Patent ID: 7667753

Claim:
An image sensor, comprising: a matrix of active pixels, wherein each pixel comprises a photodiode and a follower transistor whose gate is connected to the photodiode; one pair of sampling capacitors per matrix column for processing the information delivered by the matrix of active pixels; a differential amplifier per matrix column configured in follower mode and connected between the pixels of the column and the pair of sampling capacitors via a pair of switches; and an additional amplifier with unity gain connected between the output of the differential amplifier and the pair of switches associated with the sampling capacitors, the additional amplifier sourcing current for sufficiently and quickly charging the capacitors; wherein the differential amplifier configured in follower mode comprises: a differential pair comprising the follower transistor of the pixel and an additional transistor, the source of the follower transistor being connected to a source of biasing current via a row-selection transistor, the source of the additional transistor being also connected to the said biasing current source, the drain of the additional transistor being fed back onto the gate of the additional transistor, and a current mirror connected between the drain of the follower transistor and the drain of the additional transistor, wherein the gate of the follower transistor of the pixel forms the positive input of the differential amplifier and the gate of the additional transistor forms the negative input of the differential amplifier.