An Offset Double Conversion Technique for Digital Calibration of Pipelined ADCs

An offset double conversion technique to calibrate pipelined analog-to-digital converters (ADCs) is presented, in which self-equalization is performed using one ADC, resulting in fast convergence for high-resolution applications. The approach also promises significant improvement of signal-to-noise-plus-distortion ratio (SNDR), simultaneous multistage calibration, and minimal analog circuit modification. The design tradeoffs involved in this technique, especially the conversion rate reduction, are discussed in detail. Behavioral simulation results are presented to demonstrate the effectiveness of the technique, in which the learning of 39 error parameters is simultaneously accomplished with SNDR and spurious-free dynamic range improvements from 43 and 52 dB to 90 and 108 dB, respectively, for a 15-bit pipelined ADC.