US Patent 7145123 CMOS light sensing cell

A light sensing cell comprising output circuitry for generating an output voltage depending on the voltage of a sensing node, the voltage of the sensing node varying as a function of a received light; a reset transistor operable to force the voltage of the sensing node to a reset voltage; a feedback loop including an operational amplifier operable to add through a capacitive voltage divider a correction voltage to the voltage of the sensing node, said correction voltage depending on the output voltage; and preset mean circuitry for, during the operation of the reset transistor and until the amplifier is operated, setting the input of the capacitive voltage divider to a predetermined voltage.