design of a two-channel solid-state - course …一个双通道固态课程设计…

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1、24DESIGNOFATWO-CHANNELSOLID-STATECLASS-AAUDIOPOWERAMPLIFIERBYWENGLOONGFOONGDAVIDNEOECE345InSeopLee,TA4-30-99Team#4724ABSTRACTAtwo-channelClass-Aaudiopoweramplifierwasdesignedandoperatedwithhighfidelityandlowdistortion.Theamplifierperformsamplificationofalin

2、esignalandoutputsthroughan8Wload.Thetransistorsarerestrictedtooperationinthelinearregiontoachievegreatestlinearity.Biasingwasdonewithaconstantcurrentsourceinapush-pullconfigurationtoreducethepeakcurrentneededforbiasingtohalf.Usingthiscircuitry,anefficiencyo

3、f39.7%wasachieved,greaterthantheusual20-25%ofnormalClass-Aamplifiers.Themaximumdeviationofthegainfrequencyresponsewasdemonstratedtobewithin1dBinthe20Hzto20kHzrange.Thedistortionoftheamplifieraveragedaround2.5%overthesaidfrequencyrange.24241.IntroductionThep

4、rojectinvolveddesigningandconstructingahigh-fidelityClass-Aamplifier.Designwassolid-statebasedandbiasedwithaconstantcurrentsourceinapush-pullconfiguration.Thefinalproductistobecompatibleforusewithanyconventionalaudioinput,whichhasbeenpre-amplified,andoutput

5、istobecoupledthroughconventional8Wspeakers.Thechoiceofsolid-stateovervacuumtubesislargelybecausesolid-stateamplifiersaremoredynamicinnature,andarehencebetterabletoamplifyfrequenciesinthelowtomid-range,andbecausesolid-stateamplifiersaremorecosteffectiveAgood

6、pairofmatchedMOSFETswillcostapproximately$20whereasamatchedpairoftubescanrunintohundredsofdollars.andhavelowermaintenanceDependingonusage,tubesneedtobechangedonceeveryonetotwoyearswhilesolid-stateamplifiersarerelativelymaintenancefree.coststhantheircounterp

7、arts.1.1OverviewofOutputClassificationsOutputstagesofamplifiersareclassifiedaccordingtothestandardsshowninTable1.1.Table1.1ClassificationofOutputStagesClassDefinitionALinearoperationwith360°operationofasinewave.Operatingpointissetataboutthecenteroftheoperat

8、ingrangeandinoperation,theoutputsignalproducesapproximatelyequalexcursionstowardsthetwoaxesBTransistorsarebiasedtocut-off,suchthatonly180°conductioncanoccur.“Push-pull”operationisnecessarywitheachhalfo