Exploring the Transistor’s Influence on Technology
In this article, we embark on a captivating journey to explore the profound impact of transistors on technology. We will delve into the origins of this remarkable invention, tracing its humble beginnings and monumental breakthroughs. From the pioneering work of Bell Labs to the collaborative efforts of brilliant minds, we will uncover the story behind the transistor’s rise to prominence.
Transistor
It is one of the most important semiconductor devices. It was invented by William Shockey in the year 1947. The term transistor is derived by contracting the word transfer resistor.
The current transfer occurs from low resistance to high resistance circuit. The transistor revolutionized electronics, leading to other inventions like integrated circuits IC, optoelectronic devices, and microprocessors. Transistor has replaced vacuum tubes in almost all applications.
The basic function of a transistor is to amplify a weak signal used in analog circuits. It is also used as a switch or a gate in a digital circuit.
Bipolar Junction Transistor
An electronic circuit device that consists of two P-N junctions formed by sand wishing either a P-type or N-type semiconductors between a pair of opposite layers is known as a transistor.
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The junction transistor is a three-layer (terminal) semiconductor device consisting of two P-type and one N-type region or two N-type and one P-type region. These formations are called PNP transistors or NPN transistors.
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Thus there are two types of junction transistors. The emitter and base P-N regions are from the diode, while the collector and the base P-N regions are from the collector diode.
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Generally, the transistor can be regarded as two P-N junctions connected back to back in series, as shown in Fig. The middle section, a very thin layer called the base, acts as the most important region in the function of a transistor.
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The abbreviation BJT, from bipolar junction transistor, is often applied to this three-terminal device. The term bipolar reveals the fact that holes and electrons participate in current flow.
Transistor terminals
A transistor has three doped regions: emitter, base, and collector. All these regions are provided with the terminals.
Emitter
The left-hand region of the transistor shown in the fig is called the emitter, and it is more heavily doped than the other two regions of a transistor.
Its main function is to supply the majority of carriers, either electrons or holes, to the base. The emitter is always forward-biased with respect to the base so that it can supply many majority carriers.
Base
The narrow central region of the transistor is called the base. The thickness of this region is very thin and is very lightly doped. The base-emitter junction is forward-biased, offering low resistance for the emitter current.
Collector
The right-hand region of the transistor, as shown in the figure, is called a collector. It is moderately doped. The collector region is always reverse-biased with respect to the base. The collector region of physically larger than the emitter region because it has not dissipated much greater power.
The junction between the emitter and base regions is the emitter-base junction. Similarly, the junction between the collector and base regions is known as the collector-base junction. The schematic symbol of the PNP and NPN transistors is shown in the figure.
The arrow in the circuit symbol of the transistor indicates the direction of conventional current flow and can be used to differentiate an NPN transistor from a PNP transistor. It is represented at the emitter terminal.
