Abstract: An approach to A/D converter architecture is based on a "pipelined and submerged" architecture which includes a pipeline of elemental stages (10.sub.i). Each stage of the pipeline comprises a low-resolution flash A/D subconverter (12), a D/A converter (14), and a unity-gain buffer (16). To minimize converter nonlinearity due to component mismatches, a self calibration technique based on an "interpolation" scheme is used. This technique employs an on-chip delta-sigma A/D converter (32) to provide the reference for calibration and a 100-bit memory (50) to store nonlinearity information. Long term drift is corrected by a calibrator (34) in parallel with data conversion.

Abstract: A pipelined analog-to-digital converter architecture comprises three pipeline stages wherein the first stage includes a low-resolution flash A/D subconverter (10), two sample-and-hold amplifiers (12 and 14), two D/A converters (16 and 18), and two unity-gain buffers (20 and 22). Parallel-autozero analog processing is accomplished by alternately passing the analog signal through one or the other of two parallel processing channels. The sampled analog signal is delivered to the flash A/D subconverter and the D/A converters simultaneously. The residue from the D/A converters is delivered to the second stage, passing through a flash A/D subconverter (24), an additional D/A converter (26), and alternately through two comparators (28 and 30) each having a gain of eight. The second stage produces and delivers its residual voltage to the final pipeline stage comprising a flash A/D subconverter (32).