Dynamic Element Matching to Prevent Nonlinear Distortion From Pulse-Shape Mismatches in High-Resolution DACs

Abstract

This paper shows analytically and experimentally that properly-designed dynamic element matching (DEM) eliminates pulse shape, timing, and amplitude errors arising from component mismatches as sources of nonlinear distortion in high-resolution DACs. A set of sufficient conditions on the DEM encoder that ensure this effect, and a specific segmented DEM encoder that satisfies the sufficient conditions are presented. Unlike most previously published DEM encoders, the new DEM encoder's complexity does not grow exponentially with the number of bits of DAC resolution, so it is practical for high-resolution Nyquist-rate DACs. These analytical results are demonstrated experimentally with a 0.18 mum CMOS 14-bit DAC IC that has a sample rate of 100 MHz and worst case, single and two-tone spurious-free dynamic ranges of 83 dB and 84 dB, respectively, across the Nyquist band.