电子信息技术专业英语-教学-作者-丁宁-Unit-4ppt课件

Unit4OperationalAmplifier,1,运算放大器,一.NEWWORDS,2,1.amplifiermplifain.放大器，扩音器2.analoguenln.模拟adj.模拟的3.varietyvraitin.变化,多样性,种类4.discretediskri:tadj.不连续的,离散的5.internalint:nladj.内在的,国内的6.denotedinutvt.指示,表示7.invertinv:tvt.使颠倒,使转化8.availableveilbladj.可获得的9.packagepkin.包裹,包,管壳10.pinpinn.钉,管脚，引线11.impedanceimpi:dnsn.电阻抗，阻抗,1.operationalamplifier运算放大器,3,invertinginputnon-invertinginput8pindual-in-line,反向输入端同向输入端8管脚双列直插式,二.Technicalterms:,三.Expressions:,4,avarietyofeventhoughbeinterestedinbeknownaswithrespecttobeequalto,各种各样的即使对.感兴趣被称为关于,至于等于，与相等,四.Questionsfortextdiscussion:,5,1.Whyisoperationalamplifiergiventhename?2.Drawthecircuitsymbolofanoperationalamplifier.3.Talkabouttheapplicationoftheoperationalamplifier.,Thefirstparagraph:Theoperationalamplifieristhemostimportantbasicblockofalllinearcircuits.Ithasawiderangeapplicationsinsuchfieldsasanaloguesignaloperations,amplification,filtering,waveformsproducing,linearandnon-linearsignalshanding,etc.译：运算放大器是所有线性电路中最重要的基本器件。它的应用十分广泛，包括模拟信号的运算，放大，滤波，波形发生器，以及进行线性和非线性信号的处理等。,6,五Learnthetext:,Thesecondparagraph:Theterm“operationalamplifier”wasoriginallyappliedtohighgainamplifiersoperatingdowntozerofrequencywhichwereusedinanaloguecomputerstoperformcertainmathematicaloperations.Thesehighgainamplifierarenowusedforawidevarietyofapplications,butthename“operationalamplifiers”or“op-amp”isnormallyuseeventhoughnomathematicaloperationareinvolved.Theearlyoperationalamplifieremployeddiscretecomponents,butitisnowmuchmoreconvenienttoemployanintegratedcircuit.Thecircuitdesignersisnotgenerallyinterestedintheinternalcomponentsofanintegratedcircuit,butonlyintheperformanceoftheunitasawhole.Therefore,thesymbolinFig.2isusedtodenotetheamplifier.Itcanbeseenthattherearetwoinputs,oneoutputandconnectionthepositiveandnegativesupplylines.,7,注：这里whichwereusedmathematicaloperational为定语从句，修饰前面的highgainamplifiers,因为定语从句并未直接跟在所修饰的先行次后，语法上称其为分割定语。而定语从句中的toperformcertainmathematicaloperations为动词不定式短语，作目的状语。,8,译：运算放大器这一术语最早适用于下限频率可低到零赫兹的高增益放大器，它可用于模拟计算机中执行某些数学运算。这种高增益的放大器现在已被广泛应用于各个方面，早已远远超出数值运算的范围，但通常仍称之为运算放大器或OP-AMP。早期的运算放大器适用分立元件，但现在适用集成电路就更为方便了。电路设计者通常对集成电路内波元件并不感兴趣，只关心作为一个整体的单元性能。因此，图2所示的符号用来表示运算放大器。由图可见，运放有两个输入端，一个输出端以及正、负电源端子。,9,Thethirdparagraph:,10,Iftheinvertinginputismadeslightlymorepositive,theoutputwillbecomemorenegative,thisiswhythename“inverting”isgiventothisinput.if,thenon-invertinginputismademorepositive,theoutputwillalsobecomemorepositive.译：如果反向输入端正电压略微增加一点，那么输出负电压变得更强，这就是为什么称这个输入端为“反向输入端”的原因。然而，如果同相收入电压正向增大，输出端正电压也将变得更强。