What is JFET?
A Junction Field-Effect Transistor (JFET) is a sort of semiconductor device that is distributed across a lot of applications in electronic circuits including signal amplifying, impedance matching, and switching functionality. Different from Bipolar Junction Transistors (BJTs), JFETs are unipolar devices and are capable of only minority charge carriers’ movement, either, electrons or holes and by using on a single type of semiconducting material. JFETs come in two main types: N-channel and P-channel of which one is doped (in N-type) and the other one is not doped (in P-type).
The key component of a JFET is the semiconductor channel between two terminals: the upstream end and the downstream end. The source and drain terminal current such flow been became dependent on the applied voltage, which regulates the width of the channel through the gate terminal. For N-channel JFETs, a gate potential of negative voltage (mnas) widens channel width enabling higher current flow, while a gate voltage of positive potential (mas) achieves the same in P-channel JFETs.
The JFETs are appreciated because they have high impedance input, low noise and their design is simple. They are used for those applications which include amplifiers, as voltage-controlled resistors, and analog switches.
Symbol of N-Channel JFET and P-Channel JFET
The symbol of N-Channel JFET and P-Channel JFET is shown below
Symbol of N-Channel JFET and P-Channel JFET
Difference Between BJT and JFET
Bipolar Junction transistors (BJT) & Junction Field-Effect transistors (JFET) are important components that are used in many electronic circuits, which are based on semiconductors. In a BJT, there are three different layers of semiconductor material: N-type and P-type semiconductor material forming either an NPN or PNP configuration. As its functioning principle is based either on the movement of electrons via the junction or the flow of holes from the emitter to the collector terminal, it is one of the most effective and robust devices.
As JFET’s counterpart, the gate features a channel in which semiconductor material either will be N-type or P-type. The flow of current in a JFET is governed by a voltage being connected across the junction, which is responsible for the variation in the channel’s width and, in turn, the current between the source and drain terminals.
The JFET, unlike the BJT, works mainly on the ground of the voltage rather than the current. As for BJT and JFET, these two components exhibit key roles in amplification, switching, and signal processing applications supporting the design diversity of circuits through their peculiar traits and features.
Table of Content
- BJT
- JFET
- Operations
- Comparison
- Advantages
- Disadvantages
- Applications