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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.Inadditi
2、ontodeterminingtheconditionsrequiredforoscillationtotakeplace,thefrequencyandamplitudestabilityarealsostudied.Fig.1-1showanamplifier,afeedbacknetwork,andaninputmixingcircuitnotyetconnectedtoformaclosedloop.Theamplifierprovidesanoutputsignalasaconsequenceofthesigna
3、lapplieddirectlytotheamplifierinputterminal.Theoutputofthefeedbacknetworkisandtheoutputlfthemixingcircuit(whichisnowsimplyaninverter)isFormFig.1-1theloopgainisLoopgain=Fig.1-1AnamplifierwithtransfergainAandfeedbacknetworkFnotyetconnectedtoformaclosedloop.Supposeit
4、shouldhappenthatmattersareadjustedinsuchawaythatthesignalisidenticallyequaltotheexternallyappliedinputsignal.Sincetheamplifierhasnomeansofdistinguishingthesourceoftheinputsignalappliedtoit,itwouldappearthat,iftheexternalsourcewereremovedandifterminal2wereconnected
5、toterminal1,theamplifierwouldcontinuetoprovidethesameoutputsignalasbefore.Note,ofcourse,thatthestatement=meansthattheinstantaneousvaluesofandareexactlyequalatalltimes.Thecondition=isequivalent8to,ortheloopgainmustequalunity.TheBarkhausenCriterionWeassumeinthisdisc
6、ussionofoscillatorsthattheentirecircuitoperateslinearlyandthattheamplifierorfeedbacknetworkorbothcontainreactiveelements.Undersuchcircumstances,theonlyperiodicwaveformwhichwillpreserve,itsformisthesinusoid.Forasinusoidalwaveformtheconditionisequivalenttotheconditi
7、onthattheamplitude,phase,andfrequencyofandbeidentical.Sincethephaseshiftintroducedinasignalinbeingtransmittedthroughareactivenetworkisinvariablyafunctionofthefrequency,wehavethefollowingimportantprinciple:Thefrequencyatwhichasinusoidaloscillatorwilloperateisthefre
8、quencyforwhichthetotalshiftintroduced,asasignalproceedfromtheinputterminals,throughtheamplifierandfeedbacknetwork,andbackagaintotheinput,ispreciselyzero
