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1、函数信号发生器设计外文资料及翻译英文资料原文WAVE-FORMGENERATORS1.TheBasicPricipleofSinusoidalOscillatorsManydifferentcircuitconfigurationsdeliveranessentiallysinusoidaloutputwaveformevenwithoutinput-signalexcitation.Thebasicprinciplesgoverningalltheseoscillatorsareinvestigated.Inadditiontode
2、terminingtheconditionsrequiredforoscillationtotakeplace,thefrequencyandamplitudestabilityarealsostudied.Fig.1-1showanamplifier,afeedbacknetwork,andaninputmixingcircuitnotyetconnectedtoformaclosedloop.Theamplifierprovidesanoutputsignalasaconsequenceofthesignalapplieddire
3、ctlytotheamplifierinputterminal.Theoutputofthefeedbacknetworkisandtheoutputlfthemixingcircuit(whichisnowsimplyaninverter)isFormFig.1-1theloopgainisLoopgain=Fig.1-1AnamplifierwithtransfergainAandfeedbacknetworkFnotyetconnectedtoformaclosedloop.Supposeitshouldhappenthatma
4、ttersareadjustedinsuchawaythatthesignalisidenticallyequaltotheexternallyappliedinputsignal.Sincetheamplifierhasnomeansofdistinguishingthesourceoftheinputsignalappliedtoit,itwouldappearthat,iftheexternalsourcewereremovedandifterminal2wereconnectedtoterminal1,theamplifier
5、wouldcontinuetoprovidethesameoutputsignalasbefore.Note,ofcourse,thatthestatement=meansthattheinstantaneousvaluesofandareexactlyequalatalltimes.Thecondition=isequivalent8to,ortheloopgainmustequalunity.TheBarkhausenCriterionWeassumeinthisdiscussionofoscillatorsthattheenti
6、recircuitoperateslinearlyandthattheamplifierorfeedbacknetworkorbothcontainreactiveelements.Undersuchcircumstances,theonlyperiodicwaveformwhichwillpreserve,itsformisthesinusoid.Forasinusoidalwaveformtheconditionisequivalenttotheconditionthattheamplitude,phase,andfrequenc
7、yofandbeidentical.Sincethephaseshiftintroducedinasignalinbeingtransmittedthroughareactivenetworkisinvariablyafunctionofthefrequency,wehavethefollowingimportantprinciple:Thefrequencyatwhichasinusoidaloscillatorwilloperateisthefrequencyforwhichthetotalshiftintroduced,asas
8、ignalproceedfromtheinputterminals,throughtheamplifierandfeedbacknetwork,andbackagaintotheinput,ispreciselyzero
