Lecture

Active Pixel Sensors: Design and Functionality

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Description

This lecture discusses the design and functionality of 7T active pixel sensors used in CMOS cameras. It begins by explaining the structure of the sensor, which includes a pinned photodiode, a reset transistor, and a floating diffusion. The instructor details the role of three transistors and CCDs that act as reservoirs, facilitating the transfer of signals. The layout of the sensor is described, highlighting the components such as the source follower and raw selector. The lecture emphasizes the advantages and disadvantages of the 7T design, particularly regarding the field factor. The process of correlated double sampling and global shutter operation is explained, detailing how the sensor captures images simultaneously across all pixels. The instructor outlines the steps involved in transferring data from the photodiode to the mid reservoir and then to the output diffusion, ensuring accurate signal reading. The lecture concludes with a mention of Sony's Pregius sensors, which utilize a similar three-reservoir system for enhanced performance.

Official source

Ontological neighbourhood

Information engineering

Signal processing: Digital image processing

Related concepts (32)

Image sensor

An image sensor or imager is a sensor that detects and conveys information used to form an . It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of current that convey the information. The waves can be light or other electromagnetic radiation. Image sensors are used in electronic imaging devices of both analog and digital types, which include digital cameras, camera modules, camera phones, optical mouse devices, medical imaging equipment, night vision equipment such as thermal imaging devices, radar, sonar, and others.

Active-pixel sensor

An active-pixel sensor (APS) is an , which was invented by Peter J.W. Noble in 1968, where each pixel sensor unit cell has a photodetector (typically a pinned photodiode) and one or more active transistors. In a metal–oxide–semiconductor (MOS) active-pixel sensor, MOS field-effect transistors (MOSFETs) are used as amplifiers. There are different types of APS, including the early NMOS APS and the now much more common complementary MOS (CMOS) APS, also known as the CMOS sensor.

Sensor

A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends the information to other electronics, frequently a computer processor. Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, and in innumerable applications of which most people are never aware.

Back-illuminated sensor

A back-illuminated sensor, also known as backside illumination (BI) sensor, is a type of digital that uses a novel arrangement of the imaging elements to increase the amount of light captured and thereby improve low-light performance. The technique was used for some time in specialized roles like low-light security cameras and astronomy sensors, but was complex to build and required further refinement to become widely used. Sony was the first to reduce these problems and their costs sufficiently to introduce a 5-megapixel 1.

Video camera

A video camera is an optical instrument that captures videos (as opposed to a movie camera, which records images on film). Video cameras were initially developed for the television industry but have since become widely used for a variety of other purposes. Video cameras are used primarily in two modes. The first, characteristic of much early broadcasting, is live television, where the camera feeds real time images directly to a screen for immediate observation.

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