[第3章1] coms vlsi design

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1、CMOSVLSIDesign延边大学工学院电子信息通信学科许一男IntroductionIntegratedcircuits:manytransistorsononechip.VeryLargeScaleIntegration(VLSI):verymanyComplementaryMetalOxideSemiconductorFast,cheap,lowpowertransistorsToday:HowtobuildyourownsimpleCMOSchipCMOStransistorsBuildingl

2、ogicgatesfromtransistorsTransistorlayoutandfabricationRestofthecourse:HowtobuildagoodCMOSchipSiliconLatticeTransistorsarebuiltonasiliconsubstrateSiliconisaGroupIVmaterialFormscrystallatticewithbondstofourneighborsDopantsSiliconisasemiconductorPuresiliconh

3、asnofreecarriersandconductspoorlyAddingdopantsincreasestheconductivityGroupV:extraelectron(n-type)GroupIII:missingelectron,calledhole(p-type)p-nJunctionsAjunctionbetweenp-typeandn-typesemiconductorformsadiode.CurrentflowsonlyinonedirectionnMOSTransistorFo

4、urterminals:gate,source,drain,bodyGate–oxide–bodystacklookslikeacapacitorGateandbodyareconductorsSiO2(oxide)isaverygoodinsulatorCalledmetal–oxide–semiconductor(MOS)capacitorEventhoughgateisnolongermadeofmetalnMOSOperationBodyiscommonlytiedtoground(0V)When

5、thegateisatalowvoltage:P-typebodyisatlowvoltageSource-bodyanddrain-bodydiodesareOFFNocurrentflows,transistorisOFFnMOSOperationCont.Whenthegateisatahighvoltage:PositivechargeongateofMOScapacitorNegativechargeattractedtobodyInvertsachannelundergateton-typeN

6、owcurrentcanflowthroughn-typesiliconfromsourcethroughchanneltodrain,transistorisONpMOSTransistorSimilar,butdopingandvoltagesreversedBodytiedtohighvoltage(VDD)Gatelow:transistorONGatehigh:transistorOFFBubbleindicatesinvertedbehaviorPowerSupplyVoltageGND=0V

7、In1980’s,VDD=5VVDDhasdecreasedinmodernprocessesHighVDDwoulddamagemoderntinytransistorsLowerVDDsavespowerVDD=3.3,2.5,1.8,1.5,1.2,1.0,…TransistorsasSwitchesWecanviewMOStransistorsaselectricallycontrolledswitchesVoltageatgatecontrolspathfromsourcetodrainCMOS

8、InverterAY01CMOSInverterAY010CMOSInverterAY0110CMOSNANDGateABY00011011CMOSNANDGateABY001011011CMOSNANDGateABY0010111011CMOSNANDGateABY00101110111CMOSNANDGateABY001011101110CMOSNORGateABY0010101001103-inputNANDGateYp