Digital foreground calibration methods for SAR ADCs

New foreground digital calibration methods are proposed for successive approximation register (SAR) analog-to-digital converters (ADCs) to reduce the performance loss due to digital-to-analog converter (DAC) mismatch. A set of calibration coefficients which represent the actual weights of the specified patterns is obtained during foreground calibration, and then used during normal operation to correct the SAR ADC output using only a few multiplexers and an accumulator. The simulation results of a 10-bit SAR ADC with the proposed calibration methods show almost 10 effective number of bits (ENOB) with up to 0.5 % binary-weighted DAC mismatch, and more than 12 dB SNDR improvement for even larger DAC mismatch, compared to that without calibration.