Correction of capacitor errors during the conversion cycle of self-calibrating A/D converters

The conversion cycle of self-calibrating, successive approximation (analog/digital) A/D converters (ADCs) is analyzed. The effects of capacitor ratio mismatch errors on the transfer characteristics of unipolar and bipolar ADCs are presented. Error correction during conversion is shown to eliminate linearity errors in unipolar ADCs and offset and linearity errors in bipolar ADCs. It is shown that for bipolar ADCs, the correction algorithm depends on the way the average unit capacitor is defined, which essentially depends on the calibration algorithm used during the ADC calibration cycle. High-resolution ADC considerations are presented, and computer simulations are reported