High Conversion-Gain Pinned-Photodiode Pump-Gate Pixels in 180-nm CMOS Process

Abstract

This paper presents the design and characterization of high conversion-gain pixels in a 180-nm CMOS image sensor process. By reducing overlapping capacitance between a floating diffusion and transfer gate, output-referred pixel conversion gain as high as 118uV/eand read noise as low as 1.8erms are experimentally achieved without significant lag. A dark current of 38 pA/cm2 is measured at 60°C. Comparison between the proposed devices and a baseline pixel regarding device structure and characterization results is also presented.

Keywords

• CMOS image sensor
• high conversion gain
• pump gate
• low light imaging
• pinned photodiode