SAR ADC讲稿.ppt

模数转换器,主要内容,1、ADC的性能指标2、SARADC的设计3、ADC的测试方法,采样速率,奈奎斯特ADC,过采样ADC,SARADC,PipelinedADC,CyclicADC,Dual-slopeADC,FlashADC,Sigma-deltaADC,品质因子（FOM-figureofmerit）,SARADC的设计,25,AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY.ChiuECE581Fall2009,ChargeRedistributionSAADC,4-bitbinary-weightedcapacitorarrayDACCapacitorarraysamplesinputwhen1isasserted(bottom-plate),26,AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY.ChiuECE581Fall2009,ChargeRedistribution(MSB),27,AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY.ChiuECE581Fall2009,Comparison(MSB),IfVXVR/2,andMSB=1,C4remainsconnectedtoVRIfVX0,thenVi0,thenVi3VR/4,andMSB-1=0,C3isswitchedtoground,30,AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY.ChiuECE581Fall2009,ChargeRedistribution(OtherBits),Testcompleteswhenallfourbitsaredeterminedw/fourchargeredistributionsandcomparisons,31,AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY.ChiuECE581Fall2009,AfterFourClockCycles,DAC设计,比较器设计,由于生产工艺过程中的误差造成电路结构不能和设计中的那样对称，引起比较器的失调。比较器的失调电压会对比较器的性能和比较器后续电路的工作有影响，会造成误码现象。比较器一般有下面两种形式的失调消除方式：输入失调电压存储方式输出失调电压存储方式其电路包括前置放大器，失调存储电容，还有锁存单元。,输入失调电压存储方式,输出失调电压存储方式,多级简单预放大+锁存结构,低输入电容SARADC,全差分输入SARADC,时域比较器,ADC的测试方法,1、静态测试2、动态测试,DynamicTesting,TypesofDynamicTestsHistogramorCode-DensityTestFFTTest,Fischer08,44,HistogramorCode-DensityTest,DNLappearsasdeviationofbinheightfromidealvalue.Integralnonlinearity(INL)iscumulativesum(integral)ofDNL.Offsetismanifestedbyahorizontalshiftofcurve.Gainerrorshowsashorizontalcompressionordecompressionofcurve.,Fischer08,45,HistogramTest,Inputfrequencymustbeselectedcarefullytoavoidmissingcodes(fclk/finmustbenon-integerratio).InputSwingiscritical(coverfullrange)Requiresalargenumberofconversions(o2nx1,000).,Fischer08,46,SimulatedHistogramTest,Fischer08,47,FFTTest,ProsandConsofFFTTestOffersquantitativeInformationonoutputNoise,Signal-to-NoiseRatio(SNR),SpuriousFreeDynamicRange(SFDR)andHarmonicDistortion(SNDR).FFTtestrequiresfewerconversionsthanhistogramtest.Completecharacterizationrequiresmultipletestswithvariousinput