Shared readout low noise global shutter image sensor method

A method for operating a global shutter image sensor includes performing both a global shutter (image capture) operation and a rolling shutter (readout) operation. During the global shutter operation, image information (charges) are captured by photodiodes in every pixel, and then simultaneously transferred to charge coupled gate (CCG) devices provided in each pixel. The rolling shutter operation includes performing multiple correlated double sampling (CDS) readout phases utilizing readout circuits that are shared by groups of pixels (e.g., four pixels share each readout circuit) having CCG devices connected in a chain. After resetting a floating diffusion in the readout circuit, a first captured charge is transferred to floating diffusion for readout, and the remaining charges are shifted along the CCG chain. The remaining CCG devices are then sequentially read out by repeating the read-and-shift operation. The readout operation is then repeated for each row of pixel groups.