FETs are divided into two families: junction FET (JFET) and insulated gate FET (IGFET). The IGFET is more commonly known as a metal–oxide–semiconductor FET (MOSFET), reflecting its original construction from layers of metal (the gate), oxide (the insulation), and semiconductor. Unlike IGFETs, the JFET gate forms a p–n diode with the channel which lies between the source and drain. Functionally, this makes the n-channel JFET the solid-state equivalent of the vacuum tube triode which, similarly, forms a diode between its grid and cathode. Also, both devices operate in the depletion mode, they both have a high input impedance, and they both conduct current under the control of an input voltage. COUNT 5
QSN1 How many groups are FETs split into? ANS1 two QSN2 How is a JFET different from an IGFET? ANS2 the JFET gate forms a p–n diode with the channel QSN3 What are the names of the groups of FETs ANS3 junction FET (JFET) and insulated gate FET (IGFET) QSN4 What mode do both JFET and IGFET operate in? ANS4 depletion mode QSN5 What is the common term for an IFGET? ANS5 a metal–oxide–semiconductor FET (MOSFET)