LAB 9: Final System and Circuit Simulationsrmh072000/Site/Software_and_Links... · ·...

ADS Fundamentals – 2009

LAB 9: Final System and Circuit Simulations

Overview–Thislastlabexercisebringstogetherallthecircuitsbuiltduringthecourse:theamplifierandfilters.Theyreplacethebehavioralsystemmodelsusedintheearlierexercise.

OBJECTIVES • Createasub‐circuitforthe1900MHzamplifierforuseinthesystem.

• UsetheSmartSimulationWizard.

• SetupandrunaCEsimulationusingaCDMAsource.

• SimulateACPRandpowerspecsusinganexampledatadisplay.

• ProgramMarkersliderstocustomizedatadisplays.

• OPTIONAL‐Co‐simulationswithminimalinstructions.

©CopyrightAgilentTechnologies2009

Lab 9: Final System and Circuit Simulation

9‐2©CopyrightAgilentTechnologies2009

TABLE OF CONTENTS

1. Create the final AMP_1900 sub-circuit for the library...........................................3

2. Simulate AMP_1900 with the Smart Simulation Wizard. .....................................4

3. Create the final HB swept LO schematic and equations......................................6

4. Final HB simulation: 2 tones with swept LO power and noise. ............................8

5. Plot the data: NF, Conv Gain, dbm_out, and IF_gain. .......................................10

6. Final Envelope simulation: CDMA source. .........................................................11

7. Use an Example DDS to plot ACPR and Power for your circuit.........................13

8. Plot the spectrum using a programmed marker slider. ......................................14

9. CDMA Envelope Simulation with Frequency Sweep .........................................17

10. OPTIONAL - Co-simulation of the behavioral RF system..................................22


9‐3©CopyrightAgilentTechnologies

2009

PROCEDURE

1. CreatethefinalAMP_1900subcircuitforthelibrary.

a. Savethelastamplifiercircuitenvelopedesign(ckt_env_gsm)as:AMP_1900.Thisschematicwillbecomethefinalamplifierdesigntobeusedinyoursystemprojectyoucreatedearlierinthecourse.

b. Asshownhere,deleteallsimulationcomponents,variables,source,etc.SetVdc=5V.SetFile>DesignParametersforComponentInstanceName:AMP_1900andSymbolName:SYM_Amplifier.Also,putportconnectors1and2ontheinputandoutput.CheckthecircuitandthensaveandclosetheAMP_1900design.

c. GototheADSMainwindowandopen/changetothesystem_prj.Thisiswhereyouhavetherf_sysdesignandthefilters.

d. Insystem_prjopenanewschematicwindow.ThenclickFile>CopyDesign.AsshownforFromDesign,clickBrowseandclicktotheamp_1900project/networksandselectAMP_1900.IntheToPath,clickWorkingDirectoryandclickOK‐thefileanditshierarchy(bjt_pkg)willbecopiedintoyoursystemproject.

Copyingfromadifferentproject.

File>DesignParameters/GeneralTab



2. SimulateAMP_1900withtheSmartSimulationWizard.

Thewizardhasmanystandardsimulationsetups.AlthoughthiswizarddoesnottaketheplaceofknowinghowtouseADSonyourown,itisvaluable.Inthesenextsteps,youwilluseittosimulatetheAMP_1900wherefrequencyisswept.

a. Inthesystem_prj,openanewschematicandclicktheSmartSimulationWizardiconshownhere.

b. Dialogswillappearforthefirst5steps:1)selectAmplifierandNext.2)selectUseanexistingADSdesignastheAmplifiersubcircuitandNext.3)selectAMP_1900andNext.4)verifytheportsarecorrect,clickNextand,5)clickFinish.



