Draw the input and output characteristics of a junction transistor and explain their nature. A bipolar junction transistor bjt is a transistor whose operation depends on the contact made by two semicondutors. 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 circuits voltage and power amplifier circuits common emitter amplifier the circuit shown on figure 1 is called the common emitter amplifier circuit. Power bipolar junction transistor bjt is the first semiconductor device to allow full control over its turn on and turn off operations. That means it can handle large voltage and current. The vertical power bipolar junction transistor bjt has a fourlayer structure of alternating ptype and ntype doping as shown in figure 7. Bipolar junction transistor an overview sciencedirect. Transistor switch we can use a transistor switch to control a big current with a small current. The transistor is a terminal device and the three terminals are base, emitter, and collector. Pdf advanced drivers for power bipolar junction transistors bjt. Technical feats previously requiring relatively large, mechanically fragile, power hungry vacuum tubes were suddenly achievable with tiny, mechanically rugged, power thrifty specks of crystalline silicon. This chapter introduces the bipolar junction transistor bjt operation and then. There are two limitations on the power handling ability of a transistor.
If the power supply uses a high switching frequency, then a faster transistor will run cooler since it spends much less time in the linear region during transitions. Bipolar power transistor selection guide january 2003 table of contents product page general purpose transistors horizontal deflection output transistors product page dpak d2pak sot223 ipak to126 todarlington transistors dpak ipak to126 to220 to220f to3p to3pf switching transistors dpak d2pak to92 to126. These packages are designed for use in highpower amplifier and. Applications of bipolar junction transistor or bjt. The structure and construction of a power transistor is entirely different. It doesnt matter if you want to calculate the power in a resistor, transistor, circuit, or waffle, power is still the product of voltage and current. This could be an audio signal or perhaps some high frequency radio signal. Bipolar transistor characteristics the static characteristics for a bipolar transistor can be divided into the following three main groups. Ideally, a high power switch should be able to turn on and turnoff controllably and with minimum switching loss. The 2n2222 bjt belongs to a sort of npn bipolar junction transistor, used for general purpose lowpower amplifying or switching applications. The bipolar junction transistor was invented in 1947 by shockley, brattain, and bardeen. Over the past 3 decades, the higher layout density and lowpower advantage of cmos technology has eroded away the bjts dominance in integratedcircuit. Includes details of bjt device operation which is not covered in this course. The ratio of these two currents is of the order of 15 to 100.
Bjts are available in voltage ratings up to 1400v and current ratings of a few hundred amperes. Since a bjt is a threeterminal device, each of which may have a. The major functional area of 2n2222 is enclosed in to92. The invention of the bipolar transistor in 1948 ushered in a revolution in electronics. Bipolar junction transistors learn about electronics. Before transistors came into existence vacuum tubes were used. Bjt amplifier one of the primary uses of a transistor is to amplify ac signals. As the name implies, the power transistor is designed to work at power levels. It simplified the design of a large number of power electronic circuits. It has to be able to do this without distorting the. It is a semiconductor device and it comes in two general types. We begin with the concept of a bipolar junction transistor bjt in the inverting amplifier configuration, with an emitter resistor and the base bias provided by a voltage divider from the main supply voltage.
In electronics, vacuum tube triodes were used almost for half a century before the bjt s. Bipolar junction transistor circuits voltage and power. Bipolar junction transistor amplifiers biasing, gain. The light bulb invented by thomas edison in the early 1880s was one of the first uses of vacuum tubes for any electrical applications. Since a bjt is a threeterminal device, each of which may have a different current and voltage, for the purposes of power calculation it helps to consider the transistor as two parts. Bipolar junction transistors bjt general configuration and definitions the transistor is the main building block element of electronics. Of the two versions npn and pnp only the npn has been widely used in inverters. This is just a current source with the device you wish to switch in place of the load resistor. How a bjt bipolar junction transistor works its all in the doping the way a transistor works can be described with reference to fig. List the salient constructional features of a power bjt and explain. Power transistors are devices that have controlled turnon and turnoff characteristics.
It is known as a bipolar transistor since its operation requires two types of charge carriers holesandelectrons. The transistor bjt was not the first three terminal devices. The transistor has three terminals labeled collector, base, and. The bipolar junction transistor is an important power. The bipolar power transistor is a three layer npn or pnp device within the working range, the collector current ic is a function of the base current ib, a change in the base current giving a corresponding.
If you are testing pnp transistor, you should see ol over limit. The transistor is the main building block element of electronics. The way a transistor works can be described with reference to fig. Pdf new concept to drive a bipolar junction transistor with low drive losses find, read and cite all the research you need on researchgate. For an good npn transistor, the meter should show a voltage drop between 0. The bipolar power transistor is a three layer npn or pnp device within the working range, the collector current ic is a function of the base current ib, a change in the base current giving a corresponding amplified change in the collector current for a given collector emitter voltage vce. Sumit thakur ece seminars transistor ppt powerpoint presentation pdf.