A second-order high-resolution incremental A/D converter with offset and charge injection compensation

Measurement and instrumentation applications require absolute accuracy, e.g. offset and gain errors cannot be tolerated. These applications are characterized by DC performance such as differential and integral nonlinearities, offset and gain errors, and they often require high resolution. The second-order incremental A/D converter, which makes use of sigma-delta modulation associated with a simple digital filter, is capable of achieving such requirements. Experimental results of circuits fabricated in a SACMOS 3- mu m technology indicate that 15-bit absolute accuracy is easily achievable, even with a low reference voltage.<>