A bipolar junction transistor bipolar transistor or bjt is a type of transistor that uses both electrons and holes as charge carriers. Nptel provides elearning through online web and video courses various streams. Introduction to bipolar junction transistor bjt slideshow. Today, i am going to discuss the details on the introduction to bjt bipolar junction transistor. Because of this, such junctions are very useful for operation at the frequencies as high as 10 ghz. Autoplay when autoplay is enabled, a suggested video will automatically play next. Bipolar junction transistors bjt and its applications. It is an electronic component mainly used for amplification and switching purpose.
Solid state devices electronics and communication engineering course from iit madras nptel lecture videos by prof. The light bulb invented by thomas edison in the early 1880s was one of the first uses of vacuum tubes for any. A bipolar junction transistor bjt consists of three differently doped re gions. Lecture 3 bipolar junction transistor bipolar junction. These can have the configuration of npn or pnp and the various layers can either be. The operation of the transistor is very dependent on the degree of doping of the various parts of the. Introduction, semiconductor, equilibrium carrier concentration, carrier transport, excess carriers, pn junction, procedure for device analysis, bipolar junction transistor bjt, metaloxidesemiconductormosjunction, mos field effect transistor mosfet. Electronic materials, devices, and fabrication by prof s. Lecture 3 bipolar junction transistor free download as powerpoint presentation. Bjt circuit analysis pdf currently this section contains no detailed description for the page, will update this page soon. As the name suggests, it is composed of two junctions called emitterbase junction and collectorbase junction. The hetero bipolar junction transistor is also a type is the bipolar junction transistor.
Bipolar junction transistors solidstate device theory. Bipolar junction transistors pdf 46p download book. The point contact junction has very low value of the capacitance. Methods of transistor biasing s bharadwaj reddy august 14, 2016 september 27, 2016 in the interest of simplicity and economy, it is desirable that transistor circuit should have a single source of supplythe one in the output circuit i. Parasuraman,department of metallurgy and material science,iit madras. The early voltage va has a typical value of 150 volts. A bipolar junction transistor, or bjt, is a type of transistor in which the current flow between the collector and the emitter is controlled by the amount of current that flows through the base. Before transistors came into existence vacuum tubes were used. Bjt bipolar junction transistor construction, types and. Lecture series on electronics for analog signal processing i by prof. Jan 17, 2017 56 videos play all basic electronics nptel arsh sharma the evolution of computing vacuum tube to transistor to integrated circuit documentary duration. It is a semiconductor device and it comes in two general types. The three layers are called the emitter, base and collector.
Basic construction, biasing and operation of npn and pnp type transistors. The bipolar junction transistor ii regimes of operation outline regimes of operation largesignal equivalent circuit model output characteristics reading assignment. Transistor action baseemitter junction is forward biased and collectorbase junction is reverse biased electrons emitted into base much more than holes since the doping of emitter is much higher magic. The operation of npn and pnp transistors are same if the roles played by the electrons and holes are interchanged. A bipolar transistor consists of a threelayer sandwich of doped extrinsic semiconductor materials, a and c either pnp or npn b and c. Summary the bipolar junction transistor bjt is constructed of three regions. Each layer forming the transistor has a specific name, and each layer is provided with a wire contact for connection to a circuit. Sep 01, 2008 38 videos play all electronics electronics for analog signal processing i nptelhrd lecture 21 transistor bjt inverter duration. Bipolar junction transistor working, definition, application. Bipolar junction transistor 2 general construction a bipolar junction transistor consists of two pn junctions in close proximity to each other two arrangements are possible according to whether the middle region is n or ptype material npn or pnp leads are attached to the three regions, known as emitter, base, and. Bipolar junction transistor theory pdf 27p currently this section contains no detailed description for the page, will update this page soon.
Applications of bipolar junction transistor or bjt. These videos are provided by nptel elearning initiative. Bipolar junction transistors emitter p n collector base pnp transistor emitter n p base npn transistor bipolar. It is a type of transistor that uses both electron and hole charge carriers. Up next transistor as an amplifier and as a switch phy duration. There are two junctions in bipolar junction transistor.
