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首页 Spice模型转换为HyperLynx Databook格式

Spice模型转换为HyperLynx Databook格式.pdf

Spice模型转换为HyperLynx Databook格式

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2017-09-26 0人阅读 举报 0 0 暂无简介

简介:本文档为《Spice模型转换为HyperLynx Databook格式pdf》,可适用于IT/计算机领域

ShanghaiWinnetElectronicsCo,LtdAwebmasterwinnetcomcnhttp:wwwwinnetcomcnHyperLynxApplicationNote:ConvertingaSpiceModeltoHyperLynxDatabookFormatIntroductionOccasionally,youmayhavenomodelforadriverICotherthanaSpicemodelThisapplicationnotedescribesarelativelysimplewayinwhichyoucanconvertaSpicemodel鈥�aslongasyoucanrunitinSpicetoextractsomebasicbehavioralinformation鈥�intoaHyperLynxdatabookformat(ie,鈥�MOD鈥�modelNote:Ifyoucannotrunthestepsdescribedbelow(because,forexample,youdonothaveaSpicepackagecapableofcompilingandexercisingthemodel),anotheroptionistogetthesemiconductorvendorwhocreatedthemodeltorunthestepsforyouAnothermeansofconvertingfromSpicemodelsexists鈥�auniversitywrittenSpicetoIBIStranslator鈥�butHyperLynxbelievesthatforcustomers,themethoddescribedinthisapplicationnoteisconsiderablyeasierandmorelikelytosucceedthanusingtheconverterTheconverterisnotacommercialproductispoorlydocumentedhasbugsandisnottrivialtounderstandorrunThemethoddescribedhereisrelativelystraightforwardRequirementsforConvertingInordertoimplementthemethoddescribedinthisapplicationnote,thefollowingmustbetrue:鈾�youhaveaccesstoaversionofSpicethatcompilesandrunsthemodelyouwanttoconvert鈾�youcanembedtheSpicemodelinasimpleSpicetestcircuitthatallowsthemodel鈥檚output(s)tobeswitchedhighandlow鈾�youcanplotthewaveformresultsofsuchasimulationsoyoucanmeasurecertainfeaturesofthewaveformsAccesstoaSpiceSimulatorHavingaSpicepackageandhavingonethatcompilesaparticularSpicemodelaresometimesdifferentthingsSomesemiconductorvendorsuppliedSpicemodelsaredevelopedtoruninaproprietaryinhouseSpicepackage,andmaynotcompileinacommercialpackageOthersmayrequireparticularversionsofAvanti鈥檚HspicesimulatorIfyoulackasuitableSpicepackage,faxthesemiconductorvendorwhocreatedtheSpicemodelthisapplicationnoteandhavethemgeneratethedataforyouSpiceTestCircuitTheSpicetestcircuitrequiredbythisapplicationnoteissimple:itentailsaddingonlyafewextranodestothemodel鈥檚SpicedeckHowever,inordertounderstandwhereintheSpicedecktoaddthenewnodes,youneedtoknowwhichexistingShanghaiWinnetElectronicsCo,LtdAwebmasterwinnetcomcnhttp:wwwwinnetcomcnnodesrepresenttheinputandoutputofthebufferyou鈥檙emodelingInsomecases,youmayalsoneedtotiecertainotherinputnodes(eg,anenablepin)highorlowtomakethebufferoutputrespondtoinputstimulusIftheSpicemodelyou鈥檙etryingtoconvertiscomplexorpoorlydocumented,requestaschematicdiagramorlistofkeynodesfromthesemiconductorvendorHowThisMethodWorksTheconversionmethoddescribedbelowhasasimplegoal:findoutenoughaboutthebehavioroftheSpicemodeltofillintheparametersinLineSim鈥檚BoardSim鈥檚databook(MOD)modeleditorIfyoucanfillintherequiredparameters,thentheeditorwillgenerateaMODmodelforyouandyou鈥檙ereadytosimulateToopentheeditorinLineSimBoardSim,chooseMODLibraryfromtheEditmenu(Formoreinformationontheeditorandcreatingdatabookmodelsgenerally,seetheappropriatechapterintheLineSimorBoardSimUser鈥檚Guide)Manyoftheparametersintheeditorarerelativelyeasytofillin:youcanfindtheminadatasheet,or(inafewnoncriticalcases)evenmakereasonableguessesButtwoimportantonesarehardertodetermineandmustusuallybefoundexperimentallyfromtheSpicemodel:鈾�driverresistance(highandlow)鈾�driverslewtime(highandlow)Note:Ifyouhappentofindresistanceorslewtime鈥�orboth鈥�inadatasheetorbysomeothernonSpicemeans,usethem!ThisapplicationnoteassumesthatyoulackbothandhavetoresorttotheSpicemodelIfthedatasheetcontainsIVcurvesfortheoutputbuffer,youcanconvertthecurvestoequivalentresistancesbydrawingastraightlinethroughlinearpartofthecurve(afterit鈥渢urnson鈥�butbeforeitshowsanysaturation)andmeasuringtheslope鈭哣鈭咺FindingDriverResistancefromaSpiceModelTomakeaSpicemodel鈥渞eveal鈥�adrivingresistance,youcanmakeuseofasimplefactofelectromagnetics:whenadeviceoutputdrivesatransmissionline,thetransmissionlineinitiallylooksexactlylikearesistancetogroundorVcc(dependingonwhetherthedriverrisesorfalls)Assoonasareflectionfromtheendofthetransmissionlinetravelsbacktothedevice,theline鈥檚behaviorchangesandbecomesmorecomplex,ofcourseultimately,thelinelookslikeanopencircuit(ie,presentsnoloadtothedriver)Butthetransmissionline鈥檚behaviorbeforeanyreflectionsoccurgivesasimpleandpowerfulmethodoffindingadriver鈥檚resistanceviasimplevoltagedivisionAtransmissionline鈥檚effectiveresistanceduringinitialswitchingisequaltoitscharacteristicimpedance(Z)Therefore,ifyouloadadriverwithatransmissionlineofknownimpedanceandmeasure鈥�again,beforeanyreflectionsoccur鈥�howmuchofthedriver鈥檚voltagestepactuallyappearsinthetransmissionline,youcantriviallysolveforthedriver鈥檚resistance(seebelowforformulas)ShanghaiWinnetElectronicsCo,LtdAwebmasterwinnetcomcnhttp:wwwwinnetcomcnInpractice,toisolateadriver鈥檚initialswitchingbehaviorintoatransmissionlinefromthebehaviorafterreflectionsoccur,youcansimplyuseaverylongtransmissionlineInthedetailedstepsbelow,forexample,anslineisrecommendedAnydelayvaluethatislongerthantheentireamountoftimeforwhichyousimulateinSpiceguaranteesthatyourmeasurementswillnotbe鈥減olluted鈥�bylinereflectionsFigureshowstherecommendedtransmissionlineandhowitconnectstothedrivermodel鈥檚outputNotethatdrivingresistance(andslewtime)mustbefoundseparatelyforthehighandlowstagesofadriver,becausethestagesareoftennotbalanced(Usually,thelowsidehaslowerimpedance)Figure:ConnectingtheTestTransmissionLinetotheDriverModelFindingDriverSlewTimefromaSpiceModelUnlikedriverresistance,driverslewtimeisnotdifficulttofind鈥�no鈥渢ricks鈥�arerequiredSlewtimescanbemeasureddirectlyfromplotsofthedriverswitchinghighandlowintoatransmissionlineloadSeebelowfordetailsonmakingthemeasurementsFindingDriverResistanceandSlewTimeTofindadriver鈥檚highandlowresistancesandslewtimes:First,addatestcircuittotheSpicemodel:Openthedriver鈥檚SpicemodelinatexteditorFindtheSpicenoderepresentingthedriver鈥檚outputAddanewlinetothemodelthattiesthedriveroutputtoasimple,losslesstransmissionlineSettheline鈥檚parameterstodelay=nsandcharacteristicimpedance=ohmsLeavethefarendofthetransmissionlineopenForexample,ifthedriver鈥檚outputnodenumberis,addthefollowinglinetotheSpicemodel:TZ=TD=nsThistiesoneendofatransmissionlinetothedriveroutputnode(node)createsanew,opennodeattheotherend(nodeuseanyunusednodenumber)andsetsdelayandimpedanceasdescribedaboveThe鈥�鈥檚鈥�referencethelinetoSpice鈥檚globalgroundnodeShanghaiWinnetElectronicsCo,LtdAwebmasterwinnetcomcnhttp:wwwwinnetcomcnOpenthedriver鈥檚SpicemodelinatexteditorFindtheSpicenoderepresentingthedriver鈥檚inputAddanewlinetothemodelthattiesthedriverinputtoarampingvoltagegeneratorSetthegenerator鈥檚ramptimetonsmakeitswitchfromthedriver鈥檚lowpowersupplytothehighsupplyForexample,ifthedriver鈥檚inputnodenumberis,addthefollowinglinetotheSpicemodel:VPWLnsV,nsVThistiesaohm(ideal)voltagesourcetothedriverinputnode(node),andswitchesthesourceinalinearrampfromVtoVinnsIfthedriverisinverting,thencompensatebyreversingthepolarityoftheinputvoltagesourceIfthedrivermodelrequirescertainotherinputnodestobetiedhighorlowinorderfortheoutputtoswitch,tiethemtoVccorgroundasneededThen,runasimulationwiththedriverswitchinghigh,andplotthedriver鈥檚outputnode:RunatransientSpicesimulationToensurethatyourmeasurementsarenot鈥減olluted鈥�byreflections,setthetotalsimulationtimetobegreaterthanthedriver鈥檚switchingtime,butlessthanthedelaytimeofthetransmissionlineyouaddedaboveinstepForexample,ifthedrivermodelswitchesinaboutnsandyouusedanstransmissionlineasrecommendedabove,runthetransientsimulationfornsThisislongenoughtoseethedriverswitchcompletely,butnotlongenoughforreflectionstoreturnfromtheline鈥檚farendPlotthesimulationvoltageversustimeatthedriver鈥檚outputnode(Thisisthevoltageatthenearendofthetransmissionline,notthefar,openend)Setuptheplotsothattheswitchingfillsmostofthehorizontalscale,soyoucanmakeanaccuratemeasurementoftheswitchingtimeThen,fromtheplot,calculatethedriver鈥檚highstageresistanceandslewtime:Calculatethedrivingresistancewiththefollowingformula:Rdrv(rise)=Z(VfinalVstep),whereZ=characteristicimpedanceofthetransmissionline(ohms),Vfinal=finalDCvoltageswingofthedriver,Vstep=voltageswingoftheinitialstepintothetransmissionline(ignoresignsofthevoltagevalues)The鈥渇inalDCswing鈥�meanshowmanyvoltsthedriverswitchesedgetoedgeafteranytransmissionlinereflectionsdieoutForexample,foraVCMOSdriver,thiswouldbeVforaTTLdevice,aboutVShanghaiWinnetElectronicsCo,LtdAwebmasterwinnetcomcnhttp:wwwwinnetcomcnThe鈥渋nitialstep鈥�swingisthelessernumberofvoltsthatthedriverswingsinthesimulationplotThevalueislessthanthefinalDCswingbecause,initially,beforereflections,thevoltagedividesbetweentheresistanceofthedriverandtheresistance(characteristicimpedance)ofthetransmissionlineSeeFigure(There鈥檚nothingmysteriousaboutthisformula鈥�it鈥檚asimplevoltagedivision,solvedfortheunknowndrivingresistance)Then,calculatetheslewtimebymeasuringtheamountoftimetogofromtooftheplottedwaveformvoltageFinally,rerunthesimulationwiththedriverswitchinglow,andusethesamemethodstofindthelowsideresistanceandslewtime:AltertheinputvoltagesourcetoswitchintheoppositedirectionRunanothersimulationandplotthedriveroutputnode(fallingedgethistime)UsethesameformulaasabovetocalculatethedrivingresistancemeasurethetotimeastheslewtimeUseabsolutevaluesofallquantities,ie,ignorenegativesignsShanghaiWinnetElectronicsCo,LtdAwebmasterwinnetcomcnhttp:wwwwinnetcomcnFigure:HowtoMeasureVstepFindingOtherRequiredModelParametersDriverresistanceandslewtime(highandlow)areusuallytheonlyparametersthatmustbederivedfromtheSpicemodelTheremainingdatabookmodelvaluescangenerallybefoundinadatasheet,orinafewnoncriticalcases,canbeguessedatThefollowingtablesummarizeshowtofindtheotherparametersintheMODmodeleditorParameterHowtoFindType(highandlow)PulldownthecomboboxandchoosetheappropriatetechnologytypeForabipolardevice,usethedatasheet鈥檚circuitdiagramtodeterminewhetheragivenstageusesasiliconorSchottkyclampedtransistor(unlessECL)Ignore鈥渞amp鈥�use鈥渙pen鈥�forthehighsideofanopencollectordrainOffsetVoltage(highandlow)SettoVforanydevicethatswitchesfromsupplyrailtosupplyrailForstagesthatdonotswitchtoarail,setequaltotheamountbywhichthefinalvoltageisoffsetfromtherail,minusonediodedropEg,forVTTL,highsideoffsetisV鈥�V(fortheSchottkydiodedrop)FormostCMOSdevices,useV,sinceswitchingisrailtorailClampDiodes,TypeandResistance(highandlow)RelativelyunimportantfordrivermodelsCandoaSpiceDCsweepabovebelowpowersupplyrailstofinddiode鈥渞esistance,鈥�butnotusuallyworththeeffortInstead,usestandard鈥済oodguess鈥�values:Type=Silicon,Resistance=ohmsDefaultPowerSettoVccforallnonECLdevicestoVeeforECLShanghaiWinnetElectronicsCo,LtdAwebmasterwinnetcomcnhttp:wwwwinnetcomcnSupplydevicesCapacitanceGetfromdatasheet(Coutor鈥渙utputcapacitance鈥�Ifnotprovided(rare),usepFCreatingtheModelOnceyou鈥檝ecollectedalltherequiredparameters,youcanactuallycreatethedatabook(MOD)modelbyrunningLineSim鈥檚BoardSim鈥檚modeleditorenteringtheparametersandsavingthemodelunderanappropriatenameinuserlibraryFordetailsonthisprocess,seetheappropriatesectionintheUser鈥檚GuideoronlineHelpsystemOncethemodelissaved,you鈥檙ereadytosimulate

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Spice模型转换为HyperLynx Databook格式

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