模擬電子技術基礎(論文)2

經(jīng)典word整理文檔，僅參考，雙擊此處可刪除頁眉頁腳。本資料屬于網(wǎng)絡整理，如有侵權，請聯(lián)系刪除，謝謝！摘要模擬電子技術是一門研究對仿真信號處理的模擬電路學科.模擬電路作為電氣工程及其自動化專業(yè)主干課程之一,經(jīng)歷了長足的發(fā),目前已經(jīng)被廣泛應用在我們件,包括功率放大電路、運算放大電路、反饋放大電路、信號運算與處理電路、信模擬電子技術基礎每章節(jié)進行雙語詳解,從而達到深層次理解掌握模擬電子技術的目的.關鍵詞：模擬電子技術，二極管,信號發(fā)生器Electronictechnologyisthestudyofsimulationofthesimulationsignalprocessingcircuit。Analogcircuitasoneofelectricalengineeringanditsautomationprofessionalbackbonecourse,experiencedalonghair,nowhasbeenwidelyusedinour。Analogelectronictechnologyforsemiconductordiodes,semiconductortriodeandfieldeffecttubeasthekeyelectronics,includingpoweramplificationcircuit,operationalamplifiercircuit,feedbackamplificationcircuit，signaloperationandprocessingcircuit,signalcircuit,powersupplyvoltageregulatorcircuit，researchdirection,andcontinuouslyreformandinnovation,andappliedtotheproductionlife，greatlypromotedtheprogressofscienceandtechnology.Thisarticlesummarizesthedevelopmentandprospectofanalogelectronictechnology,andthenintotheanalogelectronictechnologyfoundationforeachchapterinexplanation，soastoachievetheaimofdeepunderstandmasteranalogelectronictechnology.Keywords：Analogelectronictechnology;triode;teaching;signalcircu緒論一、簡介模擬電子技術是電子技術的一個方面,他是一個非常美麗的地方,在這個領域,數(shù)學、物理、信息工程、電氣工程和自動化工程學科發(fā)現(xiàn)和諧集成點，其深刻的理論基礎和廣泛的實際應用使它有一個強大而持久的生命力。因此,對于許多相關的科學.模擬電子技術是一個非常重要的基礎理論課程。一般來說,模擬電子技術是一個實用的,非常實用的課題,本文的主要目的是研礎，為我們分析和解決問題的能力也是非常重要的。根據(jù)目前流行的說,就是使用一門外語(主要是英語)進行非語言學科的教學,為學生創(chuàng)造一個密切接觸英語環(huán)境”。認為，雙語教學被認為是一種外語教學方法是一種教學方式。雙語教學改革的實施不僅有利于培養(yǎng)素質高、能力強，而且教師的英語水平的提高。作為一個重要的專業(yè)電工基礎課程,實施雙語教學是最好的選擇。果是比較理想的，可以更好地擴大學生的知識，提高學習能力。根據(jù)雙語教學的模式,不僅讓學生根據(jù)其基本原理來解決遇到的問題的過程中學習和英語水平的提高,增強學生的學習興趣，讓他們覺得有用.模擬電子技術課程的教學目標.模擬電子技術的特點是:線性和非線性的組合,直流和交流，結合電路和設備,系和緊密整合,全面介紹網(wǎng)絡圖論，通過計算機的影響，非線性電路與系統(tǒng)的研究I科學的發(fā)展，在多通道設備，集成；在系統(tǒng)的分析方法，優(yōu)化集成;在系統(tǒng)擴展從線性到非線性，從被動到主動，從單一元素離散擴展到集成電路系統(tǒng)。進入21世紀，電子技術快速發(fā)展的時代，隨著技術的不斷改進，使設備規(guī)模繼續(xù)縮小，以不斷提高集成，降低功耗,旗艦性能得到了改進。技術來取代。多媒體課件的教學方法是一個基本出發(fā)點是基于文本、圖像、聲音、動畫和其他方式合作,刺激學生的感官，激發(fā)學生的興趣和嚴格的形式的多媒體課件和黑板,粉筆是沒有區(qū)別,獲得教學效果并不顯著。課件的制作適當?shù)牟牧?適用于木材。多媒體課件可以充分發(fā)揮學生的潛能，強化教學效果,提高教學質量為重心。但最終多媒體只是一種輔助教學手段,為了更好地利用先進的知識傳播工具。隨著當今世界的發(fā)展,外語的應用越來越廣泛，國內外語環(huán)境較差。所以教育需要創(chuàng)新,為此我們學校領導及老師讓我們以雙語課件為主題寫一篇論文。雙語教中國這個多元化國家，雙語教學不僅是一種教學模式，更是一種語言政策.模擬電子技術作為一門電類相關專業(yè)的重要專業(yè)基礎教程之一,實施雙語教學模式是非常合適的。II二、課題研究目的及意義習的過程中可以掌握兩種語言，提高對英語的理解,增強學習興趣，擴大學生的知識面。經(jīng)過一系列研究實踐和探索，雙語教學的效果理想,不僅專業(yè)上學以致用，外語能力也得到提高，學習也更加有興趣了.這就是模擬電子技術雙語教學的目的所在了。三、國內研究現(xiàn)狀和發(fā)展趨勢及綜述模擬電子技術的特點為：線性與非線性相結合，直流與交流相結合,電路與器件相結合，基本估算與物理概念相結合。目前，模擬電子技術的現(xiàn)狀可簡單地鬼難為：與系統(tǒng)理論緊密結合、全面引入網(wǎng)絡圖論、深受計算機的沖擊、非線性電路與最佳化、可集成化;在體系上從線性擴展到非線性、從無源擴展到有源、從單元件分立擴展到電路系統(tǒng)的集成。進入21實際，電子技術進入了飛速發(fā)展的時代，隨著工藝技術的不斷改進，使得器件的尺寸不斷縮小，從而集成度不斷提高，功耗降低，旗艦性能得到提高.1AnalogConcept..............................................................................................................11。1Elementandparameter......................................................................................11。2Electroniccomponent........................................................................................11。3Analogsignalanddigitalsingnal.......................................................................21.4TroubleshootingAnalogCircuits..........................................................................31.5Basictestinstrument.............................................................................................42DiodesandApplications.................................................................................................52。