折疊式級聯(lián)運放的仿真1a折疊式級聯(lián)運放的仿真1aTheTypicalPerformanceofOp-AmpOpen-LoopDifferentialGain(AV)Common-modeRejectionRatio(CMRR)PowerSignalRejectionRatio(PSRR)PhaseMargin(PM)InputCommonModeRange(ICMR)OutputSwingRange(OSR)Input/OutputImpedance(CIN/ROUT)SlewRateNoise2aTheTypicalPerformanceofOp-TheSchematicofFoldedCascodeOp-AmpInordertodeceasethepowerConsumption,IBIASisonly30nA.

3aTheSchematicofFoldedCascodCreateSchematicandSymbolinSpectreTocreateasymbolofaschematic:FromDesign->CreateCellview->FromCellview4aCreateSchematicandSymbolinOpen-LoopDifferentialGainDCSweepVP-VN(largesignal)ACSweepVP-VNwithfixedfrequency(smallsignal)TwomethodsofsimulatingOpen-LoopDifferentialGainisavailableinADE(AnalogDesignEnvironment)5aOpen-LoopDifferentialGainDCTest-BenchofOpen-LoopDifferentialGain(method1)

DCSweepVP-VN(largesignal)Inthismethod,VP=VCM_IN+x,andVN=VCM_IN-xWhere,VCM_IN

isthecommonvoltage,xisadesignvariables.SetupVNSetupVP6aTest-BenchofOpen-LoopDifferADEofOpen-LoopDifferentialGain(method1)ToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaDCSweepFromADE->Analyses->Choose->DC7aADEofOpen-LoopDifferentialWaveformofOpen-LoopDifferentialGain(method1)Where,

DifferentialGainis71.56dBToobtainVCOM_OUT

FromCalculator->SpecialFunctions->ValueVOUT-VCOM_OUTToobtainDCgainFromCalculator->SpecialFunctions->deriv8aWaveformofOpen-LoopDifferenTest-BenchofOpen-LoopDifferentialGain(method2)

ACSweepVP-VNwithfixedfrequencySetupVNSetupVPInthismethod,VP=VCM_IN+x+VAC,andVN=VCM_INWhere,VCM_IN

istheinputcommonvoltage,xisadesignvariables,VACisaACvoltageforACSweep.9aTest-BenchofOpen-LoopDifferADEofOpen-LoopDifferentialGain(method2)ToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaACSweepFromADE->Analyses->Choose->ACFixedFreq10aADEofOpen-LoopDifferentialWaveformofOpen-LoopDifferentialGain(method2)DifferentialGainis65.56dBTheresultsofthetwomethodsaredifferent,Infact,method1ismoreaccurateforDCgain.11aWaveformofOpen-LoopDifferenCommon-modeRejectionRatio

Youcangetdetailillustrationfrom“CMOSAnalogCircuitDesign”,PhillipE.Allen,OxfordUniversityPress,Inc.12aCommon-modeRejectionRatioYoTest-BenchofCMRRWhere,

VCOM_IN

istheinputcommonvoltage,VACisaACvoltageforACSweep.13aTest-BenchofCMRRWhere,VCOMADEofCMRRToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaACSweepFromADE->Analyses->Choose->AC14aADEofCMRRToaddamodelforWaveformofCMRR1/CMRRCMRRToobtainCMRR:FromCalculator->1/x1/CMRRandCMRRplotdirectly.15aWaveformofCMRR1/CMRRCMRRTooWaveformofCMRRToobtainmagnitudePlotofCMRR:FromCalculator->dB20FrequencyresponseofCMRRTheCMRRis72.14dBatlowfrequencyrange.ToobtainphasePlotofCMRR:FromCalculator->phase16aWaveformofCMRRToobtainmagnPowerSignalRejectionRatio

Youcangetdetailillustrationfrom“CMOSAnalogCircuitDesign”,PhillipE.Allen,OxfordUniversityPress,Inc.17aPowerSignalRejectionRatioYTest-BenchofPSRRWhere,

