Patent ID: 8023391

Claim:
A photodetection device comprising: a photoelectric converter portion that converts light to an electric current; an electrical current/voltage converter portion that includes a feedback circuit that returns at least part of an output to an input side, that converts the electrical current received from the photoelectric converter portion to a voltage corresponding to a resistance value of the feedback circuit and that outputs a voltage; a control portion that generates control signals to control the gate voltage of a first MOS transistor; and a voltage generating portion that generates a voltage based on the control signals generated by the control portion, and applies the generated voltage to a gate of the first MOS transistor, wherein, the feedback circuit includes the first MOS transistor to allow the resistance value to be varied in accordance with a gate voltage, the voltage generating portion includes (a) a reference resistor that generates a voltage corresponding to a current supplied by a variable-current source, (b) a second MOS transistor in which a first terminal is connected to a fixed current and in which a second terminal is connected to the reference resistor, and (c) a gate voltage generating portion that generates a voltage such that a voltage arising between the first and the second terminals of the second MOS transistor is equivalent to the voltage generated by the reference resistor, and the second MOS transistor gate voltage generated by the gate voltage generating portion is applied to the first MOS transistor gate.