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c. Intheschematic,doubleclickthesimulationsetupdrawingthatlookslikeaNWAshownhere.

d. Whenthedialogappears,intheSimulationSelectiontab,selecttheNonlinear1‐ToneSpectrum,Gain,HarmonicDistortionvsFreqandclickthearrowtoadditasshownhere.

e. IntheSimulationSettingstab,settheRFfrequencyto1.9GHzandthesweepfrom1to3GHzin0.1GHzstepsasshown.Also,clicktheRFInputPowerandsetitto–40dBm‐andthebiassourcesto0V.

f. ClicktheSimulatebuttonandwhenwhenfinished,clickDisplayResults.Results.



g. Thedatadisplaywillopenandtheresultswillbeautomaticallyplottedasshownhere.Setthemarkertothedesiredfrequency.

h. Asyoucansee,thewizardcanprovidequicksimulationresultsforyourcircuits.Examinetheresults.Youcanplacemarkersonothertracesandyouwillseethattheymatchsomeofthesimulationsyouhavealreadypreformed.Fornow,closetheschematicanddatadisplay–noneedtosavethese.ThenextstepswillbetoputAMP_1900andthefilterstogetherinthesystemdesign.

ImportantNoteontheWizardschematics–Alwaysviewtheschematicsforyourdesigntoverifythecomponentsused,suchasblockingcapacitors,variables,etc.Thewizardcansaveyoualotoftimeandissimilartousingtemplatesordesignguides.ButnothingcanreplaceyourknowledgeofhowADSoperates,especiallywhenresultsareuncertainorwhenthewizardsetupdoesnotmatchyourtopologyorconfiguration.

3. CreatethefinalHBsweptLOschematicandequations.

Setthemarkerto1.9GHzoranydesiredvalue.



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a. Opentheexistingsystem_prjdesign:rf_sys.dsn.Now,saveitwithanewname:final_hb_lo_swp.Modifythedesignbyreplacingtheexistingfiltersandamplifierwithyourdesignsasshownhere.Step‐by‐stepinstructionsfollow,ortrysettingitupbyreferringtothisdrawing:

b. Fromthelibrary,replacethebehavioralfilterbehavioralfilterwith:filter_1900.ThenThenreplacetheLPF_BesselwiththeDesignDesignGuidefilter:DA_LCLowpass.PushintoPushintothemtoverifythecircuits.

NOTEonDTcomponenttext–Theparameters(Fp,Fs,etc.)mayappearasdefaultvalues.ThisisOK–donotchangethem.

c. Alsofromthelibrary,replacethesystemampwithyourAMP_1900andpushintoittocheckitalso.

d. SetuptwoP_1TonesourcesfortheRFandLOasshownhere.BesureNum=,P=,andFreq=aresetwithvariablesasshown.

e. OntheMixer,setthePminspec:PminLO=5forastarvationeffect(mixerdiodesnotresponding).Conversiongainis3dBandS11,22,33areallsettozerosasshown.Nootherparametersarenecessary.

f. SetupVARsforRFandLOFreqandPwrasshownhere.Also,setVinandVoutnodelabels.



g. WritethemeasurementequationforoutputpoweroftheIF.Becausethereismixing,usethemixfunctiontoidentifythetone:dbm_out=dBm(mix(Vout,{1,1})).Insidecurlybraces,theindexvaluesare:‐1fortheLOand1fortheRF.Theresult,dbm_out,isthepoweroftheIFsignalatVout.

4. FinalHBsimulation:2toneswithsweptLOpowerandnoise.

a. Withallothercontrollersdeletedfromtheschematic,insertandsetupaHarmonicBalancecontrollerasshownhere.Youcandothisbyturningonthedisplaysettingsfirstandthentypinginthevaluesonscreen.Or,youcanuseeachtabtosetthevalues.Eitherway,gototheDisplaytabfirstandturnonthedisplaysettingsshownhere.Thefollowingbulletstepsshowhowtosetupthecontrollerusingthetabs.

• Freqtab–SetMaxOrder(mixingproducts)=3.SetFreq[1]=LO_freqwithOrder[1]=3harmonics.SetFreq[2]=RF_freqwithOrder[2]=1harmonicsbecauseitspowerislowcomparedtotheLO.Also,settheStatusLevel=4todisplaymoreinformation(statuswindow),includingNFandconversiongain.

Display tab settings:



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• Sweeptab–SetLO_pwrasalinearsweep:Start=–30andStop=10,withStep=1,asshown.

• NoiseTabandNoise[1]and[2]:TurnonNonlinearnoise(bottomofTab).InNoise[1],setaSinglepointFrequencyto100MHzandInputfrequencytoRF_freq.AlsosetNoiseports1inputand2outputasshown.InNoise[2],usetheEditlistboxtoaddVoutasthenoisenode.Leaveallothersettingsintheirdefaultasshown.

