A/D CONVERSION APPARATUS AND ERROR CORRECTION DEVICE FOR A/D CONVERTER

PROBLEM TO BE SOLVED: To correct error due to irregularities of a reference transition voltage peculiar to products of A/D converters, and realize high resolution of an A/D converter. SOLUTION: A zero transition voltage and a full transition voltage are inputted in the A/D converter 4, the respective digital conversion values are fed back to a device irregularity correcting circuit 53, and an H side reference voltage AVRH and an L side reference voltage AVRL are so determined that digital outputs corresponding to the respective transition voltage can be obtained. A digital output of the A/D converter 4 is fed back to a high resolution coping circuit 56, and AVRL or AVRH is changed in accordance with an analog input voltage to the A/D converter 4, thereby making the difference one-half. By repeating that A/D conversion is again performed, a value of high order bits is obtained. The value of high order bits is merged with a value of low order bits outputted from the A/D converter 4 by a merging circuit 57.