Discussions of holes and electrons area unit higher left to a special chapter in my opinion. Here I want to explore the way to use these elements, not analyze their intimate internal details.
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 revolution made possible the design and manufacture of lightweight, inexpensive electronic devices that we now take for granted.
Understanding how transistors function is of paramount importance to anyone interested in understanding modern electronics. The Function and Applications for Bipolar Junction Transistors My intent here is to focus as exclusively as possible on the practical function and application of bipolar transistors, rather than to explore the quantum world of semiconductor theory.
Discussions of holes and electrons are better left to another chapter in my opinion. Here I want to explore how to use these components, not analyze their intimate internal details.
In taking this approach, however, I assume that the reader possesses a certain minimum knowledge of semiconductors: Each layer forming the transistor has a specific name, and each layer is provided with a wire contact for connection to a circuit. The schematic symbols are shown in the Figure below a and d.
The functional difference between a PNP transistor and an NPN transistor is the proper biasing polarity of the junctions when operating. For any given state of operation, the current directions and voltage polarities for each kind of transistor are exactly opposite each other. Bipolar transistors work as current-controlled current regulators.
In other words, transistors restrict the amount of current passed according to a smaller, controlling current.
The main current that is controlled goes from collector to emitter, or from emitter to collector, depending on the type of transistor it is PNP or NPN, respectively.
The small current that controls the main current goes from base to emitter, or from emitter to base, once again depending on the kind of transistor it is PNP or NPN, respectively. According to the standards of semiconductor symbology, the arrow always points against the direction of electron flow.
Figure below Small Base-Emitter current controls large Collector-Emitter current flowing against emitter arrow.
Bipolar Transistors Contain Two Types of Semiconductor Material Bipolar transistors are called bipolar because the main flow of electrons through them takes place in two types of semiconductor material: P and N, as the main current goes from emitter to collector or vice versa.
|Bipolar Junction Transistors (BJT)||History of the transistor A replica of the first working transistor. The thermionic triodea vacuum tube invented inenabled amplified radio technology and long-distance telephony.|
|How an npn Bipolar Junction Transistor (BJT) works||This is called conventional current. However, current in many metal conductors is due to the flow of electrons which, because they carry a negative charge, move in the direction opposite to conventional current.|
|Transistor - Wikipedia||Because transistors are able to control current in an analog infinitely divisible fashion, they find use as amplifiers for analog signals.|
|Bipolar junction transistor - Wikipedia||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.|
|Note that the polarity of and direction of associated with the PN-junction between E and B are the same as those associated with a diode, voltage polarity: The forward biased base-emitter BE PN-junction allows the free electrons in emitter to go through the PN-junction to arrive at the base, forming the emitter current.|
In other words, two types of charge carriers—electrons and holes—comprise this main current through the transistor. This is the first and foremost rule in the use of transistors: The small, controlling current is usually referred to simply as the base current because it is the only current that goes through the base wire of the transistor.
Conversely, the large, controlled current is referred to as the collector current because it is the only current that goes through the collector wire.A variety of effects occur in bipolar transistors, which are not included in the ideal transistor model.
These include the base-width modulation effects and the . Bipolar Junction Transistor (BJT) is a Semiconductor device constructed with three doped Semiconductor Regions (Base, Collector and Emitter) separated by two p-n Junctions, Figure 1.
The p-n Junction between the Base and the Emitter has a Barrier Voltage (V 0) of about V, which is an important parameter of a BJT.
The Bipolar Junction Transistor (BJT) as a Switch. Meter Check of a Transistor (BJT) Active-mode Operation (BJT) The Common-emitter Amplifier. The Common-collector Amplifier. The Common-base Amplifier. The Cascode Amplifier. Biasing Techniques (BJT) Transistor Biasing Calculations. Input and Output Coupling.
Chapter 4 - Bipolar Junction Transistors The invention of the bipolar transistor in ushered in a revolution in electronics. 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.
A bipolar junction transistor (bipolar transistor or BJT) is a type of transistor that uses both electron and hole charge carriers. In contrast, unipolar transistors, such as field-effect transistors, only use one kind of .
This chapter introduces the bipolar junction transistor (BJT) operation and then presents the theory of the bipolar transistor I-V characteristics, current gain, and output conductance. High-level injection and heavy doping induced band narrowing are introduced. SiGe transistor, transit .