通信與電子信息專(zhuān)業(yè)英語(yǔ) 課件 Unit 1 Electric Circuits

Unit1ElectricCircuits1.1CircuitElements

1.2BasicLaws

1.3CircuitAnalysis1.1CircuitElementsWordsandExpressionsBackgroundsTextWordsandExpressionscircuitelement 電路元件passivedevice 無(wú)源器件Adevicethatdoesnotrequireasourceofenergyforitsoperation.4WordsandExpressionsactivedevice 有源器件Adevicethatrequiresapowersupplytodisplaytheircharacteristics,typicallyusedforsignalamplification,conversion,etc.5WordsandExpressionsresistor n.電阻器capacitor n.電容器inductor n.電感器；電感線圈6RLCparallelcircuitRLCseriescircuitWordsandExpressionsgenerator n.生成器，發(fā)電機(jī)7Ageneratorinelectricalcircuittheoryisoneoftwoidealelements:anidealvoltagesource,oranidealcurrentsource.Realelectricalgeneratorsaremostcommonlymodelledasanon-idealsourceconsistingofacombinationofanidealsourceandaresistor.Theresistorisreferredtoastheinternalresistanceofthesource.Non-idealvoltagesourcemodel(left)andnon-idealcurrentsourcemodelWordsandExpressionsbattery n.電池deadbattery 廢電池batteryoperated/powered 用電池運(yùn)行/驅(qū)動(dòng)的rechargeablebattery 充電電池batterycharger 電池充電器batterypack 電池組carbattery 汽車(chē)蓄電池8WordsandExpressionsoperationalamplifier 運(yùn)算放大器gain n.增益Anoperationalamplifier(oftenopamporopamp)isaDC-coupledhigh-gainelectronicvoltageamplifierwithadifferentialinputand,usually,asingle-endedoutput.9Pinconfiguration: V+:non-invertinginputV?:invertinginputVout:outputVS+:positivepowersupplyVS?:negativepowersupplyWordsandExpressionsvoltagesource 電壓源currentsource 電流源independentsource 獨(dú)立源dependentsource

受控源DC/constantvoltagesource 直流/恒定電壓源time-varyingvoltagesource 時(shí)變電壓源10WordsandExpressionstransistor n.晶體管Atransistorisasemiconductordeviceusedtoamplifyorswitchelectricalsignalsandpower.Thetransistorisoneofthebasicbuildingblocksofmodernelectronics.11B:BaseTerminalE:EmitterTerminalC:CollectorTerminalWordsandExpressionsintegratedcircuit(IC) 集成電路12（Silicon)Die:（硅）裸片Pin:引腳Chip:芯片Plasticcase:塑料外殼Backgrounds13IntroductiontoElectronicsCourse(GeorgiaTech)_Coursera,https:///learn/electronicsTextOutlineConceptandtypesofcircuitelementsIdealindependentsourceIdealdependent(orcontrolled)sourceFeaturesofidealsource14ConceptandtypesofcircuitelementsAnelementisthebasicbuildingblockofacircuit.Anelectriccircuitissimplyaninterconnectionoftheelements.Circuitanalysisistheprocessofdeterminingvoltagesacross(orthecurrentsthrough)theelementsofthecircuit.15ConceptandtypesofcircuitelementsTherearetwotypesofelementsfoundinelectriccircuits:passiveelementsandactiveelements.Anactiveelementiscapableofgeneratingenergywhileapassiveelementisnot.電路中有兩種元件：無(wú)源元件和有源元件。有源元件能產(chǎn)生能量，而無(wú)源元件不能。16IdealindependentsourceAnidealindependentsourceisanactiveelementthatprovidesaspecifiedvoltageorcurrentthatiscompletelyindependentofothercircuitelements.理想的獨(dú)立電源是提供完全獨(dú)立于其他電路元件的指定電壓或電流的有源元件。17IdealindependentsourceInotherwords,anidealindependentvoltagesourcedeliverstothecircuitwhatevercurrentisnecessarytomaintainitsterminalvoltage.換句話說(shuō)，理想的獨(dú)立電壓源可以為電路提供維持其終端電壓所需的任何電流。18IdealindependentsourceSimilarly,anidealindependentcurrentsourceisanactiveelementthatprovidesaspecifiedcurrentcompletelyindependentofthevoltageacrossthesource.Thatis,thecurrentsourcedeliverstothecircuitwhatevervoltageisnecessarytomaintainthedesignatedcurrent.19Idealdependent(orcontrolled)sourceAnidealdependent(orcontrolled)sourceisanactiveelementinwhichthesourcequantityiscontrolledbyanothervoltageorcurrent.理想非獨(dú)立（或受控）電源是有源元件，其電壓或電流的大小由另一個(gè)電壓或電流控制。20Idealdependent(orcontrolled)source1.Avoltage-controlledvoltagesource(VCVS).2.Acurrent-controlledvoltagesource(CCVS).3.Avoltage-controlledcurrentsource(VCCS).4.Acurrent-controlledcurrentsource(CCCS).21Idealdependent(orcontrolled)sourceDependentsourcesareusefulinmodelingelementssuchastransistors,operationalamplifiers,andintegratedcircuits.非獨(dú)立源可用于晶體管、運(yùn)算放大器和集成電路等元件的建模。22FeaturesofidealsourceItshouldbenotedthatanidealvoltagesource(dependentorindependent)willproduceanycurrentrequiredtoensurethattheterminalvoltageisasstated,whereasanidealcurrentsourcewillproducethenecessaryvoltagetoensurethestatedcurrentflow.Thus,anidealsourcecouldintheorysupplyaninfiniteamountofenergy.23FeaturesofidealsourceItshouldalsobenotedthatnotonlydosourcessupplypowertoacircuit,theycanabsorbpowerfromacircuittoo.還應(yīng)注意的是，電源不僅向電路供電，也可以從電路中吸收功率。241.2BasicLawsWordsandExpressionsBackgroundsTextWordsandExpressionsOhm’sLaw 歐姆定律WordsandExpressionsresistance n.電阻值；抵抗力；阻力conductor n.導(dǎo)體insulator n.絕緣體semiconductor n.半導(dǎo)體；半導(dǎo)體裝置WordsandExpressionsmetallicalloy

