Histogram-based calibration of capacitor mismatch in SAR ADCs

An all-digital, histogram-based calibration technique to correct capacitor mismatch in successive-approximation register (SAR) ADCs is proposed. Using a windowing technique to detect non-uniform code densities, the calibration recursively tunes the bit weights to correct capacitor errors. Simulations of an 8-bit SAR ADC suffering from capacitor mismatch show significant improvements in differential non-linearity, integral non-linearity, and signal-to-noise-and-distortion ratio after employing the proposed calibration.