 Click on the Right Arrow button This moves all the selected freguencies to the Calculated Freguencies column 291 Sonnet User s Guide 10 Click on the Calculate command button There is a delay while the far field viewer calculates the requested data The cal culations for each frequency are performed using the defaults cited above for phi theta port excitation and exclusions since none of these items were changed be fore selecting Calculate A status box appears on your display to provide updates on calculation progress The display is updated when the calculation is completed Be aware that for larger more complicated circuits this delay might be a considerable one Selecting the Response 292 11 The far field viewer allows you to select which data items you wish displayed at any given time In the next session you display 1 GHz data at different phi s Select Graph gt Select gt Frequencies from the far field vi
327. tioning 44 Conformal meshing is a technique which can dramatically reduce the memory and time required for analysis of a circuit with diagonal or curved polygon edges For a detailed discussion of conformal mesh and its rules of use please refer to Con formal Mesh page 185 Only the effect of conformal mesh on subsectioning is discussed in this chapter This technique groups together strings of cells following diagonal and curved met al contours to form long subsections along those contours Whereas staircase fill results in numerous small X and Y directed subsections conformal mesh results Chapter 3 Subsectioning in a few long conformal subsections The illustration below shows the actual met alization of a conformal section in close up alongside the same section using stair case fill Conformal section Staircase Fill Conformal sections like standard subsections are comprised of cells so that the actual metalization still shows a jagged edge when the polygon has a smooth edge However the sections can be much larger due to conformal meshing These larger sections yield faster processing times with lower memory requirements for your analysis Standard subsectioning requires a lot of subsections to model the correct current distribution across the width of the line Conformal subsections have this distribu tion built into the subsection Sonnet conformal meshing automatically includes the high edge current in e
328. tions 148 sensitivity 148 symbol component 83 symmetric dimension parameter 136 139 adding 161 first reference point 140 second reference point 140 symmetry 222 335 port placement 67 T T attenuator 202 204 with ungrounded internal ports 208 TEM 317 TEM modes 113 terminal number 83 terminal width feedline width 73 89 one cell 73 89 user defined 74 89 terminations 280 default values 289 theory 21 22 theta 282 283 default values 289 selecting values to plot 303 305 specifying range for calculation 283 thick metal 66 253 262 arbitrary cross section 260 creating a polygon 255 number of sheets 253 restrictions 259 viewing in the current density viewer 261 viewing in the project editor 257 thick metal type 55 253 Index thickness metal 52 thin film resistor 48 200 two connected 200 Thkthru 261 threads 24 3 D 241 tool bar 245 303 full view button 296 zoom in button 295 Tools Add Subdivider 229 Subdivide Circuit 233 top cover 336 337 resistive 339 top hemisphere 282 translator 16 GDSII 17 Gerber 17 transmission line 317 transmission line parameters 125 transmission lines 197 structures 205 transverse electromagnetic 317 triangular subsections 281 Tripat 279 tutorial 287 optimization 155 parameter sweep 155 two port T attenuator 202 type cartesian 303 polar 299 surface 306 U ungrounded internal ports 205 207 update nominal values 182 user interface 23 V validation 287 variables
329. tions on Microwave Theory and Techniques Vol 47 No 1 January 1999 pp 115 117 James C Rautio and George Matthaei Tracking Error Sources in HTS Filter Simulations Microwaves and RF Vol 37 No 13 December 1998 pp 119 130 J C Rautio Electromagnetic Analysis for Microwave Applications Computational Electromagnetics and Its Applications Vol 5 Boston Kluwer Academic Publishers 1997 pp 80 96 Yasumasa Noguchi Shin ichi Nakao Hideaki Fujimoto and Nobuo Okamoto Characteristics of Shielded Coplanar Waveguides on Multilayer Substrates Electronic Information and Communications Univerisity Meeting Electronics Society Conference June 29 1998 Japanese Article Erik H Lenzing and James C Rautio A Model for Discretization Error in Electromagnetic Analysis of Capacitors EEE Transactions on Microwave Theory and Techniques Vol 46 No 2 February 1998 pp 162 166 J C Rautio Retracing Key Moments In the Life of Maxwell Microwaves amp RF Vol 36 No 11 November 1997 pp 35 51 J C Rautio Electromagnetic Analysis for Microwave Applications NASA CEM Computational Electromagnetics Workshop Newport News VA May 1996 J C Rautio Seven Years Later Applied Microwave and Wireless November December 1996 pp 99 100 J C Rautio Questionable Reviews The Institute IEEE newspaper Jan 1996 pg 11 J C Rautio An Investigation of an Err
