App Note Quickfil V1 0
Contents
1. Nominal value PI 70 190 113 p 1 000 000 1 000 000 1 000 000 B 50 000 000 f 1 50 000 000 f Automatic Morton s transformation Undo transformation Move circuit Cursor keys S TRANSFORMATION Smart Measurement Solutions NH A ECD E F G H U PI TEE Quit 7 ry OMICRON ee Bode 100 Application Note Passive Filter Design with QuickFil Page 9 of 18 The transformation always works from top to down We now want to perform a transformation in a way that the inductor L5 gets the same inductance value as the inductor L3 This can be done by setting the lt Component No gt to 5 This means that component No 5 will be changed Since we want the inductor L5 to have the same value as the inductor L3 the lt Nominal compon gt has to be set to 3 QuickFil now calculates the transformation factor which is displayed in the lt Nominal factor gt field Norton s transformation P Previous component combination N Next component combination Kind of circuit A Min factor 70 190 1135 p I a x 5 E OO ome 8 8 C Nominal factor 6 446 737 m CEN Ge 3 Nominal value 54 pH H Automatic Norton s transformation U Undo transformation Move circuit Cursor keys ORTON S TRANSFORMATION NH A ECD E F G amp G H U PI TEE Quit 7 In addition the lt Kind of circuit gt is set to TEE as this gives a better structure for the second transformation The transformation now has to be made acti2. as shown in the following figures M Trace 1 TR1 __ Trace 2 TR2 Ymin 100 0048 Scale Lin Start and stop frequency are set to 100 kHz and 350 kHz The attenuator for cannel 1 to O dB and the attenuator for channel 2 to 10 dB The receiver bandwidth is set to 30 Hz M Sweep Center Frequency 225 000 kHz M Configuration Span 250 000kkz TES aM E 0 00 dBm Sweep Mode Line p O Number of Points 201 y Attenuator CH2 Receiver Bandwidth 30 Hz OMICRON Smart Measurement Solutions E L AB Bode 100 Application Note Passive Filter Design with QuickFil Page 14 of 18 The 50 Ohm termination has to be switched on as the filter is designed to be terminated To do so open the configuration window and click on the termination switch see figure below Configuration Device Configuration Connection Setup Measurement Gain Phase Impedance Reflection SOURCE DUT delay 0 00s 85 69 ms The Bode 100 is now ready to perform the measurement To remove the influence of the connection cables on the measurement results it is advisable to perform a calibration before measuring the filter 4 2 Calibration A thru calibration removes the influence of the cables on the measurement To do so the two cables from output and channel 2 have to be connected together using the thru connector as shown in the
3. Fiiase radl Input reflection factor Phase Output reflection factor Group delay s Real part 1 Imaginary part 1 60 000 G00 dB 106 000 000 kHz 350 000 000 kHz Merged graphs GO 160 Points linear Quality factor Induct infinite Capacit infinite IRCUIT ANALYSIS G Hold Property Repres Transfer Default YDefault Yfrom Y to from x to pOints Lin Log Ind Cap Quit 7 Clicking on lt Graph gt starts the plot window and shows the transfer function as shown in the following figure Hagnitude dB Transf 200k aaak 220k 2fok 300k 329k 350k Frequency CHz appnote filter oomdut Parameters optImize Output Harker ry OMICRON ee Smart Measurement Solutions Bode 100 Application Note Passive Filter Design with QuickFil Page 13 of 18 4 Filter Measurement The assembled bandpass filter transfer function shall be measured with the Bode 100 In the following is shown step by step how to configure and calibrate the Bode 100 for the filter measurement 4 1 Device Setup The transfer function of the bandpass filter can be measured in the Frequency Sweep Mode of the Bode Analyzer Suite To do so the Bode Analyzer Suite has to be started and the Frequency Sweep Mode has to be selected by clicking on the Frequency Sweep Mode icon We want to measure the magnitude and phase of the filter Therefore trace 1 is set to Measurement Gain Format Mag dB and trace 2 to Measurement Gain Format ohase
4. QuickFil Page 18 of 18 Calculated gain magnitude in dB Bee Ness a ee ees a eee ear ee ee eee eee eee jaa T a Sa T a AE E E ee oe E A oe E tee emo Reet oct A eben So eect ee ee ee eee EEN T LT c BW Meters S secrets asm cs pean BI seperate ta pp eds heart ly BE secede am ars ls lacey Wer ne Desai sea aver ich Shorea nh 4D d 2 oon den ne ee oe nn en pen nen penn ne tp en ee ee ee ee ee hig wee eee et m he SNe ee EEN EEE tage ose ceased EE N E E E aes ae cenaemecannceesebesencecineneel E a eetceeee vi c m p Sa WEN aan ie eee aie eee eer che le E a a ice ee eet ie ete te eee 100k L25k 150k L753k 200k aaok 200k aok 300k 323k 3530k Frequency CHz 1 Measured gain magnitude in dB mn TT iam no lal I T a TR1 dB O1 Qo D I I O sai 1 1 1 T TTT 80 100 150K 200K 250K 300K 350K Hz mum TR1 Mag Gain 6 Conclusion The first part of this application note shows how to design passive filters using the filter design software QuickFil QuickFil offers many functions for passive filter design e g Norton s transformation to optimize the filter design The second part of the application note shows how to measure the filter characteristics of the designed bandpass filter using the Bode 100 It is shown how to terminate the filter correctly using the internal 50 O
