Abstract: A method of digital calibration for analog-to-digital converters providing implicit gain proration. In accordance with the method, the calibration begins at the center of the transfer curve rather from one end or the other. By beginning in the center, calibrating in the positive direction and then calibrating in the negative direction, the interstage gain errors are also corrected without an extra gain-proration cycle. In addition, the number of accumulated measurements is reduced by a factor of two for the final correction coefficient by using the preferred method. Therefore, the roundoff errors are also reduced.