DC OFFSET CORRECTION METHOD AND CIRCUIT OF A-D CONVERTER

摘要

PROBLEM TO BE SOLVED: To automatically restore an offset regardless of a variation resulting from disturbance by preventing erroneous leading-in caused by an offset variation resulting from frequency deviation in an A-D converter. SOLUTION: The DC offset correction circuit which inpus an output signal of the A-D converter and corrects an offset of a reference voltage in the A-D converter is provided with; a maximum/minimum value detection part which obtains a maximum value and a minimum value from an inflection point of the output signal of the A-D converter; an offset discrimination part which obtains a half of the difference between the obtained maximum and minimum values; a loop filter which takes an output of the offset discrimination part as an input and averages it; and an addition circuit which subtracts an output of the loop filter from the output signal of the A-D converter. The offset discrimination part is provided with a circuit for alternately switches detection points of time of maximum and minimum values of the output signal of the A-D converter. COPYRIGHT: (C)2005,JPO&NCIPI