Abstract: A plurality of different reference voltages are generated. A set of differential conversion circuits has first input terminals subjected in common to an analog input signal and second input terminals subjected to the respective reference voltages, and converts differences between voltages at the first and second input terminals into differential output voltages. A first A/D conversion circuit compares the analog input signal with the reference voltages to perform a higher-order A/D conversion of the input analog signal. At least two of the differential output voltages are selected. An interval between the selected differential output voltages is divided, and divided voltages are generated in accordance with the division. A second A/D conversion circuit compares the divided voltages to perform a lower-order A/D conversion of the analog input signal.