IntegratedCircuits集成电路电子信息类专业英语计算机类专业英语文章10页.docx
- 文档编号:26109205
- 上传时间:2023-06-17
- 格式:DOCX
- 页数:14
- 大小:28.27KB
IntegratedCircuits集成电路电子信息类专业英语计算机类专业英语文章10页.docx
《IntegratedCircuits集成电路电子信息类专业英语计算机类专业英语文章10页.docx》由会员分享,可在线阅读,更多相关《IntegratedCircuits集成电路电子信息类专业英语计算机类专业英语文章10页.docx(14页珍藏版)》请在冰豆网上搜索。
IntegratedCircuits集成电路电子信息类专业英语计算机类专业英语文章10页
IntegratedCircuits(集成电路)
与当今“教师”一称最接近的“老师”概念,最早也要追溯至宋元时期。
金代元好问《示侄孙伯安》诗云:
“伯安入小学,颖悟非凡貌,属句有夙性,说字惊老师。
”于是看,宋元时期小学教师被称为“老师”有案可稽。
清代称主考官也为“老师”,而一般学堂里的先生则称为“教师”或“教习”。
可见,“教师”一说是比较晚的事了。
如今体会,“教师”的含义比之“老师”一说,具有资历和学识程度上较低一些的差别。
辛亥革命后,教师与其他官员一样依法令任命,故又称“教师”为“教员”。
英文原稿:
教师范读的是阅读教学中不可缺少的部分,我常采用范读,让幼儿学习、模仿。
如领读,我读一句,让幼儿读一句,边读边记;第二通读,我大声读,我大声读,幼儿小声读,边学边仿;第三赏读,我借用录好配朗读磁带,一边放录音,一边幼儿反复倾听,在反复倾听中体验、品味。
TheIntegratedCircuit
我国古代的读书人,从上学之日起,就日诵不辍,一般在几年内就能识记几千个汉字,熟记几百篇文章,写出的诗文也是字斟句酌,琅琅上口,成为满腹经纶的文人。
为什么在现代化教学的今天,我们念了十几年书的高中毕业生甚至大学生,竟提起作文就头疼,写不出像样的文章呢?
吕叔湘先生早在1978年就尖锐地提出:
“中小学语文教学效果差,中学语文毕业生语文水平低,……十几年上课总时数是9160课时,语文是2749课时,恰好是30%,十年的时间,二千七百多课时,用来学本国语文,却是大多数不过关,岂非咄咄怪事!
”寻根究底,其主要原因就是腹中无物。
特别是写议论文,初中水平以上的学生都知道议论文的“三要素”是论点、论据、论证,也通晓议论文的基本结构:
提出问题――分析问题――解决问题,但真正动起笔来就犯难了。
知道“是这样”,就是讲不出“为什么”。
根本原因还是无“米”下“锅”。
于是便翻开作文集锦之类的书大段抄起来,抄人家的名言警句,抄人家的事例,不参考作文书就很难写出像样的文章。
所以,词汇贫乏、内容空洞、千篇一律便成了中学生作文的通病。
要解决这个问题,不能单在布局谋篇等写作技方面下功夫,必须认识到“死记硬背”的重要性,让学生积累足够的“米”。
Digitallogicandelectroniccircuitsderivetheirfunctionalityfromelectronicswitchescalledtransistor.Roughlyspeaking,thetransistorcanbelikenedtoanelectronicallycontrolledvalvewherebyenergyappliedtooneconnectionofthevalveenablesenergytoflowbetweentwootherconnections.Bycombiningmultipletransistors,digitallogicbuildingblockssuchasANDgatesandflip-flopsareformed.Transistors,inturn,aremadefromsemiconductors.Consultaperiodictableofelementsinacollegechemistrytextbook,andyouwilllocatesemiconductorsasagroupofelementsseparatingthemetalsandnonmetals.Theyarecalledsemiconductorsbecauseoftheirabilitytobehaveasbothmetalsandnonmetals.Asemiconductorcanbemadetoconductelectricitylikeametalortoinsulateasanonmetaldoes.Thesedifferingelectricalpropertiescanbeaccuratelycontrolledbymixingthesemiconductorwithsmallamountsofotherelements.Thismixingiscalleddoping.Asemiconductorcanbedopedtocontainmoreelectrons(N-type)orfewerelectrons(P-type).Examplesofcommonlyusedsemiconductorsaresiliconandgermanium.PhosphorousandboronaretwoelementsthatareusedtodopeN-typeandP-typesilicon,respectively.
