vco压控振荡器分析和总结.docx

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Inthisdocument,youwillseethecircuitconstructionof a“voltagecontrolledoscillator”andhowdifferentkeyparametersaresimulatedwithHSPICERF.

VCO

Voltagecontrolledoscillator(VCO)iswidelyusedinwirelesscommunicationsystems,suchasfrequencysynthesizer.AhighperformanceVCOshouldbecarefullyconsideredfromalotofaspects.HSPICERFprovidespowerfultools,whichtakecareofeverycharacteristicsofVCOandmakecomplicateddesigneasytoimplement.

Belowisthecircuitschematicthatwewilldiscussinthisdocument:

Figure1.VCOschematicInthispart,avcoisdesignedtooscillateat1.6v.

OscillatorSimulation–Steady-StateSignalSimulation

Inthisfigure,M4~M7areparallelconnectedPMOS,whichareusedasvaractorsforfrequency tuning purpose; M1~M3 offers negative conductance to fulfill theoscillatingpre-condition;R0andR1isusedtorepresenttheparasiticresistanceofL0andL1;m_multis aparameter,whichisdefinedasthe parallelconnectedPMOSs

number.Bytuningthem_multvalue,wecangetafrequencyvaluethatmorecloseto1.6GHz.

Inordertoachieveaproperm_mult,wecanusesnsweepfunction.Here,Synospsys

SIMIFisusedtosetupnewanalysisandgeneratenetlist.Thesettingisshownbelow.

Thissettingwillinsertacommandas

.sntone=1.6gnharms=10trinit=100noscnode=out1SWEEPm_multLIN10500560

intonetlist.

Severalwayscanbeusedtostimulateanoscillator

UsingIConaninductor

UsingaPWLsourcetoinjectapulseorrampVDD.

UsingUICoptionintheanalysiscommand.Here,weusethefirstmethod.

Addaprobecommandinanincludefile(inc1.spi)as

.probesnfdparam=Hertz[1]

Thesnresultwillbe

So,wecansetm_mult=518asthenumberthatwewilluselater.

Phasenoise

Asotheranalogcircuits,oscillatorsaresusceptibletonoise.Innoisyenvironment,outputsignalwillchangeinamplitudeandperiod.Phasenoiseisusedtoevaluateoscillators