AWR® Connected for CapeSym SYMMIC™
Contents
1. about 10 of that for field effect transistors FET in the PA stage s Figure 1 HPA LNA design Stee Sem Power Margin dB SUSCAT De 52 NETe Orvar FET Figure 2 Simple LNA design starting point added for early thermal analysis STEP 2 PREPARE AND RUN MICROWAVE OFFICE SYMMIC SCRIPT In this section the SYMIMIC data is created in Microwave Office and prepared for exporting to SYMMIC 1 First run the script from the Script pull down menu Depending on how the script was installed in the AWR Design Environment this script will appear in different places global scripts or project scripts See the AWR Design Environment User Manual if you cannot find the script or the proper procedure for its installation The script begins by prompting you for the layout that will be used for the physical data and the schematic that will be used for the electrical information figure 3 The schematic containing the entire MMIC layout should be selected from the first column here HPA_MMIC The schematic containing the placed MMIC which has the TOT_PWRA annotation should be selected from the second column here NL_WholeAmp Click Begin Layout Two windows open SYMM Clayout is a datafile window which will be populated xml information describing the FETs and their location SYMMICPwr is a table formatted graph which will display the annotated power information from the TOT_PWRA annotations for the d2. DataFile ISMN_Connect4FETs_Gate a ISMN_DrainLine ISMN_GateLine Interconnect_Module MN LoadT arget_ISMN IMN_Connect2FETs LoadT arget_OMN IMN_GateLine NL_OutputPeripher ISMN ISMN_Connect2FETs_Drain NL_WholeAmp_PowerS weep10GHz ISMN_Connect2FETs_Gate OMN ISMN_Connect4FETs_Gate OMN_Connect2FETs ISMN_DrainLine OMN_Connect4FETs ISMN_GateLine OMN_Connect8FETs Interconnect_Module OMN_DrainLine LoadT arget_ISMN OutputFET LoadT arget_OMN OutputFET DataFile Figure 3 SYMMIC thermal analysis script dialog 1 Selection of MMIC layout and MMIC electrical information Figure 4 SYMMIC thermal analysis script dialog 2 From the top level hierarchy the layout is traversed to find the source analysis devices 7 ANY AVA ie CapeSym a VAI 041 E Application Note If this were a new MIMIC design using a different FET periphery the design would need to be imported into SYMMIC and the xml template Fal Add to SYMMIC Thermal Analysts Use SYMMIC Device Template file updated from within SYMIMIC Consult the SYMMIC documentation for cuments and Settings heimlich My Documents AWR Projects MMIC_PA outputFE T xm more information Mirror template in X Angle of device relative to template 90 CounterClockwise v Analyze selected devices z TUE SUBCKT S1 FET_1 Once the xml template is available for a given device layout it is re KTSS FET im useable for all devices with that layou
3. HIGH POWER AMPLIFIER AWR Connected DESIGN EXAMPLE for CapeSym featuring AWR Microwave Office and CapeSym SYMMIC software SYMMIC Application Note INTRODUCTION SYMMIIC from CapeSym is a template based thermal simulator that has been optimized for monolithic microwave integrated circuit MMIC design This application note demonstrates the integration of Microwave Office and SYMMIIC The integration is script based and requires minimum manual intervention as compared to non integrated thermal solvers The example used here is an extension of the MMIC high power amplifier HPA example that is part of the standard Microwave Office set of examples BACKGROUND SYMMIC s template based approach allows the user to define the process SYMMIC Thermal technology and thermal stackup separately from the circuit layout These Simulation from templates can then be reused for different designs Once a template is defined for Microwave Office your GaAs MMIC for example it s a simple matter to switch to an RF microwave Projects design focus simply updating the layout and DC power settings in SYMMIC to analyze the thermal performance of your designs SYMMIC can be used beyond the MMIC for modules and subsystems as well as for transient and steady state analysis with flexible boundary conditions that includes radiative effects This application note will focus on a MMIC in steady state to show the basic operation and utility of the integrat
