电子信息与通信工程专业英语lesson2-20

2026/7/30可编辑1

Chapter2

CircuitSystemandDesign

Outline2.1CircuitandSystem2.2AnalogandDigitalCircuitsDesign2.3RadioReceiverCircuit2026/7/30可编辑22.2AnalogandDigitalCircuitsDesignOutlineAnalogcircuits

DigitCircuits2026/7/30可编辑3Terminologybipolaradj.双极型CMOS

abbr.ComplementaryMetalOxideSemiconductor互补型金属氧化物半导体semiconductingmaterial

半导体材料Integratedcircuits

集成电路transistorn.晶体管DCabbr.DirectCurrent直流ACabbr.AlternateCurrent交流digitaladj.数字的,计数的binaryadj.

具有两个的;二进制的;二变量的Booleanalgebra

布尔代数positiveadj.确实的;积极的;肯定的;现实的;正的;阳性的2026/7/30可编辑4negativeadj.否定的,否认的;反面的,消极的反对的;负的;阴极的hexadecimaladj.十六进制的numbersystem

计数制CommutativeLaw

交换律AssociativeLaw

结合律DistributiveLaw

分配率invertern.变换器;倒相器,倒换器;反演器;逆变器;“非”门truthtablen.真值表combinationaladj.组合的sequentialadj.

时序的Flip-flopn.触发器2026/7/30可编辑5Analogcircuitsarecircuitsdealingwithsignalsfreetovaryfromzerotofullpowersupplyvoltage.Analogcircuitsareoftenreferredtoaslinearcircuitstoemphasizethevalidcontinuityofsignalrangeforbiddenindigitalcircuits,butthislabelisunfortunatelymisleading.IntroductionTexttour1.AnalogcircuitsModerncircuitdesignisa"mixedsignal"endeavorthankstotheavailabilityofsophisticatedprocesstechnologiesthatmakeavailablebipolarandCMOS,powerandsignal,passiveandactivecomponentsonthesamecircuit.2026/7/30可编辑6Justbecauseavoltageorcurrentsignalisallowedtovarysmoothlybetweentheextremesofzeroandfullpowersupplylimitsdoesnotnecessarilymeanthatallmathematicalrelationshipsbetweenthesesignalsarelinearinthe"straight-line"or"proportional"senseoftheword.Manyso-called"linear"circuitsarequitenonlinearintheirbehavior,eitherbynecessityofphysicsorbydesign.Thisrelativemobilityofelectronswithinamaterialisknownaselectricconductivity.Conductivityisdeterminedbythetypesofatomsinamaterial(thenumberofprotonsineachatom'snucleus,determiningitschemicalidentity)andhowtheatomsarelinkedtogetherwithoneanother.2026/7/30可编辑7

NPNtransistorsInfact,inthemostbasicandmostcosteffectiveanalogICprocesses,thechipdesignerhasatitsdisposaljustthatagoodNPNtransistor.2026/7/30可编辑8Inthiscomponentthecurrentflowentersthecollectorandbaseandexitstheemitter.Simplystated,thetransistorconductsacollectorcurrentwhichisacopyofthebasecurrentamplifiedbyafactorofbeta.Itfollowsthattheemittercurrentisoneplusbetatimesthebasecurrent.Atypicalvaluefortheamplificationfactoris100.2026/7/30可编辑9ThePNPtransistoriscomplementarytotheNPN,withthecurrentflowenteringtheemitterandexitingthecollectorandbase,theoppositeofwhathappensintheNPN.SimplicitydictatesthatPNPsareaby-productoftheNPNconstruction,hencetheyoftenhavelessbetacurrentgainandareslowerthanNPNs.

PNPtransistors2026/7/30可编辑10MOStransistorsThedualofBipolarNPNandPNPtransistorsinCMOStechnologyaretheP-ChannelandN-ChannelMOStransistors.Thegeneralfunctionofthetransistorsisthesameindependentlyastheirimplementationbutthereareprosandconstousingbothtechnologies.Generallyspeaking,thebase,theemitter,andthecollectorofthebipolartransistorareanalogoustothegate,sourceanddrainoftheMOStransistor,respectively.2026/7/30可编辑11

Thebipolartransistors'mainproblem,whichisnotpresentinCMOS,istheirneedforabasecurrentinordertofunction.Suchcurrentisanettransferlossfromemittertocollector.Whilethebasecurrentissmallinsmallsignaloperation,inpowerapplications,wherethetransistorisusedasaswitch,thebasecurrentnecessarytokeepthetransistoroncanbeveryhigh.2026/7/30可编辑12Thishighbasecurrentcanleadtoimplementationswithverypoorefficiency.Withthepopularityofportableelectronicsandtheneedtoextendbatterylife,itisnowonderthatCMOSoftentendstohavetheupperhandoverbipolartechnologies.TheadvantageofbipolaroverCMOSthatithasbettertrans-conductancegainandbettermatching,leadingtobetterdifferentialinputgainstagesandbettervoltagereferences.Thebestperformanceprocessesaremixed-modeBiCMOS(BipolarandCMOS)orBCD(BipolarCMOSandDMOS)processesinwhichthedesignercanusethebestcomponentforthetaskathand.2026/7/30可编辑132.DigitCircuits

