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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.Inadd
2、itiontodeterminingtheconditionsrequiredforoscillationtotakeplace,thefrequencyandamplitudestabilityarealsostudied.Fig.1-1showanamplifier,afeedbacknetwork,andaninputmixingcircuitnotyetconnectedtoformaclosedloop.Theamplifierprovidesanoutputsignalasaconsequenceofth
3、esignalapplieddirectlytotheamplifierinputterminal.Theoutputofthefeedbacknetworkisandtheoutputlfthemixingcircuit(whichisnowsimplyaninverter)isFormFig.1-1theloopgainisLoopgain=Fig.1-1AnamplifierwithtransfergainAandfeedbacknetworkFnotyetconnectedtoformaclosedloop.
4、Supposeitshouldhappenthatmattersareadjustedinsuchawaythatthesignalisidenticallyequaltotheexternallyappliedinputsignal.Sincetheamplifierhasnomeansofdistinguishingthesourceoftheinputsignalappliedtoit,itwouldappearthat,iftheexternalsourcewereremovedandifterminal2w
5、ereconnectedtoterminal1,theamplifierwouldcontinuetoprovidethesameoutputsignalasbefore.Note,ofcourse,thatthestatement=meansthattheinstantaneousvaluesofandareexactlyequalatalltimes.Thecondition=isequivalent8to,ortheloopgainmustequalunity.TheBarkhausenCriterionWea
6、ssumeinthisdiscussionofoscillatorsthattheentirecircuitoperateslinearlyandthattheamplifierorfeedbacknetworkorbothcontainreactiveelements.Undersuchcircumstances,theonlyperiodicwaveformwhichwillpreserve,itsformisthesinusoid.Forasinusoidalwaveformtheconditionisequi
7、valenttotheconditionthattheamplitude,phase,andfrequencyofandbeidentical.Sincethephaseshiftintroducedinasignalinbeingtransmittedthroughareactivenetworkisinvariablyafunctionofthefrequency,wehavethefollowingimportantprinciple:Thefrequencyatwhichasinusoidaloscillat
8、orwilloperateisthefrequencyforwhichthetotalshiftintroduced,asasignalproceedfromtheinputterminals,throughtheamplifierandfeedbacknetwork,andbackagaintotheinput,ispreciselyzero