金屬合金carboncompound

碳化合物WordsandExpressionsaluminum

n.鋁germanium n.鍺silicon n.硅mica n.云母teflon

n.特氟隆，聚四氟乙烯WordsandExpressionsKirchhoff’sCurrentLaw(KCL) 基爾霍夫電流定律Kirchhoff’sVoltageLaw(KVL) 基爾霍夫電壓定律Backgrounds31麻省理工公開(kāi)課：電路和電子學(xué)/newview/movie/courseintro?newurl=%2Fspecial%2Fopencourse%2Fcircuits.htmlTextOutlineOhm’sLawKirchhoff’slawsKirchhoff’scurrentlaw(KCL)Kirchhoff’svoltagelaw(KVL)32Ohm’sLawThisphysicalproperty,orabilitytoresistcurrent,isknownasresistanceandisrepresentedbythesymbolR.這種物理特性或抵抗電流的能力稱(chēng)為電阻，用符號(hào)R表示。33Ohm’sLawTheresistanceofanymaterialwithauniformcross-sectionalareaAdependsonAanditslengthl,asshowninFigure1.5(a).whereρisknownastheresistivityofthematerialinohm-meters.34Ohm’sLawGoodconductors,suchascopperandaluminum,havelowresistivities,whileinsulators,suchasmicaandpaper,havehighresistivities.良導(dǎo)體（如銅和鋁）的電阻率較低，而絕緣體（如云母和紙）的電阻率較高。35Ohm’sLawOhmdefinedtheconstantofproportionalityforaresistortobetheresistance,R.(Theresistanceisamaterialpropertywhichcanchangeiftheinternalorexternalconditionsoftheelementarealtered,e.g.,iftherearechangesinthetemperature.)36Kirchhoff’slawsOhm’slawbyitselfisnotsufficienttoanalyzecircuits.However,whenitiscoupledwithKirchhoff’stwolaws,wehaveasufficient,powerfulsetoftoolsforanalyzingalargevarietyofelectriccircuits.歐姆定律本身不足以分析電路。然而，當(dāng)它與基爾霍夫兩定律結(jié)合在一起時(shí)，我們就有了一套足夠強(qiáng)大的工具來(lái)分析各種各樣的電路。37Kirchhoff’scurrentlaw(KCL)Kirchhoff’sfirstlawisbasedonthelawofconservationofcharge,whichrequiresthatthealgebraicsumofchargeswithinasystemcannotchange.基爾霍夫第一定律基于電荷守恒定律，該定律要求系統(tǒng)內(nèi)電荷的代數(shù)和不能改變。38Kirchhoff’svoltagelaw(KVL)Kirchhoff’ssecondlawisbasedontheprincipleofconservationofenergy:Kirchhoff’svoltagelaw(KVL)statesthatthealgebraicsumofallvoltagesaroundaclosedpath(orloop)iszero.基爾霍夫第二定律基于能量守恒原理：基爾霍夫電壓定律（KVL）規(guī)定閉合路徑（或回路）上電壓的代數(shù)和為零。391.3CircuitAnalysisWordsandExpressionsBackgroundsTextWordsandExpressionsNodalAnalysis 節(jié)點(diǎn)分析法MeshAnalysis 網(wǎng)格分析法；網(wǎng)孔分析法referencenode

