High-precision DAC (Digital-to-Analog Converter) for CMOS (Complementary Metal Oxide Semiconductor) image sensor

Abstract

The invention provides a high-precision DAC (Digital-to-Analog Converter) for a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The high-precision DAC comprises M-bit high-bit conversionand (K-M)-bit low-bit conversion being set separately, as well as high-bit high-reference output buffer and high-bit low-reference output buffer, wherein an M-bit high-bit conversion output end provides 2K intervals of high-reference output and low-reference output; the high-reference output and the low-reference output of each interval are connected to an analog reference end of low-bit conversion through corresponding high-bit high-reference output buffer and high-bit low-reference output buffer in order to provide an analog reference voltage; and the output after the low-bit conversion is the final analog output. Through adoption of the high-precision DAC, area and power consumption overhead optimization of a multi-channel high-precision DAC is realized; the problem of voltage mutationin the process of high-low bit switching is solved; the non-monotonic problem of the high-precision DAC is solved; and the uniformity of black-level correction and column fixed pattern noise correction of the CMOS image sensor is ensured.

Description

technical field [0001] The invention relates to a CMOS image sensor, in particular to a high-precision DAC for the CMOS image sensor. Background technique [0002] In recent years, with the continuous development of CMOS manufacturing technology, its advantages such as low cost, fast speed, on-chip integrated image processing unit, strong radiation resistance, and low power consumption have gradually emerged, and the imaging quality has also steadily improved. Markets, such as high-definition cameras, SLR cameras, mobile phones and other fields have replaced CCD and occupy the mainstream position. Its applications have also begun to expand from the civilian market to the aerospace field. Some domestic scientific research institutions have begun to try to use large-area CMOS detectors to replace traditional linear array CCDs as the main detectors for space detection. [0003] For the ultra-large area array CMOS image sensor mainly based on the column-level readout method, du...

AI Technical Summary

Problems solved by technology

Generally, it can be realized by configurable DAC technology, but in order to realize the black level correction of all pixels and the fixed pattern noise correction between channels and column levels, multiple DACs are required, which seriously increases the area and power consumption overhead.

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