Explain the Naming of Transistor Terminals

Explain the Naming of Transistor Terminals

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- A transistor (pnp or npn) has three sections of doped semiconductors. The section on one side is the emitter and the section on the opposite side is the collector. The middle section is called the base and forms two junctions between the emitter and collector.

(i) Emitter: The section on one side that supplies charge carriers (electrons or holes) is called the emitter. The emitter is always forward biased w.r.t. base so that it can supply a large number of *majority carriers. In Fig. 4.2 (i), the emitter (p-type) of pnp transistor is forward biased and supplies hole charges to its junction with the base. Similarly, in Fig. 4.2 (ii), the emitter (n-type) of npn transistor has a forward bias and supplies free electrons to its junction with the base.

(ii) Collector: The section on the other side that collects the charges is called the collector. The collector is always reverse biased. Its function is to remove charges from its junction with the base.
In Fig. 4.2 (i), the collector (p-type) of pnp transistor has a reverse bias and receives hole charges that flow in the output circuit. Similarly, in Fig. 4.2 (ii), the collector (n-type) of npn transistor has reverse bias and receives electrons.


(iii) Base: The middle section which forms two pn-junctions between the emitter and collector is called the base. The base-emitter junction is forward biased, allowing low resistance for the emitter circuit. The base- collector junction is reverse biased and provides high resistance in the collector circuit.

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Wilfykil answered the question on August 14, 2019 at 12:25

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