ANALOG-TO-DIGITAL CONVERTING CIRCUIT AND IMAGE PROCESSING CIRCUIT CYCLICALLY REPEATING AD CONVERSION

A first AD converting part of an AD converter converts an input voltage into a digital value of a predetermined number of bits and output the digital value to a digital output circuit and a DA converting part. The DA converting part converts the digital value into an analog value. A subtracting part outputs a difference between the analog value output from the DA converting part and the original input voltage. An amplifying part amplifies the difference output from the subtracting part. An output from the amplifying part is input to the first AD converting part via a feedback path. A subsequent output from the amplifying part is input to the second AD converting part via a branch path so as to produce a digital value of a predetermined number of bits. While the second AD converting part performs conversion, a subsequent input voltage is subjected in parallel to AD conversion by the first AD converting part.