Definition: CMOS sensor

A CMOS-based chip that records the intensities of light as variable charges similar to a CCD chip. Although initially used in less expensive digital cameras, the quality of CMOS sensors has improved steadily.

CMOS sensors have advantages over CCDs. They can be made like other CMOS chips on standard CMOS fabrication lines, which makes fabrication less costly, and auxiliary circuitry, such as analog-to-digital conversion, can be combined on the same chip. In addition, CMOS chips use less power than CCDs.

Active-Pixel Sensors
Another advantage is speed. Also called "active-pixel sensors," CMOS sensors perform in parallel with amplifiers in each pixel that convert charges to electrical voltages. In contrast, CCDs transfer their charges to shift registers before converting to voltage at a single amplifier stage.

Sony's Exmor CMOS Sensor
Exmor shortens the analog path even more by performing A/D conversion on each column of pixels. While all CMOS sensors perform noise cancellation in the analog domain, Exmor also deploys it in the digital domain. Contrast with CCD sensor. See CMOS camera and digital camera.