Shared Readout Low Noise Global Shutter Image Sensor Method

摘要

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.

主权项

1. A method for operating a global shutter image sensor, the image sensor including an array of pixels and a readout circuit, wherein each of the pixels includes a photodiode and a charge coupled gate (CCG) device, wherein the readout circuit includes a floating diffusion, and wherein the method comprises:
controlling the plurality of pixels such that said photodiode of each of the plurality of pixels simultaneously captures a corresponding charge in accordance with first global control signals simultaneously transmitted to every pixel in said image sensor; controlling the plurality of pixels such that said corresponding captured charges are simultaneously transferred from the photodiode to the CCG device in each of said plurality of pixels in accordance with second global control signals simultaneously transmitted to every pixel in said image sensor; and performing a rolling shutter readout operation following the transfer phase, wherein the rolling shutter readout operation includes:
performing a first correlated double-sampling (CDS) readout operation including transferring a first captured charge generated in a first pixel of the plurality of pixels to the floating diffusion of the readout circuit, and generating a first CDS readout value on an output signal line connected to the readout circuit in accordance with the first captured charge; andperforming a second CDS readout operation including transferring a second captured charge generated in a second pixel of the plurality of pixels to the floating diffusion of the readout circuit, and generating a second CDS readout value on the output signal line in accordance with the second captured charge.