1TheAtomicStructureOfSemiconductors.........................................................52。2ThePNJunction.................................................................................................72.3BiasingtheSemiconductorDiode........................................................................92。4Diodeclassification..........................................................................................103BipolarJunctionTransistors.........................................................................................123。1StructureofBipolarJunctionTransistors........................................................123。2Transistoroperatingprinciple..........................................................................133.3CharacteristiccurveofBJT................................................................................153。4BJTBiasCircuits.............................................................................................163.5Faultdiagnosisoftransistorbias........................................................................174FieldEffectTransistors.................................................................................................184.1StructureofFieldEffectTransistors...................................................................184。2JFETCharacteristics........................................................................................204.3ThetransconductancecurveofJFET..................................................................214.4InputresistanceofJFET.....................................................................................224。5Differentialamplifier.......................................................................................235Basic—AmpCircuits..............................................................................................255。1Comparators.....................................................................................................255。2TheEffectofNoiseonTheComparator.........................................................265。3IntegratorsandDifferentiators........................................................................27ConcludingRemarks........................................................................................................28Thank...............................................................................................................................30Reference.........................................................................................................................3111.1ElementandparameterAccordingtothetypesofsignalsthatweuse,wecantheelectroniccreditsintotwoparts:digitalelectronicsandanalogTheanalogcircuitisusedforcontinuousvariation,whilethedigitalcircuitisusedtocorrespondtothediscretelevel.Analogelectronicsisthesignalprocessing，suchasamplification，differential，integral，andsoon.Anddigitalelectronics，includingarithmeticandlogicoperations,asistheuseofcomputersandcalculatorstocompletetheoperation.1.2ElectroniccomponentIntwentiethCentury，theelectronicsystemfromthesendertoChittagongvacuumtubes,transistorsandintegratedcircuits.Integratedcircuitisthefunctionofthecompletionoftheitisdividedintodigitalintegratedcircuitwithanalogintegratedcircuit,oneistousetwodiscretevoltage，andtheotheristodealwiththecontinuouschangeoftheinputsignalwiththeoutputsignal.Inordinaryalgebra,linearequationscanbeexpressedinalinearrepresentationofvariables，andaregenerallywritteninaformula.Y=mx+bYsaidXisthedependentindependentvariable,Mslope,BistheinterceptontheYaxis。