Patent ID: 7893729

Claim:
A voltage/current conversion circuit which outputs a differential output current signal corresponding to a potential difference between differential input signals respectively input to a first input terminal and a second input terminal, the voltage/current conversion circuit comprising: a first capacitor and a second capacitor; a first resistor having one terminal connected to the first input terminal; a second resistor having one terminal connected to the second input terminal; a first current source that outputs a current in response to a first control signal; a second current source that outputs a current in response to a second control signal; a first output terminal and a second output terminal that output currents respectively corresponding to the currents output from the first current source and the second current source; a third resistor connected to an output of the first current source; a fourth resistor connected to an output of the second current source; a differential amplifier that outputs the first control signal and the second control signal for respectively controlling the currents output from the first current source and the second current source in accordance with a potential different between one input and the other input; and a control unit that performs a control such that: in a first state, the first input terminal is connected to one terminal of the first capacitor; the second input terminal is connected to one terminal of the second capacitor; one input of the differential amplifier is connected to the other input terminal of the first resistor; the other input of the differential amplifier is connected to the other terminal of the second resistor; the output of the first current source is connected to the other input of the differential amplifier; and the output of the second current source is connected to the one input of the differential amplifier, and in a second state, the first capacitor is connected between the output of the first current source and the other input of the differential amplifier, and the second capacitor is connected between the output of the second current source and the one input of the differential amplifier.