Patent ID: 6864919

Claim:
A method of processing an output signal of an image sensor pixel in readout circuitry having a first capacitor element coupled to a second capacitor element, comprising the steps of: a. applying a reference voltage V REF to the first and the second capacitor elements; b. applying a first sample signal V S1 from the image sensor pixel to the first capacitor element placing a charge on the first capacitor element; c. transferring the charge from the first capacitor element to the second capacitor element; d. applying a second sample signal V S2 from the image sensor pixel to the first capacitor element placing a charge on the first capacitor element; and e. transferring the charge from the second capacitor element to the first capacitor element so as to provide an output signal that is a function of the difference between the second sample signal V S2 and the first sample signal V S1 .