VACisaACvoltageforACSweep,andVDCisaDCvoltage18aTest-BenchofPSRRWhere,VACADEofPSRRToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaACSweepFromADE->Analyses->Choose->AC19aADEofPSRRToaddamodelforWaveformofPSRR1/PSRRPSRRToobtainCMRR:FromCalculator->1/x1/PSRRandPSRRplotdirectly.20aWaveformofPSRR1/PSRRPSRRTooWaveformofPSRRToobtainmagnitudePlotofPSRR:FromCalculator->dB20FrequencyresponseofPSRRTheCMRRis79.17dBatlowfrequencyrange.ToobtainphasePlotofPSRR:FromCalculator->phase21aWaveformofPSRRToobtainmagnPhaseMarginofOpen-loopfrequencyResponse

Where,VCM_INistheinputcommonvoltage,VACisaACvoltageforACSweep,AndCListheloadingcapacitor.22aPhaseMarginofOpen-loopfreqTest-BenchofPMVCM_INVACThedominantpoleiscontrolledbyCL

infoldedCascodeopamp.23aTest-BenchofPMVCM_INVACThedADEofPMToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaACSweepFromADE->Analyses->Choose->AC24aADEofPMToaddamodelforthWaveformofPMToobtainmagnitudePlotofopen-loop:FromCalculator->dB20open-loopfrequencyresponseThePMis74owhenCLis5pf.ToobtainphasePlotofopen-loop:FromCalculator->phase

Therehavetwopolesinopen-loopfrequencyresponse,oneisthedominantpoleofoutputnet,andtheanotheristhemirrorpolecausedbyactivecurrentmirror.

25aWaveformofPMToobtainmagnitInputCommon-modeRangeWhere,xisadesignvariablesandCListheloadingcapacitor.26aInputCommon-modeRangeWhere,Test-BenchofICMR27aTest-BenchofICMR27aADEofICMRToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaDCSweepFromADE->Analyses->Choose->DC28aADEofICMRToaddamodelforWaveformofICMRICMRTheinputcommon-moderangeis0~4.2V29aWaveformofICMRICMRTheinputOutputSwingRangeWhere,VCM_IN

istheinputcommonvoltage,xisadesignvariables.

ToobtainOSR30aOutputSwingRangeWhere,VCM_ITest-BenchofOSRDCSweepVP-VN

Inthismethod,VP=VCM_IN+x,andVN=VCM_IN-xWhere,VCM_IN

isthecommonvoltage,xisadesignvariables.SetupVNSetupVP31aTest-BenchofOSRDCSweepVPADEofOSRToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaDCSweepFromADE->Analyses->Choose->DC32aADEofOSRToaddamodelforWaveformofOSRYoucangettheleftwaveformfrompage8.OSRTheoutputswingrangeisfrom842.5mVto4.381V.PS:OSRisdependenceofapplicationsandisnotconstant.

33aWaveformofOSRYoucangeInputCapacitorWhere,VCM_IN

istheinputcommonvoltage,VACisACvoltageforACSweep.

34aInputCapacitorWhere,VCM_INiTest-BenchofCINVCM_INVAC35aTest-BenchofCINVCM_INVAC35aADEofCINToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaACSweepFromADE->Analyses->Choose->AC36aADEofCINToaddamodelfortWaveformofCIN

Theinputcapacitorisapproximateof5pf37aWaveformofCINTheinputcapaOutputResistanceTheschematicofobtainingopen-loopoutputresistanceRO.TheequivalentmodelbyusingTheveninformOntheopamp.Thus,simulatingROUTandknowingAVallowsonetocalculatetheoutputresistanceROoftheopamp.38aOutputResistanceTheschematTest-BenchofROUTIOUTVOUT200RR=1GVIN=0V39aTest-BenchofROUTIOUTVOUT200RADEofROUTToaddamodelforthesimulationFromADE->Setup->ModellibrariesTocreateaTRANSweepFromADE->Analyses->Choose->TRAN40aADEofROUTToaddamodelforWaveformofROUT

IOUTROUT41aWaveformofROUTIOUTROUT41aSlewRateTheunity-gainconfigurationplacestheseverestrequirementsonstabilityandslewratebecauseitsfeedbackisthelargest,resultinginthelargestvaluesofloop-gain,andshouldalwaysbeusedasaworst-casemeasurement.42aSlewRateTheunity-gainTest-benchofSlewRateTheinputstepmagnitudeis2V.43aTest-benchofSlewRateTheinpADEofSRT