MOSFETs

A MOSFET (metal-oxide semiconductor field-effect transistor) is a field-effect transistor (FET) used for switching or amplifying signals. MOSFETs are now even more common than BJTs (bipolar junction transistors) in digital and analog circuits. MOSFETs have 3 terminals (source, drain and gate) that allow a voltage applied to the gate to control the flow of current between the source and drain. MOSFETs are particularly useful in amplifiers due to their input impedance being nearly infinite which allows the amplifier to capture almost all of the incoming signal.

Types: The most common MOSFET types include N-channel MOSFETs, P-channel MOSFETs, enhancement-mode MOSFETs, depletion-mode MOSFETs, power MOSFETs, RF MOSFETs, and automotive-qualified MOSFETs, each optimized for specific switching, amplification, or power management requirements.

Applications: MOSFETs are commonly used in power supplies, motor drives, switching regulators, amplifiers, computing devices, and automotive electronics.

Selection requirements: Choosing a MOSFET requires evaluating voltage and current ratings, on-resistance (Rds(on)), switching speed, gate drive requirements, thermal performance, and package type to ensure efficient and reliable operation in the intended application.