Field Effect Transistor

• In switching applications, field effect transistors are preferred because they consume less power.
• FET's also have a NPN (or PNP) sequence of materials.
• However, the conductivity is controlled through the so-called gate that is electrically insulated from the device itself.
• By adjusting the voltage between the gate and the substrate, the width of a conducting channel between source and drain can be controlled.
• Functionally, the following correspondences between BJT and FET exist:
  • base - gate
  • source - collector
  • drain - emitter
• The most common FET technology is called MOSFET for metal-oxide-semiconductor FET.
• In digital electronics, P-type and N-type MOSFETs are combined to form CMOS (complementary MOS) logic gates.