Image sensor controlling a conversion gain, imaging device having the same, and method of operating the same

An image sensor comprising:

• a first pixel;
• a second pixel;
• a third pixel;
• and
• a fourth pixel,
• wherein each of the first to fourth pixels comprises:
• a first transistor configured to connect at least one photodiode and a first floating diffusion node based on a transfer gate signal;
• a second transistor configured to connect the first floating diffusion node and a second floating diffusion node based on a first conversion gain signal;
• a third transistor comprising a drain connected to the second floating diffusion node;
• a fourth transistor comprising a source connected to a power supply terminal configured to provide a pixel driving voltage and a gate connected to the first floating diffusion node;
• and
• a fifth transistor comprising a source connected to a drain of the fourth transistor, a drain connected to a column line, and a gate configured to receive a selection signal,
• wherein the second floating diffusion node of the first pixel and the second floating diffusion node of the second pixel are directly connected through a metal line,
• wherein a second floating diffusion node of the third pixel and the second floating diffusion node of the fourth pixel are directly connected through a metal line, and
• wherein a third floating diffusion node of the second pixel and a third floating diffusion node of the third pixel are directly connected through a metal line.

A method of operating an imaging device, the method comprising:

• receiving an operating mode from an image sensor;
• and
• controlling a size of a floating diffusion region of a pixel group based on the received operating mode,
• wherein the operating mode comprises at least three operating modes,
• wherein the pixel group comprises:
• a first pixel comprising a first floating diffusion region and a second floating diffusion region;
• a second pixel comprising a first floating diffusion region, a second floating diffusion region, and a third floating diffusion region;
• a third pixel comprising a first floating diffusion region, a second floating diffusion region, and a third floating diffusion region;
• and
• a fourth pixel comprising a first floating diffusion region and a second floating diffusion region,
• wherein the second floating diffusion region of the first pixel and the second floating diffusion region of the second pixel are directly connected through a first metal line,
• wherein the third floating diffusion region of the second pixel and the third floating diffusion region of the third pixel are directly connected through a second metal line, and
• wherein each of the second pixel and the third pixel comprises a second conversion gain transistor provided directly between a second floating diffusion node corresponding to the second floating diffusion region of each of the second pixel and the third pixel and a third floating diffusion node corresponding to a third floating diffusion region of each of the second pixel and the third pixel based on a second conversion gain signal.