US Patent 10498998 Image sensor

An image sensor including a plurality of pixel-group sensors is provided. Each of the pixel-group sensors includes a first pixel group, a second pixel group and a read out circuit. The first pixel group includes a plurality of first pixels. A floating diffusion node of each of the first pixels is coupled to a first node. The second pixel group includes a plurality of second pixels. A floating diffusion node of each of the second pixels is coupled to a second node. The read out circuit is coupled to the first node and the second node, and configured to compare a voltage of the first node with a voltage of the second node, so as to sequentially obtain a digital pixel value of each of the first pixels and the second pixels.