CMOS数字集成电路chapter3.ppt

DigitalIntegratedCircuits

ADesignPerspectiveTheDevicesJanM.RabaeyAnanthaChandrakasanBorivojeNikolicJuly30,2002

GoalofthischapterPresentintuitiveunderstandingofdeviceoperationIntroductionofbasicdeviceequationsIntroductionofmodelsformanualanalysisIntroductionofmodelsforSPICEsimulationAnalysisofsecondaryanddeep-sub-microneffectsFuturetrends

TheDiodenppnBASiO2AlABAlABCross-sectionofpn-junctioninanICprocessOne-dimensionalrepresentationdiodesymbolMostlyoccurringasparasiticelementinDigitalICs

DepletionRegion

DiodeCurrent

ForwardBiasTypicallyavoidedinDigitalICs

ReverseBiasTheDominantOperationMode

ModelsforManualAnalysis

JunctionCapacitance

DiffusionCapacitance

SecondaryEffects–25.0–15.0–5.05.0VD(V)–0.1ID(A)0.100AvalancheBreakdown

DiodeModel

SPICEParameters

WhatisaTransistor?ASwitch!|VGS|AnMOSTransistor

TheMOSTransistorPolysiliconAluminum

MOSTransistors-

TypesandSymbolsDSGDSGGSDDSGNMOSEnhancementNMOSPMOSDepletionEnhancementBNMOSwithBulkContact

ThresholdVoltage:Concept

TheThresholdVoltage

TheBodyEffect

Current-VoltageRelations

Agoodol’transistorQuadraticRelationship00.511.52210-4VDS(V)ID(A)VGS=2.5VVGS=2.0VVGS=1.5VVGS=1.0VResistiveSaturationVDS=VGS-VT

TransistorinLinear

TransistorinSaturationPinch-off

Current-VoltageRelations

Long-ChannelDevice

Amodelformanualanalysis

Current-VoltageRelations

TheDeep-SubmicronEraLinearRelationship-4VDS(V)00.511.522.500.511.522.5x10ID(A)VGS=2.5VVGS=2.0VVGS=1.5VVGS=1.0VEarlySaturation

VelocitySaturationx(V/μm)xc=1.5un(m/s)usat=105Constantmobility(slope=μ)Constantvelocity

PerspectiveIDLong-channeldeviceShort-channeldeviceVDSVDSATVGS-VTVGS=VDD

IDversusVGS00.511.52210-4VGS(V)ID(A)00.511.522.500.511.522.5x10-4VGS(V)ID(A)quadraticquadraticlinearLongChannelShortChannel

IDversusVDS-4VDS(V)00.511.522.500.511.522.5x10ID(A)VGS=2.5VVGS=2.0VVGS=1.5VVGS=1.0V0