DigitalCircuitSimulationusingVirtuoso.docx

DigitalCircuitSimulationusingVirtuoso.docx

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DigitalCircuitSimulationusingVirtuoso

SachinShinde

XiaolaiHe

CadenceInverterCircuitTutorial

SchematicEntryforDigitalDesigns-InverterCircuits

Inthistutorial,wewillbuildthecircuitshowninfigurebelow,usingtheCadenceComposertool.

1.AccessingCadence

UsingExceed

HummingbirdConnectivity9.0ExceedExceedXDMCPBroadcast 

Chooseees2（129.118.19.10）

Typeusernameandpassword

2.Openterminal

Type“whoamI”,thentype“setenvDISPLAYdomainname”.Thedomainnameistheipaddressforthecomputer.Type“icfb”toopenyourpersonaldirectoryasthenextfigure.

Afteropenicfb,makesureNCSUlibrarieshavebeencompletelyinstalled.Ifnosentence“LoadingNCSUSKILLRouting…”showsup,itmeanstheinstallationisnotcorrect.ThenselectToolsLibraryManager……toopenLibraryManager.

OntheCIWbanner,selectFileNewLibrary

IntheNewLibrarywindow,underLibrarytype“AMI06”andchoose“Compiletechlibrary”.Inthetechlibrary,select“AMI0.60uC5N（3M,2P,high-res）”.Thefigureshouldbeasthenextfigure.

3.CreatingaNewDesign

FromtheCIW,selectFileNewCellview,andfillintheformasshownbelowinordertodefinethenewschematiccellview.

IntheCellNamefield,type“Inverter”.

IntheToolselection,chooseComposer-Schematic.ThisautomaticallydefinestheViewNametoschematic.

Here,wenoteinToolthevariousdesignentrytools.ClickOK.

AnemptyComposerWindownowappears.

4.SchematicCapture

Theprocessofeditingadesigniscalledschematiccapture.

4.1PlacingtheIntances

ClickontheInstanceIcon.ClicktheBrowsebuttonintheform.TheLibraryBrowserformappears.

Selectthefollowing:

UndertheLibrarycolumn,selectNCSU_analog_parts.

UnderCell,selectpmos4.

UnderView,selectsymbol

NotethattheAddComponentwindowhasexpandedtodisplayvariousotherparameters.EdittheAddInstanceformbymodifyingthe,asshownbelow.Otherwiseselectpmos4iconinschematic,EditPropertiesObjects…tomodifyparameters.

Nowclickinthecomposerwindowtoplacethepmos.

Addnmosasaboveprocedure.SelectitinNCSU_analog_parts\nmos4\symbol.Modifyparametersasfollowingfigure.

AddtheotherinstancessymbolsfromtheNCSU_analog_partsasindicatedbelow:

Voltagesource（NCSU_analog_parts,vdd,symbol）

Ground（NCSU_analog_parts,gnd,symbol）

ClickonCancel.

4.2AddingtheI/OPins

Toaddtheinputandoutputpins,clickonthePiniconinthelowerleftsideoftheComposerwindow.TheAddPinformappears.

UnderPinNames,typeINorOUT.NotethatDirectionintheformreadsinputoroutput.

4.3ConnectingWires

Toconnectwires,clickontheiconWire（narrow）.

Clicktwoendsthewiretobeconnected.

Wirethecomponentsasshowbelow.

4.5CheckingandSaving

Tocheckandsavetheschematic,clickonthedesigniconontheleft,CheckandSave.

IfWarning/Errorappears,gobacktotheschematicandfixtheproblemasnecessary.WarningsarenotascrucialasErrors.

RepeatuntilyouhavenoErrors.

5.CreatingtheSymbolCellview

Nowwe’llcreateasymbol（blackbox）torepresentourcircuit.ThesymbolCellviewwillbecreatedbasedonthealready-availableschematicCellview.Thisiscalled creatingaCellviewfromanotherCellview.FromschematicviewgoDesignCreateCellviewFromCellview.

Awindowasbelowappears.

ClickOK.Anewschematicwindowshowsupandeditsymbolasnextfigure.

6.CreatingtheTestFixture（testbench）

Createanewschematiccellusingtherlcsymbolasoneofitsinstances.

FromtheCadenceCIW,goto:

FileNewCellview...

Fillitasshownbelow,creatinganewCellcalledInverter_Test,withaschematiccellview.

ClickOK.AnewComposer-Schematicwindowappears.

Selectfollowingcomponents.

vdd（NCSU_analog_parts,vdd,symbol）

vdc（NCSU_analog_parts,vdc,symbol）,DCVoltage=5V

ground（NCSU_analog_parts,gnd,symbol）

capacitor（NCSU_analog_parts,cap,symbol）,Capacitance=500fF

Pulsevoltagesource（NCSU_analog_parts,vpulse,symbol）,Voltage1=0V,Voltage2=5V,Delaytime=0s,Risetime=500fs,Falltime=500fs,Pulsewidth=3ns,Period=6ns.

Connectwiresasfollowingfigure.

8.InitializingtheSimulationEnvironment

Beforestartingthesimulation,makesurethatyourInverter_Testschematicisopen.

Intheschematicwindow,selectToolsAnalogEnvironment.Inafewmoments,theAnalogArtistSimulationwindowappears,asshownbelow.

9.ChoosingaSimulationEngineandModelLibraries

IntheSimulationwindow,selectSetupSimulator/Directory/Host

EnsuretheSimulatorcyclicfieldisreadingSpectre.

Inthesimulationwindow,selectSetupModelLibraries…

Inthepop-upwindow,clickbrowsetoselectpmonsandnmosmodellibraries.Themodelfilesareami06N.mandami06P.m.

Note:

UnderSpectre,Spectremodelscanbeused;underSpectreS,Spectremodelscanbeused;undercdsSpice,hspiceandspectremodelscanbeused;atthetimeofthistutorialwritten,hspicedoesnotwork.

ThedetailinformationaboutSpectremodels,SpectreSmodels,cdsSpicemodelsandhSpicemodelsaswellastheiruseenvironmentareintroducedinthepresentation“Simulator”.

10.ChoosingtheAnalyses

IntheAffirmaAnalogCircuitDesignEnvironmentwindow,selectAnalysisChoosepulldownmenu.Theformappears.

Transientanalysis:

Thisprovidesthetransientoutputresponseofthecircuitwithrespecttotime.Theuserspecifiesthetimeperiodandthetimevariantinputwave-formwhilethesimulatorcalculatestheoutputresponse.

Setupstoptimeas20nsasnextfigure.

11.SavingandPlottingSimulationData

Thesimulationenvironmentisconfiguredtosaveallnodevoltagesinthedesignbydefault.Youcanmodifythedefaulttosaveallterminalcurrentsalso,oryoucanselectspecificsetofnodestosave.We’llselectthesenodesfromtheschematicwindow.

Select OutputTobePlottedSelectonSchematic.

12.RunningtheSimulation–TheWaveformWindow

Clickonthe RunSimulationicon.

Whenitcomplete,theplotsareshownautomatically.

We’llnextmodifytheappearanceofthedisplayedwaveformsasnextfigure.

13.Exiting

Closeeverywindow.

Rightclickdesktop,amenupopsupasnext.Thenclicklogouttoexit.

Reference

1）http:

//www.engr.sjsu.edu/~dparent/ICGROUP/CDS_1.pdf