电子信息专业英语第6章

,Unit6OperationalAmplifier,TextKeywordsTechnicaltermsExpressionsNotestothetext,TextTheoperationalamplifierisoneofthemostwidelyusedanalogintegratedcircuits.Actually,itisthemultileveldirectcouplingamplifierwithhighgain,highinputimpedanceandlowoutputimpedance.Withthedevelopmentofintegratedcircuittechnology,theperformancehasbeenmoreperfect.Today,thedevelopmentdirectionofintegratedoperationalamplifierislowerdrift,noiseandpowerdissipation;higherspeed,gainandinputvoltage;moreovermuchmoreoutputpoweretc.,Therearemanystylesofoperationalamplifiers.Thecircuitsarenotsosame,butgenerallythecircuitsconsistofthreestages(asshowninFig.6-1):input,middleandoutputstage.Normally,theinputcircuitisthedifferentialamplifierusedtoreducethezerodrift.Theprimarypurposeofthemiddlestageistoobtainhighvoltagegain.Theoutputstageismadeupofthevoltagefollowertodecreasetheoutputimpedanceandimprovetheoutputpowerandtheloadcapability.,Fig.6-1theconstituteframeofintegratedcircuit,Theoperationalamplifieristhemostimportantbasicbuildingblockofalllinearcircuits.Ithasawiderangeofapplicationsinsuchfieldsasanaloguesignaloperations,amplification,filtering,waveformsproducing,linearandnon-linearsignalshandling,etc.Theterm“operationalamplifier”wasoriginallyappliedtohighgainamplifiersoperatingdowntozerofrequencywhichwereusedinanaloguecomputerstoperformcertainmathematicaloperations.Thesehighgainamplifiersarenowusedforawidevarietyofapplications,butthename“operationalamplifiers”or“op-amp”isnormallyusedeventhoughnomathematicaloperationareinvolved.,Theearlyoperationalamplifiersemployeddiscretecomponents,butitisnowmuchmoreconvenienttoemployanintegratedcircuit.Thecircuitdesignersarenotgenerallyinterestedintheinternalcomponentsofanintegratedcircuit,butonlyintheperformanceoftheunitasawhole.Therefore,thesymbolinFig.6-2isusedtodenotetheamplifier.Itcanbeseenthattherearetwoinputsoneoutputandconnectionstothepositiveandnegativesupplylines.,Fig.6-2theICsymbol,Iftheinvertinginputismadeslightlymorepositive,theoutputwillbecomemorenegative,thisiswhythename“inverting”isgiventothisinput.If,however,thenon-invertinginputismademorepositive,theoutputwillalsobecomemorepositive.Type741deviceisoneofthebestknowngeneralpurposeoperationalamplifiersandisalsooneofthecheapestofalllinearintegratedcircuits.Thedeviceisactuallyavailableinanumberofdifferentpackages.Readerswillusuallyfindthetypeof741showninFig.6-3.Thistypeofpackageisknownasthe8pindual-in-line.,Fig.6-3thetypeof741,Abasiccircuitofa741invertingamplifierisshowninFig.6-4.Theinputsignalisfedtotheinvertinginputofthe741viaR1andthereforetheoutputisinvertedinphasewithrespecttotheinput.Operationalamplifiersaredesignedtohaveveryhighinputimpedance.Theinputcurrentsofthe741circuitarethereforeverysmall.Astheinvertinginputisvirtuallyatgroundpotential,thecurrentwhichflowsthroughR1isequaltotheinputvoltageuidividedbyR1.Similarly,thecurrentflowingthroughR3isuo/R3whereuoistheoutputvoltage.Thesetwocurrentsarealmostequal,thusthevoltagegainofcircuitisequaltotheresistorvaluesG=R3/R1.,Fig.6-4741invertingamplifier,Keywordsmultileveln.多级couplevt.连合，连接，结合driftn.漂移differentialadj.差动的capabilityn.(实际)能力，性能analogn.模拟；adj.模拟的amplificationn.扩大filtern.滤波器；vt.过滤frequencyn.频率varietyn.变化，多样性，种类,convenientadj.便利的，方便的internaladj.内在的，国内的denotevt.指示，表示invertvt.使颠倒，使转化availableadj.可用到的，可利用的packagen.包裹，包，管壳pinn.钉，管脚，引线virtuallyadv.事实上，实质上,Technicaltermsoperationalamplifier运算放大器directcouplingamplifier直接耦合放大器powerdissipation功耗zerodrift零点漂移voltagefollower电压跟随器linearandnon-linearsignalshandling线性和非线性信号处理invertinginput反相输入端non-invertinginput同相输入端8pindual-inline8管脚双列直插式,Expressionsavarietyof各种各样的eventhough即使beinterestedin.对感兴趣beknownas.被称为withrespectto关于，至于,Notestothetext1.Normally,theinputcircuitisthedifferentialamplifierusedtoreducethezerodrift.一般来说，输入级是差动放大器，用于减小零漂。句中的“usedtoreducethezerodrift”为过去分词作后置定语，修饰前面的“amplifier”。,2.Theoutputstageismadeupofthevoltagefollowertodecreasetheoutputimpedanceandimprovetheoutputpowerandtheloadcapability.输出级由电压跟随器构成，用于减小输出阻抗，提高输出功率和带负载能力。句中，“bemadeupof”意为由构成，为被动语态；动词不定式“todecreaseandimprove”作目的状语，“improve”前面承前省略“to”。,3.Theterm“operationalamplifier”wasoriginallyappliedtohighgainamplifiersoperatingdowntozerofrequencywhichwereusedinanaloguecomputerstoperformcertainmathematicaloperat