Large dynamic range semi-floating gate image sensor

Abstract

The invention discloses a large dynamic range semi-floating gate image sensor, comprising a pixel array, a current processing column level circuit and a voltage processing column level circuit, the pixel array includes a plurality of pixels, each of the pixels includes a semi-floating gate A transistor and a first voltage conversion circuit, the first voltage conversion circuit is used to convert the current signal output by the semi-floating gate transistor into a voltage signal, and sample and output the reset voltage and the signal voltage respectively, so as to realize pixel-level correlated double sampling, reduce read noise. In the present invention, a voltage column-level processing circuit is added to the semi-floating gate image sensor, and a voltage conversion circuit is added to each pixel, so that the image sensor can take into account the large full well charge capacity and high conversion gain, and can be used in high background and low background. It can be imaged at any time, which greatly expands the application range of the semi-floating gate image sensor; in addition, binning between pixels can also be realized, which further expands the dynamic range of the image sensor.

Description

technical field [0001] The invention relates to the field of image sensors, in particular to a semi-floating gate image sensor with a large dynamic range. Background technique [0002] Floating gate devices have been widely used in various non-volatile memories since they were first proposed. In recent years, semi-floating gate devices are gradually being used in image sensors. The half-floating gate device can realize the function of the traditional 3T CMOS image sensor with a simple 1T structure, which can improve the fill factor and increase the integration level; the half-floating gate 1T pixel uses the floating gate to store the photogenerated charge during the working process, and can output The changing MOS tube current is used to represent the image information; the current signal can pass through the column-level capacitive transimpedance amplifier, use the input current to integrate on the feedback capacitor to convert it into a voltage signal, and then read it out...

AI Technical Summary

Problems solved by technology

Therefore, it is often difficult to design a large dynamic range image sensor that can be applied to both low background imaging conditions and high background imaging conditions

[0004] For semi-floating gate image sensors, the full well charge and conversion gain are directly related to the capacitance of the photodiode, and it is difficult to take into account the large full well and high gain at the same time; in addition, with regard to noise, the existing technology can be solved by placing a correlation in the column-level circuit The circuit can realize the column-level correlated double sampling operation of the half-floating gate 1T pixel output current, but because the correlated double sampling is not at the pixel level, it has certain limitations in eliminating KTC noise and fixed pattern noise

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