METHODS FOR CLOCKING AN IMAGE SENSOR

摘要

A method of clocking an image sensor which eliminates well bounce effects caused by global current flow in large image sensors during frame readout and line transfer is described. During charge transfer operations in which voltages are applied to VCCD gate contacts that are adjacent to the photodiodes, a compensating voltage may be applied to the lightshield that is associated with, and at least partially formed over the photodiode. Depending on polarity, the compensating lightshield pulse allows holes to locally flow from under the VCCD gates to the photodiode P+ pinning region or vice-versa, and in such a manner to eliminate the global flow of hole current. Lightshields may also be biased during electronic shuttering operations.

主权项

1. A method of clocking an image sensor that includes a photodiode that is adjacent to a vertical charge-coupled device (VCCD), wherein the photodiode has an associated light-shielding structure that is formed over at least a part of the photodiode and the VCCD, the method comprising:
transferring charge in the photodiode to the VCCD; and while transferring the charge from the photodiode to the VCCD, applying a compensating bias voltage to the light-shielding structure to compensate for net charge imbalance caused by transferring the charge.