Image sensor, operating method of image sensor and camera module including image sensor

A method of operating an image sensor, the method comprising:

• turning off a select-gate transistor connecting a source-follower transistor to a current source, wherein the source-follower transistor is connected to a floating diffusion node;
• during a time when the select-gate transistor is turned off, trapping electrons in trap sites of the source-follower transistor, and resetting the floating diffusion node to a reset voltage;
• turning on the select-gate transistor;
• and
• during a time when the select-gate transistor is turned on, transmitting a signal of a photodiode to the floating diffusion node, and sensing a signal of the floating diffusion node through the source-follower transistor.

An image sensor comprising:

• a photodiode;
• a transfer gate transistor connected between the photodiode and a floating diffusion node;
• a source-follower transistor including a first source/drain terminal, a second source/drain terminal, and a gate electrode coupled to the floating diffusion node;
• a first switch transistor selectively connecting the first source/drain terminal of the source-follower transistor to a first voltage node supplying a first voltage;
• a second switch transistor selectively connecting the first source/drain terminal of the source-follower transistor to a second voltage node supplying a second voltage;
• and
• a select-gate transistor selectively connecting the second source/drain terminal of the source-follower transistor to a current source,
• wherein during a non-readout time period in which the select-gate transistor is turned off, the first switch transistor is turned off, and the second switch transistor is turned on to supply the second voltage to a first/source drain terminal of the source-follower transistor and trap electrons in trap sites of the source-follower transistor using the second voltage, and
• wherein during a readout time period in which the select-gate transistor is turned on, the second switch transistor is turned off, and the first switch transistor is turned on to supply the first voltage to the first/source drain terminal of the source-follower transistor for sensing a signal of the floating diffusion node.