PART1ElectricalandElectronicEngineeringBasicsSection2TheOperationalAmplifierNewWordsandExpressions

LanguagepointsExercisesNewWordsandExpressionsamplifiern.放大器integratedcircuit集成電路buildingblocks積木potentialn.(電)勢cascaden.,v.串聯；adj.串聯的ontheorderof屬于同類的，約為tradeoff換取cumbersomeadj.麻煩的intrinsicadj.內在的circuitryn.電路LanguagePoints[1]Oneproblemwithelectronicdevicescorrespondingtothegeneralizedamp-lifiersisthatthegains,AUorAI,dependuponinternalpropertiesofthetwo-portsystem(、、RI、Ro,etc).[2]Atthispointwewillmakenoattempttodescribetheseinnerworking.LanguagePoints[3]AtotallygeneralanalysisoftheOp-Ampisbeyondthescopeofsometexts.[4]Onlythreeconnectionsareshown:thepositiveandnegativeinputs,andtheoutput.NotshownareotherconnectionsnecessarytoruntheOp-Ampsuchasitsattachmentstopowersuppliesandtogroundpotential.LanguagePoints理想運算放大器的符號如圖1-2A-1所示。圖中只給出三個管腳：正輸入、負輸入和輸出。讓運算放大器正常運行所必需的其它一些管腳，諸如電源管腳、接零管腳等并未畫出。圖1-2A-1運算放大器LanguagePoints在實際電路中使用運算放大器時，后者是必要的，但在本文中討論理想的運算放大器的應用時則不必考慮后者。兩個輸入電壓和輸出電壓用符號U、U和Uo表示。每一個電壓均指的是相對于接零管腳的電位。運算放大器是差分裝置。差分的意思是：相對于接零管腳的輸出電壓可由下式表示(1-2A-1)式中A

是運算放大器的增益，U

和U

是輸入電壓。換句話說，輸出電壓是A乘以兩輸入間的電位差。LanguagePoints[5]Onekeytothesuccessofanoperatio-nalamplifieristhe“cascading”ofanum-beroftransistoramplifierstocreateaverylargetotalgain.Asecondimportantfactoristhatthesecircuitscanbebuiltinsuchawaythatthecurrentflowintoeachoftheinputsisverysmall.Athirdimportantdesignfeatureisthattheoutputresistanceoftheoperationalamplifier(R0)isverysmall.LanguagePoints[6]ThisisoneofthekeyfeaturesofOp-Ampdesign—theactionofthecircuitonsignalsdependsonlyupontheexternalelementswhichcanbeeasilyvariedbythedesignerandwhichdonotdependuponthedetailedcharacteroftheOp-Ampitself.LanguagePoints[7]AsimilarmathematicalanalysiscanbemadeonanyOp-Ampcircuit,butthisiscumbersomeandtherearesomeveryusefulshortcutsthatinvolveapplicationofthetowlawsofOp-Ampswhichwenowpresent.a.ThefirstlawstatesthatinnormalOp-Ampcircuitswemayassumethatthevoltagedifferencebetweentheinputterminalsiszero.LanguagePointsb.ThesecondlawstatesthatinnormalOp-Ampcircuitsbothoftheinputcurrentsmaybeassumedtobezero.ExercisesI.TranslatethefollowingintoChinese

Allthesimplecircuitelementsthatwillbeconsideredintheworkthatfollowscanbeclassifiedaccordingtotherelationshipofthecurrentthroughtheelementtothevoltageacrosstheelement.Forinstance,ifthevoltageacrosstheelementisdirectlyproportionaltothecurrentthroughit,oru=ki,weshallcalltheelementaresistor.Othertypesofsimplecircuitelementshaveaterminalvoltagewhichisproportionaltothetimederivativeortheintegralwithrespecttotimeofthecurrent.ThereExercisesI.TranslatethefollowingintoChinese

arealsoelementsinwhichthevoltageiscompletelyindependentofthecurrentorthecurrentiscompletelyindependentofthevoltage;thesearetheindependentsources.Furthermore,weshallneedtodefinespecialkinds