LAB 5: S-parameter Simulation, Matching and Optimizationrmh072000/Site/Software_and... · LAB 5: S-parameter Simulation, Matching and ... RF out of the DC path ... S-parameter Simulations
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ADS Fundamentals - 2009
LAB 5: S-parameter Simulation, Matching and Optimization
a. Besurethenameofthedatasetis:s_paramsandthensimulate.
b. Whenthesimulationisfinished,insertarectangularplotofS21(dB).Insertamarkeron1900MHzandverifythatthegainisabout20dB.
c. InsertaSmithchartofS11andplaceamarkeron1900MHz.Tomovethemarker,selectthereadoutandusethearrowkeys.
d. Editthemarkerreadout(doubleclick).GotothetheFormattabandchangeZoto50asshown.ClickClickOKandthemarkerwillnowreadthevalueinvalueinohms,referencedto50ohms.
3. WriteanequationtovarytheTermportimpedance.
a. Inschematic,writeanequationforport2TermZtobe35ohmsabove400MHz:Z=iffreq<400MHzthen50else35endif.
b. SimulateandtheninsertalistofPortZ(2).VerifythatZis35Ohmsabove400MHz.
a. Indatadisplay,writeanequation,XC,forthecapacitivereactanceof10pFat1900MHz.ThenlistequationXCasshownhere.Ifdesired,titlethelistusingPlotOptions.Withthislowreactance,10pFwillbetheblockingcapacitorvalues.
b. ChangethevalueofthecapacitorintheequationandverifythatXCisautomaticallyupdatedinthelist.
c. Createatableforarangeofinductorvaluesandreactances.L_valisarangeofsweptvaluesfrom1nanoto200nanoin10nanosteps.InADS,thesyntaxoftwocolonsisawildcard(allvalues)andcanalsobeusedtoindicatearangeasshownhere.Thesquarebracketsareusedtogeneratethesweep.Afterwritingtheequationsandlistingthemasshownhere,scrollthroughthelist.Astheinductorvalueincreases,thereactanceat1.9GHzincreases.Therefore,avalueof120nHshouldbeenoughfortheDCfeed(RFchoke).
b. Changethecomponentname(DC_Block)ofbothblockingcapacitorstoCandtheywillautomaticallybecomelumpedcapacitorsasshownhere.AssignthevalueforeachC=10pF.
c. Changetheidealinductors(DC_Feed)inthesamemannerandsetL=120nHforeach.AccordingtotheXLandL_valtable,thereactanceat1900MHzisabout1.5K,whichisreasonableatthispointinthedesign.
d. Theschematicshouldnowlookliketheoneshownhere.CheckyourvaluesandthenSimulate.
e. Inthedatadisplay,plotthetransmission(S12andS21)andreflection(S11andS22)datawithmarkersasshownhere.Noticethegainstaysrelativelyflat,theleakageisreasonable,buttheimpedanceisnotnear50ohms.Thenextstepistocreateaninputmatchingnetwork.
c. Intheschematic(s_match),inserttheSmithChartMatchingNetworkcomponent(alsoknownasaSmartSmartComponent)neartheinputoftheamplifier–no–noneedtoconnectit–butitisrequired.Also,clickOKclickOKwhenamessagedialogappears.
d. GobacktotheSmithChartcontrolwindowandtypeintheFreq(GHz)to1.9asshownhere.
e. InthelowerrightcorneroftheSmithChartChartutilitywindow,selecttheZLcomponentandtypeintheimpedanceimpedancelookingintotheamplifierfromfromthelastsimulation:554‐j*220asasshownhereandclickEnter.
f. NoticethattheloadsymbolontheSmithcharthasrelocatedasshownhere.Next,selecttheshuntcapacitorfromthepaletteandmovethecursorontheSmithchart:whenyougettothe50Ohmcircleofconstantresistance,clicktostop,asshownhere(itdoesnothavetobeexactforthisexercise).
g. Next,selecttheseriesinductorandmovethecursoralongthecircleuntilyoureachthecenteroftheSmithchartandthenclick.
Nowyouhavea50Ohmsmatchbetweentheloadandsource.
h. MovethecursorintothelowerrightcornerofthewindowandclickoneachofthecomponentsintheSchematicasshownhere.Youwillseethevaluesfortheinductorandcapacitor:approximatelyL=14nHandC=400fFor0.4pF.
i. Toclearlyseetheresponseofthisnetwork,changetheStopFreqto4GHz(4.0e9)andyouwillseethenull(S11)at1900MHz.Also,setTrace2toS21toseebothreflectionandtransmission.
j. TohavetheDesignGuidebuildthecircuit,clickthebuttonbuttononthebottomofthewindow:BuildADSCircuit.Circuit.ClickOKtoanymessagesthatappear.
