Pixels with an active reset circuit in CMOS image sensors

摘要

The invention disclosure describes pixels arranged into CMOS image sensor arrays that may be back side illuminated and may operate in a global shutter mode. The image sensor pixels may also be front side illuminated. The pixel charge storage sites for the global shutter operation are formed by floating diffusions that are small and do not collect a significant number of stray charge, which contributes to the sensor's high shutter efficiency. The floating diffusions are reset by an active reset circuit that significantly reduces generation of kTC reset noise. The active reset circuit consists of an in-pixel inverting amplifier formed by a p-channel gain transistor with an n-channel transistor load, and a feedback reset transistor connected from the amplifier output to the amplifier input, which is the FD node. The active reset circuit does not utilize a significant portion of the pixel area and has low power consumption.