CMOS Cameras: Shutter Mechanisms and Noise Sources

This lecture discusses the properties of 3D Active Pixel Sensors in CMOS cameras, focusing on the rolling shutter effect and its implications for image capture. The instructor explains how the rolling shutter records each line of an image at slightly different times, leading to potential image deformation. Solutions to this issue, such as using mechanical shutters for instantaneous snapshots, are presented. The lecture then transitions to an analysis of noise sources in CMOS cameras, including photon noise, dark current noise, and reset noise. The instructor elaborates on the significance of correlated double sampling and the impact of amplifier noise on image quality. The discussion includes the advantages of using pinned photodiodes in CMOS image sensors to minimize dark current and reset noise. The lecture concludes with a comparison of standard photodiodes and the technology used in CMOS image sensors, emphasizing the importance of noise management in achieving high-quality imaging.