Atransistorisconstructedbycreatingasandwichofdifferentlydopedsemiconductorlayers.Thetwomostcommontypesoftransistors,thebipolar-junctiontransistor(BJT)andthefield-effecttransistor(FET)areschematicallyillustratedinFigure2.1.Thisfigureshowsboththesiliconstructuresoftheseelementsandtheirgraphicalsymbolicrepresentationaswouldbeseeninacircuitdiagram.TheBJTshownisanNPNtransistor,becauseitiscomposedofasandwichofN-P-Ndopedsilicon.Whenasmallcurrentisinjectedintothebaseterminal,alargercurrentisenabledtoflowfromthecollectortotheemitter.TheFETshownisanN-channelFET,whichiscomposedoftwoN-typeregionsseparatedbyaP-typesubstrate.Whenavoltageisappliedtotheinsulatedgateterminal,acurrentisenabledtoflowfromthedraintothesource.ItiscalledN-channel,becausethegatevoltageinducesanN-channelwithinthesubstrate,enablingcurrenttoflowbetweentheN-regions.
Anotherbasicsemiconductorstructureisadiode,whichisformedsimplybyajunctionofN-typeandP-typesilicon.Diodesactlikeone-wayvalvesbyconductingcurrentonlyfromPtoN.Specialdiodescanbecreatedthatemitlightwhenavoltageisapplied.Appropriatelyenough,thesecomponentsarecalledlightemittingdiodes,orLEDs.Thesesmalllightsaremanufacturedbythemillionsandarefoundindiverseapplicationsfromtelephonestotrafficlights.
Theresultingsmallchipofsemiconductormaterialonwhichatransistorordiodeisfabricatedcanbeencasedinasmallplasticpackageforprotectionagainstdamageandcontaminationfromtheoutsideworld.Smallwiresareconnectedwithinthispackagebetweenthesemiconductorsandwichandpinsthatprotrudefromthepackagetomakeelectricalcontactwithotherpartsoftheintendedcircuit.Onceyouhaveseveraldiscretetransistors,digitallogiccanbebuiltbydirectlywiringthesecomponentstogether.Thecircuitwillfunction,butanysubstantialamountofdigitallogicwillbeverybulky,becauseseveraltransistorsarerequiredtoimplementeachofthevarioustypesoflogicgates.
Atthetimeoftheinventionofthetransistorin1947byJohnBardeen,WalterBrattain,andWilliamShockley,theonlywaytoassemblemultipletransistorsintoasinglecircuitwastobuyseparatediscretetransistorsandwirethemtogether.In1959,JackKilbyandRobertNoyceindependentlyinventedameansoffabricatingmultipletransistorsonasingleslabofsemiconductormaterial.Theirinventionwouldcometobeknownastheintegratedcircuit,orIC,whichisthefoundationofourmoderncomputerizedworld.AnICissocalledbecauseitintegratesmultipletransistorsanddiodesontothesamesmallsemiconductorchip.Insteadofhavingtosolderindividualwiresbetweendiscretecomponents,anICcontainsmanysmallcomponentsthatarealreadywiredtogetherinthedesiredtopologytoformacircuit.
AtypicalIC,withoutitsplasticorceramicpackage,isasquareorrectangularsilicondiemeasuringfrom2to15mmonanedge.DependingontheleveloftechnologyusedtomanufacturetheIC,theremaybeanywherefromadozentotensofmillionsofindividualtransistorsonthissmallchip.Thisamazingdensityofelectroniccomponentsindicatesthatthetransistorsandthewiresthatconnectthemareextremelysmallinsize.DimensionsonanICaremeasuredinunitsofmicrometers,withonemicrometer(1mm)beingonemillionthofameter.Toserveasareferencepoint,ahumanhairisroughly100mmindiameter.SomemodernICscontaincomponentsandwiresthataremeasuredinincrementsassmallas0.1mm!
Eachyear,researchersandengineershavebeenfindingnewwaystosteadilyreducethesefeaturesizestopackmoretransistorsintothesamesiliconarea,asindicatedinFigure2.2.