5. compared with the theoretical values 1 More information at http www omicron lab com filter design software html 3 OMICRON Smart Measurement Solutions LAB Bode 100 Application Note Passive Filter Design with QuickFil Page 4 of 18 3 Filter Design with QuickFil 3 1 About QuickFil QuickFil is a software for designing passive electronic filters QuickFil Supports many types of filters and different approximations Types of Filters Lowpass Highpass Bandpass Bandstop Allpass Asymmetric bandpass filters Parametric bandpass filters Approximations Butterworth maximally flat filters Chebyshev equal ripple filter Inverse Chebyshev Elliptic Cauer Bessel maximally flat delay Modified Bessel General Equal ripple approximation General maximum flat approximation Note If you plan to run QuickFil on Windows Vista or Windows 7 you have to use a small workaround Details on this are described in the QuickFil Installation Guideline go to http www omicron lab com filter design software html in the download tab 3 2 Bandpass Filter Design The following chapters are structured like a step by step guideline on how to design a filter using QuickFil 3 2 1 Filter Type and Specifications The first step is to define the filter type and approximation After starting QuickFil the main screen is shown By clicking on lt Filtertype gt the type of filter and the approximation method can be chosen as sh
6. picture below Smart Measurement Solutions Bode 100 Application Note Passive Filter Design with QuickFil Page 15 of 18 After connecting the cable the thru calibration can be done by clicking on User GAIN OFF IMP OFF r Gain Phase Replace DUT by thru cable Afterwards press Start to perfom Calibration Impedance Connect the comesponding part and perform the calibration Connect the comesponding part and perform the calibration by pressing the start button by pressing the start button 4 3 Measurement After performing the calibration the thru connection is replaced by the bandpass filter as shown in the picture below Now the measurement can be started by pressing the single sweep button OMICRON Smart Measurement Solutions E L A B Bode 100 Application Note Passive Filter Design with QuickFil Page 16 of 18 5 Results Performing the measurement described above leads to results as shown below The first graph shows the amplitude gain in decibel and the second graph the phase in degree 0 10 20 30 40 50 60 70 TR1 dB h a 80 l l 100K 150K 200K 250K 300K 350K f Hz mums R1 Mag Gain 200 150 100 50 0 50 100 150 200 l l 100K 150K 200K 250K 300K 350K f Hz TR2 mum R2 Phase Gain Comparing these results with the calculations in QuickFil shows tha
7. Bode 100 Application Note Passive Filter Design with QuickFil Page 1 of 18 Passive Filter Design with QuickFil and the Bode 100 QuickFil 5 1 Software standard for PC filter design By Florian Hammerle 2011 Omicron Lab V1 0 Visit www omicron lab com for more information Contact support omicron lab com for technical support Smart Measurement Solutions Bode 100 Application Note Passive Filter Design with QuickFil Page 2 of 18 Table of Contents DEMOS UEIV CSUN Yoo cca cece cece gee emcee AREE aE A eiaa EEEE AEAEE EEEE EREE EE Eei 3 PA NAS OTE EN ETENE EE E E EAA E EE 3 3 PIER D si gn With QUICKP II ssssisssiniiinicnsiin nonini aain aiaiai aiaiai 4 3 1 About QuickFil eee oe ne ee 4 32 DAMN D ass Fier DESO ereere rnn aE E E EN 4 3 2 1 Filter Type and SPCC CANONS pte scedccteectdctecatdectessedncteestiesesnsiiesteasedncteestdestcaatdere 4 3 2 2 Circuit Manipulation ccc cece eececeeeceseceeeeee cece eeseeeeseeeseeeceueeseeesseessueeseeeseeesaeeeas 8 e250 GINCUIT ITALY SIS xe caceaiczcectaesscaehanetcacsdaceacdaqesees deadopenceacuenicuadanasdueseneeseqsenesdeasepesee 11 4 Filter Measurement eee oe ee ee eee nae 13 aB Ee cane i ee ee ee en eee ene ene ee 13 4 2 Calibration eseeeeeeneeenennenernerernnrernernnrennnrerinnirinrint ere ntn nerta reran nE annan Eran neran nanana 14 AO EEEE E E E E EEA E E NAA EA A A 15 Oy PS SUNS E EE AE A A E E E AAE EEEE EE EA E S E E E E 16 6 ConcluSioOn