4. dated with the identifying information and locations for these devices 8 Repeat steps 5 through 7 for all the devices you wish to include in the analysis Figure 6 SYMM Clayout data file created by the Pa l SYMMIC script in Microwave Office 9 Once all the devices have been selected for inclusion in the analysis click the Complete button to finalize the SYMMIClayout and exit the script 10 From the Data Files node of the project palette find the SYMM1Clayout file right mouse click and select Export Data File You must include the xml extension to the file name before exporting the design You are free to name the file whatever you want but it must include the xml extension 11 Simulate your circuit to get the TOT_PVVRA annotation values or to calculate the values in the power table if generated Figure 7 Exporting the xml file from the Data Files node of the Project palette y ANY AVA ma CapeSym SYMMIC Application Note STEP 3 IMPORTING LAYOUT INTO AND ANALYZING WITH SYMMIC SYMMIC is a stand alone application run separately from AWR software SYMMIC can be run anytime after the SYMM Clayout datafile is exported as an xml file from Microwave Office Additionally for each device in the desired thermal analysis it will be necessary to have the total dissipated power from the TOT_PWRA annotation as additional input data for the SYMMIC simulation For a detailed guide to the use of SYMMIC
5. evices you select Note If you do not select the Create Power Table From checkbox in the dialog figure 3 then the graph will not be created The graph does not need to be created as the information can be read directly from the related schematic and entered manually in SYMMIC In the next few steps the layout hierarchy is traversed to find the devices which will be used as sources and analysis points within the thermal simulation 4 Click the Browse button and select a template to use for the chosen devices The templates are xml files exported from SYMMIC and are technology based Since the HPA_MMIIC has been previously analyzed by SYMMIC templates are already available for the FETs These device templates contain all of the material and layout information regarding the device The electrical information is stored separately This allows for fast transfer of data from Microwave Office to SYIVIMIC as it reduces the datafile size where FETs of common size are re used in the design This also allows SYMMIC to separate material and layout information from electrical power dissipation information which speeds up iteration time as bias schemes vs temperature are explored 7 ANY AVA Ea CapeSym SYMMIC Application Note Ed Choose Schematics for SYMMIC Thermal Analysis Main Layout of MMIC Create Power T able from Cripps_ISMN ISMN Cripps_OMN ISMN_Connect2FETs_Drain DriverFET ISMN_Connect2FETs_Gate DriverFET
6. ion and the ease of use of SYMMIC with Microwave Office It is assumed that SYMMIC has been installed on the same computer as Microwave Office and that the Microwave Office script provided by SYMMIC has been installed properly within the AWR Design Environment WHAT MAKES SYMMIC DIFFERENT Most thermal analysis tools are optimized and designed for general problems in thermal simulation This generalitzation makes them difficult to learn and use SYMMIC takes a totally different approach to significantly reduce complexities and barriers for a MIMIC designer The template based notion of thermal design relieves the electrical engineer from nearly all the burden of creating robust thermal simulations To be sure issues like thermal boundary conditions and material properties still need to be understood but the particulars involved can be investigated as part of the design process and not a precursor to it SYMMIC is the first tool that brings thermal analysis to the realm of MMIC design What s more SYMMIC is fast If you have a desktop workstation that uses a multi processor 64 bit AXIEM SYMMIC can take full advantage of this same hardware configuration The simulations in this application note were run on an 8 core 16GB Windows PC running 64 bit XP This is highly conducive to an iterated design flow where FET bias points can be chosen with regard to thermal conditions as well as electromagnetic It is entirely possible to now design c
7. lanar EM simulation Figure 10 HPA and LNA running simultaneously AWR 1960 East Grand Avenue Suite 430 El Segundo CA 90245 USA Tel 1 810 726 3000 Fax 1 810 726 3005 www awrcorp com Copyright 2011 AVVR Corporation All rights reserved AVVR and the AVVR logo and AXIEM are registered trademarks and AWR Design Environment and Microwave Office are trademarks of AWR Corporation All other trademarks are trademarks of their respective owners
8. o different simulations were run with HPA LNA MMIC In the first simulation figure 9 the HPA is off and the LNA is running at its nominal value of 50 mW The channel temperature for the LNA FETs is approximately 8 deg above baseplate In the second simulation the HPA and the LNA are both operational The HPA is running at approximately 450 mW dissipated power per FET in the output stage and in the driver stage clearly this is an exceptionally hot test condition In this configuration figure 10 the output stage FETs vary over about 20 deg C with the hottest FET running almost 90 deg C above baseplate The LNA FETs though are now about 13 deg C above the baseplate perhaps a bit warmer than h h h Wih b h id Figure 9 SYMMIC simulation for HPA LNA MMIC with when they are the only thermal source but not as hot as one wou HPA off and LNA at nominal expect with the HPA in an extreme condition CONCLUSION Thermal simulation is now a reality for the MMIC designer not as an esoteric piece of mechanical engineering software but as an integrated part of an RF microwave design flow SYMMIC s template based approach and sheer simulation speed combined with its scripted integration to Microwave Office means that more accurate device simulation is possible for electrical circuit design Reliability can be concurrently considered with electrical performance in simulations that take no longer than a detailed 3D p
