Patent ID: 7291822

Claim:
A method of operating a pixel cell, the method comprising: providing first and second bias voltages to operate a capacitive transimpedance amplifier; generating charges with a photodetector during an integration period; resetting a charge storage node that receives photo generated charges generated by said photodetector to a reset level; with the storage node at the reset level, reading and sampling a first output signal from said capacitive transimpedance amplifier having an input coupled to said storage node; opening a first switch circuit to float a reset line; closing a second switch circuit to connect the capacitive transimpedance amplifier input to an output stage of the capacitive transimpedance amplifier and to operate said capacitive transimpedance amplifier during a readout operation; receiving charges at said charge storage node generated by said photodetector during said integration period; and reading and sampling a second output signal from said capacitive transimpedance amplifier after said integration period.