BooleanalgebrafundamentalsThephrase“Digitalelectronics”isusedtodescribethosecircuitsystemswhichprimarilyoperatewiththeuseofonlytwodifferentvoltagelevelsortwootherbinarystates.Analogdevicesandsystemsprocesstime-varyingsignalsthatcantakeonanyvalueacrossacontinuousrangeofvoltage,currentorothermetric.Thedifferenceisthatwecanpretendthattheydon’t.2026/7/30可编辑14TheNOToperationchangesthevaluetothecomplementofthevalue.Thisisalsoreferredtoasinversionornegation.TheANDoperationisaBooleanmultiplyandis1onlywhenallvaluesare1.TheANDisliketheoldstringofChristmaslights.Allthelightshavetoworktohavethestringylight.TheORoperationresultsina1ifanyofthevaluesare1.InBooleanalgebra,1+1=1isvalid.Logicallythestatementmeansifthereareoneormoretruevalues,theresultistrue.2026/7/30可编辑15CommutativeLaw:A+B=B+AAssociativeLawofAddition:A+B+C=A+(B+C)AssociativeLawofmultiplication:A(BC)=(AB)CDistributiveLaw:A(B+C)=AB+ACIdentity:1·A=A,0+A=AComplement:A+A=1.A·A=0DeMorgan'sTheorem:2026/7/30可编辑16LogicgatesIngeneral,agatehasoneormoreinputsandproducesanoutputthatisafunctionofthecurrentinputvalue(s).Witheachlogicelementthereisa“truthtable”thatexplainshowtheunitworks.Andthereisasymboltorepresenteverygate.ThebasicelectronicdigitaloperationsarealsoNOT,AND,OR,buttherearecombinationsofthesethatarealsocommonlyused:theNAND,NOR,andEXCLUSIVENOR.2026/7/30可编辑17CombinationallogicandsequentiallogiccircuitLogiccircuitsareclassifiedintotwotypes:combinationalandsequential.Acombinationallogicisonewhoseoutputsdependonlyonitscurrentinput.Acombinationallogiccircuitmaycontainanarbitrarynumberoflogicgatesandinvertersbutnofeedbackloops(asignalpathofacircuitthatallowstheoutputofagatetopropagatebacktotheinputofthatsamegate).2026/7/30可编辑18Whentheinputiscombinedwiththepreviousstateofthelogiccircuits,itisreferredtoassequentiallogic.Theuseofthepreviousstateiscalledfeedback.Theoutputsofsequentiallogiccircuitdependnotonlyonthecurrentinputsbutalsoonthepastsequenceofinputs,possiblyarbitrarilyfarbackintime.Aseal-incircuitisanexampleofasequentiallogiccircuit.2026/7/30可编辑19Intheanalysis,uselogicdiagramandproceedtoaformaldescriptionofthefunctionperformedbythatcircuit,suchasatruthtableoralogicexpression.Inthesynthesis,fromaformaldescriptionandproceedingtoalogicdiagram.Wehavelearnedthattherearefivepossiblerepresentationsforacombinationallogicfunction:1.truthtable2.analgebraicsumofminterms,thecanonicalsum3.amintermlistusingthenotation4.analgebraicproductofmaxterms,thecanonicalproduct5amaxtermlistusingthenotation2026/7/30可编辑20Karnaughmap,likeBooleanalgebra,isasimplificationtoolapplicabletodigitallogic.BooleansimplificationisactuallyfasterthantheKarnaughmapforataskinvolvingtwoorfewerBooleanvariables.Itisstillquiteusableatthreevariables,butabitslower.Atfourinputvariables,Booleanalgebrabecomestedious.Karnaughmapsarebothfasterandeasier.Karnaughmapsworkwellforuptosixinputvariables,areusableforuptoeightvariables.Formorethansixtoeightvariables,simplificationshouldbebyCAD(computerautomateddesign).Itsimplifiesalogicfunctionbycombiningpairsofadjacent1cellsintoaSum-Of-Productstermsthatcoversallofthe1cells.Formgroupsof1stocoverall0s.TheProduct-Of-Sumssimplifiedresultisbuilt.Bythedefinitionofminimalcostsolution,theSOPsolutionissimpler.2026/7/30可编辑21"Flip-flop"isthecommonnamegiventotwo-statedeviceswhichofferbasicmemoryforsequentiallogicoperations.Flip-flopsareheavilyusedfordigitaldatastorageandtransferandarecommonlyusedinbankscalled"registers"forthestorageofbinarynumericaldata.Flip-Flops2026/7/30可编辑222026/7/30可编辑23InanS-Rlatch,activationoftheSinputsetsthecircuit,whileactivationoftheRinputresetsthecircuit.IfbothSandRinputsareactivatedsimultaneously,thecircuitwillbeinaninvalidcondition.TheJ-Kflip-flopisamodifiedversionofanS-Rflip-flopwithno