• Outputtab–ClicktheAdd/Removebutton.ThenselecttheRF_pwrvariableandclicktheAddbutton.

Youwillusethisinthedatadisplaytowriteanequation.YouselectVarEqnsthiswaybecausetheyarenotsenttothedatasetbydefault.Onlynamednodes(pinandwirelabels)andmeasurementequationsareoutputtothedatasetbydefault.NodevoltagesandMeasEqnssetintheOutputstabwillappearon‐screenfortheSavedEquationNameparameter.

b. CheckthecircuitandHBcontrollersetupafinal



setupafinaltimetobesuretheyarecorrect(asshown)andthenSimulate,watchingthestatuswindowasthepowerisswept.Thesimulatorinformation(statuslevel4)iswrittenintothewindow–thisdoestakelongerthanlowerstatussettings.Butinthiscase,youwantthemixerconversiongainandnoisefigure.

5. Plotthedata:NF,ConvGain,dbm_out,andIF_gain.

a. Whenthesimulationcompletes,scrollinthestatuswindowtoseethecalculatedconversiongainandthenoisefiguresNFasshownhere.NOTEonwarnings:metallossmessage–youcanignorethismessage.

b. Plotthedbm_outequationandyouwillseetheeffectsofthesweptLOpower.Noticethatnear‐10dBmthemixergoesintostarvation.

c. WriteanequationforIF_gainasshownhere.BysubtractingRFinputpowerfromtheoutputpower,theresultisthegainatallvaluesofthesweptLO.Puttheequationinalistandscrolltoseetheresults.

d. Savetheschematicanddatadisplays.



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6. FinalEnvelopesimulation:CDMAsource.

a. Savethelastdesignas:final_env_cdma.

b. ReplacethesourcewithaPtRF_CDMA_ESG_FWDsourcefromtheSources‐modulatedpalette–besuretoinsertthesameCDMAsourceshownherewhichisbasedonarealsignalgenerator.SetFO=RF_freqandPower=dbmtow(RF_pwr)asshown.

c. AddanewVARblockfort_step,t_stop,bit_rate,sam_per_bit,andnum_symasshownhere.Also,addanOptionsblockwhich,bydefault,forcesS‐parameterstobeusedforthelinearelements(BPF).IfyouedittheoptionsblockyouwillseethesettingtouseS‐parameterswhenpossible.

d. Changethemeasurementequationtoreadliketheoneshownhere:IF_out=mix(Vout,{1,1}).

e. ReplaceHBwithanEnvelopecontrollerandsetitupusingusingthevariablesasshown.Also,intheOutputtab,leaveleavebothboxesuncheckedandselectIF_outandVoutusingVoutusingtheAdd/Removebuttonssothatthisistheonlytheonlydatainthedataset.

f. Simulate.



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7. UseanExampleDDStoplotACPRandPowerforyourcircuit.

a. Whenthedatadisplaywindowopens,click:File>OpenandusethedialogtogototheADSinstallationdirectorytofind:examples/Tutorial/ModSources_prj/IS95_FwdLinkSrc.dds

b. OpenthisDDSandthenclicktheDDScommandFile>File>SaveAsandsaveitinyoursystem_prj(scroll(scrollusingthearrowbuttons).SaveitwiththesamesameexampleDDSname.

c. Noticethevalueswillberedorinvalidwithouttheexampledata.Changethedefaultdatasettoyourfinal_env_cdmadataset.ThenchangetheEqnVfundtoyourIFoutputequation:Vfund=IF_out.

d. Theresultistheexamplecalculationsarenowusedforyourdataset.Examinebothpagesinthedatadisplay(ACPRandPwr).Youcanuseanyexampledatadisplayforyoudatainthiswaylikeatemplate.

e. ExaminethedataandthenSaveandclosethedatadisplaywindow.

