Input-independent self-calibration method and apparatus for successive approximation analog-to-digital converter with charge-redistribution digital to analog converter

摘要

A method and apparatus for correcting the offset and linearity error of a data acquisition system. A charge redistribution digital to analog convertor (CDAC) is connected to one of the differential inputs of a comparator whose second input comes from a function CDAC. The calibration algorithm is built into a digital control unit. The digital control unit detects the offset and capacitor mismatch errors sequentially, stores the calibration codes for each error in calibration mode and provides the input-dependent error correction signals synchronized with the binary search timing to adjust the differential input of the comparator and compensate the input-dependent errors present at the output of the non-ideal function CDAC during normal conversions.