A/D CONVERTER

PROBLEM TO BE SOLVED: To provide an A/D converter that can reduce an offset of a comparator without increasing the power consumption and the circuit scale. SOLUTION: The A/D converter of this invention is provided with a plurality of comparators 1 each comparing an analog input voltage Vin with a reference voltage and a digital decoder 2 that generates a digital signal in response to the analog input voltage Vin based on an output of each comparator 1. Each comparator 1 has a preamplifier 3 and a multi-input differential amplifier section 4a connected to the post-stage of the preamplifier 3. The multi-input differential amplifier section 4a averages differential signals outputted from three adjacent preamplifiers 3 respectively to output a final differential signal. Thus, offsets by the preamplifiers 3 can be cancelled to attain highly accurate A/D conversion. Furthermore, since no resistor is employed for the averaging processing, the cost can be reduced and the power consumption can also be decreased.