一种具有分段式DEM的二阶噪声整形SAR ADC

A Second-Order Noise-Shaping SAR ADC with Segmented Dynamic Element Matching

设计了一种具有分段式动态元件匹配(DEM)的高分辨率、低功耗噪声整形SAR ADC。该电路实现了具有无源增益的二阶噪声整形滤波器,从而增强了噪声整形能力。此外,提出了一种分段式动态元件匹配电路来解决由DAC电容失配引起的谐波失真问题,以进一步提高ADC的信噪失真比(SNDR)。仿真结果表明,在4 MS/s的采样速率和40倍过采样率(OSR)的情况下,所设计的噪声整形SAR ADC的信噪失真比达到91.1 dB。当电源电压为1.8 V时,该ADC的功耗仅为231μW,并实现了174.5 dB Schreier优值(FOM)。

A high-resolution and low-power noise-shaping SAR ADC with segmented dynamic element matching(DEM)was designed.It realized a second-order noise-shaping filter with passive gain to enhance the noise-shaping capability.Besides,a segmented DEM circuit was proposed to solve the problem of harmonic distortion caused by the DAC capacitor mismatch to further improve the signal-to-noise-and-distortion ratio(SNDR)of the ADC.The simulation results show that the designed noise-shaping SAR ADC achieves 91.1 dB SNDR at the sampling rate of 4 MS/s and the oversampling ratio(OSR)of 40.The designed ADC consumes 231μW at 1.8 V supply voltage,achieving Schreier figure of merit(FOM)of 174.5 dB.