A bipolar junction transistor (BJT) is a transistor that uses both electrons and holes as charge carriers. It has two semiconductor junctions, an emitter, base, and collector. There are two types - NPN transistors have an N-type material between two P-type materials, while PNP transistors have a P-type material between two N-type materials. BJTs can be used as amplifiers to increase voltage, current, or power of a signal, or as switches to drive high-current devices by using current gain to increase collector current substantially.
3. What is BJT?
A bipolar junction transistor is a type of transistor that uses
both electron and hole charge carriers. In contrast, unipolar transistors, such
as field-effect transistors, only use one kind of charge carrier. For their operation,
BJTs use two junctions between two semiconductor types, n-type and p-type.
5. NPN: The transistor in which one p-type
material is placed between two n-type
materials is known as NPN transistor.
PNP: The transistor in which one n-type
material is doped with two p-type materials
such type of transistor is known as PNP
transistor.
8. What is Amplifier?
• An amplifier is an electronic device, that increases the voltage, current or
power of a signal.
• Amplifier used in wireless communications and broadcasting and in audio
equipment of all kinds.
• They can be categorized as either weak signal amplifiers or power
amplifiers.
10. What is Switch?
• The Bipolar Junction Transistor can be used as a switch.
• This is required when the typical digital output does not provide sufficient current
drive for high current devices like lamps, solenoids or motors.
• The transistor current gain provides the order of magnitude increase in collector
current.
