Column analog-to-digital conversion circuit for cmos image sensor

Abstract

A column analog-to-digital conversion circuit for a CMOS image sensor, the innovation of which is: the column analog-to-digital conversion circuit is composed of a comparison link, a first inverter, a test link, a second inverter and a digital converter; The beneficial technical effect is: a column analog-to-digital conversion circuit is provided, the column analog-to-digital conversion circuit can remove the fixed pattern noise of the pixel and the column circuit during the sampling process, improve the imaging quality of the image sensor, and reduce the cost of the column-level processing circuit. At the same time, the column analog-to-digital conversion circuit also has a test function, which can test the timing control and digital converter.

Description

technical field [0001] The invention relates to a CMOS image sensor signal processing technology, in particular to a column analog-to-digital conversion circuit for a CMOS image sensor. Background technique [0002] With the advancement of technology, the requirements for CMOS image sensors in the engineering field are also getting higher and higher, that is, CMOS image sensors are required to have a large-scale pixel array and a high signal processing speed. As the size of the pixel array increases, the size of a single pixel in the pixel array continues to shrink, which leads to a continuous decline in sensor sensitivity, dynamic range, and signal-to-noise ratio. It is becoming more and more difficult to design a single analog-to-digital conversion circuit, and it is difficult to meet the needs of large pixels. Array, low noise, high speed and other requirements, therefore, a signal acquisition and conversion circuit based on column analog-to-digital conversion (Column Lev...

AI Technical Summary

Problems solved by technology

[0002] With the advancement of technology, the requirements for CMOS image sensors in the engineering field are also getting higher and higher, that is, CMOS image sensors are required to have a large-scale pixel array and a high signal processing speed. As the size of the pixel array increases, the size of a single pixel in the pixel array continues to shrink, which leads to a continuous decline in sensor sensitivity, dynamic range, and signal-to-noise ratio. It is becoming more and more difficult to design a single analog-to-digital conversion circuit, and it is difficult to meet the needs of large pixels. Array, low noise, high speed and other requirements, therefore, the signal acquisition and conversion circuit based on column level analog-to-digital conversion (Column Level, ADC) will produce

[0003] The existing column analog-to-digital conversion circuit for CMOS image sensors generally samples and converts the reset voltage and signal voltage of the pixel row by row, and performs analog correlation double sampling and amplifies the signal to the column modulus through the automatic gain control circuit. The input range of the conversion circuit, the output signal of the automatic gain control circuit is processed by the column analog-to-digital conversion circuit, and the effective signal value of the light is obtained. During the aforementioned processing, since the reset voltage and the signal voltage are subtracted by the automatic gain control circuit , which is not conducive to reducing noise, improving dynamic range and speed, and increasing the complexity of column-level circuits; at the same time, there is no relevant test circuit in the existing column analog-to-digital conversion circuits that can be used to realize column circuits and digital signal processing in a timely manner Sequence Control Testability

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