lab 6: design guide, transient, momentum simulation and the dac
TRANSCRIPT
ADS Fundamentals – 2009
LAB 6: Design Guide, Transient, Momentum Simulation and the DAC
Overview‐ThisexerciseteachesthefundamentalsofcreatingfiltersinADSandusingtheTransientsimulator.TheDesignGuideisusedtobuildalumpedcomponentfilterandMomentumisusedtotestamicrostripfilter.
OBJECTIVES • Builda200MHzIFlowpasslumpedfilterusingaDesignGuide
• Builda1900MHzRFbandpassfilterinmicrostrip.
• PerformaTransientanalysisonthemicrostripfilter.
• SimulatethemicrostripfilterinMomentum.
• OPTIONAL–DAC(dataaccesscomponent)exercise.
©CopyrightAgilentTechnologies2009
Lab 6: Design Guide, Transient, Momentum, DAC
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TABLE OF CONTENTS
1. Change projects and start the Design Guide. ......................................................3
2. Insert the LPF Smart Component and design the filter. .......................................3
3. Microstrip 1900 MHz bandpass filter. ...................................................................7
4. Transient Analysis on the microstrip filter. ...........................................................9
5. Momentum simulation from layout. ....................................................................11
6. OPTIONAL - Impedance response Data Access Component. .........................17
Lab 6: Design Guide, Transient, Momentum, DAC
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PROCEDURE1. ChangeprojectsandstarttheDesignGuide.
NOTE:IfyoudonothaveaccesstotheDesignGuide,buildthefilterwithlumpedcomponentsandsaveitasfilter_lpfanduseitforthefinalanalysislab.
Thesestepswillshowhowadesignguidecanquicklyandaccuratelyproduceafilter,similartoE‐syn,butwithmoreoptionsandgreatercontrol.
a. GototheADSMainWindowandclickFile>OpenProject.
b. AnswerYestoAllifyouarepromptedtosaveallyourcurrentwork.Thenopenyourearlierproject:system_prj.
c. Createanewschematicnamed:filter_lpf.
d. Besureitistheonlyschematicopenedonyourscreen.Now,threeNow,threestepsareneededtostarttheprocess:
♦ Clickthecommands:DesignGuide>Filter>FilterControlControlWindow.
♦ Thenewwindow,FilterDesignGuide,DesignGuide,willnotbeactiveuntilyouinsertaschematicsmartcomponentfromthepalette(nextstep).
♦ IntheFilterDesignGuidecontrolwindow,clickontheComponentPalette–Allicon(shownhere).Immediately,thepalettewillappearonyourschematicwindow.Youarenowreadytoinsertsmartcomponent.YoucouldalsoinsertthecomponentfirstandthenopentheFilterDesignwindow–eithermethodworks.
2. InserttheLPFSmartComponentanddesignthefilter.
a. IntheFilterDGpalette,selecttheLowPassLumpedfilterfiltershownhere(DT=dualterminated).Ifamessageappears,(shownhere)clickOKtodismissit.Theninsertthethecomponentontheschematic.UsetheEsckeytoendthethecommand.
Lab 6: Design Guide, Transient, Momentum, DAC
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b. PositiontheFilterDesignGuidewindownexttotheschematicsoitisactiveandclickontheFilterAssistanttab–itshouldactivateasshownhere.Ifnot,selectthefilterintheSmartComponentlist.Youarenowreadytosetthespecifications.
c. IntheFilterDesignGuidewindow(shownhere),enterthefollowingthreefilterspecifications:
(ripple)Ap(dB)=0.1,(passband)Fp=0.2GHz,(stopband)Fs=1.2GHz
d. Aftersettingthefilterresponse,clickRedrawtoseetheresponseplotchange.ThisisaButterworthresponse.ItwillprovidealowpasslumpedfilterforthesystemIFoutput.
e. Todesignthefilter,clicktheDesignbutton.
Lab 6: Design Guide, Transient, Momentum, DAC
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f. Inyourschematic,theSmartComponentnowhasyourfilterspecificationsandthefiltercircuitiscreated.Toverifythis,pushintopushintotheDTcomponent.Afterward,popoutasshownhere:here:
g. GototheSimulationAssistantandsetthesweepsweepfrom0MHzto1.3GHzin10MHz10MHzsteps.ThenclicktheSimulateSimulatebuttonandwatchwhathappens:happens:atemplaterunstheS‐parameterparametersimulationanddisplaysthetheresults.
h. ExaminethedatadisplayandmovethethemarkerM1to100MHz.Noticethethespeclineat–20dB(AtoB)andthetheperformancetablethatcomparesthecomparestheinputparameterstotheresults:the–20dBstopbandisat800MHzwhichwillbeOKforoursystem.
i. Scrolldownandexamineallthedata.
j. SaveandcloseallwindowsusingtheADSmainwindowcommand:File>CloseAll.Youwillusethisoutputsignalfilterlateroninthecourse.Next,youwillbuildtheinputfilter.
