As we have seen a semiconductor offer less resistance to flow current in one direction and high resistance is another direction and we can call transistor as the device mode of the semiconductor. Bipolar junction transistor bjt few most important applications of transistor are. The transistor is a threelayer semiconductor device consisting of either two n and one ptype layers of material or two p and one ntype layers of material. The basic structure of the bipolar junction transistor bjt determines its operating characteristics. Physical representations of the two types of bjts are shown in figure b and c.
Pdf be8251 basic electrical and electronics engineering. Bipolar junction transistors emitter p n collector base pnp transistor emitter n p base npn transistor bipolar. Because the transistor operation is carried out by two types of charge carriers majority and minority carriers, an ordinary transistor is called bipolar. An npn transistor can crudely be described, as being made up of a layer of p type semiconductor, sandwiched between two pieces of n type semiconductor. Bipolar junction transistors tlt8016 basic analog circuits 20052007 9 example 4. Introduction to bipolar junction transistor bjt youtube. Lecture 9 random variables, probability density function pdf. Analysis that replaces the transistor with a pair of batteries representing the two junction turn on voltages cvd model.
The transistor will operate as an amplifier or other linear circuit if the transistor is biased into the linear region. Computer science and engineering 32, mechanical engineering 65. The twocarrier flow from 1 and 4 forms the emitter current ie. Bjt basics department of electrical engineering, iit. It is a semiconductor device and it comes in two general types. Mar 15, 2020 a bipolar junction transistor is a three terminal semiconductor device consisting of two pn junctions which is able to amplify or magnify a signal. Bipolar junction transistor is 3 terminal semiconductor device which can be used as a switch or as an amplifier in the electronic circuits. Because of this, such junctions are very useful for operation at the frequencies as high as 10 ghz. Nptel video course electronics and communication engineering adv.
Collector npn transistor pnp transistor p n p n p n. Oct 25, 2016 bjt is constructed with three doped semiconductor regions separated by two pn junctions that are called emitter, base and collector. Bipolar junction transistors also known as bjts can be used as an amplifier, filter, rectifier, oscillator, or even a switch, which we cover an example in the first section. Analysis of a bipolar transistor showing that 1 amplification is a. Bipolar junction transistor and bjt circuits overview prerequisites. Bipolar junction transistors bjt general configuration and definitions the transistor is the main building block element of electronics. Bipolar junction transistor bjt field effect transistor fet transistors are used in. Types of bipolar junction transistor polytechnic hub. Typically a thin wafer of germanium was used for the base of the. Knowledge of basic circuit analysis exposure to theory of semiconductor pn junction optional. In this first transistor lecture, well spend time a. The three layers are called the emitter, base and collector. Bipolar junction transistors bjts basic construction. Lecture series on electronics for analog signal processing i by prof.
The reason it is known as bipolar because there is a. Bipolar junction transistors learn about electronics. May 11, 2018 today, i am going to discuss the details on the introduction to bjt bipolar junction transistor. Bjt bipolar junction transistor video lecture by prof r. The former is called an npn transistor, while the latter is called a pnp transistor. Bipolar junction transistors bjt and its applications. Gate preparation, nptel video lecture dvd, electronicsandcommunication engineering, analogcircuits, transistorbiasstability, small signal, equivalent circuits. Bipolar junction transistor construction engineering tutorial. Module 3 bipolar junction transistors semiconductors module 3 pdf 3 e. Bjt bipolar junction transistor construction, types and. Microelectronic engineering bjt basics page 3 definitions bipolar junction transistor bjt both holes and electrons participate in the conduction of current, hence the name bipolar. Srinivasan, dept of electrical engineering, iit madras for more details on nptel.
Controlled rectifier bjtbipolar junction transistor transistor in cb. The bipolar junction transistor bjt as a switch bipolar. Each junction can be forward or reverse biased independently. As the name suggests, it is composed of two junctions called emitterbase junction and collectorbase junction. Bipolar junction transistor 1 video lecture by prof s. Bipolar junction transistor bjt faculty of engineering. And the saturation current is a very small number, typically about 1 times 10 to the minus 15 amps. Modeling in frequency domain, mechanical system, electromechanical system, electric. Video lecture series from iit professorsbasic electronics by prof. In this page you can learn various important bipolar junction transistor questions answers,sloved questions on bipolar junction transistor and lots of important mcq on bipolar junction transistor amplifier etc. There are two junctions in bipolar junction transistor.
