Introduction
Electroniccircuitsimulation(English:Electroniccircuitsimulation),referstotheuseofmathematicalmodelstoverifytherealityofelectroniccircuitsTheengineeringmethodofbehaviorsimulation.
Thesimulationsystemcansimulatethefunctionalbehaviorofthecircuitwithouttheneedtobuildtheactualcircuit(thisprocessmaybecumbersomeandexpensive),soitisaverypracticaltool.Asthesimulationsystemsimulatestherealsituationmoreandmorerealistically,manyuniversitiesandresearchinstitutionswillusesuchtoolstoassisttheteachingofelectronicengineering.Sinceelectroniccircuitsimulationsystemsgenerallyhavebettergraphicalinterfaces,theycanoftenmakeusersfeelimmersive.Forbeginners,theycananalyze,synthesize,organizeandevaluatewhattheyhavelearnedwiththehelpofsimulationsoftware.
Beforeconstructingtheactualcircuit,simulationandverificationofthedesigncangreatlyimprovethedesignefficiency.Thisisbecausethedesignercanobserveandstudythebehaviorofthecircuitinadvancebeforeconstructingthecircuit,withouthavingtopaytimeandeconomiccostsforthephysicalrealizationofthecircuit.Especiallyforintegratedcircuits,thecostofelectronicprocessessuchasphotomasksrequiredtophysicallyimplementcircuitsisexpensive,andthehighcomplexityofintegratedcircuitsisdifficulttoachieveonbreadboards,anditisdifficulttostudythebehaviorofcircuitsusingtraditionalmethods.Therefore,almostallintegratedcircuitdesignsrelymoreonsimulation.ThemostfamousanalogsimulationisSPICE,andthemostfamousdigitalcircuitsimulatorsarebasedonVerilogorVHDL.
Someelectronicsimulationsystemsintegrateschematiceditors,simulationengines,andwaveformdisplayfunctions,sothatuserscaneasilyobservethereal-timestateofcircuitbehavior.Usually,thesimulationsystemwillalsoincludeextendedmodelsandelectroniccomponentlibraries.Themodelsmainlyincludetransistormodelsdedicatedtointegratedcircuits,suchasBSIM;andthecomponentlibrarywillprovidemanycommoncomponents,suchasresistors,capacitors,inductivecomponents,transformers,anduser-definedmodels(suchascontrolledcurrentsourcesandvoltagesources).Inaddition,somemodelsinVerilog-AorVHDL-AMScanbeprovided).Printedcircuitboarddesignalsorequiresspecialmodels,suchastransmissionlinemodelsandIBISmodelsforlinerouting.
Type
Althoughtherearestrictanalogsignalelectroniccircuitsimulators,mostsimulatorsincludebothanalogandevent-drivendigitalsimulators.Theyareoftencalledmixed-modesimulators.Thismeansthatmostsimulationsystemsincludeanaloganddigitalcomponents.Inthisway,mixedsignalprocessingcanbedoneonthesameintegratedschematic.Inthemixed-modesimulationsystem,thedigitalmodeprovidesaccuratespecificationsfortiming,risingedge,andfallingedgedelay.
Themixedmodesimulatorprovidesevent-drivenalgorithmsandsupportsnon-digitaldata.Forexample,realnumbersandintegerscanbeusedtosimulatethefunctionsofadigitalsignalprocessorordatasamplingfilter.Becauseevent-drivenalgorithmsarefasterthanstandardSPICEmatrixsolutions,usingevent-drivenalgorithmstoreplaceanalog-typemodelscansavetime.
Mixedmodesimulationisdividedintothefollowingthreelevels:
Digitallogicsimulatorusingoriginaldigitalelementsandtimingmodels
Usingthesub-circuitmodeloftheactualtransistortopologyoftheintegratedcircuit
Usinglogicalalgebraicexpressions
Intheanalysisofthetransmissionlinemodelandsignalintegrity,itisnecessarytocarefullycheckthenatureoftheinputandoutputportsoftheintegratedcircuit.Atthistime,accuratecircuitdescriptionsshouldbeused.Logicalgebraicexpressionsdonothaveatimedelayfunction.Inananalogenvironment,theycanprovideprocessingoflogicsignals.ThesetwomodelsuseSPICEtosolvetheproblem,whileinthethirdmethod,ahybridmodelofthesimulatorisused.Eachoftheabovemethodshasitsownadvantagesandissuitablefordifferentapplications.Infact,manysimulationsystems(especiallythoseinvolvinganalog-to-digitalanddigital-to-analogconversion)requiretheintegrationofvariousmethods,andasingleapproachisnotenoughtosolvetheproblem.
Anothertypeofsimulationismainlyaimedatpowerelectronicstechnology,whichhasapiecewiselinearalgorithmmodel.
Complexity
Inthemanufactureofsiliconintegratedcircuits,duetothelevelofcraftsmanship,theremaybeacertaindeviationbetweenitselectricalpropertiesandthenominalvalue,andcircuitsimulatorsoftendonotConsiderthesedeviationsinactualsiliconintegratedcircuits.Thedeviationoftheseparametersmaybesmall,butoftenaccumulatedintheentirecircuitwillseriouslyaffecttheoutputofthechip.
Temperaturecanalsocausedeviation,buttherearesometechniquesthatcanmodeltheeffectoftemperature,allowingdesignerstocheckitsperformanceatdifferenttemperatureswhensimulatingthecircuit.