k. Ontheschematic,pushintotheSmithChartcomponentandyoushouldseethenetworksimilartotheoneasshownhere.YouvaluesmaybeslightlydifferentwhichisOK.Popoutwhenfinished.
l. Eithercopy/pastetheL‐CandgroundcomponentsontotheamplifierorsimplyinsertanLandConyourschematic.ThensetthevaluestoL=14.3nHandC=0.4pF.Theamplifierinputshouldnowbeasshownhere.
m. DeletetheSmithChartcomponentfromtheschematicandclosetheSmithChartutilitywindow.
a. SelecttheinputL‐Cnetworkandusethecopyicon(shownhere)tomakeacopytothecomponents.Thenplacethemneartheoutput,withagroundonthecapacitor.Deletethewiresandinsertthemasshownattheoutput.
b. Simulateandchecktheresponse.YourdatashouldbesimilartotheresultsshownherewhereS22isnowcloserto50ohms.However,S11hasshifted,asyoushouldexpect.SettheS‐22markerreadouttoZo=50.
e. Onscreen,changethegoalexpressionto“dB(S(2,2))”asshownhere.Now,youhavetwogoalsfortheinputandoutputmatch.
f. SetuptheOPTIMcontroller.Forthislabexercise,mostofthedefaultsettingscanremain,includingtheRandomtype.However,editthecontrollerandsettheMaxIter=125andsettheFinalAnalysis=“SP1”.Thesesettingsmeanthattheoptimizerwillrunforupto125iterationstoachievethegoals.TheNormalizegoalssettingmeansthatallgoalswillhaveequalweighting.Also,afinalanalysisisautomaticallyrunwiththelastvaluessothatyoucanplottheresultswithoutrunninganothersimulation.
a. Inschematic,gotoOptions>Preferences>andselectthetabtabmarked:ComponentText/WireLabel.TurnontheFullFulldisplayforOptasshownhereandclickOK.Thiswillallowallowyoutoseetherangesettings.
b. Edit(doubleclick)theinductorL_match_in.Whenthedialogdialogappears,clicktheTune/Opt/Stat/DOESetupbutton.IntheOptimizationtab,settheinductortobeEnabledasshownandtypeinthecontinuousrangefrom1nHto40nHasshownhere.ClickOKandthecomponenttextwillshowtheoptfunctionandrange.
c. GoaheadandEnabletheotherthreematchingcomponentsasshown.Editeachoneusingthedialogboxoryoucantypedirectlyon‐screenusingtheoptfunctionandcurlybracesfortherange.Also,usetheF5keytomovecomponenttextasneeded:
d. CheckthecircuitasshownhereandthenSimulateandwatchthestatuswindow.
e. Thestatuswindowreportsprogress.Ifthegoalsaremet,theEF(errorfunction)=0.AsuccessfuliterationoccursiftheEFmovesclosertozero.WithEF=0(orcloseinsomecases),thenextstepistoupdatecomponentvaluesandplottheresults.IfyourEFisnotzero,checktheschematicandtryitagain.
a. Inthedatadisplay,insertarectangularplot.Then,asshownhere,addthecompleteSmatrixofthefinalanalysisindBtoseeallfourSparameters.Thiswayyoucanquicklyverifytheresults.Yourvaluesmaydifferslightlybutthegoalsfromtheoptimizationshouldbemet.
b. PlottheimpedanceS11andS22onaSmithchart.ChangethemarkerreadouttoZo=50.Asyouwillsee,theimpedanceisnotcloseenoughto50ohms,eventhoughthegoalsweremet.Therefore,somemodificationswillbemadeinthenextsteps.Butfirst,youwillupdatetheschematicwiththevaluesfromtheoptimization.
a. Clickthecommand:Simulate>UpdateUpdateOptimizationValues.Theenabledenabledcomponentsshouldnowhavethethefinal(best)valuesasthenominalvalues.values.Forexample,theinputinductormayinductormaylookliketheoneshownhere‐here‐yourvaluesmayvaryalittlebecauseofbecauseoftherandommodeandnoseeding.seeding.
b. Disableacomponent.Edit(doubleclick)L_match_ininductor.ThenclicktheTune/Opt/Stat/DOEbutton.SelectDisabledDisabledasshownhereandclickOK.NoticeNoticethatthecomponentfunctionchangeschangesfromopttonoopt.Thismeansthecomponentwillnotbeusedinanoptimization.Youcanalsodisableacomponentbyinsertingthecursoron‐screenandtypingnoinfrontoftheoptfunctiontomakeitnoopt–tryit.
c. Savethes_optschematic.Inthenextsetofsteps,youwillsetupafinalmatchedcircuit.
b. Deactivate(usetheicon)theoptimizationcontrollerandgoals.
