FET

FET stands for Field Effect Transistor. It doesn’t behave like a BJT, it doesn’t amplify a base current. Instead a voltage on the gate (that hardly demands current) opens or closes the current in the source-drain. Hence, the input impedance of a FET can be very high (GOhm). It resembles therefore the behaviour of an electronic tube.

The PDF on FET’s

JFET-Theory-and-Applications