1Whentheinterceptiszero,istogothroughtheorigin，theBiszero，thentheformulaisY=mxLinearoriginalistheincreaseinthecurrentandthevoltageisproportionaltotheadded,butalsoinlinewiththeFormostelectroniccomponents，thecharacteristiccurveisthecurveofthecurrentversusvoltage(thegraphoftherelationshipbetweenthetwoelementsofacomponentingeneral）isdefinedasthecharacteristiccurve.Ifthepowersupplyreverseconnection，thenthecircuitwillbewhatisnotthesame？Thistimewillproducemorereadings,willmakepeoplelookverymessy,pronetoerror。Theabovementionedcharacteristiccurveofresistanceisastraightorigin，andYaxiswithzerointercepttime.Theslopeofastraightlineisconstantandisequaltotheresistanceoftheelectricalconductivity,thatis,thereciprocaloftheslopeistheresistance.1.3AnalogsignalanddigitalsingnalInanalogelectronics,asignalisavoltageorcurrentthatcontainsinformation.AndelectronicsystemsignalisoftenusedinawaytodealwithorcantransformthewaveformaswellasthroughtheamplificationtoimproveThiswaycanbecarriedoutinacontinuousWeknowthatthesignalisdividedintocontinuousordiscretetype,inwhichthecontinuoussignaltransformationisflatandslow，whichisnotinterrupted。Butdiscretesignalscanonlytakeonepart(forexample,someofthem)。Continuousanddiscretecanbeusedfortheamplitudeofthesignalcanalsobeusedfortime.Ontheotherhand，anothertypeofencoderonlysomedatayouchoosetostepin。2Inordertomakethesignalcarryinginformationtransmission,electronicwaveformofthevoltageorfrequencyofsomeenergyneedstochange,telecom,generalwillinafixedtimeintervalrepeat,therepetitivewaveformcalledperiodicwaveform.Cycleisthetimerequiredtocompleteacyclewaveform.Whichisdividedintomanykindsofwaves,suchassinewave。Sinewaveisthemostbasicandmostimportantwaveform。Itisthewaveformofthecurrentorvoltage,withthesamewaveformasthetrigonometricfunctionofthesinwaveinthealgebra.SinewaveisakindofwaveformwhichcanbenaturallygeneratedbyACgeneratororradiowave。Italsohaslasergeneratingprocess，sonicvibrationphenomenon。1.4TroubleshootingAnalogCircuitsInanalogelectronics，asignalisavoltageorcurrentthatcontainsinformation.Andelectronicsystemsignalisoftenusedinawaytodealwithorcantransformthewaveformaswellasthroughtheamplificationtoimproveenergy。Thiswaycanbecarriedoutinacontinuousmanner.Weknowthatthesignalisdividedintocontinuousordiscretetype,inwhichthecontinuoussignaltransformationisflatandslow，whichisnotinterrupted。Butdiscretesignalscanonlytakeonepart（forexample,someofthem).Continuousanddiscretecanbeusedfortheamplitudeofthesignalcanalsobeusedfortime.Ontheotherhand，anothertypeofencoderonlysomedatayouchoosetostepin.Inordertomakethesignalcarryinginformationtransmission，electronicwaveformofthevoltageorfrequencyofsomeenergyneedstochange，telecom，generalwillinafixedtimeintervalrepeat,therepetitivewaveformcalledperiodicwaveform.Cycleisthetimerequired3tocompleteacycleWhichisdividedintomanykindsofwaves,suchassinewave.Sinewaveisthemostbasicandmostimportantwaveform.Itisthewaveformofthecurrentorwiththesamewaveformasthetrigonometricfunctionofthesinwaveinthealgebra.SinewaveisakindofwaveformwhichcanbenaturallygeneratedbyACgeneratororradiowave。