330. ts IEEE Transactions on Microwave Theory and Techniques Letters Vol 52 No 10 October 2004 pp 2448 2449 353 Sonnet User s Guide 354 7 8 9 10 11 12 13 14 15 16 17 18 19 James C Rautio A Space Mapped Model of Thick Tightly Coupled Conductors for Planar Electromagnetic Analysis IEEE Microwave Magazine Vol 5 No 3 September 2004 pp 62 72 James C Rautio Accurate and Efficient Analysis of Large Spiral Inductors with Thick Metal and Narrow Gaps Using Space Mapping IEEE MTT S International Microwave Symposium Workshop Notes amp Short Courses WFD 7 6 11 June 2004 James C Rautio In Defense of Uselessness IEEE Microwave Magazine Vol 5 No 1 March 2004 pp 100 102 James C Rautio A Conformal Mesh for Efficient Planar Electromagnetic Analysis IEEE Transactions on Microwave Theory and Techniques Vol 52 No 1 January 2004 pp 257 264 David I Sanderson James C Rautio Robert A Groves and Sanjay Raman Accurate Modeling of Monolithic Inductors Using Conformal Meshing for Reduced Computation Microwave Magazine Vol 4 No 4 December 2003 pp 87 96 James C Rautio Testing Limits of Algorithms Associated with High Frequency Planar Electromagnetic Analysis European Microwave Conference Digest Munich October 2003 pp 463 466 Rautio James C Generating Spectrally Rich Data Sets
331. tterns using the current density data created during an em analysis In this example we analyze an infinitesimal dipole antenna above a ground plane shown below and compare the results to the exact theoretical antenna pattern shown on page 303 as provided by reference 2 For more information about modeling antennas and using the far field viewer please refer to Chapter 19 Although this example is not very practical it is a good example to use for valida tion because of its simplicity The infinitesimal electric dipole is placed one wave length 300 mm at 1 GHz above the ground plane an electric field reflection boundary 287 Sonnet User s Guide Uniform Current Element Ground Plane R Close up of the project editor layout 4 Creating an Antenna Pattern File 288 This tutorial uses an infinitesimal dipole one wavelength above the ground plane The project Infpole is provided in the Sonnet example files If you do not know how to obtain a Sonnet example select Help gt Examples from any program menu then click on the Instructions button Save a copy of infpole son to your working directory The file infpole son is the circuit geometry project file for the dipole antenna which was created using the project editor The dipole geometry can be viewed by using the project editor It is important to remember that in order to produce data for input into the far field viewer the
332. ty Viewer The current density viewer allows you to view the current density distribution in your circuit When you select the Compute Current Density option in the Analysis Setup dialog box in the project editor em calculates current density data for all the metal levels in your circuit When you have thick metal in your circuit which ends in the interior of a dielectric layer then the current density viewer creates sublev els of metal in order to display all the current density data 261 Sonnet User s Guide For instance you have a circuit with 3 mil thick metal using the default 2 sheets placed on metal level 1 below a 25 mil dielectric layer as pictured below The top of the thick metal structure is placed in the interior of the dielectric layer The cur rent density viewer displays levels 1b and 1a where 1b is the metal level on which the thick metal was drawn and 1a is the top of the thick metal structure embedded in the dielectric layer Z direction A cae mils Level 0 3 mils B 25 mils Level 1 Dielectric Thick metal Below are shown the views of level 1a and 1b in the current density viewer Note that 1a is the top of the thick metal structure and is not visible in the project editor 1b is the bottom where the polygon was drawn and is visible in the project editor pa DJ 13 SeS lt EE amp k laleJa sis sisi 4 Amps Meter 1 80 1 54 1 29 1 03 0 77 0 5
333. ty in both the current density viewer and the far field viewer which al lows you to choose a parameter combination whose data you wish to display FLEXnet 11 5 Support Sonnets license manager is now based upon FLEXnet version 11 5 which officially supports the Windows Vista operating system Below is a summation of the major changes in release 12 of Sonnet For new fea tures in release 12 refer to New Features page 24 Parameters In release 11 parameters were used to identify dimensions in your geometry and sweep those dimensions in an analysis These parameters are now defined as dimension parameters The command to add an anchored dimension 27 Sonnet User s Guide 28 parameter is now Tools Add Dimension Parameter gt Add Anchored and to add a symmetric dimension parameter is Tools gt Add Dimension Parameter gt Add Symmetric For details about the new variables feature and how they relate to dimension parameters please refer to Chapter 10 Parameterizing your Proj ect on page 129 Highlighting in 3D View Enhancements have been done in the 3D view to high light the metal levels and dielectric layers Menu Name Change in the Current Density Viewer The Parameters menu in the current density viewer has been changed to the Plot menu in release 12 Chapter 3 Subsectioning Chapter 3 Subsectioning The Sonnet subsectioning is based on a uniform mesh indicated by the small
334. u are running an ABS analysis over a narrower band than the previ ous ABS analysis of the project as shown in the diagram below This provides higher resolution over the narrower band since the ABS analysis defaults to ap proximately 300 data points In order for the caching data to be valid for the sec ond analysis your Advanced Subsectioning controls must be set such that the Chapter 9 Adaptive Band Synthesis ABS subsectioning frequency is the same for both runs If the subsectioning frequency remains the same the second analysis will not require any re analysis and the re sults should be provided very quickly Frequency band of lst ABS analysis 10 GHz 30 GHz 15 GHz Frequency band of 2nd ABS analysis 25 GHz Extending the Band You are running an ABS analysis which overlaps a previous ABS analysis of the project pictured in the diagram below The caching data for the overlap between the two analyses will be reused although some calculation may need to be done in the extension of the frequency band where it does not over lap with a previous analysis In order for the caching data to be valid for the second analysis your Advanced Subsectioning controls must be set such that the subsec tioning frequency is the same for both runs Frequency band of 1st ABS analysis lt lt 30 50 GHz e Overlap 40 60 GHz Frequency band of 2nd ABS analysis Accuracy Assurance If you wish to che
