Fundamental study of complementary metal oxide semiconductor image sensor for three-dimensional image processing system

In this paper, we describe a fundamental study of a complementary metal oxide semiconductor (CMOS) image sensor for a threedimensional (3D) image-processing system. We proposed a pixel circuit with correlated double sampling (CDS) and high-speed image capturing for high-speed image processing. The CDS and high-speed image-capture circuit should be realized simultaneously to allow high-speed image processing. The pixel circuit can realize CDS and high-speed image-capture functions simultaneously. The CDS and high-speed image capturing are realized by using a pixel sample hold capacitor and shared coupling capacitor. Appending extra capacitors causes the pixel circuit size to become large in the two-dimensional (2D) CMOS image sensor. We proposed a 3D CMOS image sensor that can reduce the pixel circuit size and the electrical wiring length and increase the fill factor, even with CDS and high-speed image capturing. Therefore, small, high-speed parallel-processing systems can be realized by using our 3D CMOS image sensor. We fabricated the prototype 2D pixel circuit with CDS and high-speed image capturing. The prototype pixel circuit is successfully implemented in the simultaneous function. We believe the proposed pixel circuit is very effective for 3D CMOS image processing.