06-03-2013, 10:42 AM
MOSfet
MOSfet.ppt (Size: 156 KB / Downloads: 27)
INTRODUCTION
The metal oxide semiconductor field effect transistor
(MOSfet) acts like a voltage controlled current source.
The gate voltage controls the drain current.
There are more of these transistors than any other.
A major use is in digital systems.
MOS transistors can be very small with a length less than
one micron (red light has a wavelength of 0.63 microns.).
MOS Transistor
Metal Oxide Semiconductor (MOS) transistor current flows from the drain to the source through the p-type silicon. A positive voltage on the gate induces electrons in the channel enabling current to flow.
Modern MOS transistors have a polycrystalline silicon gate
rather than metal. The distance between the source and drain
can be less than a micron. Precise alignment of the gate source
and drain is achieved by placing the gate first. The gate
then prevents the N diffusion from entering the p-type region.