大工CMOS数字集成电路总复习.ppt

*Startingatthebottomofthedesignabstractionchart GateOxide–insulator NMOS–sincecarriersareelectrons(ntypecarriers) M–metal;O–oxide;S–semiconductorFieldoxideisolatesonedevicefromneighboringdevicesBasetechnologyforthesemester0.25microntransistorlengthL(drawnseparationfromsourcetodrain)–0.24effective1.0microntransistorwidthWforminimumsizetransistor2.5VsupplyvoltageVDD0.43(-0.4)thresholdvoltageforNMOS(PMOS)devicessominW/Lratioinmaxfor250nmtechnologyis1/.24Viewtransistorasaswitchwithaninfiniteoff-resistanceandafiniteon-resistance**Inverter–thenucleusofalldigitaldesigns;foundationofmoreintricategatesDesignmetrics–cost(area);integrityandrobustness(static–steady-statebehavior);performance(dynamicortransientbehavior);energyefficiency*Forclasshandout–hideforclass*Agooddevicehasasmalloxidethickness(-3nm),asmalllength(-25nm),ahigherwidth(+30nm)andasmallerthreshold(-60mV).Theoppositeistrueforabaddevice.*VTCcharacteristicsaredependentuponthedatainputpatternsappliedtothegate(sothenoisemarginsarealsodatadependent!)ThresholdvoltageofM2willbehigherthantransistorM1duetobodyeffectCase1–bothtransistorsinthePUNareonsimultaneouslyforA=B=0,representingastrongpull-up.Intheothertwocasesonlyoneofthepull-updevicesison.SotheVTCisshiftedleftasaresultoftheweakerPUNforthesecondandthirdcases.Case2–seeCase3,smalldifferencecanbeattributedtothebodyeffectofM2andthedrivevoltageCase3–M2asresistorinserieswithM1,soonlysmalleffectonVTC;sincepulldownisstrongandpullupweakerthancase1,VTCshiftedtotheleft(alsohavetodischargebothCL(ontheoutput)andCint(possibly)thruM1sowillalsobeslower!)**Assumesinputsof0and1areequallylikely.只要当输出在上一个求值阶段被放电时，预冲阶段就会发生0－1翻转。Ford