335. u wish to analyze the geometry subprojects before subdividing the circuit These frequen cies should cover the same frequency range as the analysis frequencies for the whole circuit but use a coarser step size The subprojects should be analyzed at the same minimum and maximum frequency as the overall analysis and at enough points in between to provide for reasonable interpolation of the response By inputting the coarse frequency sweep prior to subdivision the master netlist and geometry subprojects created by the subdivide command will all inherit the analysis setup After subdividing you will need to enter the desired finer frequen cy step size in the master netlist project before analyzing it In addition you will need to turn off Hierarchy Sweep The figure below shows a Smith chart with a circuit analyzed at five frequency points next to the same circuit analyzed at only two points As you can see using only two data points would result in more interpolating error than using five data points Whether or not two data points is acceptable depends upon the proximity of points A and B If A and B are very close then two data points are sufficient If A and B are far away then five or more data should be used k It is always a good idea to check the Smith chart for the response data of your sub projects to ensure that you have chosen enough freguency points at which to cal culate data so that any interpolated data is reasonably
336. ubdivide the circuit such that the via is simulated separately thus providing an accurate via simulation For more information on cir cuit subdivision see Chapter 14 Circuit Subdivision on page 211 Chapter 17 Thick Metal Chapter 17 Thick Metal Thick Metal Type The Thick Metal metal type allows you to model physically thick metal All other metal types are modeled as having zero thickness where the entered thickness val ue only affects the metal loss calculations The Thick Metal type allows you to more accurately model the true 3D characteristics of thick conductors Using a thick metal model not only allows for proper modeling of loss but also includes the EM effects of physically thick metal such as coupling between closely spaced conductors Since thick metal increases both your processing time and memory requirements it should only be used when necessary Metal is considered to be thick metal when its thickness is comparable to other dimensions in the circuit such as the width of a conductor or gap between conductors 253 Sonnet User s Guide 254 When using thick metal the structure is approximated by two or more infinitely thin sheets of metal For the typical two sheet model one sheet represents the top surface of the structure and a second sheet represents the bottom surface of the structure Vias are placed automatically around the perimeter to allow current to flow between the sheets An example usin
337. ue manually You specify the number of iterations For each iteration em selects a value for each of the variables included in the optimization then analyzes the circuit at each frequency specified in the goals Depending on the complexity of the circuit the number of analysis frequencies and the number of variable combinations an op timization may take a significant amount of processing time The number of iter ations provides a measure of control over the process Note that the number of iterations is a maximum An optimization can stop after fewer iterations if the op timization goal is achieved or it finds a minima finds no improvement in the error in further iterations 153 Sonnet User s Guide 154 Once the optimization is complete the user has a choice of accepting the optimal values for the variables resulting from the em analysis Note that for dimension parameters if the results of the optimization are accepted the actual metalization in the project editor is the closest approximation which fits the present grid set tings As a matter of fact em analyzes snapped circuits and interpolates to pro duce responses for circuits which do not exactly fit the grid For more information about the grid see Chapter 3 Subsectioning on page 29 Chapter 11 Parameter Sweep and Optimization Tutorial Chapter 11 Parameter Sweep and Optimization Tutorial This tutorial shows you how to set up variables and dimens
338. uerque June 1992 J C Rautio Current Developments in 3 D Planar Microwave Electromagnetics Microwave Hybrid Circuits Conference Oct 1991 Arizona J C Rautio Current Developments in 3 D Planar Microwave Electromagnetics Microwave Hybrid Circuits Conference Oct 1992 Arizona J C Rautio Current Developments in 3 D Planar Microwave Electromagnetics Microwave Hybrid Circuits Conference Oct 1993 Arizona J C Rautio Current Developments in 3 D Planar Microwave Electromagnetics Microwave Hybrid Circuits Conference Oct 1994 Arizona J C Rautio Experimental Validation of Electromagnetic Software International Journal of Microwave amp Millimeter Wave Computer Aided Engineering Vol 1 No 4 Oct 1991 pp 379 385 J C Rautio Electromagnetic Microwave Analysis IEEE International Microwave Symposium Workshop WSA Digest Albuguergue June 1992 J C Rautio EM Visualization Assists Designers Microwaves and RF Nov 1991 pp 102 106 J C Rautio Reviewing Available EM Simulation Tools Microwaves amp RF June 1991 pp 16A 20A Generating Spice Files Using the em Electromagnetic Analysis Sonnet Application Note 104a Dec 1998 J C Rautio A New Definition of Characteristic Impedance MTT International Symposium Digest June 1991 Boston pp 761 764 J C Rautio A De Embedding Algorithm for Electromagnetics International Jour
