What Are Field Effect Transistors?

Field effect transistors, or FETs, are a commonplace electronic component found in many circuit assemblies. Coming in the form of assembled discrete electronic components, FETs are capable of managing the flow of current through the voltage that is induced at the gate terminal. While FETs are often found in numerous power control, electronic switching, and amplification applications, their primary use is within integrated circuits where they enable large scale assemblies to operate with ease. In this blog, we will discuss FETs in more detail, allowing you to have a better understanding of their common functionalities and types.

Field effect transistors are three-terminal electronic devices, those of which include the drain, source, and gate. The source is the terminal which charge carriers traverse when entering the FET channel, while the drain is the exit terminal. Meanwhile, the gate is the component terminal that governs the conductivity present between the source and drain terminals.

During standard operations, the FET will handle charge carriers that come in the form of electrons or holes. Passing through the active channel, the charge carriers will move from the source channel to the drain channel. The active channel itself is made from semiconductor materials, those of which are either N-type or P-type materials. To manage the amount of conductivity present in the component, the input voltage can be manipulated as needed.

Depending on the application in question and the particular needs of a device, there are numerous field effect transistor types that one may take advantage of. To begin, FETs are broken up into two main categories, those of which are junction and insulated gate FETs. Junction FET (JFET) components are those that feature a reverse biased diode junction as their gate connection. For their semiconductor materials, the channel may be an N- or P-type material. To ensure proper functionality, a semiconductor diode is fabricated onto a channel so that the diode voltage governs aspects of the FET channel. As a type of reverse biased device, only diode reverse current may flow between the channels.

Insulated gate FETs serve as the other main category, the most common subtype being the Metal Oxide Silicon FET (MOSFET). MOSFET transistor components are semiconductor devices that are most commonly implemented within electronic assemblies for amplification and switching purposes. In order for a MOSFET to have its conductivity alternate between the source terminal and drain terminal, the voltage induced at the gate terminal is adjusted.

While MOSFET transistors are a subtype of insulated gate FETs, they also come in different types as well. N-channel MOSFETs are a form in which the movement of electrons allows for conduction to be carried out. As compared to other MOSFETs, the N-channel MOSFET exhibits high efficiency and low resistance, all while being fairly compact. P-channel MOSFET components are the other major MOSFET subtype, and their conduction is made possible through the movement of holes, rather than electrons. P-channel MOSFETs exhibit a lower amount of efficiency as compared to N-channel types, though their resistance is much higher.

With JFETs, MOSFETs, and other various field effect transistor components available on the market, countless circuit assemblies and electronic devices may benefit from their use. As some examples, FETs support the operations of analog switches, current limiters, cascode amplifiers, choppers, phase shift oscillators, multiplexers, and buffer amplifiers. If you are designing or maintaining an electronic device or assembly and require field effect transistors, there is no better alternative to AFR Enterprises.

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