Junction field effect transistors are three-terminal semiconductor devices (Drain, Source, Gate) in which the voltage-current characteristics of the output port (Drain, Source) are controlled by the voltage applied to the input port (Gate, Source). JFETs may be n-channel or p-channel both types having similar characteristics except for the terminal polarization. JFETS are depletion mode devices due to their intrinsic bias, they conduct even when no bias voltage is provided at the gate terminal unlike enhancement FETs which require the gate to source voltage to be turned ON.

JFETs