Thisfilterwillbeavailableinthelibraryforuselater.Editthecomponenttodisplaythedesiredparameters.
filter_lpf
Lab 6: Design Guide, Transient, Momentum, DAC
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Lab 6: Design Guide, Transient, Momentum, DAC
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3. Microstrip1900MHzbandpassfilter.
Inthesenextsteps,youwillbuildandsimulateacoupledlinefilterwiththeADScircuitsimulator.Afterward,youwilltransferittoADSlayoutandsimulateusingMomentum.ThisstepisonlyintendedtobrieflyshowhowMomentumworksinasimplemicrostripapplication.
a. Createanewschematicinthecurrentproject(system_prj)named:named:filter_1900.
b. FromtheTLinesMicrostrippalette,insertanMCFILasshown.Becausethetwoendcomponentsaresymmetrical(CLin1andCLin2),savetimebytypingtheW,S,andLparameters(shownhere)forthefirstoneandthencopyit.Theninsertthemiddlecomponent(Clin3)andtypeinitsvalues.
c. Insertportconnectorsoneachendasshownalso.
d. FromtheMicrostrippalette,insertthesubstratedefinitionMSUBasshown‐noothersettingsarerequired–thedefaultsubstratewillbeused.
Thesetwohavethesamevalues.
Lab 6: Design Guide, Transient, Momentum, DAC
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NOTEonthefilterS‐21response–TheS‐parametersimulation(S‐21)ofthisfilterisshownhereasareference‐thereisnoneedtosimulateitwiththeS‐parametersimulatoratthistime.
e. Intheschematic,click:File>DesignParameters.Whenthedialogappears,selecttheADSbuilt‐insymbolforabandpassfilter:SYM_BPFandclickOK.
f. Savethedesignagainsothatallthemodificationsarealsosaved.Thisisthefilterthatwillbeusedforthefollowingstepsandforthefinalsystemdesign.
Saveddesign:filter_1900foruselateroninthesystem.
Lab 6: Design Guide, Transient, Momentum, DAC
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4. TransientAnalysisonthemicrostripfilter.
a. Savetheschematic(filter_1900)withanewname:filter_trans.
b. Modifytheschematictolookliketheoneshownbelowbydeletingtheportconnectors.
c. FromtheSources‐TimeDomainpalettepaletteinsertaVtSineattheinput(beinput(besuretogrounditasshown).Itshown).ItisrecommendedtouseTimeuseTimeDomainsourcesforTransientTransientanalysis.
d. Inserta50ohmresistorattheinputandontheoutput(withground).
e. Labelpin/nodesVinandVoutasshown.Thecircuitshouldlookliketheoneshownhere.
f. FromtheSimulationTransientpalette,insertaTransientsimulationcontrollerandsettheStopTimeandMaxTimeStepasshown.Thesimulationwillbeginattimezero(default)andstopafterfifteenperiodsoftheinputsignal(8ns).Inaddition,thetimestepwillsampleattwice(Nyquistrule)therateofthehighestspectralcomponentdesired,herethe15thharmonic.
Lab 6: Design Guide, Transient, Momentum, DAC
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g. Simulateandafterthesimulation,insertarectangularplotofVinandVoutandediteachtrace(TraceOptions)toplacesymbolatdata–thiswillshowyouthetimepointstakeninthesimulation.
h. Zoomintotheplotafter5nsandputandputthemarkersonthepeaksofpeaksofVinandVoutasshownhere.here.
i. Writeanequationasshowntocalculatethedelaythroughthefilter:filter:marker_difference.ThiscalculatestheXaxisdifferencebetweenmarkersusingtheindepindepfunction(independentvariable=time).
j. Insertalistofmarker_differenceandusePlotOptionstoremovetheindependentdataasshown.Thevalueisthedelaythroughthefilterafterstartup(settling).Dependinguponwhereyouzoominandwhereyouplacethemarkers,yourvaluemaydifferslightly.Thedelaythroughthefilterisabout44picosecondsasshownhere.
k. Savetheschematicbutkeepitopened.Saveandclosethedatadisplay.
l. ThenextstepswillbetosimulatethisfilterinMomentum.