DDSpages:1)ACPRandTrajectoryand2)PowerCalcs



8. Plotthespectrumusingaprogrammedmarkerslider.

Thenextseveralstepswillshowyouhowtousepowerfulexpressionstopassamarkervaluetoafunctionandplotthedatawheneverthemarkerismoved.

a. Openanewdatadisplayandnameit:Marker_Slider.Marker_Slider.

b. Insertanequation.ClicktheVariableInformationbutton.Youwillseethatfreqisdependentupontime.time.Closethedialog.

c. Writetheequationmarker_freqshownhere.Thiswillaccessallfrequenciesatonepointintime.Youcanuseanytimepointbecausethenumberofcalculatedfrequenciesarethesameatanytimepoint,accordingtotheorderandmaxorderyousetintheenvelopesimulationcontroller.Usezeroasshown.

d. Insertaplotofthemarker_freqequationwhichisplottedagainsttheindependentvariable:freq.Next,youwillmakeitlooklikeaslider.

e. Edittheplot.RemovetheAutoScalefortheY‐axis.SettheY‐axisMin,MaxandStepto:6e12,6e12,and6e12asshown.ThenclicktheMorebuttonandsettheYaxisfontsize=0(typeitin).Thickenthetraceifyouwant.ClickOKandthenputamarkeron1900MHz.Besuretosizeitsothatitlooksliketheslidershownhere.



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f. Writetheequationfreq_indexusingthefind_indexfunction.Themarkervalueandmarker_freqarepassedintotheargumenttoreturntheindexvalueofthemarkerposition.Thisequationwillbethelook‐upvaluefortheVoutdatayouwanttoplot.

g. Writetheequationmarker_spectrumtoplotthespectrumaroundthemarkerfrequencyvalue.Thefsfunctiontransformstheenvelopetimedataintofrequency‐thetwocolons(::)representalltimepointsandfreq_indexistheindexvalueofthemarkerfrequency.Use5commasafterthebracketandtypeinthe“Kaiser”windowfunction.InallADSfunctions,youcandisregardanyargumentbyusingcommas.

h. Plotthemarker_spectrumequationandchangetheTraceType(TraceOptions)tolinear.Thenmovethesliderto100MHz.Puttwomarkersonthespectrumasshownandwriteanequation,BW,usingindeptogettheindependentvariableofthemarkers(x‐axis).InsertalistofBWasshown,changingtoEngineeringformatwith4significantdigitsandremovingtheindependentdata(PlotOptions).

i. Movethemarker‐BWremainsthesame.Examineyourwork,savethedatadisplayandtheschematic.Yourcircuitshavenowbeensimulatedinthesystemandyouhavecompletedthecourse!



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9. CDMAEnvelopeSimulationwithFrequencySweep

Dothisonlyifyouhavetime…

ThissimulationshowshowtosweeptheRFfrequencyandadjusttheLOvariableforfrequencysothatisalwaysproducingthesameIFoutputfrequency.Afterward,theIFoutputspectrumcanbeplottedtoshowtheresultsforavaryingRFinputfrequencysweep.Todothis,youneedtosetupaparametersweepoftheRF,redefinetheLOvariable,andthenplottheIFoutputforeachoftheRFfrequencies.

a. Savethecurrentdesign(final_env_cdma)withanewname:final_env_cdma_swp.

b. Insertaparametersweepfromfromanysimulationpaletteandpaletteandsetitupasshownshownhere.Thequoteswillappearifyouappearifyoueditthecontrollerandenterandenterthevaluesthere–ifnot,besurebesuretotypethemontotheschematic.schematic.

SweepVar=RF_freq

SimInstanceName=Env1

Start=1700MHz

Stop=2100MHz

Step=200MHz

ThiswillsweeptheRFsignalwith3frequencies:1700MHzwillcoverthelowendand2100MHzthehighendwhicharebothjustoutsideoftheBPFresponse.Ofcourse,youcouldsweepitmorefinelybutthatwouldtakemoretime.

c. ChangetheLO_freqvariabletotrackthetracktheRFsignalsweepbysettingitassettingitasshown:LO_freq=RF_freq–RF_freq–100MHz.ThiswillmaketheLOtheLOalwaysbe100MHzlessthantheRFtheRFforanynumberofstepsinthetheparametersweep.

d. Savethedesign‐nootherschematicschematicchangesarerequired.



