Interpolation type A/D converter

摘要

According to the present invention, an A/D converter for receiving an input voltage and outputting a digital signal representing a level of the input voltage by a number n (where n is a natural number equal to or larger than 2) of upper bits and a number m (where m is a natural number equal to or larger than 2) of lower bits is provided. The A/D converter includes: a reference voltage generator for generating a plurality of reference voltages; an upper bit generator for generating the upper bits by comparing the input voltage with the plurality of reference voltages; a selector for selecting a first voltage equal to or higher than the input voltage and a second voltage equal to or lower than the input voltage from the plurality of reference voltages; a first differential amplifier for amplifying a difference between the first voltage and the input voltage and outputting an amplified voltage; a second differential amplifier for amplifying a difference between the second voltage and the input voltage and outputting an amplified voltage; a lower bit generator for generating the lower bits by using the output voltage of the first differential amplifier and the output voltage of the second differential amplifier; and a synthesis circuit for generating the digital signal by synthesizing the upper bits with the lower bits.