CMOS image sensors with photogate structures and sensing transistors, operation methods thereof, and image processing systems including the same

ACMOS image sensor includes a pixel array having a plurality of pixels. Each of the plurality of pixels includes: a photogate structure configured to be controlled based on a first gate voltage; and a sensing transistor including a charge pocket region formed in a substrate region, the sensing transistor being configured to be controlled based on a second gate voltage. Based on the first gate voltage, the photogate structure is configured to integrate charges generated in response to light incident on the substrate region. The sensing transistor is configured to adjust at least one of a threshold voltage of the sensing transistor and a current flow in the sensing transistor according to charges transferred from the photogate structure to the charge pocket region based on a difference between the first gate voltage and the second gate voltage.