9. oncurrently for reliability and electrical performance ANY AVA oe hes CapeSym SYMMIC Application Note As with any analysis tool and MMIC designers are well aware of this with EM analysis an absolutely necessary condition for successful and productive use is to profile them against known problems or laboratory measurements One of the difficulties in doing this with thermal analysis and MMIC design is that there is a great deal of variability in the various methods used to measure channel temperatures While this may create controversy in the minds of some engineers as to the absolute temperature values indicated by a thermal analysis tools like SYMMIC are still powerful guides to trends and relative values STEP 1 INITIAL ELECTRICAL DESIGN Three easy steps using SYMMIC 1 Develop your MMIC design as you normally would When the design has progressed far enough that you have a layout containing thermal sources then you will be able to run the SYMMIC script 2 Prior to running the script set up an annotation on your MMIC level schematic using TOT_PVW RA This annotation will provide the proper information for SYMMIC to use as the heat source s for the thermal analysis 3 In this application we simply open the HPA_MMIC emp file From this basic design an initial low noise amplifier LNA design is added simply by taking two of the FETs already in the design copying them and rebiasing them so their drain current is
10. see the SYMMIC user documentation As an example step by step instructions are given here using the HPA with the added LNA 1 Start the SYMMIC application 2 Import the layout by going to the File pull down menu and opening the xml file exported from Microwave Office 3 Input the device dissipated power for each device by going to the Device pull down menu and using the Device selection command to select a device Then open up the heat generation dialog from the same pull down menu and update the power based on the TOT_PWRA annotation from Microwave Office figure 8 by selecting the first row Total ON Power and right mouse clicking Edit Change the selected device and repeat validate that all your devices have the proper power Additional parameters for the device can be edited from this dialog See the SYMMIC documentation for more details 4 Run the thermal analysis from the Solve pull down menu 5 Results can be viewed from the results pull down menu MMIC HPA LHA smp AWR Design Emirenmont 9 00 4047 AWR_MESFET AWR Module 0 9 9995 10 0005 Frequency GHz Cripps Estimation L Cripps Esbmation L lt Cripps Estimation L Cripps Estimation R Pout_Mex_o6 Pout_dB Q1_Pout dB PowerMargin Figure 8 SYMMIC with imported xml file and dialog for updating verifying dissipated power for each FET 7 ANY AVA ie CapeSym a VAI 041 E Application Note RESULTS FOR HPA LNA Tw
11. t even if they have different power SUBCKT S6 FET_1mm dissipations SUBCKT S FET_1mm SUBCKT S8 FET 1mm 5 From the Analyze Selected Devices box select the device you wish to include in the thermal analysis A device template in SYMMIC sPUBLES v the entire device in the simulation using mirror symmetry click the checkbox Mirror Template in X The Angle Of Device Relative Figure 3 SYMMIC thermal analysis script dialog 3 Select devices corresponding to layout cells which are to be analyzed using the template often models half of a symmetrical device If you wish to analyze To Template dropdown item can be used to indicate the difference in orientation of the device in the MWO library in your layout as outputFET xml Clicking Add to Layout will compared to how it was stored in relative to that of the template in force these to appear in the SYMMIClayout SYMMIC data file 6 For the device selected in step 5 above find the hierarchical element corresponding to the layout cell for that device In the case of the OutputFET selected in figure 4 we must go down 1 level of hierarchy To do this click the Enter Hierarchy Subcircuit button and select all of the elements associated comprising the artwork described by the template In figure 5 the eight elements selected all use this single template 7 Click Add To Layout to add these devices to the layout to be analyzed The SYMM Clayout datafile window is up
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