Patent ID: 6563445
Filing Date: 2003-05-13
Classification: H03M

Abstract:
A method for obtaining calibration constants that calibrate an analog-to-digital converter which has serially-connected converter stages with at least one converter stage having a residue transfer characteristic that includes a transition step, the method comprising the steps of:for a first converter stage, applying a residue signal Sres and digital input signals Din that cause said first converter stage to generate a first transition step; obtaining digital output signals that correspond to said digital input signals Din and that measure gain error at said first transition step; differencing said digital output signals to obtain a first calibration constant Ccal; and for converter stages that successively precede said first converter stage, successively performing the steps of: a) applying a respective residue signal Sres and respective digital input signals Din that cause a preceding converter stage to generate a preceding transition step; b) obtaining respective digital output signals that correspond to said respective digital input signals Din and that measure gain error at said preceding transition step; c) multiplying the calibration constant Ccal of each succeeding converter stage with that stage's respective digital input signals Din to realize respective weighted calibration constants Ccalwtd; d) summing said respective digital output signals with the respective weighted calibration constants Ccalwtd of succeeding converter stages to realize respective weighted digital output signals; and e) differencing said respective weighted digital outpusignals to realize a preceding calibration constant Ccal; wherein said first and preceding calibration constants Ccal provide a calibrated analog-to-digital converter when they are multiplied by respective digital input signals Din and summed with digital output signals of said analog-to-digital converter.