CMOS图像传感器的硬复位电路研究

Research on CMOS Image Sensor Hard Reset Circuit

像素复位电路是CMOS图像传感器的重要组成部分，其特性直接影响着图像的质量．本文对CMOSAPS图像传感器的动态范围、抗饱和能力、图像滞后以及非线性等性能进行了分析，并讨论了通过复位电路改善CMOS图像传感器性能的方法．在本文中，设计了两种带有抗饱和电路的硬复位电路，一种是采用传统的交叉耦合结构实现电压转换，另一种是基于改进的锁存器结构并增加阈值补偿管来实现，两种方案各具特点，分别适用不同的应用要求．仿真结果表明，两种电路方案均能够使动态范围提高2—3dB，增强像素抗饱和能力，同时消除了图像滞后与弱光下的非线性．

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 cir- cuit 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 Iransistor 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 2dB- 3dB,increase the ability of anti-blooming, and remove image lag and non-linearity at low-light level.