參考節(jié)點(diǎn)；參考點(diǎn)nodevoltage 節(jié)點(diǎn)電壓branchcurrent 支路電流WordsandExpressionsground n.地電位potential n.電位；電勢(shì)；電壓groundpotential 地電位，地電勢(shì)potentialdifference 位差，勢(shì)差potentialenergy 位能，勢(shì)能potentialdistribution 電位分布；位勢(shì)分布WordsandExpressionsSimultaneousequations

聯(lián)立方程組；聯(lián)立方程式substitutionmethod

替換法；代入法；代換法eliminationmethod

消除法；消元法Cramer’sRule

克萊姆法則WordsandExpressionsMatrixinversion 矩陣求逆Identitymatrix單位矩陣WordsandExpressionsmeshcurrent 網(wǎng)孔電流；網(wǎng)格電流loop

n.回路；環(huán)路Aloopisanyclosedpathinacircuit,inwhichnonodeisencounteredmorethanonce.Ameshisaloopthathasnootherloopsinsideofit.WordsandExpressionscoefficient

n.系數(shù)radiationcoefficient 輻射系數(shù)dischargecoefficient 放電系數(shù)dampingcoefficient 阻尼系數(shù)Backgrounds47可汗學(xué)院公開(kāi)課：電子工程-網(wǎng)易公開(kāi)課,https:///newview/movie/courseintro?newurl=MD5B0JHKBTextNodalanalysisMeshanalysis48CircuitAnalysisHavingunderstoodthefundamentallawsofcircuittheory(Ohm’slawandKirchhoff’slaws),wearenowpreparedtoapplytheselawstodeveloptwopowerfultechniquesforcircuitanalysis:nodalanalysis,whichisbasedonasystematicapplicationofKirchhoff’scurrentlaw(KCL),andmeshanalysis,whichisbasedonasystematicapplicationofKirchhoff’svoltagelaw(KVL).理解電路理論的基本定律（歐姆定律和基爾霍夫定律）后，我們現(xiàn)在準(zhǔn)備應(yīng)用這些定律來(lái)開(kāi)發(fā)兩種強(qiáng)大的電路分析技術(shù)：基于基爾霍夫電流定律（KCL）系統(tǒng)應(yīng)用的節(jié)點(diǎn)分析法和基于基爾霍夫電壓定律（KVL）系統(tǒng)應(yīng)用的網(wǎng)孔分析法。49NodalAnalysisNodalanalysisprovidesageneralprocedureforanalyzingcircuitsusingnodevoltagesasthecircuitvariables.Choosingnodevoltagesinsteadofelementvoltagesascircuitvariablesisconvenientandreducesthenumberofequationsonemustsolvesimultaneously.節(jié)點(diǎn)分析法使用節(jié)點(diǎn)電壓作為電路變量來(lái)分析電路。選擇節(jié)點(diǎn)電壓而不是元件電壓作為電路變量很方便，并且減少了聯(lián)立方程的數(shù)量。50NodalAnalysisThekeyideatobearinmindisthat,sinceresistanceisapassiveelement,bythepassivesignconvention,currentmustalwaysflowfromahigherpotentialtoalowerpotential.要記住的關(guān)鍵思想是，由于電阻器是無(wú)源元件，根據(jù)無(wú)源符號(hào)慣例，電流必須始終從較高的電勢(shì)流向較低的電勢(shì)。51MeshAnalysisMeshanalysisprovidesanothergeneralprocedureforanalyzingcircuits,usingmeshcurrentsasthecircuitvariables.Usingmeshcurrentsinsteadofelementcurrentsascircuitvariablesisconvenientandreducesthenumberofequationsthatmustbesolvedsimultaneously.網(wǎng)孔分析法使用網(wǎng)孔電流作為電路變量。使用網(wǎng)孔電流而不是元件電流作為電路變量很方便，并且減少了聯(lián)立方程的數(shù)量。52MeshAnalysisAlthoughameshcurrentmaybeassignedtoeachmeshinanarbitrarydirection,itisconventionaltoassumethateachmeshcurrentflowsclockwise.盡管每個(gè)網(wǎng)孔的電流可以指定為任意方向，但通常假定網(wǎng)孔電流順時(shí)針?lè)较蛄鲃?dòng)。53MeshAnalysisNoteinEq.(1.17)thatthecoefficientofi1isthesumoftheresistancesinthefirstmesh,whilethecoefficientofi2isthenegativeoftheresistancecommontomeshes1and2.注意在式（1.17）中，i1的系數(shù)是第一個(gè)網(wǎng)孔中電阻的總和，而i2的系數(shù)是網(wǎng)孔1和2共有電阻的負(fù)值。54HOWTOWRITEASUMMARYHowtoWriteaSummaryDAILYWRITINGTIPS/how-to-write-a-summary/55Exercises561.Matchtheterms(1)-(6)withthedefinitionsA-F.(1)nodeA.achainofcomponentswithasinglecurrentpath(2)branchB.anarbitraryreferenceforagivencircuitthatcannotnecessarilybeequatedwithearthground(3)groundC.acircuitthroughwhichnocurre