Patent ID: 8319262

Claim:
A CMOS image sensor, comprising: a lightly doped semiconductor substrate of a first conductivity type; and at least one CMOS pixel of a second conductivity type formed substantially in the semiconductor substrate, comprising: a highly doped sense node of the second conductivity type; a reset transistor of the second conductivity type in signal communication with the sense node; a source follower transistor of the second conductivity type in signal communication with the sense node; a row select transistor of the second conductivity type in signal communication with the source follower transistor; and a highly doped return contact of the first conductivity type configured to receive a return potential for providing a return reference for the reset transistor, the source follower transistor, and the row select transistor; and a well of the second conductivity type substantially surrounding the at least one CMOS pixel to form a depletion region about the at least one CMOS pixel operable to form a minimum predetermined barrier to the depletion edge within the semiconductor substrate to pinch off substrate bias in proximity to the return contact; wherein the semiconductor substrate is configured to receive a bias voltage applied for substantially depleting the semiconductor substrate and for forming a depletion edge substantially within the semiconductor substrate.