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Research on CMOS image sensor hard reset circuit

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Abstract

Pixel reset circuit is an important component of CMOS image sensor, whose characteristics affect the image quality directly. The performances of CMOS image sensor, such as dynamic range, anti-blooming, image lag and non-linearity, are analyzed. This paper also discusses the methods to improve performance through reset circuit. In this paper, two kinds of hard reset circuit with anti-blooming circuit are designed, one is the use of conventional cross-coupled configuration to implement reset level shift, the other is based on improved latch configuration with adding compensation transistor of threshold value, both schemes with different advantages and disadvantages adapt for different applications. The simulations reveal that both circuits implement can enhance dynamic range by 2 dB~3 dB, increase the ability of anti-blooming, and remove image lag and non-linearity at low-light level.

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