![]() The typical operation of this transistor happens within this region. The active region is also called a linear region which lies in between the two regions like the cutoff & the saturation. So, the active region can be mainly used for the purpose of amplification wherever this transistor performs like an amplifier through a gain ‘β’ with the following equation ![]() Here, the base current (Ib) is used to control the quantity of Ic (collector current). In this region, one junction is connected in a forward bias whereas the other one is connected in reverse bias. The operating of BJT can be done in three different regions like active, saturation, and cut-off. So, between these three junctions, the BE junction can be connected in forwarding bias & the BC junction is reverse biased. The emitter section is doped highly as compared to the remaining layers.īoth the layers like base and collector include the same concentrations of charge carriers. The flow of charge within a transistor is because of the charge carrier’s diffusion among the two sections which belongs to different concentrations of charge carriers. In NPN transistor, two semiconductor junctions are there which have a thin anode region doped with ‘P’ whereas PNP transistor includes two semiconductor junctions that include a thin cathode region doped with ‘N’. Working of BJTīipolar junction transistor is classified into two types namely PNP and NPN based on types of doping of the terminals. The BE junction shows high resistance as this junction can be connected in reversed bias. So, being the central part of the BJT will allow it to manage the charge carriers flow among emitter & collector terminals. The base terminal is the most lightly doped segment in the transistor. The base terminal is the center part among collector & emitter terminals which forms two PN junctions among them. A wire lead unites to every region and these leads are branded with C, B & E for the collector, base, and emitter respectively. Similarly, once the pn-junction connects the base & the collector region then it is known as the BC-junction. When PN-junction connects the base and emitter region then it is known as BE-junction. In BJT, the term bipolar refers to the utilization of both the charge carriers like electrons and holes within the structure. In NPN, it includes two N-regions separated by one P-region whereas, in PNP, it includes two P-regions and separates with one N-region. Construction of Bipolar Junction Transistor These transistors are available in two types namely PNP and NPN and their physical structure is shown below. This transistor includes three layers namely base, emitter, and collector. So, the construction of BJT can be done through three doped semiconductor sections which are separated through two PN-junctions. The construction of BJT will determine its working characteristics. The three configurations are: 1) The Common Base, which has no current gain but has voltage gain, 2) The Common Emitter, which has both current and voltage gain, and 3) The Common Collector, which has current but no voltage gain.Construction of Bipolar Junction Transistor Each connection method responds to a circuit’s input signal in a different way. There are three ways to connect a BJT in an electronic circuit since it is a three terminal device. BJTs regulate current in proportion to the amount of biasing voltage applied to their base terminal and act as a controlled switch as a result. The labels used on BJTs are Base (B), Emitter (E), and Collector (C ). What are BJTs?Ī BJT (Bipolar Junction Transistor) consists of two PN-junctions that produce three terminals that connect with each one given a unique name to distinguish it from the other two. Bipolar Junction Transistors can operate in three different regions: the active region where the device acts as an amplifier, the saturation region where the transistor is fully on and acts as a switch, and the cut-off region where the device is fully off and acts as a switch. Its ability to switch between these two states allows it to act as a switch or amplifier. What is a Transistor?Ī transistor is an active three terminal device that is made up of different semiconductor materials that act as either conductors or insulators through the application of small signal voltage. They have also been combined with MOSFETs to create hybrid circuits. BJTs are normally used in discrete circuit design as well as high-demand analog circuits such as RFs for wireless systems. The BJT is a three layer, three terminal, and two junction device. They share a common N or P terminal, which forms the basis of a BJT or Bipolar Junction Transistor. When two single diodes are connected to each other back-to-back, two PN-junctions that are connected in series are created. Basic diodes are constructed from two semiconductor materials, germanium or silicon, to create a basic PN-junction.
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