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1、Chapter5P5.1.Foreachproblem,restateeachBooleanequationintoaformsuchthatitcanbetranslatedintothepandn-complexofaCMOSgate.a.b.c.P5.2.P5.1.First,converttheequationintoitspandn-complex.P5.2.Thetruthtableisgivenbelowintermsofvoltages.ThefunctionisABF00Vdd0VDD0VDD00VDDVDD0Thew
2、orsecaseVOHisVDDandtheworsecaseVOLis0V.P5.3.ThefirstcircuitisaNORgatewhilethesecondisaNANDgate.TheVOLandVOHcalculatedarefortheworst-casescenario.Tofindthis,assumeonlyonetransistorturnson,thisjustreducestoapseudo-NMOS/PMOSinverter,sotheothertransistorsarenotimportant.a.Th
3、eVOLforthepseudo-NMOS(in0.18μm)is:Sincetheminimumwidthis2λ,wemakethatthewidth.TheVOHforthepseudo-PMOS(in0.18μm)is:Thepseudo-PMOScircuitwillhavebiggerdevicesthanthepseudo-NMOS.P5.1.Thestepstosolvingthisquestionarethesameasthepseudo-NMOSquestioninChapter4.a.ForVOH,recogniz
4、ethatforoperationsotheoutputcanonlybeashighas.Since,bodyeffectmustbetakenintoaccountandthefullequationis:IterationproducesVOH=0.73V.b.ForVOL,wemustfirstrecognizethattheworst-caseVOLoccurswhenonlyoneofthepull-downtransistorsison.Nextweidentifytheregionsofoperationofthetra
5、nsistors.Inthiscase,thepull-uptransistorisalwaysinsaturationandthepull-downismostlikelyinthelinearregionsinceitwillhaveahighinput(highVGS)andalowoutput(lowVDS).Then,weequatethetwocurrentstogetherandsolveforVOL:Usingaprogrammablecalculatororaspreadsheetprogram,VOL=0.205V.
6、Thedccurrentwiththeoutputlowis:Thepowerwiththeoutputlowis:P5.1.SeeExample5.2whichisbasedontheNANDgate.ThisquestionisthesameexceptthatitaddressestheNORgate.Withbothinputstiedtogether,IntheSPICEsolution,thereasonwhytheresultsvaryforinputAandBisduetobody-effect.P5.2.Thesolu
7、tionisshownbelow.NoticethatthereisnorelevancewiththelengthsandwidthsofthetransistorswhenitcomestoVOH,althoughtheythedomatterwhencalculatingVOL.P5.3.FortPLH,weneedtosizethepull-upPMOSappropriately.ForVOL:P5.1.Thecircuitisshownbelow:Becausethenumberoftransistorsinseriesism
8、orethanone,wemustmultiplythewidthsbytheappropriatenumber.Here,alltheNMOStransistorswillhaveawidthof54λ.
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