Italsohaslasergeneratingsonicvibration1.5BasictestinstrumentInanalogelectronics,asignalisavoltageorcurrentthatcontainsinformation.AndelectronicsystemsignalisoftenusedinawaytodealwithorcantransformthewaveformaswellasthroughtheamplificationtoimproveThiswaycanbecarriedoutinacontinuousWeknowthatthesignalisdividedintocontinuousordiscretetype,inwhichthecontinuoussignaltransformationisflatandslow，whichisnotinterrupted.Butdiscretesignalscanonlytakeonepart（forexample,someofthem)。Continuousanddiscretecanbeusedfortheamplitudeofthesignalcanalsobeusedfortime.Ontheotherhand，anothertypeofencoderonlysomedatayouchoosetostepin.Inordertomakethesignalcarryinginformationtransmission,electronicwaveformofthevoltageorfrequencyofsomeenergyneedstochange，telecom,generalwillinafixedtimeintervalrepeat，therepetitivewaveformcalledperiodicCycleisthetimerequiredtocompleteacyclewaveform.Whichisdividedintomanykindsofwaves,suchassinewave.Sinewaveisthemostbasicandmostimportantwaveform。ItisthewaveformofthecurrentorwiththesamewaveformasthetrigonometricfunctionofthesinwaveintheSinewaveis4akindofwaveformwhichcanbenaturallygeneratedbyACgeneratororradiowave。Italsohaslasergeneratingprocess,sonicvibrationphenomenon.2.1TheAtomicStructureOfSemiconductorsInanalogelectronics，asignalisavoltageorcurrentthatcontainsinformation。Andelectronicsystemsignalisoftenusedinawaytodealwithorcantransformthewaveformaswellasthroughtheamplificationtoimproveenergy。Thiswaycanbecarriedoutinacontinuousmanner.Weknowthatthesignalisdividedintocontinuousordiscretetype,inwhichthecontinuoussignaltransformationisflatandslow，whichisnotinterrupted。Butdiscretesignalscanonlytakeonepart(forexample，someofContinuousanddiscretecanbeusedfortheamplitudeofthesignalcanalsobeusedfortime.Ontheotherhand,anothertypeofencoderonlysomedatayouchoosetostepin。Inordertomakethesignalcarryinginformationtransmission,electronicwaveformofthevoltageorfrequencyofsomeenergyneedstochange，telecom，generalwillinafixedtimeintervalrepeat，therepetitivewaveformcalledperiodicwaveform.CycleisthetimerequiredtocompleteacycleWhichisdividedintomanykindsofsuchassinewave.view2-2Sinewaveisthemostbasicandmostimportantwaveform。Itisthewaveformofthecurrentorvoltage，withthesamewaveformasthetrigonometricfunctionofthesinwaveinthealgebra.SinewaveisakindofwaveformwhichcanbenaturallygeneratedbyACgeneratororradiowave。Italsohaslasergeneratingprocess，sonicvibrationphenomenon2.2ThePNJunctionAPNjunctionisadiode。Intheequilibriumstate，thereisnocurrentinthePNjunction.Themainuseofthesemiconductordiodeistheonewayelectricconductivity.—錯誤Whenapuresemiconductorisgenerallydopedntype,thegeneraldopingofPtheninbetweenthetworegionsontheformationofaPNIntheNarea,therearemanyfreeelectronsandseveralholeswhicharethermallyproduced.Therearemanyholesinthepregion。Thefreeelectron.PnstructureproducedbythehotelectronsisthebasicdiodeandthebasisoftheworkofallsolidstateDiodeisacomponentthatonlyallowscurrenttoflowinonedirection.2.3BiasingtheSemiconductorDiodeThetermbiasinelectronicsreferstoafixedDCvoltagewhichisaddedtothesemiconductorelementtosetitsworkingForwardbiasistheconditionthatallowsthecurrenttoflowthroughthePNReversebiasisthebiasconditiontopreventthecurrentflowingthroughthePNjunction?！e誤3.1StructureofBipolarJunctionTransistorsBipolartransistor，itisabbreviatedasBJT.Isconstructedfromthreedopedsemiconductorregions.Thesethreeregionsareknownastheemissionregion,thebaseregionandthecollectorregion(FigureA,b）；—錯誤thesethreeregionsareseparatedbytwopn。