Simplified digital calibration for multi-stage analog-to-digital converters

A digital-domain code-error calibration, modified to work with a reduced number of error measurements, greatly simplifies the task of self-calibrating multi-step analog-digital converters (ADCs) and opens up the possibility of moving all self-calibration hardwares into the digital domain, leaving only switching functions for calibration in the analog domain. By digitally subtracting pro-rated interstage gain errors from the code errors of the following stage, the proposed method achieves gain matching between multistage code errors individually measured. Simulations of multi-step ADCS based on a capacitor-array multiplying digital-analog converter (MDAC) demonstrate a substantial saving in the number of measured code errors and digital computations during normal conversions