DAC归纳总结报告.pdf

《DAC归纳总结报告.pdf》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。

1、High-ResolutionAudioDACsFinalReportAReviewoftheDigitalAudioConversionProcess.IvarLøkken,2005-08-17IvarLøkkenPage117.08.20051IntroductionThisreportistheendresultofaPhD-levelcourseintendedtoprovideinsightintochallengesandsolutionsinaudioDACsystemsdesign.Itwillre

2、viewtheconceptsrelevanttothisapplicationandprovidethereaderwithasystem-leveloverviewaswellasinsightintofundamentalprinciplesandrelations.Figure1:TypicalAudioD/A-conversionsystem.Figure1showsatypicalaudioDACsystem.ThesignalistypicallytransferredthroughtheSony/P

3、hilips-DigitalAudioInterface(SP-DIF)whichisaone-wireserialtransmissionwithbiphase-markencodingandembeddedclocksignal.TheSP-DIFreceiverrecoverstheembeddedclockanddecodesthedata.ItisthentransferredtosubsequentchipsusingtheInter-IC-Sound(I2S)interface,whereserial

4、data,bitclockandwordclockaresentviathreeseparatewires.InmanysystemsithasinlateryearsbecomenormaltoinsertanasynchronoussamplerateconverterbeforetheDAC.Thisenablesthesystemtoacceptawiderangeofinputsampleratesandcanalsoimprovejitterperformance.Thenthesignalisinte

5、rpolatedtoaveryhighsamplerateanddecimatedusinganoise-shapingquantizerordelta-sigmamodulator.Traditionally,1-bitconvertershavemostlybeenused,butinlateryearsfew-bitthermometerDACswithdigitalelementmatchinghavebecomethenorm.Thereasonsforthiswillbecomeevidentasthe

6、readerprogressesthroughthisreport.Theanalogoutputsignalisnextfedtoalarge-scaleamplifierandultimatelyloudspeakers.Thelasttwoprocesseswillnotbereviewedhere.Thisreportwillbeginwithanintroductiontochallengessurroundingjitterandjittersuppression,withspecialemphasis

7、oninterfacingandtheSP-DIFformat.Boththeoreticalmodelsandassessmentsonhowtominimizetheresultingdistortionwillbepresented.Next,wewilllookattheprocessofsampling.ThissectionwillbeginwithashortrecapofShannon’ssamplingtheoremand,asmostaudioDACsystemsareoversamplingd

8、evices,alsolookatinterpolationanddecimation.Furthermore,asynchronoussamplerateconvertershavebecomeverypopularinaudioDACdesign.Wewillreviewtheprinciplesandlookatthebenefitsanddrawba