(
Junction
Field-
Effect
Transistor) Both JFETs and MESFETs (metal semiconductor FETs) are used for analog applications. However, JFETs are used in low-frequency applications such as audio amplifiers, whereas MESFETs are used in microwave and radar systems. See
FET.
Current Flow in a JFET (Junction FET)
Dating back to the 1940s and used in analog circuits, JFET squeezes the flow of electricity whereas a MOSFET switches the flow. With no pulse on the gate, current flows from source to drain. As electricity is applied to the gate, the depletion region grows, impeding current flow. Although electrons are shown (e) in this example, there are really trillions flowing.