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 drains. 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.
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 drains 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