《电子信息类专业英语》课件-第5章

Unit5IntegratedCircuit科技英语中的定语从句

Firstly,let’sseethedevelopmentofIntegratedCircuit(IC).

Before1947,theheartoftheelectroniccircuitwasvacuumtubeinventedin1904byaBritishengineer,thoughthisdeviceunderwentconstantimprovement,inrealityforitscomplexdesign,thevacuumtubeisinherentlyunstable,power-hungry,andsubjecttoburnoutsandinternalshortcircuits.Italsotakesupalotofspace.TheseareamongtheshortcomingsofthevacuumtubethatledtothedevelopmentofthetransistorbyBellTelephoneLaboratoriesengineers.

Thekeytothetransistor’srapiddevelopmentwastheuseofsiliconinsteadofwireasthebasicconductivematerial.Thiselement,whichcomprises28percentoftheearth’scrust,isnotonlystableoverawiderangeoftemperatures,butalsooffersdependablemanufacturingcontrol.

Then,whatisIC?

Integratedcircuits,orICisacombinationofafewinterconnectedcircuitelementssuchastransistors,diodes,capacitors,andresistorsproducedinasinglemanufacturingprocessononeandthesamebearingstructure,calledthesubstrate,andintendedtoperformdefinitefunctioninvolvedinconvertinginformation.

TheelectricallyinterconnectedcomponentsthatmakeupanICarecalledintegratedelements.Ifanintegratedcircuitincludesonlyonetypeofcomponents,suchasonlydiodeorresistors,itissaidtobeanassemblyorsetofcomponents.

Theprincipleofintegratedcircuitelementsliesinthefollowing.Agreatnumberof“set”areproducedsimultaneouslyonawafer.Eachsetcontainsallthecomponentssuchastransistors,diodes,andresistorswhichareinterconnectedwithshortfinemetallicstripesdepositedonthewafersurface.Theymakeupafunctionalblock.EachICsofcomponentsisareadyintegratedcircuit.AllICsareregularlydistributedonthewafersurface.

ICscanbeclassifiedbyfunctionintotwo:circuitstobeappliedindigitalsystemsandthosetobeappliedinlinearsystems.ThedigitalICsareemployedmostlyincomputers,electroniccounters,frequencysynthesizersanddigitalinstruments.AndtheanalogorlinearICsoperateoveracontinuousrange,andincludesuchdevicesasoperationalamplifiers.

科技英语中的定语从句

定语从句一直是科技英语阅读中经常遇到却又难以把握的问题。定语从句一般位于所修饰的名词(先行词)后，紧跟先行词,或与先行词有一定的间隔。定语从句究竟修饰文中的哪个先行词,一要靠语言知识理解，二要根据上下文进行逻辑判断。

定语从句有限定性和非限定性之分。前者是主句意义中不可缺少的部分，而后者主要对主句起附加说明作用，一般与主句用逗号隔开。

定语从句的一般结构：

先行词 + 引导词(包括关系代词who、that、which、whom、whose和关系副词when、where、why)+ 从句

例如：

①Atransformeriscomposedofsomecoilsthatarecoupledtogetherbymagneticinduction.

变压器由磁感应耦合线圈组成。

②ISDNisanewserviceofferedbymanytelephonecompaniesthatprovidesfast,high-capacitydigitaltransmissionofvoice,data,stillimagesandfull-motionvideoovertheworldwidetelephonenetwork.

综合业务数据网(ISDN)是由电话公司提供的一项新型业务，这项业务可以在世界范围内的电话网上进行语言、数据、静止图像和运动视频的快速、大容量的数字传输。

③Whenthepointerstopsmoving,thereadinggivenbytheohmmeteristheinsulationresistance,whichisnormallyhighifthecapacitorisingoodcondition.(非限制性定语从句)

指针停止移动时的读数就是电容器的绝缘电阻值,假如电容器正常工作,绝缘电阻值通常很高。

注意：

1.在限定性定语从句中,引导词指代先行词,定语从句的引导词在从句中充当某个成分，有时可将其省略。例如：

TheGPSreceivercomparesthetimeasignalwastransmittedbyasatellitewiththetimeitwasreceived.

GPS接收机把卫星发送信号的时间和接收信号的时间相比较。

2.在非限定性定语从句中不能使用that为关系代词，而只能who,whom,whose等指人，用which指物或事。

3.在非限定性定语从句中，定语从句的引导词不仅可以指代先行词，有时还可指代前面的整个句子。

例如：