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手机音频设计的演变（完整版）实用资料(可以直接使用，可编辑完整版实用资料，欢迎下载）音频设计的演变Withinthecellularhandsetthereareavarietyofaudiodevices,suchasamplifiers,analoganddigitalconverters,microphones,andspeakers.Therearealsoseveralcategoriesofeachtypeofdevice.Inaddition,therecanbeavarietyofaudiogeneratorsintheformofRadio,TV,andmusicplayers.ArchitecturesAreviewofsomecellphonearchitecturessupportingvariousaudiofunctionsisagoodwaytounderstandtheaudiodevicescurrentlyusedincellularhandsets.Figure1belowdescribesabasiccellularhandsetfromanaudiorequirementspointofview.TheFMradio,musicsynthesizer,MP3/WMAdecoder,andMUXfunctionsareoptional,dependingupontherequirementsofaparticularmodel.Theshadedareashowstheoptionalelements.Thebasicaudiodevicesare,ofcourse,thevoicebandcodec,themicrophone,andanearpiecespeaker.Forthesilentringindicator,itiscommontouseaDCmotorwithanoff-centerweightattachedtothemotorshafttocreatethevibrationeffect.DependingupontheearpiecespeakerimpedanceandamplifierGainandoutputpowerdesign,theearpiecespeakeroftendoublesastheringsoundspeaker.TheMUXblockinFig.1isnotonesinglecomponent,butindicatesthatsomesortofswitchingandmixingmaybeneedediftheoutputsofthevariousaudiogeneratorsmustbeusableonsomeoralloftheaudiooutputdevices(speakersormono/stereoheadset).Inthissimplecase,theMUXelements(ifanyareneeded)areusuallybuiltusingdiscreteanalogswitches.Whenusedinfrontoftheaudiopoweramplifiers,theswitchingandmixingaredoneatrelativelylowsignalvoltageandpowerlevelsandtheanalogswitchesdonothavetocarryfulloutputloadcurrents.Sometimes,analogswitchesareusedontheoutputsideoftheamplifiersasshowninFigure2torouteaudiotothedesiredlocation.Thedisadvantageofthisapproachisthattheanalogswitchesmustcarrythefullloadvoltageandcurrent.Theadvantageofthisapproachisthatitiseasytodo.InterfacesThereisawidevarietyofsignalpathsusedforaudioincellularhandsets.Inadditiontothenormalanalogsignalpathsuchasamplifiersformicrophonesoroutputspeakers,audioconnectionstotheCPUsusedcanbeanalogordigital.Intheanalogcasethedataconvertersareoftencontai