339. uide 220 The subdivision line shown in the circuit on the right is wrong since the circuit is split in the middle of a via between layers In general subdivision lines should never be placed on top of discontinuities such as vias The subdivision line on the left is the correct placement MG G Good Bad The subdivision line shown in the circuit on the right splits a polygon at the box wall which is an illegal placement for a subdivision line It is illegal to subdivide polygons grounded to the box walls since such polygons do not behave like trans mission lines Also the new ports added during the subdivide would be shorted to the boxwall The circuit on the left is correct since there is no contact between the top and bottom polygons with the top and bottom box wall sl s2 s1 s2 psss SSS SS Tnn gt SE MS GG Good Bad Chapter 14 Circuit Subdivision Subdivision Line Orientation Subdividers may split the circuit on a horizontal axis or a vertical axis but you may not mix orientation Choosing the direction in which you split your circuit is dependent upon the structure of your circuit Shown below is a typical circuit in which you would use the vertical orientation and another example in which you would use the horizontal orientation sl s2 s3 s s5 s6 sf Example of Vertical Subdividers sl PZ s2 N N N N N s3 v Example of H
340. up To gain a deeper understanding of the co calibrated ports implementation and uses we highly recommend that you also read Chapter 6 Components on page 81 Via Ports A via port has the negative terminal connected to a polygon on a given circuit level and the positive terminal connected to a second polygon on another circuit level A via port can also have the negative terminal connected to the top or bottom of the box An example of this port type on an edge via is shown below Upper Polygon Level 1 Via Port Lower Polygon An example of a circuit with a standard via port A side view of the enclosed area on the circuit is shown in the middle Unlike co calibrated ports em cannot de embed via ports However in a circuit which contains a combination of via ports and other port types the other port types can still be de embedded Em will automatically identify all of the other ports present in the circuit and de embed them but leave the via ports un de embedded The example file Dual patch has an example of a via port used in a patch antenna This example file can be found in the Sonnet example files 75 Sonnet User s Guide In most cases where you need grounded ports your first choice would be to use co calibrated ports as discussed earlier especially since it is possible to accurate ly de embed co calibrated ports The most common case where a via port would be used is when you
341. ur display Probing the Plot To evaluate the pattern response at any location in your plot you simply click at the desired location 296 Chapter 20 Far Field Viewer Tutorial 25 Click on the theta 45 point on the plot A square appears around the point as shown below The readout for the point in cluding the frequency value of theta and phi and the gain appear in the status bar at the bottom of the far field viewer window infpole son 2 3 JJS Je e Plot over theta infpole son Gain dB Frequency GHz 1 0 GHZ Phi 0 0 Degrees O 00 860 60 40 20 0 20 40 60 80 100 Theta 1 0GHZ Theta 45 0 Phi 0 0 4 642402 dB Pointer Probe readout on status bar Probe Location 26 Press the left arrow key lt to move to the theta 40 point on the plot or alternately click on that point The probe box now appears at that point and the data is updated in the status bar Note that if there is more than one data curve displayed the up and down arrow keys T and 4 would move the data probe between curves while the left and right arrow keys lt and move between data points on any given curve Re Normalizing the Plot By default the far field viewer displays the power gain The power gain is defined as the radiation intensity divided by the uniform radiation intensity that would ex ist if the total power supplied to the antenna were radiat
342. using this technique The differences in resonant 279 Sonnet User s Guide frequency i e the reflection zeros then determine the differences in the rest of the plot The degree to which these differences are due to analysis error fabrica tion error and measurement error cannot be determined from this data ig A tripat son tripat_measured snp Secor Jaa KS Cartesian Plot Z0 50 0 30 Left Axis tripat None M 25 MAG YSWR1 1 tripat measured None g 20 MAG YSWR1 n i 154 Right Axis t em empty u 104 d e 5 0 2 2 1 22 23 24 25 26 Sonnet Software Inc Frequency GHz Click mouse to readout data values Pointer The measured and calculated data for the triple patch antenna were obtained completely separately so there was no chance to tweak the model for agreement If the typical differences between measured and calculated data shown above are acceptable given the specific requirements for a particular project then the Open Waveguide Simulator technique can provide useful results Far Field Viewer 280 The purpose of the far field viewer is to calculate the far field pattern of an antenna for a given excitation and set of directions for example phi and theta ranges The far field viewer starts by reading the current density data generated by em for the antenna at the desired frequencies The far field viewer uses the current distribu tion information in the project
