Patent ID: 7745776

Claim:
A photo detecting apparatus, comprising: a photo detecting element which generates a current in response to incident light; a first capacitance, caused by said photo detecting element, which is charged or discharged by the current flowing through said photo detecting element; a second capacitance, connected in parallel with said photo detecting element, which charges or discharges an electric charge overflowing from said first capacitance; a current control element, directly connected to a terminal of said second capacitance on a side where the electric charge flows in, which causes a current to cancel part of an electric charge when the electric charge overflowing from said first capacitance is stored in said second capacitance; and a detection circuit which detects a signal corresponding to the electric charge stored in said first capacitance and said second capacitance, wherein the current control element is constituted by a P-channel transistor wherein a drain terminal thereof is connected to the second capacitance, a predetermined fixed potential is applied to a source terminal thereof, and the gate terminal and the drain terminal thereof are connected with each other by way of a diode.