What is BJT?
A bipolar junction transistor is represented by two port network. There are two types of bipolar junction transistor– NPN transistor and PNP transistor. Every transistor has three terminals- Emitter, Base and Collector.
- Emitter: It is the outer region of the transistor. It is used to transfer charge carriers (electrons in NPN transistor and holes in PNP transistor) to the base of transistor. It is doped heavily to provide large number of charge carrier to the base.
- Base: It is the middle region of the transistor. It is very small in length and lightly doped. Its function is to receive charge carriers from emitter and transfer it to collector region.
- Collector: It is another outer region of the transistor. Its doping is between that of emitter and base region. It is larger than emitter region. Its function is to collect charge carriers that was provided by emitter and transferred by base.
BJT Configurations
A transistor is also called as bipolar junction transistor or simply BJT. It is called as bipolar as only two types of charge carriers, i.e. majority charge carriers and minority charge carriers are required to perform the operations on transistor. BJT is a current-controlled device as the output voltage, current or power is controlled by the input current in the transistor. As we know, BJT is a three-terminal device , so the three configurations- we will study in this article. The three main configurations are – common emitter , common base and common collector , which has its unique characteristics and applications respectively.
Table of Content
- What is BJT?
- Configurations
- Operating regions of transistor
- Advantages
- Disadvantages
- Applications
- Comparison between CB, CE and CC configurations