343. ut for a frequency band It is possible for you to override this setting and use a coarser or finer resolution for your frequency band Entering a manual value to be used for ABS is done in the Advanced Options di alog box which is opened when you click on the Advanced button in the Analysis Setup dialog box The Analysis Setup dialog box is opened when you select Anal ysis gt Setup from the project editor menu You enter the resolution by clicking on the Manual radio button in the ABS Resolution section of the Advanced Op tions dialog box and entering the desired resolution in the adjacent text entry box For details on these dialog boxes please refer to Help for the project editor There are several things to be aware of when using the manual setting for the ABS resolution Coarse resolution does not speed things up Once a rational polynomial is found to fit the solution calculating the adaptive data uses very little process ing time A really coarse resolution could produce bad results by not allowing the ABS algorithm to analyze at the needed discrete frequencies Fine resolution does not slow down the analysis unless the number of frequency points in the band is above approximately 1000 3000 points A step size resulting in at least 50 points and less than 2000 points is recommended Q Factor Accuracy 116 There is a Q Factor analysis run option available in the Advanced Options dialog box in the project editor Select Analy
344. value to the optimization result For example in this case the optimized value for Lstub is 191 6134 You should edit the nominal value of Lstub to change it to 190 which since the cell size is 10 is on the grid Select Analysis gt Setup from the project editor main menu The Analysis Setup dialog box appears on your display Select Adaptive Sweep ABS from the Analysis Control drop list The appearance of the dialog box is changed to conform with an adaptive sweep Enter 2 0 GHz in the Start text entry box and 10 GHz in the Stop text entry box to define a frequency band of 1 10 GHz for this analysis Click on OK to close the dialog box and apply the changes Click on the Analyze button to start the em analysis If prompted save the circuit before analyzing When the analysis is complete click on the View Response button on the analysis monitor s tool bar The response viewer appears on your display with the curve group par_dstub consisting of DB S11 displayed Right click on the curve group par_dstub and select Edit Curve Group from the pop up menu which appears Select DB S21 for display move DB S11 to the Unselected list and close the dialog box Your plot should appear similar to that shown below Ei par dstub son EARMA Cartesian Plot Z0 50 0 Left Axis par_dstub O DB S21 M a g n i t u d e ju 2 3 4 5 6 Sonnet Software Inc Freguency GHz Click mouse to readout
345. ve those box resonanc es See Chapter 22 for a detailed description on identifying and removing box res onances Note that if you do de embed a circuit with box resonances em may generate a bd de embedding error code see section De embedding error codes in Help This error code indicates that em has detected bad values for Eeff and Zo Higher Order Transmission Line Modes De embedding removes the port discontinuity and the connecting length of trans mission line The de embedding assumes that there is only one mode propagating on the connecting transmission line usually the fundamental quasi TEM mode If higher order modes are propagating the de embedded results are not valid The 113 Sonnet User s Guide 114 same is true for actual physical measurements If this is the case we strongly recommend using a thinner substrate unless for some reason multi mode opera tion is desired Even when higher order microstrip modes are evanescent there can still be prob lems If the port is so close to the discontinuity of interest that their fringing eva nescent fields interact the de embedding looses validity Again this is a problem which also arises in an actual physical measurement if the device to be de embed ded is too close to the fixture connector Chapter 9 Adaptive Band Synthesis ABS Chapter 9 Adaptive Band Synthesis ABS The Adaptive Band Synthesis ABS technique provides a fine re
346. ve view of the electromagnetic interactions occurring within your circuit The currents may also be displayed in 3D Program module emvu Chapter 1 Introduction Far Field Viewer GDSII Translator DXF Translator Gerber Translator Agilent ADS Interface AWR Microwave Office Interface Cadence Virtuoso Interface Broadband Spice Extractor The far field viewer is the radiation pattern computation and display program It computes the far field radiation pattern of radiating structures such as patch antennas using the current density information from em and displays the far field radiation patterns in one of three formats Cartesian plot polar plot or surface plot Program module patvu The GDSII translator provides bidirectional translation of GDSII layout files to from the Sonnet project editor geometry format Program module gds The DXF translator provides bidirectional translation of DXF layout files such as from AutoCAD to from the Sonnet project editor geometry format Program module dxfgeo The Gerber translator provides bidirectional translation of Gerber single layer and multi layer files to from the Sonnet project editor geometry format The Agilent ADS Interface provides a seamless translation capability between Sonnet and Agilent s ADS From within ADS Layout package you can directly create Sonnet geometry files Em simulations can be invoked and the results incorporated into your des
