Blind SAR ADC Capacitor Mismatch Calibration

This paper presents an all-digital background blind calibration technique for the capacitor mismatch problem in SAR ADCs. It utilizes the redundancy offered using a sub-radix-2 DAC architecture to blindly estimate the mismatch and the assigned weight for each comparator decision. The weights are estimated by building partial histogram windows for the comparator decision vectors. To remove the dependency on the input signal's probability density function, the histogram windows are normalized with respect to their peaks. Matlab simulation results show that an ENOB within 0.12bit of the optimal is attained using the proposed algorithm.