The Structure and Working Principle of a Bipolar Junction Transistor (BJT)

S. A. L. Maftunzada *

Faryab University, Maymana, Afghanistan.

*Author to whom correspondence should be addressed.


We studied bipolar junction transistors. We will see that the bipolar junction transistor, often referred to by its short name, transistor, actually functions as a current-controlled current source. We will also see that in the current generation of bipolar junction transistors, both majority and minority carriers are involved. For this reason, they gave this name to this type of transistor. In order to get enough information about this part, in the first two parts we will examine the construction and working method of the transistor. After that, we dedicate sections to how the transistor is placed in different combinations and the characteristics of the transistor in each combination.

Keywords: P-N junctions, BJT transistor, PNP and NPN types

How to Cite

Maftunzada , S. A. L. (2022). The Structure and Working Principle of a Bipolar Junction Transistor (BJT). Physical Science International Journal, 26(11-12), 35–39.


Download data is not yet available.


Dastgeer G, Shahzad ZM, Chae H, Kim YH, Ko BM, Eom J. Bipolar junction transistor exhibiting excellent output characteristics with a prompt response against the selective protein. Advanced Functional Materials. 2022;32(38): 2204781.

Ahn SH, Sun GM, Baek H. Turn-off time improvement by fast neutron irradiation on pnp Si Bipolar Junction Transistor. Nuclear Engineering and Technology. 2022;54(2): 501-506.

Attia JO. Circuits and electronics: Hands-on learning with analog discovery. CRC Press; 2017.

Xie S. BJT induced dark current in CMOS image sensors. Integration. 2022;87:260-263.

Westcott S, Westcott JR. Basic electronics: Theory and practice. Mercury Learning and Information; 2020.

Santos LA. An overview on bipolar junction transistor as a sensor for X-ray beams used in medical diagnosis. Sensors. 2022;22(5):1923.

Liu C, Li X, Geng H, Rui E, Yang J, Xiao L. DLTS studies of bias dependence of defects in silicon NPN bipolar junction transistor irradiated by heavy ions. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2012;688:7-1.

Shokri A, Amirmazlaghani M. Feasibility of digital circuit design based on nanoscale field-effect bipolar junction transistor. Journal of Electrical and Computer Engineering Innovations (JECEI). 2023; 11(1):33-40.

Suits BH. Electronics for physicists: An introduction. Springer Nature; 2020.