347. vel ON Lossless gt Up Down i Level s To Level To Level i v drop list Cancel Help 3 Select 2 from the To Level drop list The via originates on level 0 which you do not wish to change Selecting 2 from the drop list changes the via so that it goes down to level 2 instead of level 1 Notice that the number of levels is updated from 1 to 2 249 Sonnet User s Guide 4 Click on OK to apply the changes and close the dialog box Your circuit is redrawn so that it appears as shown below Level 0 Level 1 Level 2 Note that the via polygon which appears on level 1 now has both up and down ar rows indicating that the via extends in both direction The via polygon now ap pears on level 2 the new endpoint of the modified via Deleting Vias Vias may be deleted on any metalization level on which they appear even if you are in the middle of the via between the endpoint levels Via Polygons To delete a via polygon select the via polygon while in pointer mode by clicking anywhere on the via that you wish to delete Then select Edit gt Cut from the menu or the Delete key to delete it Edge Vias To delete an edge via select the via while in pointer mode by clicking on a triangle of the via that you want deleted Then select Edit gt Cut from the menu bar or the Delete key to delete it Deleting a via deletes the via posts associated with it You should also note that if you del
348. we need to first under stand em s automatic subsectioning for a polygon when the parameters are set to their default settings Default Subsectioning of a Polygon By default Sonnet fills a polygon with staircase subsections Other more ad vanced fill types diagonal and conformal are covered in other chapters of this manual For diagonal subsections see Chapter 16 Vias and 3 D Structures on page 241 For conformal mesh see Chapter 12 Conformal Mesh on page 185 This chapter deals exclusively with staircase subsections Chapter 3 Subsectioning This fill type is referred to as staircase because when using small rectangular sub sections to approximate a diagonal edge the actual metalization takes on the ap pearance of a staircase as in the example shown below The black outline represents the polygon input by the user The patterned sections represent the actual metalization analyzed by em Staircase edge The default values for the subsectioning parameters are X Min 1 Y Min 1 X Max 100 and Y Max 100 These numbers specify the smallest and largest allowed dimensions of the subsections in a polygon With X Min 1 the smallest subsection in the X dimension is one cell With X Max 100 subsections are not allowed to go over 100 cells in length The illustration below shows how these default subsectioning parameters are used Notice in the corner the subsection size is just one
349. weep if you run with de embedding enabled de embedded data is available for the whole band Non de embedded data is available only for the discrete data points at which full analyses were performed while synthesizing the response If you wish to have non de embedded data for the whole frequency band you must perform an adaptive sweep with the de embed option disabled Select Anal ysis Setup from the main menu to open the Analysis Setup dialog box then click on the Advanced button to open the Advanced Options dialog box Click on the De embed checkbox to disable de embedding For details on these dialog box es please refer to Help for the project editor For more information about de embedding see Chapter 7 De embedding on page 97 and Chapter 8 De embedding Guidelines on page 107 Transmission Line Parameters As part of the de embedding process em also calculates the transmission line pa rameters Zp and Egg You should be aware that when running an ABS analysis these parameters are only calculated for the discrete data points at which a full analysis is run If you need the transmission line parameters at more data points analyze the circuit using a non ABS analysis Current Density Data Current density data is calculated for your circuit when the Compute Current Den sity option is enabled in the Analysis Setup dialog box For non ABS sweeps cur rent density data is calculated for all the response data For an adaptive swe
350. weep and optimization covered later in this tutorial Only independent variables may be selected for parameter sweeps and optimization Select File gt Save for the project editor main menu This saves the changes you have made to the circuit so that you can analyze it The next section of the tutorial teaches you how to setup and run a parameter sweep on the circuit Parameter Sweep 164 The parameter sweep uses only the Lstub variable You analyze the circuit at two different lengths for Lstub over a frequency band of 2 0 GHz to 10 0 GHz When the sweep is complete you view the response curves in the response viewer For a detailed discussion of a parameter sweep please refer to Parameter Sweep page 148 Chapter 11 Parameter Sweep and Optimization Tutorial Setting Up a Parameter Sweep 1 Select Analysis gt Setup from the project editor s main menu The Analysis Setup dialog box appears on your display 2 Select Parameter Sweep from the Analysis Control drop list This selects a parameter sweep as the type of analysis The dialog box s appearance changes to accommodate the input needed for a parameter sweep M Analysis Setup par_dstub son 2 x Options l Compute Current Density Speed Memory l Memory Save Advanced Analysis Control Analysis Control Parameter Sweep lt i Parameter Sweep drop list Parameter Sweeps Cancel Help 3 Click on the Add Button in the Analysis Co