Boring analysis that removes the transistor from the circuit leaving an open circuit. It is used for amplification and switching purposes. Here we will describe the system characteristics of the bjt. Analog circuits video course course outline this course is an introduction to amplifiers using transistors. Lecture 3 bipolar junction transistor free download as powerpoint presentation. The output voltage, current or power is controlled by the input current in a transistor. Nptel verilog pdf the leading online trading academy. This two resistor biasing network is used to establish the initial operating region of the transistor using a fixed current bias. There are two types of bipolar junction transistor bjt are given below npn 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 operation of the transistor is very dependent on the degree of doping of the various parts of the.
The early voltage va has a typical value of 150 volts. Bipolar junction transistors bjt transistor basics a bipolar junction transistor is a three layer npn or pnp semiconductor device. Analog circuits transistor bias stability exam study material. The bipolar junction transistor bjt is an active device. In this section we will describe the operating principles of an npn transistor. In summary, during this lesson i introduced the bipolar junction transistor, a three terminal device that consists of two pn injunctions. It is very easy to understand and help you to improve your skill. In npn transistor the current is conducted by the electrons as majority charge carriers as well as holes are minority charge carriers. 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. Bipolar junction transistor bjt semiconductor theory. Bipolar junction transistors types of bipolar junction transistors. This section contains lecture notes from the course. The holes have positive charge and electrons have negative charge. Gate preparation, nptel video lecture dvd, electronicsandcommunication engineering electroniccircuits, i, junctionfieldeffecttransistor, rectifiers, filters, dc load line, load line, operating point, bipolar junction transistor, biasing methods for bjt, bjt design stability, bias compensation, thermal stability, biasing, biasing for jfet, junction field effect transistor, biasing.
Small signal model, bjt biasing for discrete circuit design, single stage amplifier. Download pdf of bipolar junction transistor notes material offline reading, offline notes, free download in app, engineering class handwritten notes, exam notes, previous year questions, pdf free download. Introduction to bjt bipolar junction transistor the. Bc548 is general purpose silicon, npn, bipolar junction transistor. A signal of small amplitude if applied to the base is available in the amplified form. Lecture 4 bjt small signal model continuation from lecture 3. It is an electronic component mainly used for amplification and switching purpose. These regions essentially form two backtoback pn junctions in the same block of semiconductor material silicon.
Scribd is the worlds largest social reading and publishing site. Minority carrier in a ptype semiconductor electrons are the minority carrier type, in an ntype semiconductor holes are the minority carrier type. Jul 12, 2016 the basic structure of the bipolar junction transistor bjt determines its operating characteristics. Mainly the difference is that a power device has to. Lecture notes mechanical engineering mit opencourseware. The circuit shown is called as a fixed base bias circuit, because the transistors base current, i b remains constant for given values of vcc, and therefore the transistors operating point must also remain fixed. The base current i b controls the collector current i. The three terminals of the bjt are the base, the collector and the emitter. Bipolar junction transistor construction engineering. 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. Equivalent to an off state when transistor is used as a switch.
Part ilectures bipolar junction transistorsbjts and circuits. In this lecture, well introduce one of the fundamental analog devices. The bipolar junction transistor is a semiconductor device which can be used for switching or amplification in the diode tutorials we saw that simple diodes are made up from two pieces of semiconductor material to form a simple pn junction and we also learnt about their properties and characteristics. The very first bipolar junction transistors were fabricated from a bar of germanium with two closely spaced alloyed contacts. Lecture 3 bipolar junction transistor bipolar junction. Why transistor is called current controlled device. Bipolar junction transistors bjts the bipolar junction transistor is a semiconductor device constructed with three doped regions.
We will spend some time understanding how they work based on what we know about pn junctions. Germanium was used since it could easily be purified such that the minority carrier diffusion length was comparable to the distance between the two alloyed contacts. We will begin looking at transistors with the bipolar junction transistor. Fundamentals of bipolar junction transistor biasing.
One way to look at a bjt transistor is two backtoback diodes, has very different characteristics. Bipolar junction transistor notes material pdf download. Lecture 01 introductionlecture 02 introductionlecture 03 theory of semiconductorslecture 04 theory of semiconductorslecture 05 pn juctionlecture 06 rectifierslecture 07 rectifierslecture 08 rectifierslecture. Why an ordinary junction transistor is called bipolar. You see, the outward construction of this device is somewhat different from the small signal diodes and transistors which we saw. Introduction, semiconductor, equilibrium carrier concentration, carrier transport, excess carriers, pn junction, procedure for device analysis, bipolar junction transistor bjt, metaloxidesemiconductormos junction, mos field effect transistor mosfet. Sep 01, 2008 lecture series on electronics for analog signal processing i by prof. The three regions are called emitter, base, and collector. The point contact junction has very low value of the capacitance. Bipolar junction transistor electrical engineering 123. I junction field effect transistor exam study material for. Radhakrishna rao, department of electrical engineering,iit madras. Explain why an ordinary junction transistor is called bipolar.