,11,Thefourthparagraph:,Type741deviceisoneofthebestknowngeneralpurposeoperationalamplifierandisalsooneofthecheapestofalllinearintegratedcircuits.Thedeviceisactuallyavailableinanumberofdifferentpackages.Readerswillusuallyfindthetypeof741showninFig.3.Thistypeofpackageisknownasthe8pindual-in-line.,译：741型器件是众所周知的通用运算放大器之一，也是所有的线性集成电路中最便宜的一种。这种器件实际上具有不同的封装形式。读者通常会发现如图3所示的741型器件最便于使用，这种封装形式为8管脚双列直插式,11,Thefifthparagraph:,12,Abasiccircuitofa741invertingamplifierisshowninFig.4.Theinputsignalisfedtotheinvertinginputof741viaR1andthereforetheoutputisinvertedinphaserespecttotheinput.Operationalamplifieraredesignedtohaveaveryhighinputimpedance.Theinputcurrentsofthe741circuitarethereforeverysmall.Astheinvertinginputisvirtuallyatgroundpotential,thecurrentwhichflowsthroughR1isequaltotheinputvoltageUidividedbyR1.Similarly,thecurrentflowingthroughR3isUo/R3.whereUoistheoutputvoltage.Thesetwocurrentarealmostequal,thusthevoltagegainofcircuitisequaltotheresistorvaluesG=-R3/R1.,译:741反向放大器的基本电路如图4所示。输入信号经R1加在741器件的反相输入端，因此输出信号与输入信号的相位相反。运算放大器设计成具有很高的输入阻抗，因此741的净输入电流非常小。由于反相输入端虚短，流过R1的电流等于Ui除以R3，同样流过R3的电流等于-Uo/R3，其中Uo输出电压。这两个电流几乎相等，因此电路的电压增益取决于电阻值：G=-R3/R1,13,14,Dotheexercises:,1.Translatethefollowingphrasesandexpressions.(1)运算放大器,(2)tobenotgenerallyinterestedintheinternalcomponentsofanintegratedcircuit(3)正、负电源端(4)8管脚双列直插式集成块(5)tobevirtuallyatgroundpotential,5.TranslatethefollowingsentencesintoEnglish.(1)运算放大器是一种高增益的放大器。(2)741器件是最常用也是最便宜的集成电路之一。(3)将输入信号加到运放的同相输入端。,Answer:Op-ampisakindofhighgainamplifier.Type741isoneofthemostcommonlyused,andthecheapestIC.Applytheinputsignaltothenon-invertinginputofop-amp.,14,Reading:OscillatorTranslatethisparagraphintoChinese:Aunitthatgenerates（产生）asignaliscalledanoscillator（振荡器）.OscillatorsareusedtoprovideACsignalsfromfrequencies（频率）justabovezerotofrequenciesinthegigahertz（千兆赫）regionatthetopendoftheradio-frequencypartoftheelectromagneticspectrum（电磁波谱）.Theymaybedescribedinoneoftwowaysintermsofthetypeofsignalwaveformgenerated:sinusoidaloscillatorsandrelaxationoscillators（张弛振荡器）.Asinusoidaloscillatorgeneratesasignalhavingasinewaveform;arelaxationoscillatorgeneratesasignalthatisusuallyofsquarewaveform.,15,Dialogue:AmplifierDesign,16,Supervisor:Iwouldlikeyoutodoapreliminarycalculationforanamplifier.Engineer:Whatarethedetails?Howistheamplifiertobeused?,Supervisor:Itmustgiveavoltagegainofabout1000.Engineer:Thatisntenoughinformation.Ineedtoknowthedesiredinputimpedanceaswellasthetypesofloadstobeusedwiththeamplifier.Supervisor:Itmusthaveahighinputimpedancewithaninputcapacitanceofnomorethan50micromicrofarads.Theloadswillberesistiveinthefrequencytobeused.Afewkilo-ohmswill,Ibelieve,beenough.Engineer:Whatwillbethefrequency?Supervisor:Aboutonemegacyclewitha200-kilocyclebandwidth.Engineer:Howlargewilltheinputsignalsbe?Supervisor:Abouthalfavolt,Ibelieve.Butsmallersignalsm