Continuous Digital Calibration of Pipeline A/D Converters

A continuous digital calibration technique for pipeline analog-to-digital converters (ADCs) is presented. The scheme utilizes an existing digital calibration algorithm and extends it to work in real-time. This is accomplished by introducing two additional stages at the end of the pipeline which are used only during calibration process. Calibration scheme is transparent to the overall system and is demonstrated using a 14-bit ADC, with 1-bit per stage architecture and 18 identical stages (including two additional stages for calibration). Dominant static errors in a pipeline are successfully corrected by the proposed calibration. Simulation results show more than 2-bits improvement in the number of effective bits and more than 20 dB improvement in the dynamic range of the converter