8. circuit manipulation Passive design Move with Cursor keys Choosing the option lt Output circuit gt shows the current design and the calculated component values appnote filter Smart Measurement Solutions Bode 100 Application Note Passive Filter Design with QuickFil Page 8 of 18 3 2 2 Circuit Manipulation The default design proposed by QuickFil contains three inductors with two different inductance values L L 3 35 uH Le 397 uH QuickFil offers a Norton s transformation functionality to modify component values without affecting the filter characteristics In the following is explained how the filter can be modified to achieve three similar inductors The Norton s transformation option can be found by first choosing the lt Manipulation and analysis gt option in the Passive design screen Manipulation and analysis Load circuit Save circuit Output circuit Reverse circuit Dual circuit O Pito IEE conversion E CP C Exchange two ports split two ports Combine two ports Circuit analysis Move circuit with Cursor keys ANTPULATION AND ANALYSIS 5 gt 0 R D A a Quit 7 Choosing the lt Norton s transformation gt option opens the Norton s transformation screen Norton s transformation Previous component combination Next component combination Kind of circuit Min factor Hax factor Nominal factor Factor Component No Current value Nominal compon
9. ed by the Variable value B C E F G H R aA lt symbol Relative 3dB bandwidth Filter quality This option enables to SPECIFICATION B C E FRGHIJ New cOmment file Printe enter the filter bandwidth freqluencyrepres bandwithrepres reL bandwithrepres Ait 7 as relative values As described in the beginning of the document a filter with a centre frequency of 230 kHz is defined The relative passband bandiwath is defined to be 10 and the relative stopband bandwidth is defined to be 30 By defining the lt Stopband loss gt to be the variable changing value the filter degree can be defined to be 6 This results in a calculated stopband loss of 23 6 dB lt Quit gt returns to the Main screen and by choosing the option lt passive_Design gt in the Main screen QuickFil proposes the design and values for the passive filter defined in the specification screen Passive design Output circuit Input circuit Circuits with positive elements Computer circuit Dual circuit Terminating resistance Accuracy Sign real part of reflection zeros Manipulation and analysis Move with Cursor keys PASS IVE DES IGH Is DT A VU A Quit 7 ry OMICRON ee Smart Measurement Solutions Bode 100 Application Note Passive Filter Design with QuickFil Page 7 of 18 By clicking on lt Dual circuit gt QuickFil calculates the component values for the dual design In this case the dual design has some advantages for later
10. hm resistance of the Bode 100 The measured and calculated results match very well when the quality factors of the used components are considered for the calculation of the transfer function It is therefore very important to have high quality components for the passive filter design i OMICRON Smart Measurement Solutions E L A B
11. mation by clicking on lt Nominal factor gt leads to the final circuit design The circuit and component values can be displayed by clicking on lt Quit gt and lt Output circuit gt appnote filter The three inductors now have the same inductance values which can be advantageous for the practical design OMICRON E LAB Smart Measurement Solutions Bode 100 Application Note Passive Filter Design with QuickFil Page 11 of 18 The practical design is built using standard component values The capacitance values were achieved by series and parallel combination of standard capacitors The used component values are Component Calculated Value Used Value L2 L5 L9 3 354 uH 3 3 uH C3 C8 157 213 nF 158 nF C4 C7 1 553 uF 1 55 uF C6 171 371 nF 172 nF Assembled bandpass filter BANDPASS f 230kHz B 30kHz J 3 2 3 Circuit Analysis QuickFil offers tools to analyze the designed filter In the Manipulation and Analysis screen the option lt Circuit analysis gt can be chosen Manipulation and analysis Move circuit with Cursor keys OMICRON Smart Measurement Solutions E L AB Bode 100 Application Note Passive Filter Design with QuickFil Page 12 of 18 In the Circuit Analysis screen the desired property and plot settings can be set Diagram 1 Diagram 2 Diagram 3 Diagram 4 select diagram with FgUp PgDn Property Representation Macnitude 1 Input impedance Output impedance
12. own in the following figures OMICRON Smart Measurement Solutions i E L AB Bode 100 Application Note Passive Filter Design with QuickFil Page 5 of 18 In the QuickFil Main screen the option lt Filtertype gt can be chosen C 2002 ONICHOW electronics Specification Group_delay Roots Polynonial_Analysis passive Design Transfer Hacro Options Quit 7 The Filtertype screen appears and the lt Type gt is set to lt Bandpass gt and the lt Approximation gt to lt Chebychev gt Filtertype Approximation Lowpass General Equal ripple Hi i General Maximal ly f lat Bandstop Allpass Elliptic Cauer Approximation Quit 7 Note By clicking on lt Quit gt one can return to the main screen ry OMICRON ee Smart Measurement Solutions Bode 100 Application Note Passive Filter Design with QuickFil Page 6 of 18 In the Main screen the lt Specification gt option can be chosen to enter the specification values which define the filter performance SPECIFICATIONS to Chebycheyv bandpass filter appnote filter Centre frequency 230 000 G60 kHz Relative passband bandwidth 10 00 x j Input values Relative stopband bandwidth z defining the filter properties Passband bandedge loss Passband bandedge return loss Passband reflection factor 15 09 Stopband loss 23 60 dB nite N The variable value ilter degree oe oe Case ee re is indicat
13. sssssunsnnnnnnnunnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnmnnn nnmnnn 18 Note Basic procedures such as setting up adjusting and calibrating the Bode 100 are described in the Bode 100 user manual Note All measurements in this application note have been performed with the Bode Analyzer Suite V2 31 Use this version or a higher version to perform the measurements described in this application note You can download the latest version at http www omicron lab com downloads html OMICRON Smart Measurement Solutions AB Bode 100 Application Note Passive Filter Design with QuickFil Page 3 of 18 1 Executive Summary This application note targets the design and analysis of standard filter types such as high pass low pass and band pass filters lt is demonstrated how to design a passive bandpass filter using the freeware filter design software QuickFil The designed filter is realized using standard value components and the filter characteristics are then measured using the Bode 100 Finally the measured filter characteristics are compared with the calculated values from QuickFil 2 Task A passive bandpass filter with the following characteristics shall be designed e Centre frequency f 230 kHz e Passband bandwidth f 10 23 kHz e Passband loss 0 1 dB e Filter degree n 6 The designed filter shall be built and the characteristics be measured The measured characteristics will be
14. t the passband loss is higher than calculated The reason for this are the limited quality factors of the components used to assemble the filter QuickFil offers a feature to estimate this influence In the circuit analysis screen are input fields for the inductor quality factor and the capacitor quality factor The components used for the assembled filter have an approximate quality factor of Inductors Q 55 Capacitor combinations Q 40 i OMICRON Smart Measurement Solutions E L A B Bode 100 Application Note Passive Filter Design with QuickFil Page 17 of 18 The figure below shows how the quality factors are entered into QuickFil Diagram 1 ji Diagram 2 Diagram 3 Diagram 4 select diagram with PgUp LPgDn Property Representation Inductor quality factor Capacitor quality Merged graphs 160 Points factor Quality factor Induct Capacit When considering the quality factors of the components the calculated transfer characteristic results as shown in the following graph EEH DIY Preguenc ce AME ES i a oe ee i a Ser ek ey a A et de ae seqreteh oe pees eee see bee ee ss ey oe pee I Li Li Li I l L 25kHz Olve Frequency Hz a filter On the next page there is a direct comparison between measured and calculated data where the quality factors are taken into consideration OMICRON Smart Measurement Solutions E L AB Bode 100 Application Note Passive Filter Design with
15. ve by clicking on lt Nominal factor gt This means that the calculated transformation factor is applied to the circuit This leads to the following screen Norton s transformation Previous component combination Next component combination Kind of circuit TEE Min factor 1 000 000 Max factor 118 360 664 Nominal factor 1 000 000 Factor 0 446 737 m Component No Current value 3 354 037 pH Nominal compon not defined Nominal value 3 354 037 pH Automatic Norton s transformation Undo transformation Move circuit Cursor keys ORTON S TRANSFORMATION NH A BC DP E F G amp G H U PI TEE Quit 7 The first two inductors now have the same inductance value The same transformation can be applied to the third inductor as follows ry Smart Measurement Solutions OMICRON ee Bode 100 Application Note Passive Filter Design with QuickFil Page 10 of 18 Clicking two times on lt Next component combination gt marks the right components Now the lt Component No gt field is set to 8 as we want to change the value of the last inductor at position 8 The lt Nominal compon gt value is set to 6 as we want the inductor 8 to have the same inductance value as the inductor 6 Norton s transformation Kind of circuit 1 000 000 11 986 200 k 118 360 884 Factor Component No Current value 20 337 3 9 nH Nominal compon Nominal value Move circuit Cursor keys Performing the transfor
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