PURPOSE: To attain a high processing speed with a simple configuration by arranging alternately a connecting point of a voltage comparator for extracting a reference voltage and a switch connecting point among connecting points of resistors of a resistor array.

CONSTITUTION: An A/D converter 20 includes a resistor array 201 and a voltage comparator group 202 to generate a digital output corresponding to a differential analog input. Furthermore, a differential D/A converter 30 includes a resistor array 201 and a switch group 301 to generate an analog voltage corresponding to a digital value being the result of A/D conversion by the converter 20 via a switch 301. Then the A/D converter provided with a differential input operational amplifier 50 obtains a difference between an output VDAC of the converter 30 and a differential analog input voltage Vin. A connecting point of a voltage comparator 201 for extracting a reference voltage and a connecting point of the switch 301 among connecting points of the resistors of the resistor array 201 are arranged alternately. Then the operating speed of the differential amplifier 50 is improved and a high processing speed is realized with a simple configuration.