WhenanICisdesignedandfabricated,itgenerallyfollowsoneoftwomaintransistortechnologies:
bipolarormetal-oxidesemiconductor(MOS).BipolarprocessescreateBJTs,whereasMOSprocessescreateFETs.Bipolarlogicwasmorecommonbeforethe1980s,butMOStechnologieshavesinceaccountedthegreatmajorityofdigitallogicICs.N-channelFETsarefabricatedinanNMOSprocess,andP-channelFETsarefabricatedinaPMOSprocess.Inthe1980s,complementary-MOS,orCMOS,becamethedominantprocesstechnologyandremainssotothisday.CMOSICsincorporatebothNMOSandPMOStransistors.
ApplicationSpecificIntegratedCircuit
Anapplication-specificintegratedcircuit(ASIC)isanintegratedcircuit(IC)customizedforaparticularuse,ratherthanintendedforgeneral-purposeuse.Forexample,achipdesignedsolelytorunacellphoneisanASIC.Incontrast,the7400seriesand4000seriesintegratedcircuitsarelogicbuildingblocksthatcanbewiredtogetherforuseinmanydifferentapplications.
Asfeaturesizeshaveshrunkanddesigntoolsimprovedovertheyears,themaximumcomplexity(andhencefunctionality)possibleinanASIChasgrownfrom5,000gatestoover100million.ModernASICsoftenincludeentire32-bitprocessors,memoryblocksincludingROM,RAM,EEPROM,Flashandotherlargebuildingblocks.SuchanASICisoftentermedaSoC(System-on-Chip).DesignersofdigitalASICsuseahardwaredescriptionlanguage(HDL),suchasVerilogorVHDL,todescribethefunctionalityofASICs.
Field-programmablegatearrays(FPGA)arethemoderndayequivalentof7400serieslogicandabreadboard,containingprogrammablelogicblocksandprogrammableinterconnectsthatallowthesameFPGAtobeusedinmanydifferentapplications.Forsmallerdesignsand/orlowerproductionvolumes,FPGAsmaybemorecosteffectivethananASICdesign.Thenon-recurringengineeringcost(thecosttosetupthefactorytoproduceaparticularASIC)canrunintohundredsofthousandsofdollars.
ThegeneraltermapplicationspecificintegratedcircuitincludesFPGAs,butmostdesignersuseASIConlyfornon-fieldprogrammabledevicesandmakeadistinctionbetweenASICandFPGAs.
History
TheinitialASICsusedgatearraytechnology.Ferrantiproducedperhapsthefirstgate-array,theULA(UncommittedLogicArray),around1980.Customizationoccurredbyvaryingthemetalinterconnectmask.ULAshadcomplexitiesofuptoafewthousandgates.Laterversionsbecamemoregeneralized,withdifferentbasediescustomizedbybothmetalandpolysiliconlayers.SomebasediesincludeRAMelements.
Standardcelldesign
Inthemid1980sadesignerwouldchooseanASICmanufacturerandimplementtheirdesignusingthedesigntoolsavailablefromthemanufacturer.Whilethirdpartydesigntoolswereavailable,therewasnotaneffectivelinkfromthethirdpartydesigntoolstothelayoutandactualsemiconductorprocessperformancecharacteristicsofthevariousASICmanufacturers.Mostdesignersendedupusingfactoryspecifictoolstocompletetheimplementationoftheirdesigns.AsolutiontothisproblemthatalsoyieldedamuchhigherdensitydevicewastheimplementationofStandardCells.EveryASICmanufacturercouldcreatefunctionalblockswithknownelectricalcharacteristics,suchaspropagationdelay,capacitanceandinductance;thatcouldalsoberepresentedinthirdpartytools.Standardcelldesignistheutilizationofthesefunctionalblockstoachieveveryhighgatedensityandgoodelectricalperformance.StandardcelldesignfitsbetweenGateArrayandFullCustomdesignintermsofbothitsNRE(Non-RecurringEngineering)andrecurringcomponentcost.
Bythelate1980s,logicsynthesistools,suchasDesignCompiler,becameavailable.SuchtoolscouldcompileHDLdescriptionsintoag
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- IntegratedCircuits 集成电路 电子信息 类专业 英语 计算机 文章 10