电磁场与电磁波：期中考试

2010-2011-2期中考试评讲I.Tofilltheanswersinthe“()”(2’X19=38)

1.[1776]8=(3FE)16=(1111111110)2=(1000000001)Gray2.(365)10=(001101100101)8421BCD

＝(001111001011)2421BCD3.Givenan12-bitbinarynumberN.iftheinteger’spartis9bitsandthefraction’spartis3bits(N=a8a7a6a5a4a3a2a1a0.a-1a-2a-3),thenthemaximumdecimalnumberitcanrepresentis(511.875);thesmallestnon-zerodecimalnumberitcanrepresentis(0.125).I.Tofilltheanswersinthe“()”(2’X19=38)4.IfX’ssigned-magnituderepresentationXSMis（110101）2,thenit’s8-bittwo’scomplementrepresentationX2’sCOMPis(11101011),and(–X)’s8-bitcomplementrepresentation(–X)2’sCOMPis(00010101)2

5.Ifthereare2011differentstates,weneedatleast(11)bitsbinarycodetorepresentthem.I.Tofilltheanswersinthe“()”(2’X19=38)6.IfapositivelogicfunctionexpressionisF=AC’+B’C(D+E)，thenthenegativelogicfunctionexpressionF=((A+C’)(B’+(C+DE))).7.AparticularSchmitt-triggerinverterhasVILmax=0.7V,VIHmin=2.1V,VT+=1.7V,andVT-=1.3V,VOLmax=0.3V,VOHmin=2.7V.ThentheDCnoisemarginintheHIGHstateis(0.6V),thehysteresisis(0.4V).I.Tofilltheanswersinthe“()”(2’X19=38)8.

TheunusedCMOSNANDgateinputinFig.1shouldbetiedtologic(1).I.Tofilltheanswersinthe“()”(2’X19=38)9.Ifnumber[A]two’s-complement=11011001and[B]two’s-complement=10011101,calculate[-A-B]two’s-complement,[-A+B]two’s-complementandindicatewhetherornotoverflowoccurs.[-A-B]two’s-complement=[10001010],overflow:[yes][-A+B]two’s-complement=[11000100],overflow:[no]I.Tofilltheanswersinthe“()”(2’X19=38).10.ThefollowinglogicdiagramFig.2implementsafunctionof3-variablewitha74138.ThelogicfunctioncanbeexpressedasF(A,B,C)=∑A,B,C(0,1,2).II.Thereisonlyonecorrectanswerinthefollowingquestions.(3’X9=27)1.WhichofthefollowingBooleanequationsisNOTcorrect?(B)A)A+0=AB)A1=AC)A.1=A D)(A.B)’=A’+B’

II.Thereisonlyonecorrectanswerinthefollowingquestions.(3’X9=27)2.SupposeA2’sCOMP=（1011），B2’sCOMP=（1010），C2’sCOMP=（0010）.Inthefollowingequations,themostunlikelytoproduceoverflowis（

C）。

A)（A+B）2’sCOMPB)(A-C)2’sCOMP

C)(B+C)2’sCOMPD)(C-A)2’sCOMP

3.Whatisthepossibleradixofthenumbersysteminoperationof302/20=12.1.(B)A)7 B)4 C)5 D)8II.Thereisonlyonecorrectanswerinthefollowingquestions.(3’X9=27)4.A16-to-1multiplexerneed(B)controlinputs.A)3 B)4 C)6 D)85.Ifthecanonicalsumforann-inputlogicfunctionisalsoaminimalsum,howmanyliteralsareineachproducttermofthesum?(A)A)n B)2n C)n-1 D)cannotbedetermined.II.Thereisonlyonecorrectanswerinthefollowingquestions.(3’X9=27)6.Apriorityencoder74LS148’sinputis:I0-L,I1-L,I2-L,I3-L,I4-L,I5-L,I6-L,I7-L，outputisY2-L,Y1-L,Y0-L.Theinputsandoutputareallactive-low.Whenactive-lowenableinputS_L=0,andI2-L=I4-L=I5-L=0,thenY2-L,Y1-L,Y0-Lis(B).A)110 B)010 C)001 D)101II.Thereisonlyonecorrectanswerinthefollowingquestions.(3’X9=27)7.Therearetwologicfunctionswithsame4inputvariables:F1=∑ABCD(1,2,6,7,10,12)andF2=∏ABCD(3,5,8,9,13,14).Therelationshipbetweenthemis（

