Explain the Common Emitter Connection in transistors

Explain the Common Emitter Connection in transistors

Answers

- In this circuit arrangement, input is applied between base and emitter and output is taken from the collector and emitter. Here, emitter of the transistor is common to both input and output circuits and hence the name common emitter connection. Fig. 4.16 (i) shows common emitter npn transistor circuit whereas Fig. 4.16 (ii) shows common emitter pnp transistor circuit.


- Base current amplification factor ( ß): In common emitter connection, input current is I_B and output current is I_C.
The ratio of change in collector current (change in I_C) to the change in base current (change in I_B) is known as base current amplification factor i.e.


- Relation between ß and a: A simple relation exists between ß and a. This can be derived as follows:

- It is clear that as a approaches unity, ß approaches infinity. In other words, the current gain in common emitter connection is very high. It is due to this reason that this circuit arrangement is used in about 90 to 95 percent of all transistor applications.

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Wilfykil answered the question on August 14, 2019 at 13:07

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