2.2 Transistors ‐ BJT and MOSFET

Transistors are essential components in electronic circuits, acting as switches or amplifiers.

BJT (Bipolar Junction Transistor)

A BJT is a type of transistor that uses both electron and hole charge carriers. It has three regions: emitter, base, and collector.

• NPN: Current flows from collector to emitter when the base is positively biased.
• PNP: Current flows from emitter to collector when the base is negatively biased.

MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor)

MOSFETs are widely used due to their high efficiency and speed. They have three terminals: gate, source, and drain.

• N-channel: Conducts when a positive voltage is applied to the gate.
• P-channel: Conducts when a negative voltage is applied to the gate.