351. wn Carpenter Break and Interpolate Technique A Strategy for Fast EM Simulation of Planar Filters Microwave Project Digest October 2000 pp 18 27 56 58 James C Rautio The Impact on Education of Widely Available Commercial 3 D Planar Electromagnetic Software Computer Applications in Engineering Education Vol 8 No 2 September 2000 pp 51 60 G L Matthaei J C Rautio and B A Willemsen Concerning the influence of housing dimensions on the response and design of microstrip filters with parallel line couplings IEEE MTT Transactions Vol 48 August 2000 pp 1361 1368 James C Rautio Tips and Tricks for Using Sonnet Lite Free EM software will radically change the way you do high frequency design Microwave Product Digest November 1999 pp 30 34 67 70 James C Rautio An Investigation of Microstrip Conductor Loss IEEE MTT Magazine December 2000 pp 60 67 This article is available in the Support Section of the Sonnet website www sonnetsoftware com Shawn Carpenter Break and Interpolate Technique A Strategy for Fast EM Simulation of Planar Filters Microwave Project Digest October 2000 pp 18 27 56 58 James C Rautio The Impact on Education of Widely Available Commercial 3 D Planar Electromagnetic Software Computer Applications in Engineering Education Vol 8 No 2 September 2000 pp 51 60 James C Rautio Free EM Software Analyzes Spi
352. ws you to edit the en try or select the item then select the Tools gt Modify command from the main menu Netlist Example Files All of the example files used in this chapter are available in the Att example in the Sonnet examples You should copy the entire folder into your working directory if you wish to execute the examples For directions on obtaining a Sonnet exam ple select Help gt Examples from the menu of any Sonnet program then click on the Instructions button Cascading S Y and Z Parameter Data Files 200 A particularly useful feature provided by a netlist project is the ability to cascade multiple S Y and Z parameter data files There are no restrictions on the file for mats which may be cascaded For example you can cascade em Z parameter data in Touchstone format with measured S parameter data in Super Compact format In addition em can analyze at frequencies which are not included in the data files Em automatically interpolates if there are any differences between the requested frequency points and those in the data files A good example of a cascading operation is the project att_cascade son which is included in the Att example for this chapter A schematic representation of the two port circuit is shown below This circuit consists of two identical thin film re sistors connected in series The S parameters from the geometry project analysis on the thin film resistor are used as a data file element in the net
353. y the Include Adaptive Data checkbox in the File Entry dialog box If this checkbox is selected which is the default then all the adaptive data from an ABS analysis is included in the output file If this checkbox is cleared then only the data for the discrete data points is included in the output file We recommend leaving this box checked Viewing the Adaptive Response 126 When viewing an adaptive response ABS in the response viewer there are sev eral things of which you need to be aware The adaptive data is plotted as a line A symbol indicating a data point only appears at the discrete frequencies at which a full analysis was executed as shown in the picture below Chapter 9 Adaptive Band Synthesis ABS Discrete Data Point Ei dstub son PS VEN alea Cartesian Plot z0 50 0 2 Left Axis M o dstub O a 3 DB S11 0 N 4 i Right Axis t empty u g 3 e ao dB 12 14 4 r T T T T r r 4 4 5 5 5 5 6 6 5 7 75 8 Sonnet Software Inc Freguency GHz Click mouse to readout data values Pointer When exporting data you may choose to output only the discrete freguencies or the complete response data for the ABS analysis To output only the discrete fre guency data unselect the Include Adaptive Data checkbox in the Export Data di alog box in the response viewer For details see Help in the response viewer 127 Sonnet User s Guide 128 Chapter 10 Parameterizing your Pro
354. y can propagate to the top cover and become absorbed The Capability to Ask What if In the preceding section we mentioned some simple techniques for removing box resonances from simulated data But what if your package is well defined physi cally and you can t simply take the cover off In this situation Sonnet can be an invaluable tool It allows the user to make changes to the structure and evaluate the impact on box resonances As noted earlier the Box Resonance Estimator is a great tool to judge almost in real time the effect of the package size From this the user can gain an understanding of which dimension controls any one resonance type TE or TM and may provide some insight as to the solution 337 Sonnet User s Guide Some of the techniques used to mitigate box resonances include e Adding grounded metal geometries to your structure In many cases ground vias or ground planes will help prevent box resonance modes from forming In simple terms they have the effect of dividing the structure into smaller compartments thus pushing the box resonances higher in frequency The use of a via fence or CPW type transmission line can help channelize the circuit preventing unwanted coupling between traces and reducing unwanted box resonance effects All of these features can be included in the Sonnet model e Adding an absorptive material to the model Another approach which is normally used once all other packag
