CMOS有源像素传感器像素级噪声的分析与抑制

Analysis and Reduction of Pixel Noise in CMOS Active Pixel Sensor

像素级的噪声是CMOS图像传感器的主要噪声源之一。针对CMOS有源像素传感器3T结构像素级的噪声问题,分析了3种抑制像素级噪声的方法。分析结果表明,复位晶体管的软复位噪声要小于硬复位噪声的2倍,PMOS管的1/f噪声低于NMOS管的1/f噪声,同时1/f噪声会随着栅面积的减小而增大。通过对像素的噪声分析,完成了3种像素级的集成电路的设计仿真,并采用了0.5μm标准CMOS工艺进行流片制作。测试表明,噪声的相对变化与分析结果吻合。

The pixel noise is one of the fundamental noises in CMOS pactive pixel sensors. We focuse on the pixel noise of CMOS active pixel sensors with three different 3T pixel structures for reducing noise. The analysis results show that soft reset leads to lower noise by a factor of √2 than normal KTC noise level. Besides, the 1/f noise of PMOS is much lower than that of NMOS, and the 1/f noise will become larger with the decrease of grate area. Based on above analysis, the design and simulation of three different CMOS APS are accomplished. Samples are fabricated by standard 0.5 μm CMOS process. Test results show that the changes of noise with different pixels match well with analysis results.