Calibration technique for SAR analog-to-digital converters

A self-calibration technique was developed for SAR analog-to-digital converters that employ binary-weighted capacitors. High-accuracy calibration is achieved by finding and correcting the mismatch of each capacitor independently. The mismatch errors are extracted at power-up, and corrected by individual calibration DACs during the conversion. Unlike in previous schemes, in the proposed method the residual error in the calibration of a capacitor does not affect the calibration of any other capacitor. Simulation results show that the proposed method is also insensitive to the non-idealities of the calibration DACs.