Weknowthatbipolartransistorsaredividedintotwotypes。OneofthetwoPnareasinthemiddleofaPNwithathinlayer,knownasNPNtypetransistor,thereisatwoPNarea，themiddleofathinlayerofPNclip,calledPNPtypetransistor.Thesetwokindsoftransistorsarewidelyusedbyus,buttheformerismorewidelyused。Somostofuslearnaboutit.3-錯誤Inordertomakethetransistorworknormally,anexternalDCbiasvoltagemustbeprovidedontwoPnjunctionsinordertoestablishtheproperworkingconditions。NPNandPNPtubenormalbias，intwocases，thelaunchofthejunctionareforwardbias,theseasonisreversebias，knownaspositiveandnegativebias。view3-1Butinthetwocasethevoltagepolarityandthedirectionofthecurrentisjusttheopposite.FromemitteroutflowintothenarrowandlowdopingconcentrationofthebaseregionmostelectronicnocompositetwolittlecontinuestospreadtotheBCjunctiondepletionregion,onceintotheregiontheyinthereversebiasBCjunctionperiodwillbetheattractionbetweenpositiveandnegativeionsestablishedplantspull。Kirchhoff’scurrentlawpointsoutthatthetotalcurrentflowingintothenodemustbeequaltothetotalcurrentflowingoutofthenode。ApplyingthislawtotheNPNtubeandthePNPtubecanbeconcludedthattheemittercurrentIeisequaltothesetcurrentIcwhichisthesumofthebasecurrentIb.Theexpressionis:Ie=Ic+IbinwhichthecurrentrespectivelyshowstheNPNtubeandPNPtubesmallsignaltransistorofthetypicalcurrentvalue.TheBJTcharacteristiccurveisdividedintotheinputcharacteristiccurveandtheoutputcharacteristiccurve,andtheinputcharacteristiccurveisclosetothecommondiode。Thatistosayintheanalysisofbipolartransistorcircuit,ifthetransistoristurnedon,theemittervoltageatbothendsoftheregardedas0。7V.Ifthevoltageis0transistorturn-on,ifmuchlargerthan0.7thetransistoremitterjunctionisregardedasanopencircuit.InordertodrawtheoutputcharacteristiccurveoftheBJT,thebaselevelcurrentmustbeselectedandkeptForthecircuitusedtogenerateabaselevelcurrentintheroleofIcwiththeVcechangeofagroupofvoltamperecurve,thiscurveiscalledtheoutputcharacteristiccurve.3-錯誤3-錯誤BiasistheadditionofproperDCvoltagetothetransistortoworkproperly。Itcanbeachievedthroughanyoneofseveralbasiccircuits.Theselectionofbiascircuitisveryrelatedtotheapplication.Inwhichthelinearamplifier,theinputsignalmustbeinthepositiveandnegativedirectionchange。Butthetransistorsworkinasingledirection。InordertoallowthetransistortoamplifytheACsignal,theACsignalisrequiredtobesuperimposedontheDCcapacityofthesetofgoodworkingpoints.ThebiascircuitsetstheDCtoallowtheACsignaltomoveinapositiveornegativedirectionwithoutmakingthetransistorinsaturationorcutoff3.5FaultdiagnosisoftransistorbiasAsthebiascircuitdiagnosisisusuallysimple,ordinarytransistorbiascircuitbiaspoorfaultbyresultedinthefollowingtwocasesa,thefirst:transistorinsaturationstatethesecond:transistorisoffstate.Inthebeginningofthediagnosticcircuit,thefirsttocheckthebase,collectorandemittervoltage。Itisverypracticaltoobservewhethertheyaresuitableornot。Wehavetokeepinmindthatthesevoltagesareusuallyassociatedwithsomeresistanceorthebetavalueofthetransistor,butthechangeisnotmorethan10%ofit，andifthesearenormal，thecircuitcanworkproperly。Whenopencollectorduetolaunchresistancethereisnolongeracollectorcurrent，sothelaunchsomevoltagedrop:basevoltagechangewilldependsonthebias”width",thefixedbiaswillmakeanimpactonsmaller.ThistimeweneedtonoteisthatwhentheemitterReopencircuit,thebasevoltageisworkingnormallybutthetransistorismeasuredontheemittervoltageishigherthanthenormalvalue.Oftheremaybeotherproblems,butasafaultdiagnosismethod，shouldbefurtheranalysisoftheparametersofthemeasurement,inordertomoreaccuratelyidentifythefinalproblem。