Application of a novel self-calibrating scheme to a video-rate pipelined multi-stage A/D converter

An online self-calibrating technique for pipelined multistage analog-to-digital (A/D) converters is presented. The scheme is loosely based upon the stochastic gradient method. The gradient is evaluated on error-code information from the digital output of each flash comparator array. The adaptive control circuitry is implemented in mixed analog/digital mode. The scheme is generally applicable to pipelined converters of any accuracy, and especially helpful in counteracting interstage gain errors. Results from simulation of a 10-b A/D converter are given to illustrate the efficiency of the scheme and the simplicity of the corresponding circuitry