A/D conversion device and A/D converter error correction device

The present invention relates to an A/D conversion device having a tuning function and an A/D converter error correction device for realizing the tuning function of an A/D converter. A zero transition voltage and a full transition voltage are inputted into the A/D converter, digital converted values of these voltages are fed back to a device fluctuation correction circuit and H side and L side reference voltages AVRH and AVRL are determined so as to obtain digital outputs corresponding to the respective transition voltages. Also, the digital output of the A/D converter is fed back to a high resolution corresponding circuit and a difference between AVRL and AVRH is decreased to be half as before by changing AVRL or AVRH according to an analog input voltage applied to the A/D converter and A/D conversion is performed again. By repeating this operation, significant bit values are obtained. A merge circuit merges the significant bit values with less significant bit values outputted from the A/D converter.