A high-speed global exposure pixel structure for intra-pixel correlated double sampling

Abstract

A high-speed global exposure pixel structure for realizing intra-pixel correlated double sampling, comprising a photodiode (PD), a reset transistor (RST), a charge transfer transistor (TX), two source followers (SF1, SF2), a multi-function transistor (PC), three MOS switches (S1, S2, S3), selection transistor (SEL), two capacitors (C1, C2); this pixel structure enables intra-pixel correlated double sampling (CDS) operation, eliminating charge-voltage The reset noise of the conversion node (FD) improves the signal-to-noise ratio of the image and improves the image quality; the CDS operation is implemented in the pixel, avoiding additional CDS circuits, reducing the chip area while reducing the time delay and improving the frame rate; can achieve exposure and The pipeline operation of the pixel means that the next frame exposure can be performed during the current frame signal output process, making full use of the signal readout time and improving the frame rate.

Description

technical field [0001] The invention belongs to the field of image sensors, and in particular relates to a high-speed global exposure pixel structure for realizing intra-pixel correlated double sampling. Background technique [0002] The image sensor pixel array receives photons during the exposure process, converts the optical signal into an electrical signal, and the electrical signal is converted into a desired image and output by subsequent analog-to-digital conversion circuits and digital signal processing circuits. Generally, there are two types of image sensor exposure methods: drum exposure method and global exposure method. In the drum exposure method, the pixel array is exposed and read out row by row. When imaging an object with a high moving speed, the exposure time of different rows is different, and the position of the object will be different, so the problem of image distortion will occur, such as For fast-moving fans, cars, etc.; in the global exposure metho...

AI Technical Summary

Problems solved by technology

[0003] In the traditional global exposure method, the five-tube (5T) active pixel structure can achieve global exposure, but due to structural reasons, the Correlated Double Sampling (CDS) operation cannot be achieved, so the noise of the obtained image is high, while the eight-tube (8T) active pixel structure The pixel structure adds electrical signal storage nodes, but CDS operation requires additional circuits, which increases time consumption and causes problems such as a decrease in imaging frame rate

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