Circuit for eliminating dark current by using novel ramp generator and system thereof

Abstract

The invention discloses a circuit for eliminating dark current by using a novel ramp generator, and a system thereof. A second input end of a comparator in the traditional ramp generator is connectedwith a correction module and a correction capacitor in parallel, a dark current noise average digital value of dark pixel is firstly read in the circuit working process, and the digital value is fed back to the correction module; when the effective pixel is read, the read-out data of the effective pixel does not contain the dark current noise since the correction module records the noise level ofthe dark current and the noise level is overlaid in a ramp signal; the dark current noise is effectively eliminated through this architecture, the reduction of the image sensor dynamic range caused bythe dark current is reduced, and the image quality of an image sensor is effectively improved.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a circuit and system for eliminating dark current using a novel slope generator. Background technique [0002] In the CMOS image sensor (CIS), the dark current seriously affects the image quality of the image sensor. The influence of the dark current on the imaging quality of the image sensor is mainly reflected in two aspects. First, the non-uniformity of the dark current is fixed in the CIS. An important source of pattern noise, which makes the permeability of the image sensor worse; second, the dark current will push up the average value of the entire image, especially at high temperatures, the dark current value increases significantly, making the dynamic range of the image Although the inherent dark current of the photodiode can be reduced in the manufacturing process and the uniformity can be improved, it is still necessary to eliminate or suppress the dark curr...

AI Technical Summary

Problems solved by technology

[0005] Since when the image sensor system counts the average value of the signal of the dark pixel array, the digital output is not 0 and changes with the change of temperature, the use of the above ramp generator for dark current correction will lead to a decrease in the dynamic range of the image, especially Under high temperature conditions, the dark current value increases

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