TraceOptionsTab–LinearTab
Lab 6: Design Guide, Transient, Momentum, DAC
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5. Momentumsimulationfromlayout.
a. Openfilter_1900andsaveitwithanewname:filter_mom.
b. Transferthefilter_momschematictolayoutbyclickingclickingtheschematicwindowcommand:Layout>Generate/UpdateLayout.
c. Whenthenextdialogappear,besuretheStartingComponentisP1(portconnector1fromschematic)sothattheleft‐to‐rightlayoutwillbegeneratedcorrectly.ClickOKandyoushouldseeanotherdialogindicatingthatallcomponentshavebeencreatedinthelayoutwindow.
d. ThelayoutwindowandtheLayerscontrolwillopen.Inthethelayout,verifythatyouhavethreelongcoupledlineswithtwowithtwoports.Zoominonaport(shownhere),andverifythatitverifythatitisconnectedtotheedgeofthemetal.FormanymanyMomentumsolutions,itisnotnecessaryfortheporttotoconnecttothemiddleoftheline–itonlyneedstobeonthe
Zoomed‐inportconnector.Momentumportscanbeinsertedinlayoutifthedrawingiscreatedinlayout.
Lab 6: Design Guide, Transient, Momentum, DAC
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theedge.
Lab 6: Design Guide, Transient, Momentum, DAC
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e. ThenextstepistodefinethesubstrateinMomentum.Todothis,usetheLayoutcommandsshownheretotransfertheschematicschematicMSUBdefinition:Momentum>Substrate>UpdateFromSchematic.
f. Verifythatthe10milsubstratedefinitionisnowinMomentum.Click:Momentum>Substrate>Create/ModifyandyoushouldseetheMSUBvaluesinthedialog.
g. YoucanalsolookattheLayoutLayerstabtoseehowthedrawinglayersinlayoutaremappedtothesubstrate:condisametalstriplayer.ButDONOTchangeanything.ClickOKtodismissthedialog.
Lab 6: Design Guide, Transient, Momentum, DAC
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h. Beforesimulating,lookattheMomentummeshfeatures.Click:Momentum>Mesh>Setup.WhentheWhenthedialogappears,noticetherearemanymeshmeshfeatures.Butfornow,besuretheEdgeMeshboxMeshboxisuncheckedasshownandclickOK.
NOTEontheMomentumprocess‐theorderofstepsis:computethesubstratedefinition(Green’sfunctions),createthemeshorgridpattern(cells),andthensimulate.
i. Tosimulate,click:Momentum>Simulation>Sparameters.Whenthedialogappears,typeinthesweepasshown:1GHzto3GHzusing25pointsasthelimit.ClickUpdateanditwillappearintheFrequencyPlan.Next,clicktheSimulatebuttonandclickYesiftheQuestiondialogappears.Watchthestatuswindow‐theAdaptivesweeptypeisthedefaultanditscurvefitting‐likealgorithmwillruntheEM(electro‐magnetic)simulationbysolvingselectedpoints.
Momentumautoplotfeature
Lab 6: Design Guide, Transient, Momentum, DAC
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j. WhentheADSDataDisplayopens,youwillseeamessagemessageabouttheautoplot:checktheboxasshownherehereandclickOKtodismissit.NoticethattheMomentumMomentumautoplottemplatelooksslightlydifferentthanthanADS.
k. ZoomintotheS21plot.Asshownhere,theexpectedresponseissimilartotheresponsethatyouwouldgetfromthecircuitsimulatorwithanysmalldifferenceduetothesolutionmethods.Also,zoominandlookatthemeshpattern.
l. Drawasimplecruderectangle(iconshownhere)alongthelengthofthefilter.Itshouldbeabout2000milslongand60or70milswide.Whenyoudrawtherectangle,noticethatthecursorbeginsdrawingatx‐y0,0asshownhere.Also,youcanmeasureanobject,usingthecursor,byclickinginlayoutandwatchingthevalueschangehere.ThepointofthisstepistoshowhowMomentumcananalyzethecouplingbetweenthefilterandtherectangle(metal).
m.
Zoomintoseethemeshcells.
W:60‐70mils
Click,thenmovethecursorandlookatthewindowbottomor,tomeasureanobject,use:Insert>Measureandclickontwopoints.
L:about2000milsorslightlylongerthenthefilter
Spacingbetweenthefilterandtherectangleisabout10milsonthisend.
Lab 6: Design Guide, Transient, Momentum, DAC
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n. Withtherectangledrawnnexttothelayout,performanotherMomentumsimulation.Click:Momentum>Simulation>Sparametersandwhenthedialogappears,changethedatasetnameasshownhere,filter_mom_stripandclickApplyandSimulate.
o. Thissimulationwilltakealittlelongerbecausetherearenowmoreunknowns(cells)tocalculateandthereforemorecomputationtimeisrequired.Whenthedatadisplayappears,youshouldseethatthereisaresonancesomewherenearthebandpassoritsedges,dependinguponyourrectangle.ThisisthetypeofsimulationthatcanonlybeaccomplishedwithMomentum.ViewtheS‐21resultsandthenclosethelayoutanddatadisplaywindows.Itisnotnecessarytosavethisdesign.
p. YounowhavetwofiltersthatcanbeusedlaterfortheRFsystem.Theyare:1)filter_lpf‐thisisthe200MHzlowpasscreatedfirst,and2)filter_1900‐yousimulatedthismicrostripcoupledlinefilterusingtheTransientsimulatorandMomentum.Atthistime,closeandsavealldesignsandwindows.
