Patent ID: 8654230

Claim:
An image pickup circuit comprising: amplifying means for amplifying a charge corresponding to an amount of light received by a photodetector, and outputting a pixel signal; ramp signal generating means for generating a ramp signal whose voltage changes at a predetermined rate from a predetermined initial voltage; and comparing means for comparing the pixel signal output by said amplifying means with the ramp signal output by said ramp signal generating means; wherein the comparing means provides an output signal that changes to indicate a time when the ramp signal changes from being less than or greater than the pixel signal to being greater than or less than the pixel signal in order to identify the approximate value of the pixel signal and wherein, at least some of the noise in the pixel signal and some of the noise in the ramp signal applied to the comparator are substantially in phase with each other so that the output signal from the comparison means is substantially free of the noise, and wherein a reference potential of the pixel signal input to the comparator is a ground level, a floating diffusion receiving the charge output according to the amount of light received by the photodetector being connected to the ground level and a reference potential for the ramp signal output from the ramp signal generating means is the ground level, the ramp signal being supplied to a resistor that is connected to the ground level.