Photodector including photodiodes having improved dynamic range, s/n ratio and speed of light detection

Abstract

The present invention aims at providing a photodetector which can improve each of the dynamic range, S/N ratio, and speed of light detection. A photodiode PDm,n generates electric charges by an amount corresponding to the incident light intensity, and accumulates thus generated electric charges into a junction capacitance part. An electric charge amount level determining circuit 10m,n determines the level of amount of electric charges generated by the photodiode PDm,n and accumulated in the junction capacitance part. In an integrating circuit 20m, the capacitance value of an integral capacitance part 21 is set according to the result of electric charge amount level determination, the electric charges inputted from the photodiode PDm,n by way of a switch SW1m,n are accumulated into the integral capacitance part 21, and a voltage V20 corresponding to the amount of thus accumulated electric charges is outputted. The voltage Vinp fed to a non-inverting input terminal of an amplifier A in the integrating circuit 20m is set greater in a second period during which the integral capacitance part 21 of the integrating circuit 20m accumulates electric charges than in a first period during which the junction capacitance part of the photodiode PDm,n accumulates electric charges.

Dependencies are inferred from the claim text.