What is a MOSFET?

MOSFET or Metal-Oxide-Semiconductor Field-Effect Transistor is a type of field-effect transistor that is widely used in electronic devices and integrated circuits. It is a three-terminal device that can be used as a switch or an amplifier, depending on its configuration and application.

The basic structure of a MOSFET consists of a semiconductor channel, usually made of silicon. The silicon channel is sandwiched between a source terminal (S) and a drain terminal (D) and is insulated from a metal gate electrode by a thin layer of insulating material, typically silicon dioxide.

There are two main types of MOSFETs: Enhancement-mode MOSFET and Depletion-mode MOSFET.

Enhancement-mode MOSFET: In its natural state, this type of MOSFET has little or no conduction between the source and drain terminals. When a positive voltage is applied to the gate terminal, it creates an electric field that attracts free electrons from the source terminal, forming a conductive channel between the source and drain. This allows current to flow through the channel when a voltage is applied across the source and drain terminals.

Enhancement-mode MOSFETs are further classified into two: N-Channel Enhancement-mode MOSFET and P-Channel Enhancement-mode MOSFET.

• N-Channel Enhancement-mode MOSFET: An N-Channel Enhancement Mode MOSFET is a type of MOSFET where the channel is created by the presence of positive voltage applied to the gate terminal. It is called "N-Channel" because the channel is formed by the movement of negatively charged electrons in an N-type semiconductor material. N-Channel Enhancement-mode MOSFET offer several advantages, such as low on-resistance, fast switching speeds, and efficient operation. It is widely used in various electronic applications such as power amplifiers, switching circuits, motor control, voltage regulators, etc.
• P-Channel Enhancement-mode MOSFET: A P-Channel Enhancement Mode MOSFET is another type of MOSFET where the channel is created by the presence of negative voltage applied to the gate terminal. It is called "P-Channel" because the channel is formed by the movement of positively charged "holes" in a P-type semiconductor material.

Depletion-mode MOSFET: In its natural state, this type of MOSFET has a conductive channel between the source and drain terminals. When a negative voltage is applied to the gate terminal, it repels free electrons in the channel, reducing the channel's conductivity and restricting the flow of current. Applying a positive voltage to the gate terminal can restore conductivity and allow current to flow through the channel.

N-Channel Depletion-mode MOSFET: An N-Channel Depletion Mode MOSFET is a type of MOSFET where the channel is naturally present in the absence of an applied voltage to the gate terminal. It is called "N-Channel" because the channel is formed by the movement of negatively charged electrons in an N-type semiconductor material.

When no voltage is applied to the gate terminal, the MOSFET is in its "off" state and has high resistance, blocking the flow of current between the source and drain terminals. However, when a sufficient voltage is applied to the gate terminal, an electric field is created in the insulating layer, which forms a conductive channel between the source and drain. This allows current to flow through the channel, and the MOSFET is in its "on" state, exhibiting low resistance.

MOSFETs offer several advantages over other types of transistors, such as high input impedance, low power consumption, fast switching speeds, and scalability for integration in integrated circuits. They are widely used in various applications, including digital logic circuits, switching power supplies, motor control, audio amplifiers, and radio frequency (RF) circuits.

Key Specifications of a MOSFET

Types of MOSFET: It represents the mode of MOSFET. The basic modes of MOSFETs are the N or P channel depletion MOSFET and N or P channel enhancement MOSFET.

Transistor polarity: It represents the MOSFET channel polarity. It can be either be P channel or an N channel.

Number of channels: It represents the number of channels in the MOSFET.

Continuous drain current: It is the maximum continuous drain current that the MOSFET can handle.

Drain source breakdown voltage: It refers to the maximum voltage that can be applied across drain and source terminals after which the MOSFET enters the breakdown region.

Drain source resistance: It represents the drain to source on-state resistance and is usually measured in the milli-ohm range.

Gate source voltage:  It represents the voltage that can be applied across the gate and source terminal.

Gate Source Threshold Voltage: It represents the minimum voltage that is applied between the gate and source terminal to make the MOSFET turn ON.

Gate Charge: It represents the total charge that is accumulated at the gate terminal. The gate charge value is used to find how fast a MOSFET switches from ON to OFF state, and vice-versa.

Power dissipation: It represents the maximum power dissipation across the output terminal of a MOSFET.

MOSFETs from the leading manufacturers are listed on everything PE. You can use the filters on the left side to narrow down the list of products based on your requirements - Type, Configuration, Topology, and other parameters. Our parametric search tool will scan multiple manufacturer websites to identify MOSFETs that meet your requirement. You can then download datasheets, request quotations via everything PE. Your inquiry will be routed to the manufacturer or their representative who will give you more information on the product.