Patent ID: 7714921

Claim:
An operating method for an image-sensing unit, the image-sensing unit comprising a photogate, a photodiode assembled with the photogate, a source follower, a first switch, and a second switch, a first terminal of the first switch being coupled to a reference voltage, and a second terminal of the first switch being coupled to the photodiode permanently, a first terminal of the source follower is coupled to the reference voltage, a control terminal of the source follower is permanently coupled to another terminal of the photodiode, a first terminal of the second switch is permanently coupled to a second terminal of the source follower, a second terminal of the second switch outputs an output voltage, the first terminal of the first switch is coupled to the first terminal of the source follower, a control circuit is coupled to the image-sensing unit, and directly applies different voltage values at different times to the first switch, the photodiode, and the second switch, respectively, and the operating method comprising: applying a first voltage to the photogate; turning on the first switch; turning off the first switch at a first time; reducing the first voltage at a second time; increasing the first voltage at a third time; and maintaining a turn-off state of the first switch until a fourth time, wherein a voltage applied on a control terminal of the first switch at the fourth time is high.