电气自动化专业英语.ppt

Chapter1ElectricandElectronicTechnologyFundamentals Unit3Transistor Text NewWordsandExpressions Exercises End ProcessofTranslation Unit3Transistor Atransistorisasemiconductordeviceusedtoamplifyandswitchelectronicsignals Itismadeofasolidpieceofsemiconductormaterial withatleastthreeterminalsforconnectiontoanexternalcircuit Avoltageorcurrentappliedtoonepairofthetransistor sterminalschangesthecurrentflowingthroughanotherpairofterminals Becausethecontrolled output powercanbemuchmorethanthecontrolling input power thetransistorprovidesamplificationofasignal Today sometransistorsarepackagedindividually butmanymorearefoundembeddedinintegratedcircuits Thetransistoristhefundamentalbuildingblockofmodernelectronicdevices andisubiquitousinmodernelectronicsystems Followingitsreleaseintheearly1950sthetransistorrevolutionisedthefieldofelectronics andpavedthewayforsmallerandcheaperradios calculators andcomputers amongstotherthings Unit3Transistor ImportanceThetransistoristhekeyactivecomponentinpracticallyallmodernelectronics andisconsideredbymanytobeoneofthegreatestinventionsofthetwentiethcentury Itsimportanceintoday ssocietyrestsonitsabilitytobemassproducedusingahighlyautomatedprocess semiconductordevicefabrication thatachievesastonishinglylowper transistorcosts Unit3Transistor Unit3Transistor Althoughseveralcompanieseachproduceoverabillionindividuallypackaged knownasdiscrete transistorseveryyear thevastmajorityoftransistorsnowproducedareinintegratedcircuits oftenshortenedtoIC microchipsorsimplychips alongwithdiodes resistors capacitorsandotherelectroniccomponents toproducecompleteelectroniccircuits Alogicgateconsistsofuptoabouttwentytransistorswhereasanadvancedmicroprocessor asof2009 canuseasmanyas2 3billiontransistors MOSFETs About60milliontransistorswerebuiltthisyear 2002 for each man woman andchildonEarth Thetransistor slowcost flexibility andreliabilityhavemadeitaubiquitousdevice Transistorizedmechatroniccircuitshavereplacedelectromechanicaldevicesincontrollingappliancesandmachinery Itisofteneasierandcheapertouseastandardmicrocontrollerandwriteacomputerprogramtocarryoutacontrolfunctionthantodesignanequivalentmechanicalcontrolfunction Unit3Transistor TransistorasaswitchTransistorsarecommonlyusedaselectronicswitches forbothhighpowerapplicationsincludingswitched modepowersuppliesandlowpowerapplicationssuchaslogicgates Inagrounded emittertransistorcircuit suchasthelight switchcircuitshown asthebasevoltagerisesthebaseandcollectorcurrentriseexponentially andthecollectorvoltagedropsbecauseofthecollectorloadresistor Therelevantequations Unit3Transistor URC ICE RC thevoltageacrosstheload thelampwithresistanceRc URC UCE UCC thesupplyvoltageshownas6VIfUCEcouldfallto0 perfectclosedswitch thenICcouldgonohigherthanUCC Rc evenwithhigherbasevoltageandcurrent Thetransistoristhensaidtobesaturated Hence valuesofinputvoltagecanbechosensuchthattheoutputiseithercompletelyoff orcompletelyon Thetransistorisactingasaswitch andthistypeofoperationiscommonindigitalcircuitswhereonly on and off valuesarerelevant Unit3Transistor Unit3Transistor TransistorasanamplifierThecommon emitteramplifierisdesignedsothatasmallchangeinvoltagein Vin changesthesmallcurrentthroughthebaseofthetransistorandthetransistor scurrentamplificationcombinedwiththepropertiesofthecircuitmeanthatsmallswingsinUinproducelargechangesinUout Variousconfigurationsofsingletransistoramplifierarepossible withsomeprovidingcurrentgain somevoltagegain andsomeboth Frommobilephonestotelevisions vastnumbersofproductsincludeamplifiersforsoundreproduction radiotransmission andsignalprocessing