上海海事大学信息工程学院

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1、上海海事大学信息工程学院Unit3CircuitAnalysisUsingtheIdealOperationalAmplifierBackgroundWordsandexpressionsTextandnotesGrammarExercisesReadingmaterial上海海事大学信息工程学院BackgroundAnamplifier,electronicamplifieror(informally)ampisanelectronicdevicethatincreasesthepowerofasignal.Itdoesthisbytakingenergy

2、fromapowersupplyandcontrollingtheoutputtomatchtheinputsignalshapebutwithalargeramplitude.Inthissense,anamplifiermodulatestheoutputofthepowersupplytomaketheoutputsignalstrongerthantheinputsignal.Anamplifieriseffectivelytheoppositeofanattenuator:whileanamplifierprovidesgain,anattenua

3、torprovidesloss.上海海事大学信息工程学院BackgroundThetypesofamplifierscanbecategorizedindifferentways.Oneisbythefrequencyoftheelectronicsignalbeingamplified;audioamplifiersamplifysignalsintheaudio(sound)rangeoflessthan20 kHz,RFamplifiersamplifyfrequenciesintheradiofrequencyrangebetween20 kHzan

4、d300 GHz.Anotheriswhichquantity,voltageorcurrentisbeingamplified;amplifierscanbedividedintovoltageamplifiers,currentamplifiers,transconductance(跨导)amplifiers,andtransresistanceamplifiers.Afurtherdistinctioniswhethertheoutputisalinearornonlinearrepresentationoftheinput.Amplifierscan

5、alsobecategorizedbytheirphysicalplacementinthesignalchain（信号通路，信号链）.ThefirstpracticalelectronicdevicewhichcouldamplifywastheAudion(triode，三极管)vacuumtube,inventedin1906byLeeDeForest,whichledtothefirstamplifiers.Theterms"amplifier"and"amplification"(fromtheLatinamplificare,'toenlarge

6、orexpand')werefirstusedforthisnewcapabilityaround1915whentriodesbecamewidespread.[2]Forthenext50yearsvacuumtubesweretheonlydeviceswhichcouldamplify,andwereusedinallamplifiersuntilthe1960s,whentransistorsbegantobeused.Mostamplifierstodayusetransistors,althoughtubesarestillused.上海海事大

7、学信息工程学院上海海事大学信息工程学院WordsandexpressionsBuffern.缓冲器By-productn.副产品，出乎意料的结果Circuitryn.电路，线路Formulan.公式，规则Fulcrumn.杠杆的支点Groundv.使接地；n.接地，地线Impedancen.阻抗Infinitesimaladv.无穷小，极小，无限小Inherentadj.固有的，内在的，与生俱来的Intuitiveadj.直觉的Investigatev.调查，研究Latchv.闭锁(n.锁存器)Levern.杆，杠杆Mythicaladj.神话的，虚构的Of

8、fsetn.偏移量，抵消上海海事大学信息工程学院Wo