US Patent 7989753 Photodetector having wide dynamic range and low temperature dependence

A photodetector of a wide dynamic range of incident light amount detection and low temperature dependence is provided. A first signal processing unit 10m,n includes an integrating circuit 11, a first holding circuit 12, a comparing circuit 13, a second holding circuit 14, and a latching circuit 15. The integrating circuit 11 has a variable capacitor unit that is selectively set to a capacitance value among a plurality of capacitance values, accumulates charges, output from the photodiode, into the variable capacitor unit over an accumulating period that is in accordance with the capacitance value set at the variable capacitor unit, and outputs a voltage V1 that is in accordance with the amount of the accumulated charges. The comparing circuit 13 inputs the voltage V1 output from the integrating circuit 11, performs a quantitative comparison of the voltage V1 with a reference voltage Vref, outputs a compared signal S3 expressing the result of comparison, and, when the voltage V1 output from the integrating circuit 11 at the end of an accumulating period is less than the reference voltage Vref, instructs the first holding circuit 12 to hold the voltage.