Device and method for improving dynamic range of CMOS image sensor

Abstract

The invention discloses a device and a method for improving a dynamic range of a complementary metal oxide semiconductor (CMOS) image sensor. The device comprises a pixel unit array, a time sequence control circuit, a double sampling circuit, an analog front end processing circuit, an A / D converter and a storage unit, wherein the pixel unit array is provided with a plurality of types of pixel units, and the areas of FD areas of different types of pixel units are different. When the CMOS image sensor is adopted for shooting images, by using the principle that the pixel units with large-area FDareas have lower light sensitivity and the pixel units with small-area FD areas have higher light sensitivity, the pixel units with the large-area FD areas can sense a strong light part in an image and the pixel units with the small-area FD areas can sense a weak light part in the image. Therefore, the synthesized image has a wider dynamic range, the dynamic range of the CMOS image sensor is alsoobviously widened, and the implementation is simple.

Description

technical field [0001] The invention relates to a complementary metal oxide semiconductor (CMOS) image sensor, in particular to a device and method for improving the dynamic range of the CMOS image sensor. Background technique [0002] A CMOS image sensor mainly includes a pixel unit array, a timing control circuit, a double sampling circuit, an analog front-end processing circuit, an analog / digital (A / D) converter, and a storage unit. Among them, the pixel unit array is an important component of a CMOS image sensor. part. According to the structure of the pixel unit in the pixel unit array, that is, the number of transistors contained in the pixel unit, it can be divided into CMOS image sensors with 1T structure, CMOS image sensors with 3T structure and CMOS image sensors with 4T structure. [0003] figure 1 It is a schematic plan view of a pixel unit array in an existing CMOS image sensor. Such as figure 1 As shown, the pixel unit array is actually a matrix composed of...

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Problems solved by technology

In addition, since large and small pixel units have different abilities to perceive light intensity, in order to prevent the synthesized image from being greatly distorted, it is necessary to combine two large and small pixel units before compositing, which reduces the final result. image resolution

[0027] The current use of large and small pixel technology to improve the dynamic range of CMOS image sensors requires that the size difference between the two pixel units be as large as possible. However, the existing production costs and layout symmetry requirements restrict the use of large and small pixel technology to improve CMOS image. The dynamic range of the sensor

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