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5Assistant of the Department of Telecommunication Engineering, Karshi branch of Tashkent
Abstract. A bipolar transistor is a semiconductor device commonly usedfor amplification. The device can amplify analog or digital signals. It can also switch DC or function as an oscillator. Physically, a bipolar transistor amplifies current, but it can be connected in circuits designed to amplify voltage or power.
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.
If we now join together two individual signal diodes back-to-back, this will give us Two PN-junctions connected together in series that share a common P or N terminal. The fusion of these two diodes produces three layers, two junction, three terminal device forming the basis of a Bipolar Junction Transistor, or BJTfor short.
Transistors are three terminal active devices made from different semiconductor materials that can act as either an insulator or a conductor by the application of a small signal voltage. The transistor's ability to change between these two states enables it to have two basic functions: "switching" (digital electronics) or "amplification" (analogue electronics). Then bipolar transistors have the ability to operate within three different regions: Active Region - the transistor operates as an amplifier Saturation - the transistor is "Fully-ON" operating as a switch Cut-off - the transistor is "Fully-OFF" operating as a switch
Keywords: bipolar transistor, emitter, ocyllograph, generator, bode plotter, voltmeters, groundings, source, knots, resistances, electronic workbench.
Introduction
A bipolar junction transistor is a three-terminal semiconductor device that consists of two p-n junctions which are able to amplify or magnify a signal. It is a current controlled device. The three terminals of the BJT are the base, the collector, and the emitter. A signal of a small amplitude
University of Information Technologies https://doi.org/10.5281/zenodo.7989648
Typical Bipolar Junction Transistor
PNP BJT
NPN BJT
Introduction to BJT
applied to the base is available in the amplified form at the collector of the transistor. This is the amplification provided by the BJT. Note that it does require an external source of DC power supply to carry out the amplification process.
Construction of Bipolar Junction Transistor BJT is a semiconductor device that is constructed with 3 doped semiconductor Regions i.e. Base, Collector & Emitter separated by 2 p-n Junctions.
Bipolar transistors are manufactured in two types, PNP and NPN, and are available as separate components, usually in large quantities. The prime use or function of this type of transistor is to amplify current. This makes them useful as switches or amplifiers. They have a wide application in electronic devices like mobile phones, televisions, radio transmitters, and industrial control.
Operation of Bipolar Junction TransistorThere are three operating regions of a bipolar junction transistor:
Active region: The region in which the transistors operate as an amplifier.
Saturation region: The region in which the transistor is fully on and operates as a switch such that collector current is equal to the saturation current.
Cut-off region: The region in which the transistor is fully off and collector current is equal
to zero.
Types of Bipolar Junction Transistor
There are two types of bipolar junction transistors:
PNP bipolar junction transistor
NPN bipolar junction transistor
Theory
The Bipolar Transistor basic construction consists of two PN-junctions producing three connecting terminals with each terminal being given a name to identify it from the other two. These three terminals are known and labelled as the Emitter ( E ), the Base ( B ) and the Collector ( C ) respectively.
In PNP BJT, the n-type semiconductor is sandwiched between the two p-type semiconductors. The two p-type semiconductors act as emitter and collector respectively while the n-type semiconductor acts as a base.
In NPN BJT, p-type semiconductor is sandwiched between the two n-type semiconductors. The two n-type semiconductors act as emitter and collector respectively while the p-type semiconductor acts as a base. This is shown in the figure below.
Emitter Base Collector
Je • üc
B
Emitter Base Collector
Je • Je
B
Schematic representation of bipolar transistor s
Common-collector amplifier (emitter follower)
Common-emitter amplifier
Common-base amplifier
Switching circuit
In today's advanced world of electronics, bepolar transistors are used in almost all electronic devices.Training and research of bipolar transistors in the process of training our future engineers is one of the most pressing areas. The study of electronic devices and the observation of their operation is not a complex topic for us today because we have thousands of programs that study electronic devices today.
One such program is the Electronic Workbench, one of the most convenient programs for student work and device research. In this article, we will look at the process of studying a bipolar transistor developed in an electronic workbench program. we study the general emitter amplifier of a bipolar transistor and observe the input and output signals of this amplifier through the oscilloscope.
Results
In the electronic workbench, we can create an electronic circuit using a bipolar transistor, and its operation is monitored by computing devices and the results are tabulated.
Scheme 1
Using our Scheme 1, we explore the process of operating a circuit using an electronic workbench program.
The results of the diagram collected in the workbench program were completed sequentially in the table.
The following was used in assembling the circuit:
1. Ocyllograph
2.Generator
3. Bode plotter
4. 2 voltmeters 5.9 groundings
6. Source
7. 10 knots
8. 3 resistances
9. n-p-n junction transistor 2N2923
10. 2 capacitors and several wires. The process of doing work:
1. EWB program was launched and the schematic shown in Figure 1 was assembled.
2. The parameters of the scheme elements are set as shown in Figure 1.
3. The scheme is started by pressing Ctrl + G.
4. The SS connector is connected to a current source of 1 mA, in which case the emitter current is IE = 1 mA.
5. The offset parameter of the GEN generator was set to 0 V and the readings of the ammeter and voltmeter were recorded.
6. The readings of the ammeter and voltmeter for each of its values were recorded by varying the GEN from 0 V to 20 V with the step shown in Table 1.
7. The results obtained are given in the table.
Table 1
Ie, mA Offset, V
0 2 4 6 8 9 10 11 12 15 20
1 U, V 7.59 7.00 -6.08 -5.05 3.36 2.04 0.52 1.44 2.39 5.25 10.12
I, mA 0.88 0.28 0.47 0.66 0.84 0.93 0.96 0.96 0.97 0.98 1
10 U, V 8.17 7.57 -6.64 -5.36 3.84 3.08 0.48 1.44 2.41 5.30 9.91
I, mA 0.94 2.87 4.78 6.66 8.51 9.42 9.62 9.67 9.70 9.82 10.21
1. Connect the SS to the 10mA power supply of the switch and reconnect points 5,6,7
2. Based on the results obtained, the output characteristics of the connected transistor according to the general basic scheme were performed for the values of the emitter current 1mA and 10 mA.
Conclusion
This article examines the input and output signals of a bipolar transistor. The necessary results for students of electronic specialties of higher education students were analyzed. the methods of assembling the circuit through an electronic workbench were taught and the desired results were obtained.
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