电子元器件应用-模数规格和性能特性术语表

术语词汇表：模数转换的规格和性能特点ZHCA068-August2006-RevisedJanuary2008SubmitDocumentationFeedbackGlossaryofTerms应用报告ZHCA068-August2006-RevisedJanuary2008术语词汇表：模数转换的规格和性能特点Sampling�SAR�ADCOversamplingDelta-Sigma�ADCSinglesample�perconversionMultiple�samples,averagedSignal�Noise1234DataOutPipeline�ADC1234DataOut1234DataOut1212ApplicationReportSBAA147A–August2006–RevisedJanuary2008AGlossaryofAnalog-to-DigitalSpecificationsandPerformanceCharacteristicsBonnieBaker................................................................................................DataAcquisitionProductsABSTRACTThisglossaryisacollectionofthedefinitionsofTexasInstruments'Delta-Sigma(ǻȈ),successiveapproximationregister(SAR),andpipelineanalog-to-digital(A/D)Converterspecificationsandperformancecharacteristics.Althoughthereisaconsiderableamountofdetailinthisdocument,theproductdatasheetforaparticularproductspecificationisthebestandfinalreference.Todownloadorviewaspecificdataconverterproductdatasheet,seetheTexasInstrumentswebsiteat:RefertoFigurewhencomparingSAR,Pipeline,andDelta-Sigmaconverteracquisitiontime.Figure1.SARvsPipelinevsǻȈA/DConvertersSamplingAlgorithmsComparison•Acquisitiontime,Delta-SigmaA/DConverters–TheDelta-Sigma(ǻȈ)converteraveragesmultiplesamplesforeachconversionresult.TheaveragingperformedbytheconverterusuallyoccursintheformofaFiniteImpulseResponse(FIR)orInfiniteImpulseResponse(IIR)digitalfilter.Consequently,theacquisitiontimeislongerthanitiswithaSARorpipelineconverter,whichonlysamplesthesignalonceforeachconversion.FigureillustratesoneofthedifferencesbetweenthesamplingmechanismofaSAR,aPipelineandaǻȈconverter.Iftheuserpresentsastep-inputtothedelta-sigmaconverterinputorswitchesamultiplexeroutputchannel,ICisatrademarkofKoninklijkePhilipsElectronicsN.V.SPIisatrademarkofMotorola,Inc.Allothertrademarksarethepropertyoftheirrespectiveowners.SBAAA–August00–RevisedJanuary00AGlossaryofAnalog-to-DigitalSpecificationsandPerformanceCharacteristicsSubmitDocumentationFeedback数据采集系统摘要这份术语表汇总定义了TI公司Delta-Sigma(ΔΣ)技术、逐次逼近寄存器(SAR)和流水线模数(A/D)转换器，并详细说明了它们的规格和性能特点。虽然这是一份相当详尽的文档，但如果想得到最全面的参考资料，请参阅这一特定产品的资料手册。如要下载并浏览某一特定转换器的数据手册，请访问TI公司的网站术语表Sampling�SAR�ADCOversamplingDelta-Sigma�ADCSinglesample�perconversionMultiple�samples,averagedSignal�Noise1234DataOutPipeline�ADC1234DataOut1234DataOut1212ApplicationReportSBAA147A–August2006–RevisedJanuary2008AGlossaryofAnalog-to-DigitalSpecificationsandPerformanceCharacteristicsBonnieBaker................................................................................................DataAcquisitionProductsABSTRACTThisglossaryisacollectionofthedefinitionsofTexasInstruments'Delta-Sigma(ǻȈ),successiveapproximationregister(SAR),andpipelineanalog-to-digital(A/D)Converterspecificationsandperformancecharacteristics.Althoughthereisaconsiderableamountofdetailinthisdocument,theproductdatasheetforaparticularproductspecificationisthebestandfinalreference.Todownloadorviewaspecificdataconverterproductdatasheet,seetheTexasInstrumentswebsiteat:RefertoFigurewhencomparingSAR,Pipeline,andDelta-Sigmaconverteracquisitiontime.Figure1.SARvsPipelinevsǻȈA/DConvertersSamplingAlgorithmsComparison•Acquisitiontime,Delta-SigmaA/DConverters–TheDelta-Sigma(ǻȈ)converteraveragesmultiplesamplesforeachconversionresult.TheaveragingperformedbytheconverterusuallyoccursintheformofaFiniteImpulseResponse(FIR)orInfiniteImpulseResponse(IIR)digitalfilter.Consequently,theacquisitiontimeislongerthanitiswithaSARorpipelineconverter,whichonlysamplesthesignalonceforeachconversion.FigureillustratesoneofthedifferencesbetweenthesamplingmechanismofaSAR,aPipelineandaǻȈconverter.Iftheuserpresentsastep-inputtothedelta-sigmaconverterinputorswitchesamultiplexeroutputchannel,ICisatrademarkofKoninklijkePhilipsElectronicsN.V.SPIisatrademarkofMotorola,Inc.Allothertrademarksarethepropertyoftheirrespectiveowners.SBAAA–August00–RevisedJanuary00AGlossaryofAnalog-to-DigitalSpecificationsandPerformanceCharacteristicsSubmitDocumentationFeedback参看图1，对比逐次逼近寄存器(SAR)、流水线和Delta-Sigma(ΔΣ)转换器三者的采集时间。采集时间，Delta-Sigma模数转换器Delta-Sigma(ΔΣ)数模转换器对每一转换结果进行多次平均取样。转换器的采样过程通常采用有限冲击响应(FIR)或者无限冲击响应(IIR)数字滤波的方式。因此，它的采样时间和SAR或者流水线转换器相比要长，因为后两者每次转换只对信号进行一次采样。图1展示了SAR，流水线和ΔΣ模数转换器三者的取样方法差异中的一种。如果用户输入一个阶跃输入信号或者在多路复用器中切换一个输出通道，转换器需要花一定时•采集时间:参看图1，对比逐次逼近寄存器(SAR)、流水线和Delta-Sigma(ΔΣ)转换器三者的采集时间。I2C是荷兰皇家菲利浦电子有限公司的商标。SPI是摩托罗拉公司的商标。其它商标版权归各自的公司所有。术语词汇表：模数转换的规格和性能特点ZHCA068-August2006-RevisedJanuary2008SubmitDocumentationFeedbackGlossaryofTerms采集时间，流水线模数转换器在使用流水线模数转换器时，先用外输入时钟的上升沿（有的是下降沿，在产品资料表单中会有说明）进行初始化。紧随着输入信号首端的跳变，转换器开始对信号进行差分运算。参看图1和图2.采集时间，SAR模数转换器SAR转换器的采集时间是由采样运算捕获输入电压来决定的。当采样命令发出后开始计时，同时保持电容也开始充电。有的转换器会对采样管脚端做出响应并对输入信号进行采样。而其它的SARCMOS转换器的采样启动由时钟输入与CS（片选信号）下降沿决定，CS由串行外部接口产生，即SPI™。图3举了一个时钟信号启动采样过程的例子，使用的芯片是ADS7816。图1和图2中使用的是同样的芯片A片选信号下降沿.B时钟信号的下降沿结束了采样阶段.••间，因为数字滤波器要刷新信号。如果要对信号进行“快照”或需要查看某一特定时间电的信号，则最好使用SAR模数转换器。�timeor�sample�timeAperture�timeSample�Error(