SAR ADC讲稿资料.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 weightedcapacitorarrayDACCapacitorarraysamplesinputwhen 1isasserted bottom plate 26 AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY ChiuECE581Fall2009 ChargeRedistribution MSB 27 AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY ChiuECE581Fall2009 Comparison MSB IfVXVR 2 andMSB 1 C4remainsconnectedtoVRIfVX 0 thenVi VR 2 andMSB 0 C4isswitchedtoground 28 AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY ChiuECE581Fall2009 ChargeRedistribution MSB 1 29 AdvancedAnalogICDesignSuccessiveApproximationADCProfessorY ChiuECE581Fall2009 Comparison MSB 1 IfVX3VR 4 andMSB 1 1 C3remainsconnectedtoVRIfVX 0 thenVi 3VR 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 Completecharacterizationrequiresmultipletestswithvariousinputfrequencies Doesnotre