Accuracy considerations in self- calibrating A/D converters

Self-calibration techniques can remove linearity errors of weighted-capacitor data converters caused by element matching errors. However, various additional factors can affect the accuracy of a selfcalibrating A/D converter. These include charge injection from certain transistor switches, error in the capacitor in the correction path, voltage coefficient of precision-ratioed capacitors, and noise. The effects of each of these factors on a self-calibrating A/D converter are analyzed. Correction techniques for each factor are presented.