TheInfoList

An active-pixel sensor (APS) is an image sensor where each pixel sensor unit cell has a photodetector (typically a pinned photodiode) and one or more active transistors.[1][2] 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 much more common complementary MOS (CMOS) APS, also known as the CMOS sensor, which is widely used in digital camera technologies such as cell phone cameras, web cameras, most modern digital pocket cameras, most digital single-lens reflex cameras (DSLRs), and mirrorless interchangeable-lens cameras (MILCs). CMOS sensors emerged as an alternative to charge-coupled device (CCD) image sensors and eventually outsold them by the mid-2000s.

CMOS image sensor.

The term 'active pixel sensor' is also used to refer to the individual pixel sensor itself, as opposed to the image sensor.[3] In this case, the image sensor is sometimes called an active pixel sensor imager,[4] or active-pixel image sensor.[5]

## History

### Background

While researching metal–oxide–semiconductor (MOS) technology, Willard Boyle and George E. Smith realized that an electric charge could be stored on a tiny MOS capacitor, which became the basic building block of the charge-couple device (CCD), which they invented in 1969.[6][7] An issue with CCD technology was that it required the

The term 'active pixel sensor' is also used to refer to the individual pixel sensor itself, as opposed to the image sensor.[3] In this case, the image sensor is sometimes called an active pixel sensor imager,[4] or active-pixel image sensor.[5]