A Pixel Unit Structure Realizing Three Conversion Gains

Abstract

The invention discloses a pixel unit structure for realizing three conversion gains, which at least includes: a photodiode, a transfer transistor, a reset transistor, a source follower transistor, a gain control transistor, a drain of the transfer transistor, a gate of the source follower transistor, The sources of the reset transistors are commonly connected to the floating drain, the gain control transistor and the floating drain are arranged in parallel, and the gain control transistor is provided with first and second control terminals; Different voltage biases are used to make the floating drain have three different capacitance values, so that the pixel unit can be switched between three conversion gains, and high-quality image output can be obtained, while satisfying the CMOS image sensor's high sensitivity and the need for a large dynamic range.

Description

technical field [0001] The present invention relates to the technical field of image sensors, and more particularly relates to a CMOS image sensor pixel unit structure capable of realizing three conversion gains. Background technique [0002] Generally, an image sensor refers to a device that converts an optical signal into an electrical signal. According to different manufacturing processes and working principles, image sensors can be further divided into charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) image sensor chips. [0003] Compared with traditional CCD sensors, CMOS image sensors have the characteristics of low power consumption, low cost and compatibility with CMOS technology, so they are more and more widely used. CMOS image sensors are now not only used in consumer electronics, such as miniature digital cameras (DSC), mobile phone cameras, video cameras and digital single-lens reflex (DSLR), but also in automotive electronics, moni...

AI Technical Summary

Problems solved by technology

[0011] However, the conventional double conversion gain pixel unit has only two conversion gain modes, high and low, and lacks an intermediate conversion gain curve, which affects the range of use of pixel unit imaging and the fineness of imaging.

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