Mismatch shaping for a current-mode multibit delta-sigma DAC

Abstract

Mismatch shaping allows the use of multibit quantization in delta-sigma analog-to-digital converters and digital-to-analog converters (DAC's) since it noise-shapes the error caused by static element mismatch in a multibit DAC. In this paper, mismatch-shaping techniques for low-pass delta-sigma (/spl Delta//spl Sigma/) modulators are reviewed, and a mismatch-shaping technique for bandpass /spl Delta//spl Sigma/ modulators is described. The dynamic error caused by frequent element switching is identified as a major source of error in a current-mode DAC with a continuous-time output. Modifying the mismatch-shaping algorithm to account for this effect yields a continuous-time /spl Delta//spl Sigma/ DAC that is insensitive to both element mismatch and element switching dynamics. Experimental results confirm the effectiveness of the proposed techniques.