c. ModifythefourLandCmatchingcomponentvalues,addingresistancetotheinductorsasshownhere.Thiswillresultinagoodmatchandwillbeusedfortheremainderofthelabexercisessothatallstudentshavethesamecircuit.Goaheadandchangethevaluesbytypingdirectlyon‐screenasshownhere:
e. Whenthedatadisplayopens,plottheentireSmatrixbyselectingSinthedataset.AlsoplottheS11andS22ontheSmithcharttoverifythematchiscloseto50ohmsat1900MHz.Withtheseresults,thenextstepswillbetosimulatestability,gainandnoisecircles.
f. Savethefinaldesignanddatadisplay.Closethedatadisplaybutkeeptheschematicwindowopened.
b. GototheS‐parametersimulationpaletteandinserttwostabilitymeasurementequationsMuandMuPrime(iconsshownhere).Thesecanbeusedwiththeirdefaultsettings..
c. Scrolldowninthepaletteandinserttwomeasurementequations:GaCircleandNsCircleasshown.Also,inserttheOptionscontrollerandsetTemp=16.85toavoidthewarningmessagefornoise.Tnomisthetemperatureatwhichadevicemodelisextractedanyshouldnotapplyhere.AllotherOptionsdefaultsettingsareOK.
d. ChangethedBgainintheGaCircleto30asshown.NosettingisrequiredfortheNsCircle–itwilluseNFmin(calculatedminimumnoisefigure)fromthesimulationdata.
e. Changethesimulationfrequency=1850MHzto1950MHzsothatfewerdatapoints(circles)willbecreated.Checktheschematic,besurethenoisecalculationisturnedONinthecontroller,andSimulate.
f. Whenthedatadisplayopens,plotthemeasurementequations:NsCircle1andGaCircle1onaSmithchartasshown.
i. Saveandcloseallthedesignsanddatadisplaysintheproject.Atthispoint,theamplifierisreadytobetestedwiththenon‐linearsimulator,HarmonicBalance.However,beforedoingso,youwillreturntothesystemprojectinthenextlabandbuildthetwofiltersfortheRFsystem.
c. Whenthedialogboxopens,clicktheboxtoWritedatafilefromdataset,thenselecttheTouchstoneformat.Youaregoingtowrite(convert)yourexistingADSdataset(s_params)intoaTouchstonefile.Itwillrepresentmeasurementdatafromanetworkanalyzer.
d. IntheOutputFileNamefield,type:my_file.s2p.ThiswillbethenameofthetheTouchstoneformatfilethatwillbeconvertedfromADSdata.
e. SelecttheOutputDataFormatasMag/Angle.Mag/Angle.
f. IntheDatasetsfield,selectthedataset:s_params.Thiswasthedatasetfromthethesimulationusingtheidealcomponents.components.
g. ClickWritetoFile.ChecktheStatusWindow.Window.Ifsuccessful,youwillseeamessage.message.Thismeansmy_file.s2pisnowaaTouchstonefileinthedatadirectoryofthetheamp_1900project.Youcancheckthisifyouthisifyouwantandyoucanuseatexteditoreditor(ADSMainwindow:Tools>TextEditor)Editor)tolookatortomodifythefile.
i. Intheemptyschematic,insertanS2PcomponentfromtheDataDataItemspalette.Youwillnoticethatthecomponentvariablevariable(File=)isnotyetassigned
j. Toassignthedata,edittheS2Pcomponentandanotherdialogdialogboxwillappear.Next,browseforthefilename.WhentheWhenthenextdialogappears,selectmy_file.s2pandclickthetheOpenbuttonandthefilenamewillbeassigned(shownhere).
(shownhere).
k. Intheschematic,insertanS_Paramstemplate(Insert>Template)andwiretheS2PcomponenttotheTermswithgroundsasshownhere.
l. FromtheSimulation‐S_Parampalette,insertaSweepPlanandsetittoStart=100MHz,Stop=3GHzandStep=100MHzasshown.SweepplansarenormallyusedforfrequencysweepswithinsweepsbutyoucanuseitheretoseehowitreplacestheFrequencysettingsintheS‐parametersimulationcontroller.
m. TousetheSweepPlan,editthesimulationcontroller.IntheFrequencytab,selecttheSwpPlan1asshownhere.GototheDisplaytab,tab,selectSweepPlanandremovethestart,stopandstopandstepasshownhere.
n. SimulateandtheresultswillautomaticallyappearintheDataDisplaywindowbecausethetemplatehasaDDSdisplaytemplatealso.
o. ZoominontheS21measurementandaddtheS21simulationdatafromyouroriginals_paramsdatasettoverifythattheTouchstonefilecorrectlyrepresentedthedata.Asyouwillsee,thetwotracesareidenticalexceptthattheS2Psimulationonlygoesto3GHz.Here,thetracethicknessandtypeshavebeenadjusted(usingTraceOptions)toshowbothtracesmoreclearly.Markershavealsobeenadded.