Signal independent digital calibration technique for SAR ADC with one bit redundancy

A digital calibration technique for high resolution SAR ADC with only one redundant conversion bit is presented in this paper. The proposed work employs no extra calibration DAC or input signal as calibration reference. Calibration signal is generated through switching redistribution DAC in two calibration phase, so that calibration accuracy will not be affected by input signal distribution. DAC accuracy is determined by MSB capacitors with non-binary radix, which are rounded to integer unit capacitors to get smaller mismatch. Monte carlo simulation results prove the stability of calibration accuracy to over 11b with noise and offset errors under 2% capacitor mismatch.