4Beforewesaid,bipolartransistorisacurrentcontroldevice,whichusesthebasecurrenttocontrolthesizeofthecollectorThedifferenceisthatthefieldeffecttubeisakindofvoltagecontrolelement，thatis，thecurrentofthegatevoltagecontrolelement。Theycanbeusedinamplifyingcircuitandswitchingcircuit。FieldeffecttubereferredtoasFET.Itisatypeofsemiconductordevice，anditsworkingprincipleiscompletelydifferentfromthepreviousBJT.Inthefieldeffecttube,theconductivepropertyofanarrowlongconductivechanneliscontrolledbyapowerplant，whichisformedbyaddingthethirdpolegrid.Itcanbedividedintotwoclasses:thefirstclass:thejunctiontypefieldeffecttube,whichischaracterizedbytheformationofaPNjunctionbetweenthegateandthechannelofthetube。Secondclass：thisclassiscalledmetaloxidesemiconductorfieldeffecttransistor，whichisusedtocontroltheelectricalconductivityofthechannel,theinsulationlayerisaverythinlayerofglass.view4-2ThecharacteristiccurveofJFETcanbedividedintothreezones.Ohmaccess，constantcurrentarea,stoparea.UndernormaltheyareallrunningintheohmicorconstantcurrentNditchjunctiontypefieldeffecttube,Nchannelatbothendsoftheleadoutoftwowires,theupperendiscalledthedrain,thelowerendiscalledthesource.ThischannelisafortheNtheelectronisthecarrierfluid，forthePchannel，theholeisthecarrier。Whenthereisnoexternalvoltage,thechanneldoesnotgenerateanydirectionofconductivecurrent.Bychangingthegatevoltage，thewidthofthechannelandofthechannelcanbecontrolled，therebycontrollingthesizeofthedraincurrentI.WhiteareasindicatethedepletionregiongeneratedbythereverseThekeyideaisthatthechannelwidthiscontrolledbythegatevoltage。4-錯誤4.3ThetransconductancecurveofJFETAneffectivewaytoobserveanycircuitistoshowtherelationshipbetweentheoutputandtheinput.Thischaracteristiciscalledthetransfercharacteristiccurve.BecausetheJFETiscontrolledbytheinputnegativevoltageandtheoutputisthedraincurrent，thecurveoftherotatingshaftisthecurveoftherelationshipbetweenIDandVGS.Bydividingtheoutputbythetheresultistheunitoftheelectricalconductivity.Youcanthinkofitastheinputvoltageisconvertedintooutputcurrent;therefore，theprefix"cross"andinfrontoftheproducedthetransconductanceoftheword，thetransconductancecurveisJFETtransfercharacteristics.ThetransconductanceparametersintheTransconductancecurveisnotastraightline,thenonlinearrelationshipbetweentheoutputcurrentandinputvoltage，fieldeffecttransistorhasanonlineartransconductancecurves。Thisisveryimportant，whichindicatesthatthepipewilldistorttheinputDistortionisnotalwaysabadsuchasaradiomixeristheuseofthefieldeffectisbetterthanthecharacteristicsoftheBJTtocomplete?！e誤AswePNhasahighresistancewhenitisbiased.WhenJFETisworking,thePnjunctionbetweenthegatesourceisreversebiased。Therefore,thegateinputresistanceisveryhigh.ItisthisveryhighinputresistancethatbecomesthemaximumadvantageoftheBJToverthebaseJFET.JFETparametertableisoftenusedinagatesourcevoltagevaluecorrespondingtothegatereversecurrentIGSStoindicatethesizeoftheinputresistance,inputresistancecanbeobtainedbythefollowingequation。Twoverticallinesrepresenttheabsolutevalue.Intheparametertableabove，Vgsis15V，andIGSSisthemaximumvalueof-1。。