Image sensor and operation method thereof

An image sensor comprising:

• a photo diode configured to generate charges in response to an incident light;
• a first floating diffusion region configured to store the charges generated by the photo diode;
• a first reset transistor configured to electrically connect a first power supply voltage terminal with the first floating diffusion region in response to a first reset signal;
• a second floating diffusion region disposed to be spaced apart from the first floating diffusion region and including a first end connected with a gate of a drive transistor;
• a second reset transistor configured to electrically connect the first power supply voltage terminal with the second floating diffusion region in response to a second reset signal;
• a third floating diffusion region electrically connected between the first and second floating diffusion regions;
• a third reset transistor configured to electrically connect a second power supply voltage terminal different from the first power supply voltage terminal with the third floating diffusion region in response to the first reset signal;
• a transfer transistor configured to electrically connect the photo diode with the first floating diffusion region in response to a transfer signal;
• and
• a floating diffusion region transistor configured to electrically connect the first floating diffusion region with the second floating diffusion region in response to a floating control signal,
• wherein the second power supply voltage terminal is connected in common to the third reset transistor and the drive transistor, and
• wherein, in a state where the floating diffusion region transistor is turned on the first reset transistor is turned on and the third reset transistor is turned off.

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

• turning on a transfer transistor to transfer charges generated by a photo diode to a first floating diffusion region;
• after turning off the transfer transistor, decreasing a voltage level of the first floating diffusion region by applying a negative voltage signal to a boosting capacitor connected with the first floating diffusion region;
• increasing a voltage level of a second floating diffusion region such that the voltage level of the first floating diffusion region is lower than the voltage level of the second floating diffusion region;
• turning on a floating diffusion region transistor in a state where the voltage level of the first floating diffusion region decreases, such that charges integrated in the first floating diffusion region are transferred to the second floating diffusion region physically spaced apart from the first floating diffusion region;
• and
• sampling a voltage formed in the second floating diffusion region,
• wherein the increasing the voltage level of the second floating diffusion region comprises increasing the voltage level of the second floating diffusion region while the negative voltage signal is applied to the boosting capacitor.