Linearity of active pixel charge injection devices

Charge injection devices (CID), currently used for a variety of imaging applications, are discussed. The voltage response of an active CID pixel is analyzed. The linearity of the photoresponse is assessed in destructive and nondestructive read-out modes of operation. It is shown that under various conditions, CID response curves can exhibit dual-slope behavior with a steeper initial slope. If undesirable, this behavior can be avoided by adjusting various geometrical parameters of the pixel as well as the operating voltages. The theoretical analysis is in good agreement with experimental results.