355. y resolve challenging circuit dimensions without incurring excessive memory and analysis time requirements 1U S Patent No 6 163 762 issued December 19 2000 Conformal meshing should be used in places where it will reduce subsection count For rectangular polygons with no diagonal or curved edges it is more effi cient to use rectangular subsections default However if a polygon contains a curved edge conformal meshing provides a quicker analysis For a discussion on subsectioning when using Conformal Mesh see Conformal Mesh Subsectioning page 44 Chapter 12 Conformal Mesh Use Conformal Meshing for Transmission Lines Not Patches Conformal meshing assumes most of the current is flowing parallel to the edge of the conformal subsection This works well for transmission lines However this is usually not accurate for geometries like patch antennas For large areas of metal in both x and y directions high current can flow parallel to the X axis edges and parallel to the Y axis edges at the same time Conformal meshing can include only one of these currents Thus conformal meshing should only be used for transmis sion line geometries which have a line width that is small compared to wave length Applying Conformal Meshing Conformal Meshing is applied as a property of a metal polygon To use conformal meshing for a polygon do the following 1 Select the desired polygon s by clicking or lassoing The selec
356. ygons can be rectangles circles or any arbitrary shape Via polygons are vias which are a separate object from the metalization polygons They allow you to add vias of any shape whose properties are easy to modify The via polygon may also be of a different metal type than any metalization polygons to which it is adjacent Edge polygons are vias that are attached to the edge of a metal polygon The via extends for the length of the polygon edge and is one cell wide The metal type used for an edge via is always the same as the polygon to which the edge via is attached If the metal type of the polygon is modified then the metal type of the via is also changed Via polygons are added to your circuit in much the same way that metal polygons are added to your circuit You may add vias in the preset shapes of rectangles or circles or draw an arbitrary polygon by placing each vertex in its desired location Once the shape is complete the via polygon is drawn in your circuit The via con sists of a one cell wide wall of via subsections and is hollow in the middle Via polygons are hollow in the middle since all current moves on the surface of the via and modeling metal which is not used wastes processing resources If you wish to have metal in the center of a via polygon on a metalization level you may add a metal polygon on that level 243 Sonnet User s Guide Examples of via polygons are shown below The shape drawn by the user appears
357. ygons is 595 mils in the x direction Subdivision lines must be placed on the grid The closest value to halfway which still remains on the grid is 295 mils For the first subdivider you must take into account the feedline polygon which is 100 mils in length Therefore the first subdivision line should be placed at 100 mils 295 mils 395 mils from the left box wall Chapter 15 Circuit Subdivision Tutorial Select Tools Add Subdivider from the project editor menu while holding down the shift key TIP Holding down the shift key allows you to enter multiple subdivision lines without having to select the command multiple times Since there were no subdivision lines in the circuit when you selected the Add Subdivider command the Subdivider Orientation dialog box appears on your dis play Subdivider Orientation subdivide son Please specify orientation for subdivider Cancel Help All subdividers in your circuit must have either a vertical up down orientation or a horizontal left right orientation on the substrate Click on the vertical radio button to select the vertical orientation for your subdividers This sets the orientation for all subdividers subsequently added to your circuit This dialog box does not appear again if you select Tools gt Add Subdivider The new subdivider assumes the same orientation If all the subdividers are deleted from a circuit then when the Add Subdivider command is used a
358. you define the last dimension parameter which is symmetric Symmetric Parameters 16 Select Tools gt Add Dimension Parameter gt Add Symmetric from the project 17 18 editor s main menu This places the project editor in Add a Symmetric Parameter mode indicated by the change in cursor Note that the message Click mouse to specify first reference point appears in the status bar at the bottom of the project editor window As you add a dimension parameter directions for each step appear in the status bar and as tool tips on your screen To specify the first reference point for the dimension parameter click the mouse on the intersection of the inside of the top stub to the transmission line as shown in the picture below First Reference Point The first reference point is indicated by a small square which appears at the point you clicked The next step is to select the point set you want attached to the first reference point Drag the mouse until all points on the upper stub are selected ft ON N WSS oe Selected Points These points will be added to the first adjustable point set When the first reference point moves these points move in the same direction and distance as the reference point 161 Sonnet User s Guide 19 Once all the desired points are selected press Enter 20 162 This completes the first point set Your circuit should look similar to this The f

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