Ultra-wide dynamic range image sensor based on pixel charge compensation technology

Abstract

The invention belongs to the technical field of semiconductor image sensing, and relates to an ultra-wide dynamic range image sensor based on a pixel charge compensation technology. The ultra-wide dynamic range image sensor based on the pixel charge compensation technology is composed of a photoelectric conversion module 1, an upper read-out processing module 21 and a lower read-out processing module 22 for controlling and reading out data of the photoelectric conversion module 1, a column decoding module 3 and an offset signal module 4. A pixel element is integrated with an element for charge compensation near a main photodiode, so pixel output saturation is avoided by compensating charge to an integrating capacitor of the main photodiode under a highlight condition. An apparatus forms a linear response as to the light intensity under a weak light condition, and the linear response is automatically converted into the linear response to a light intensity logarithm under a strong light condition, so as to obtain an extremely wide dynamic range; the amplitude of the output voltage of a pixel circuit is large; a column amplifier circuit does not need to be integrated; an analogue-digital convertor can be directly input; the design flow of the device is simplified; the chip area is saved; and the photoreceptive dynamic range is extremely wide, and the theoretical value can reach up to 200dB.

Description

technical field [0001] The invention belongs to the technical field of semiconductor image sensing, in particular to an ultra-wide dynamic range image sensor based on pixel charge compensation technology. Background technique [0002] With the development of modern information technology, image acquisition and processing technology has also been improved accordingly. As the basic equipment of image processing, image sensor is being widely used in various fields. [0003] Electronic image sensors based on semiconductor technology and processes mainly include charge-coupled devices (CCD) and CMOS image sensors (CIS). Among them, CIS adopts standard CMOS technology, is easy to integrate with circuits, and has a series of advantages such as low power consumption and low cost. In recent years, it has been more and more widely used, especially in the fields of professional photography and other fields. [0004] Dynamic range (DR) is an important index of CIS, which is used to cal...

AI Technical Summary

Problems solved by technology

It is mainly achieved by increasing the parasitic capacitance around the DP or other gate capacitance structures, but this method will reduce the filling ratio of the pixel and reduce the response characteristics under weak light

(2) Multiple sampling technology, that is, to sample the same scene through multiple exposures, this method requires more complex external reading and storage circuits, and is not suitable for high-speed photography scenes

(3) Multi-detector pixels, that is, two photodiodes are integrated in one pixel unit, one for weak light conditions and one for strong light conditions, but its circuit structure is complex, and the problem of potential well capacity is not fundamentally solved , limited ability to increase DR

The disadvantage of this method is that it requires very complex circuits for the discrimination and conversion of linear and logarithmic modes

[0008] In addition, there are other more complex ways to improve the dynamic range, but so far there is no ideal method

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