EXAMPLE:Narrowresonanceat2.05GHzduetocouplingeffectsofrectangle.
Lab 6: Design Guide, Transient, Momentum, DAC
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6. OPTIONALImpedanceresponseDataAccessComponent.
ADACcomponentisafile‐basedcomponent.Itmaycontainvariousformatsofdatafrommeasurements,listeddata,oranyothervalidfiletypethatADScanread.Inthisstep,youwillcreateasimplefilewithcompleximpedancevaluesthatvaryoverafrequencyrange.KeepinmindthattheDACcanbeusedtocreatesuchmodelsas:frequencysensitiveimpedances,varactors,stepfunctions,bitsequencesforsources,timedomainsequences,andmanyotheruseswhereafileismoreefficientthantypinginlongequationsorlistsonyourschematic.Ingeneral,theDACworkslikethis:itisacomponentthatpointstoafileinthedatadirectory.InthisexampleyoucreateafilethatwillbeusedfortheimpedanceparameterofanADScomponent‐thesimulatorwillsimplyreadthefile.
a. Openanewschematicwiththename:Z_DAC.
b. Refertotheschematicshownhere.Insertaterminationwithground,anequationbaselinearZ1P_Eqn(Z1port)fromtheEqnBasedLinearpalette.TheninsertanS‐parametercontroller,andaDACfromtheDataitemspaletteintheirdefaultstates(nosettingyet).
c. SettheS‐parametersimulationasifitwastheLPF:10MHzto200MHzin10MHzstepsasshownandsavetheschematicagain.
d. OpentheWindowsNotepadprograminStart>>Programs>Accessories.OrusetheADSMainMainWindow(Tools>TextEditor)ifNotepadistheNotepadisthedefaulttexteditor(thiscanbechanged).
Lab 6: Design Guide, Transient, Momentum, DAC
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IMPORTANTNOTEonDACtextfiles‐YoushouldnotuseaprogramthathasformattinglikeMSWORD.However,NotepadisOK.
e. Writeanmdf(multi‐dimensionaldatafile)fileshownhereandsaveitintheDATAdirectoryas:z_dac.mdf.
NOTEonfiletype.mdf‐Ifnecessary,usewindowswindowsfileexplorertochangethenameifitisissavedasa.txtfile.Also,thesyntaxinthefirstfirstcolumnis4frequencypoints,thesecondandandthirdcolumnscontaintherealandimaginaryimaginaryimpedancevaluesateachfrequency.frequency.
f. Onschematic,edittheS‐parametercontroller.InParameterstab,settocomputeZparametersnotS.IntheDisplaytab,checkSweepVar,Start,Stopandsetthemasshowntosweepfreqfrom10to200MHzin10MHzsteps.Youwillgetinterpolateddataforallthesteps.
g. Ontheschematic,edit(doubleclick)theZ1P_Eqnanditseditdialogwillappearasshownhere.
h. Asshownhere,selectFileBasedastheParameterEntryMode,andDAC1,andsettheDependentParameterNametomy_zandclickOK.
Lab 6: Design Guide, Transient, Momentum, DAC
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i. EdittheDACasshown:Typeinthefilename,selecttheType,etc.Also,iVar1
(my_freq)istheindependentvariablenameandiVal1(freq)istheindependentvariablevalue.As“freq”isswept,“my_freq”willbeindexedinthefileandtheDACwillreturncomplexvaluesof“my_z”interpolatedovertherange.
j. Simulateandplottwotraces,realandimag,ofZ(1,1)asshown.Asyoucansee,theZportcanbeusedwhereverafrequencysensitivecomponentisrequired.Formultiplecomponents,simplycreatedifferentfilesandaccessthemasrequired.
EXTRA EXERCISES:
1. CalculatethebandwidthofthefilterinTransientsimulationusingtherule‐of‐thumb:BW=0.35/risetime.Fromtimezerountilabout6nsshouldbetherisetime.However,usethemarkersandtheequationstodothecalculation.
2. TryusingtheDesignGuideforanothercircuittypeorsomeotherdesign.
3. CreateaDACforafrequencysensitiveinductorandsimulateitinasimpleCLCfilter.TheDACwillcontaintheinductorvaluesateachfrequency.
GenericMDIF
Lab 6: Design Guide, Transient, Momentum, DAC
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