Pixel group and pixel array of image sensor

A pixel array of an image sensor, the pixel array comprising:

• a plurality of pixel groups, each pixel group comprising:
• first through fourth unit pixels in a matrix form of two pixels rows and two pixel columns;
• and
• a common floating diffusion region in a semiconductor substrate at a center of each pixel group and shared by the first through fourth unit pixels,
• each of the first through fourth unit pixels comprising:
• a photoelectric conversion element in the semiconductor substrate;
• and
• a pair of vertical transfer gates in the semiconductor substrate and extending in a vertical direction perpendicular to a surface of the semiconductor substrate, the pair of vertical transfer gates configured to transfer photo charges collected by the photoelectric conversion element to the common floating diffusion region, and the pair of vertical transfer gates are configured to be activated simultaneously to perform a low-luminance sensing.

An image sensor comprising:

• a pixel array including a plurality of pixel groups configured to collect photo charges generated by an incident light;
• a row driver configured to drive the pixel array row by row;
• and
• a controller configured to control the pixel array and the row driver, each pixel group comprising:
• first through fourth unit pixels in a matrix form of two pixels rows and two pixel columns;
• and
• a common floating diffusion region in a semiconductor substrate at a center of each pixel group and shared by the first through fourth unit pixels,
• each of the first through fourth unit pixels comprising:
• a photoelectric conversion element in the semiconductor substrate;
• and
• a pair of vertical transfer gates in the semiconductor substrate and extending in a vertical direction perpendicular to a surface of the semiconductor substrate, the pair of vertical transfer gates configured to transfer photo charges collected by the photoelectric conversion element to the common floating diffusion region, and the pair of vertical transfer gates are configured to be activated simultaneously to perform low-luminance sensing.