Bipolar junction transistor 1 by basic electronics. Electronic current is conducted by both free electrons and holes in bipolar junction transistor. How a bjt bipolar junction transistor works its all in the doping the way a transistor works can be described with reference to fig. The hbt can handle the singles of very high frequencies of several hundred ghz generally it is used in ultrafast circuits and mostly used in radiofrequency. There is no conduction between the collector and the emitter. In summary, during this lesson i introduced the bipolar junction transistor, a three terminal device that consists of two pn injunctions. The first bipolar transistor was invented at bell labs by william shockley, walter brattain, and john bardeen so late in 1947 that it was not published until 1948. Bipolar junction transistors bjt general configuration and definitions the transistor is the main building block element of electronics. These regions essentially form two backtoback pn junctions in the same block of semiconductor material silicon. The bipolar junction transistor bjt was named because its operation involves conduction by two carriers. The bjt has two pn junctions, the baseemitter junction and the basecollector junction. There are two basic types of bipolar transistor construction, pnp and npn, which basically describes the physical arrangement of the ptype and ntype semiconductor materials from which they are. Smith department of eecs university of california, berkeley eecs 105 spring 2004, lecture 22 prof. There are three terminals in bipolar junction transistors are explained below.
It uses different semiconductor materials to the emitter and base region and produces heterojunction. One pn junction of a transistor is reversebiased, whereas the other is forwardbiased. The availability of singlecrystal silicon technology with higher purity levels together. Solid state devices iit madras online course video. In electronics, vacuum tube triodes were used almost for half a century before the bjts. Power bipolar junction transistor bjt background the bipolar junction transistor was invented in 1947 by shockley, brattain, and bardeen. The transistor is the main building block element of electronics it is a semiconductor device it is a three terminal device two basic families of transistors are. Collector npn transistor pnp transistor p n p n p n. Bipolar junction transistors bjt transistor basics a bipolar junction transistor is a three layer npn or pnp semiconductor device. The transistor bjt was not the first three terminal devices. Solid state devices lecture 20 heterojunctionbipolar.
Introduction to bjt bipolar junction transistor the. Also includes some basic characteristics and parameters of the bjt. Introduction to bipolar junction transistors bjt bipolar. Unlike a normal pn junction diode, this transistor has two pn junctions. Bipolar junction transistor npn bjt shown 3 terminals. Lecture 4 outline bipolar junction transistor bjt general considerations structure otii ti d ee105spring 2008 lecture4, slide 1prof. Bipolar junction transistor bjt field effect transistor fet transistors are used in.
The three terminals of the bjt are the base, the collector and the emitter. Unipolar transistors, such as fieldeffect transistor s, use only one kind of charge carrier. The base current i b controls the collector current i c. Dc operation of bipolar junction transistors bjts there are two types of bjts, the npn and pnp the two junctions are termed the baseemitter junction and the basecollector junction in order for the transistor to operate properly, the two junctions must have the correct dc bias voltages the baseemitter be junction is.
A bipolar junction transistor is a threeterminal semiconductor device that consists of two pn junctions which are able to amplify or magnify a signal. Bipolar junction transistors transistor operation the biasing of the two types of transistor has been illustrated in the figures. Here we will describe the system characteristics of the bjt. Upon completion of the presentation you will be able to understand. Each junction can be forward or reverse biased independently.
Bipolar junction transistor bjt few most important applications of transistor are. Radhakrishna rao, department of electrical engineering,iit madras. Bipolar junction transistors tlt8016 basic analog circuits 20052007 11 distortion figure 4. Most electrons cross the base junction and are swept into collector why. The multifold advantages of replacing vacuum tubes with a solidstate device rapidly promulgated its use in applications. The word transistor is a combination of the two words trans fer var istor which describes their mode of operation way back in their early days of electronics development.
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