Thefirstdiscrete transistoraudioamplifiersbarelysuppliedafewhundredmilliwatts butpowerandaudiofidelitygraduallyincreasedasbettertransistorsbecameavailableandamplifierarchitectureevolved Moderntransistoraudioamplifiersofuptoafewhundredwattsarecommonandrelativelyinexpensive Return Unit3Transistor Unit3Transistor TypesTransistorsarecategorizedby Semiconductormaterial germanium silicon galliumarsenide siliconcarbide etc Structure BJT JFET IGFET MOSFET IGBT othertypes Polarity NPN PNP BJTs N channel P channel FETs Maximumpowerrating low medium high Maximumoperatingfrequency low medium high radiofrequency RF microwave ThemaximumeffectivefrequencyofatransistorisdenotedbythetermfT anabbreviationfor frequencyoftransition Thefrequencyoftransitionisthefrequencyatwhichthetransistoryieldsunitygain Unit3Transistor Application switch generalpurpose audio highvoltage super beta matchedpair Physicalpackaging throughholemetal throughholeplastic surfacemount ballgridarray powermodules Amplificationfactorhfe transistorbeta Thus aparticulartransistormaybedescribedassilicon surfacemount BJT NPN lowpower highfrequencyswitch Unit3Transistor PackagingThrough holetransistors tapemeasuremarkedincentimetres Transistorscomeinmanydifferentpackages semiconductorpackages seeimages Thetwomaincategoriesarethrough hole orleaded andsurface mount alsoknownassurfacemountdevice SMD Theballgridarray BGA isthelatestsurfacemountpackage currentlyonlyforlargetransistorarrays Ithassolder balls ontheundersideinplaceofleads Becausetheyaresmallerandhaveshorterinterconnections SMDshavebetterhighfrequencycharacteristicsbutlowerpowerrating Unit3Transistor Transistorpackagesaremadeofglass metal ceramic orplastic Thepackageoftendictatesthepowerratingandfrequencycharacteristics Powertransistorshavelargerpackagesthatcanbeclampedtoheatsinksforenhancedcooling Additionally mostpowertransistorshavethecollectorordrainphysicallyconnectedtothemetalcan metalplate Attheotherextreme somesurface mountmicrowavetransistorsareassmallasgrainsofsand Oftenagiventransistortypeisavailableinsundrypackages Transistorpackagesaremainlystandardized buttheassignmentofatransistor sfunctionstotheterminalsisnot othertransistortypescanassignotherfunctionstothepackage sterminals Evenforthesametransistortypetheterminalassignmentcanvary normallyindicatedbyasuffixlettertothepartnumber q e BC212LandBC212K NewWordsandExpressions transistorn 晶体管amplifyvt 放大 增强ubiquitousadj 普遍存在的calculatorn 计算器astonishinglyadv 令人吃惊地discreteadj 不连续的 离散的MOSFET金属氧化物半导体场效应晶体管flexibilityn 弹性 适应性mechatronicn 机电一体化electromechanicaladj 机电的saturatev 使饱和 浸透 使充满milliwattn 毫瓦galliumarsenide砷化镓siliconcarbide碳化硅BJT双极结型晶体管 BipolarJunctionTransistor JFET结晶型场效应晶体管 junctionfieldeffecttransistor IGFET绝缘栅场效应晶体管 isolated gatefieldeffecttransistor IGBT 绝缘栅双极型晶体管 InsulatedGateBipolarTransistor N channeln沟道abbreviationn 缩写 缩写词denotevt 指示 表示yieldv 出产 生产super beta高倍放大matchedpair推挽式放大throughhole透眼 透孔surfacemount面封装式ballgridarray球栅阵列 封装 powermodule功率模块 封装 amplificationfactor放大倍数centimetern 厘米 公分packagen 包装 封装ceramicn 陶瓷collectorn 集电极drainn 漏极grainn 谷粒 细粒sundryadj 各式各样的assignmentn 分配 安排suffixn 后缀 下标 Return ProcessofTranslation 理解阶段主要是通过辨明词义 弄清各种语法成分及其相互关系 并把前后句子贯串起来理解 形成对原文的完整印象 真正掌握原文的内容和实质 表达阶段是在理解的基础上 以忠实于原意为前提 灵活地运用各种翻译方法和技巧 写出符合汉语规范 表达习惯以及翻译标准的译文 校核阶段是理解与表达的进一步深化 是对原文内容进一步核实 对译文语言进一步推敲 进行必要的润色和修改 使译文符合标准规范 Exercises I Comprehension 1 Transistorsarecommonlyusedaselectronic forbothhighpowerapplicationsincludingswiched modepowersuppliesandlowpowerapplicationssuchaslogicgates A heatersB transformersC amplifiersD switches2 Thisarrangementwheretheemitter E