High-speed global exposure pixel structure for realizing intra-pixel correlated double sampling

Abstract

The invention discloses a high-speed global exposure pixel structure for realizing intra-pixel correlated double sampling. The high-speed global exposure pixel structure comprises a photodiode (PD), areset transistor (RST), a charge transfer transistor (TX), two source followers (SF1 and SF2), a multifunctional transistor (PC), three MOS switches (S1, S2 and S3), a selection transistor (SEL) andtwo capacitors (C1 and C2), according to the pixel structure, intra-pixel correlated double sampling (CDS) operation can be realized, reset noise of a charge voltage conversion node (FD) is eliminated, the signal-to-noise ratio of an image is improved, and the image quality is improved; the CDS operation is realized in the pixel, so an extra CDS circuit is avoided, the time delay is reduced whilethe chip area is reduced, and the frame rate is improved; exposure and pixel assembly line operation can be achieved, that is, exposure of the next frame can be conducted in the current frame signal output process, the signal reading time is fully utilized, and the frame rate is increased.

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 pixel array of the image sensor receives photons during the exposure process, and converts the light signal into an electrical signal, and the electrical signal is converted into the required image by the subsequent analog-to-digital conversion circuit and digital signal processing circuit, and then output. Generally, there are two 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 there will be problems of image distortion, such as For fast-moving fans, cars, etc.; in the global exp...

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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