Patent ID: 7442911

Claim:
A photodetector comprising: a photodiode having an anode terminal and a cathode terminal between which a reverse bias voltage is applied, generating an electric charge by an amount corresponding to an incident light intensity, and accumulating the electric charge into a junction capacitance part; an integrating circuit having an input terminal connected to the photodiode by way of a switch, inputting the electric charge accumulated in the junction capacitance part to the input terminal, accumulating the electric charge into an integral capacitance part, and outputting a voltage corresponding to an amount of the accumulated electric charge; and reverse bias voltage changing means for making the value of reverse bias voltage applied to the photodiode greater in a second period during which the integral capacitance part of the integrating circuit accumulates the electric charge than in a first period during which the junction capacitance part of the photodiode accumulates the electric charge wherein the integrating circuit includes an amplifier having a first input terminal corresponding to the input terminal of the integrating circuit, a second input terminal, and an output terminal, and the integral capacitance part is provided between the first input terminal and output terminal.