Patent ID: 7755521

Claim:
An A/D conversion device comprising: a first A/D conversion section and a second A/D conversion section that each comprise: a D/A converter that has a plurality of bit capacitors corresponding to bits of input data; a comparing section that compares a reference voltage with a difference voltage obtained by subtracting an analog input voltage from an output voltage of the D/A converter; and a control section that detects a data value of the input data at which the difference voltage is substantially the same as the reference voltage and outputs the data value as digital data according to the input voltage; and an adjusting section that serially connects the bit capacitors of the D/A converter of the first A/D conversion section and the bit capacitors of the D/A converter of the second A/D conversion section that correspond to the same bits, and adjusts a capacity of at least one of the bit capacitors so that a voltage between the two bit capacitors approaches a middle point of voltages of the two bit capacitors.