C）。A).Shannon’sexpansion B).Equivalent C).Duality D).ComplementII.Thereisonlyonecorrectanswerinthefollowingquestions.(3’X9=27)8.Howmanyinverterscanbedrivenbythesameinverter

forthe74LSTTLfamiliesinFig.3.Whentheoutputofinhignandlowlevelsare，,theinputcurrentsare,themaximumoutputcurrent,themaximumoutputcurrent=—0.4mA.(D)Fig.3CircuitofproblemII-85 B)10 C)15 D)20II.Thereisonlyonecorrectanswerinthefollowingquestions.(3’X9=27)II.Thereisonlyonecorrectanswerinthefollowingquestions.(3’X9=27)9.ACMOSgatecircuitisshownas

Fig4.Thefunctionexpressionforthecircuitis(C).A)(AB+BC)’ B)(AC+BC)’C)(AB+AC)’ D)AB+ACIII.CombinationalCircuitAnalysisAndDesign:[35]1.Minimizethelogicfunctionexpressiontorealizethecircuitwithaslessgatesaspossible.[5’]F=AB’(C+D)+BC’+A’B’+A’C+BCF=AB’(C+D)+B(C+C’)+A’B’+A’C(1’)=AB’(C+D)+B+A’B’+A’C(1’)=A(C+D)+B+A’+A’C(2’)=C+D+A’+B(1’)评分标准：1）、用卡诺图化简：填卡诺图错扣3分；由卡诺图读图错扣2分2）、公式化简或其他方法,过程每错一步扣1分，扣完5分为止。III.CombinationalCircuitAnalysisAndDesign:[35]2.SimplifythefollowinglogicfunctionintotheminimalsumexpressionandminimalproductexpressionusingKarnaughmap.F(A,B,C,D)=∑m(0,4,7,11,15)+∑d(1,5,8,9,10,12,13,14)[5’]theminimalsumexpression:F=A+C’+BD(1’)theminimalproductexpressionF=（A+B+C’）(C’+D)(1’)评分标准：若卡诺图画正确但读图错扣1分。

(3’)III.CombinationalCircuitAnalysisAndDesign:[35]3.ThereisalogiccircuitandtheinputsA,BandCarecorrespondingtotheoutputsFA,FBandFC.ThewaveformsofinputsandoutputsareshowninFig.5.Pleasewriteoutthetruthtableincludealltheinputsandoutputs,andthelogicexpressionoftheoutputsFA,FBandFC,anddescribethelogicfunction.[10’]

ABCFAFBFCIII.CombinationalCircuitAnalysisAndDesign:[35]ABCFAFB

FC

000000001001010010011001100100101001110010111001ABCFAFBFC

(6’)III.CombinationalCircuitAnalysisAndDesign:[35]FA=AB’C’(1’)FB=BC’(1’)FC=C(1’)逻辑功能：该电路为优先权排序电路，C具有最高优先权，B次之，A的优先权最低。(1’)评分标准：真值表完全正确得6分，每错一处扣0.5分；表达式完全正确得3分，每错一个扣1分；判断电路为优先权排序电路，得1分；若说明为其他合理功能，得1分；否则，扣1分。

ABCFAFB

FC

000000001001010010011001100100101001110010111001III.CombinationalCircuitAnalysisAndDesign:[35]4.AnalysisthecombinationallogiccircuitshownintheFig.6,andwriteoutthelogicexpression.Determinewhetherthestatichazardmayexistornotinthecircuit.Ifthestatichazardexists,pleasecheckitoutandfixit.Andwriteoutthefixedproduct-of-sumexpression.[7’]F=(A+B’+C)(A+C’)(A’+C’)(3’)thefixedproduct-of-sumexpression：F=(A+B’+C)(A+C’)(A’+C’)(A+B’)(B’+C’)(B+C’)或F=(A+B’+C)(A+C’)(A’+C’)(A+B’)C’或F=(A+B’)C’(3’)评分标准：正确写出题目中原图逻辑函数表达式，得3分，每错一个或项扣1分；判断出有竞争冒险发生，得1分；正确写出完全消除竞争冒险后的“或与式”逻辑函数表达式得3分。III.CombinationalCi