RIN===15Asseenfromtheresults,theinputresistanceofJFETisquitehigh.Butinpracticalapplications,thetotalinputresistanceshouldalsocontainaresistancethatisconnectedtothegate,sothetotalinputresistanceshouldbeintherangeof1～10M.4.5DifferentialamplifierDifferentialamplifierisanimportantamplifierwithmultipleapplications.Inparticular，theopampisaninputstage.Thenameofthedifferentialamplifierisderivedfromthedifferencebetweentheinputsignalwhichisaddedatthetwoinputterminals，thatis,thedifferencebetweenthetwosignals.Thesamesignalisnotamplifiedintheinput。Ithasanimportantcharacteristictoreducethecommonmodenoise。Unlikeotheramplifiers,thisamplifierhastwoinputsandtwooutputs.Thepipeswerecarefullymatchedandhadthesamecharacteristics。4-錯誤Inordertounderstanditsworkingitisassumedthatthetwobasesaregrounded.Becausethepressuredropofthebaseemitterstructureisthediodevoltagedrop,theemittervoltageis-0。7V.Theemittercurrentonbothsidesisequaltohalfofthecurrentinthecommonemitterresistance.Thecollectorcurrentofeachtubeisequaltothatoftheemittercurrent,whichisequaltothehalfoftheemitterresistancecurrent。Becausethecollectorcurrentisequal,thecollectorvoltageisequal。5.1ComparatorsTheopampisusedasanonlinearelementtocomparethemagnitudeofthetwovoltage。Inthisapplication，theoperationalamplifierisusingopenaninputterminalisconnectedwithaninputvoltage,anotherinputendisconnectedwithareferencevoltage.Nowwetalkaboutseveralbasiccomparisoncircuits。5-錯誤Acomparatorisanopencircuitthatisusedtocomparetwoinputvoltagesandgeneratetwovaluescorrespondingtotheinputsize。Anapplicationofanoperationalcomparatoristomeasurewhethertheinputvoltageisbeyondacertainvalue.Duetooperationalamplifierhasaveryhighopenloopvoltagegain,sothedifferentialmodevoltagebetweenthetwoinputendsofthesmallwillsaturatetheamplifier，theoutputvoltagereachesthelimitvalue.Tested，whenthesinewaveisnegative,theoutputreachesthemaximumnegativevalue.Whenthesinewavepasseszero,theamplifierisforcedtoentertheoppositeandtheoutputbecomesthemaximumintegrity.ItcanbeseenthatthezerocrossingcomparatorcanbeusedasasquarewavewithasinewavegeneratedbyFangBo.Withtheabovezerocrossingcomparatorisnotthesame,non-zerocomparator。Afixedreferencevoltageonthereverseinputofthezerocrossingcomparatorcanbemodifiedintoapositiveandnegativevoltagecomparator。ItismorepracticalthanHeusesavoltagedividertosetthereferencevoltageto：VREF=R2/R1+R2（+v）Amongthem,+Visthepositivesupplyvoltageamplifier,withzenerdiodesetreferencevoltage（VREF=VZ).AslongastheinputvoltageVinislessthanthereferencevoltage，theoutputwillremainthemaximumnegativevalue。Whentheinputvoltageexceedsthereferencevoltage,theoutputreachesthemaximumvalue。5.2TheEffectofNoiseonTheComparatorInmanypracticalsituations,noisecanbegeneratedontheinputline.Noisevoltagesuperimposedontheinputvoltage,willmakethecomparatorerrortochangetheoutputstate.Inordertounderstandtheeffectofnoiseonvoltage,weaddalowfrequencysinusoidalvoltagetotheinputofthezerocrossingcomparator.Observedwiththenoiseofthesinewavewiththecorrespondingoutputwaveform，canbeseen,whenthesinewavereached0，duetothepresenceofnoisesothatthetotalinputin0toseveralchanges，resultinginthewrongoutput.Mingledwiththenoiseoftheinputwillcausetheerroroftheoutputvoltage，becauseofthesameinputvoltagecomparatorOPmayfromnegativeoutputstatevariabletothepositiveoutputstate,mayalsobecausedbyachangeintheoppositedirection，i.e.fromtherightpathnegative。Thisunstableconditionoccursnearthereferencevoltage,andasmallnoisefluctuationcausesthecomparatortochangef