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e. Yourdesignshouldlookliketheoneshownhere.Ifitdoes,thenSimulate.

f. Afterthesimulationisfinished,insertarectangularplotandaddVoutastheSpectrumofthecarrierindBmdBmwithwindowingasshownhere.here.ClickOKandtheplotwillappear.

g. Editthetrace(doubleclick)anduseTraceOptionstochangethetracetoLineartobetterseetheoutputtraces.

NoticethatthespectrumisforVout[1]which100MHzIFtone.HowevertherearethreeresultingIFtonesfromthesweep.Now,youneedbeabletoseewhichtraceresultsfromwhichRF–youwilldothisinthenextstep.



h. EdittheplotonemoretimeanduseanduseTraceOptionandtheTraceTraceExpression.GototheLinearLineartabandturnonLineColorandColorandDisplayLabelasshownshownhereandclickOK.

i. Yourplotshouldlookliketheoneoneshownhere.Buttoidentifytheidentifythetracesevenbetter,useusethecommand:Insert>PlotPlotLegend.

Finally,youcanseethethreeIFspectraltracesthatresultfromeachonoftheRFtones.Thisshowshowtosweepfrequencyforacircuitenvelopesimulationandhowtheresponseofthecircuitcanbeanalyzed.



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Thiscompletesthelabexercise‐theremainingstepsareoptional.DothemonlyifyouhavetimeandhaveaccesstothePtolemysimulator.



10. OPTIONALCosimulationofthebehavioralRFsystem.

Createtwolevelsofhierarchy:1)bottomlevelsimulationofthebehavioralsystemwithacircuitenvelopesimulationsetupand2)atopleveldataflowsimulationusingtheDSPpalettes.Thestepsfollow…

a. Opentheoriginalrf_sys.dsnyoucreatedinlab2andsaveitassys_bottom.Modifythedesignasfollows:SettheMixerPminLO=–5asshownhere.Also,putportconnectorsonthecircuit.InsertanEnvelopecontrollerandsetitasshown.NotethatyoudonotneedtoinsertordeclareaVARhere–itwillbeinthetoplevel.

b. Savethedesignandcloseitusing:File>CloseDesign.

c. Openanewblankschematicwindow:File>NewDesign.Whenthedialogappears,typeinthenamesys_top,andselectDigitalSignalProcessingNetworkasthetypeandthensavethedesign.



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d. Inthenewdesign,sys_top,buildthedesignshownhere:

• DF(dataflow)‐isintheCommonComponentspalette.SetonlytheDefaultTimeStop=t_stop.

• Data‐isintheTimedSourcespalette.SetonlythefirsttwoparametersTstep=t_stepandBitTime=symbol_time/2.

• SymbolSplitter–istheDataSplitter,intheTimedDataProcessingpalette.Setonlythetwoparametersshown.

• LPF_RaisedCosineTimed–ThesefiltersareintheTimedFilterspalette.Insertonefilter,makethesettings,andthencopyit.

• QAM_Mod–themodulatorisintheTimedModempalette.Setasshown.

• Insertthesys_bottomdesignfromtheregularlibrary.

• EnvOutShort–fromtheCircuitCosimulationpalette,thiscomponentcapturestheIFsignalfromthesys_bottomdesign.

• InserttheTKplotandTK‐XYplotsfromInteractiveControlsandDisplays.

• InserttheresistorandgroundandtheVARblock.

e.



CheckallthevaluesandvariablestobesuretheyarecorrectandSimulate.Whenyoudo,youwillsetthetwoplotsinaction.UseView>ViewAlltorescaletheplotsifneeded.

f. QuitthesimulationusingthecontrolandinsertaSpectrumAnalyzercomponentfromtheSinkpalette.ConnectittotheoutputandeditittoselectthewindowtypeasKaisershownhere.Besuretosettheothervaluesasshown.

g. Whenthestatuswindowshowsthedatacollectioniscompleteforthesink(SpectrumAnalyzer),Quit.

h. OpenthedatadisplayandadddBm(CDMA_spectrum)toarectangularplot.

SUMMARY‐Thisdataistheresultofaco‐simulationbetweenPtolemyandtheEnvelopesimulator.ItmarkstheendoftheADSFundamentalslabexercises.

ENDofLABEXERCISE.

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