Patent ID: 6977682

Claim:
A solid-state imaging device having: a photodetector including a photoelectric conversion device for converting an incident optical signal into a current signal and a switch for outputting said current signal to an output terminal; an integrator circuit for inputting and integrating the current signal outputted from the output terminal of said photodetector, so as to output a voltage signal to an output terminal thereof; and a signal processing unit for processing the voltage signal from said integrator circuit; said signal processing unit comprising: a variable capacity integrator circuit having a capacitor for inputting the voltage signal outputted from the output terminal of said integrator circuit and functioning as part of a Correlated Double Sampling (CDS) circuit, an amplifier for inputting to an input terminal the voltage signal outputted from said capacitor, a variable capacity part, disposed between the input and output terminals of said amplifier, having a variable capacity value, and a reset switch disposed between the input and output terminals of said amplifier, said variable capacity integrator circuit outputting from the output terminal of said amplifier an integrated signal having a value corresponding to a change of the voltage signal inputted to said capacitor; a comparator for inputting the integrated signal outputted from said variable capacity integrator circuit, comparing the value of said integrated signal with a reference value in terms of magnitude, and outputting a comparison result signal; and a capacity control section for inputting the comparison result signal outputted from said comparator, controlling the capacity value of said variable capacity part according to said comparison result signal, and outputting a first digital signal corresponding to the capacity value of said variable capacity part when it is determined according to said comparison result signal that the value of said integrated signal and said reference value coincide with each other at a predetermined resolution.