Complementary metal-oxide semiconductor (CMOS) is a fabrication technology for semiconductor systems that can be used for the construction of digital circuitry, memories and some analog circuits. The technology is based on the pairing of two metal oxide semiconductor field effect transistors (MOSFET), one of which is a p-type and the other an n-type transistor. The term metal oxide semiconductor is a reference to the traditional structure of the device where there would be a metal gate on top of an oxide layer on top of a semiconductor. Today, the metal layer is replaced by a polysilicon layer most of the time.
CMOS dissipates power in two primary ways. When they are switching, there is a momentary short circuit across the transistor pair. Also, switching has to dissipate any stored charge (load capacitance) on the electrical connector between it and any other switches connected to it within the circuit. This is referred to as dynamic power. For older geometries, this was the majority of the power consumed by such devices. In more modern devices, the second power draw, when the device is remaining in the same state, has become more important. This is leakage power and may be a significant percentage of total power consumption.
- Other names: Complementary metal-oxide semiconductor
- Type: Semiconductor