METHOD AND CIRCUIT FOR CORRECTING DC OFFSET OF A/D CONVERTER

摘要

PROBLEM TO BE SOLVED: To correctly obtain peak timing to realize offset correction even if existence probability of a signal point does not become equal in positive/negative with respect to an orthogonal modulation signal and a peak can be detected only on one axis side.;SOLUTION: In a method for correcting offset of reference voltage of an A/D converter with respect to the signal which is orthogonally modulated, a loop filter averages 1/2 of a difference between a maximum value and a minimum value of an output signal from the A/D converter, to subtract the average from the output signal of the A /D converter and offset quantity is corrected with respect to each of an in-phase component and an orthogonal component of the orthogonally modulated signal. When the maximum value and the minimum value are obtained only on one axis side of the in-phase component or the orthogonal component, a signal level of the other axis side which corresponds to detection timing of the maximum value and the minimum value of only one side, is detected, a difference between the detected large signal level and the small signal level on the other axis side is obtained and 1/2 of the obtained difference of the signal levels is set to be offset quantity which is to be corrected on the other axis side.;COPYRIGHT: (C)2005,JPO&NCIPI