Patent ID: 7893859

Claim:
A conversion circuit for an analog/digital converter, comprising: a gain stage having a first input, a second input, first to third capacitors, and an operational amplifier circuit, the first input being provided for receiving an input analog signal in a first period and receiving a converted analog signal in a second period, the converted analog signal being associated with the input analog signal, the second input being provided for receiving the input analog signal in the first period and receiving the converted analog signal in a third period, the second period being different from the first period, and the third period being different from the first period and the second period, wherein, in the first period, the first capacitor is connected between the first input of the gain stage and an inversion input of the operational amplifier circuit, the second capacitor is connected between the second input of the gain stage and the inversion input of the operational amplifier circuit, the first capacitor receives a charge corresponding to the analog signal via the first input, and the second capacitor receives a charge corresponding to the analog signal via the second input, wherein, in the second period, the second capacitor is connected between an output of the operational amplifier circuit and the inversion input of the operational amplifier circuit, the operational amplif i er circuit generates a first operation value in the output thereof in response to the converted analog signal applied to the first capacitor via the first input, and the first operation value is stored in the third capacitor, and wherein, in the third period, the second capacitor is connected between the second input and the output of the operational amplifier circuit, the first and third capacitors are connected between the output and the inversion input of the operational amplifier circuit, and the operational amplifier circuit generates a second operation value in the output thereof in response to the converted analog signal applied to the second capacitor via the second input.