AD CONVERTER

PROBLEM TO BE SOLVED: To provide an AD converter of low power and small area suppressing the range of over range to a minimum without being limited by a relationship between a resistance value of an output resistor R1of an amplifier and a resistance value of an averaging resistance element Rave. SOLUTION: The AD converter includes: a reference voltage generator, which generates a plurality of reference voltages by dividing a gap between a first voltage and a second voltage; a plurality of amplifiers, each of which amplifies a differential voltage between each reference voltage and a voltage of an input signal; and a plurality of averaging resistance elements, which connect output terminals of the amplifiers. Further, the AD converter includes a plurality of first averaging auxiliary circuits, each of which has: a first amplifier for amplifying a differential voltage between a third voltage higher than the first voltage and the voltage of the input signal; and a first resistance element connecting an output terminal of an amplifier, to which the first voltage has been input as a reference voltage, among the plurality of amplifiers, and an output terminal of the first amplifier. COPYRIGHT: (C)2011,JPO&INPIT