Explain transistor as amplifier.

Asked by Pratibha Roy | 14th Feb, 2012, 10:48: AM

Expert Answer:

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The Transistor as an Amplifier

– Amplification is the process of linearly increasing the amplitude of an electrical signal.

– A transistor can act as an amplifier directly using the gain, b.

– Keep in mind that when a transistor is biased in the active (linear) region, the BE junction has a low resistance due to forward bias and the BC junction has a high resistance due to reverse bias.

i) DC and AC quantities

– Amplifier circuits have both ac and dc quantities.

– Capital letters are used will be used for both ac and dc currents.

– Subscript will be capital for dc quantities.

– Subscript will be lowercase for ac quantities.

ii) Transistor amplification

– A transistor amplifies current because the collector current is equal to the base current multiplied by the current gain, b.

– Base current (IB) is small compared to IC and IE.

– Thus, Iis almost equal to IE.

Answered by  | 14th Feb, 2012, 11:09: AM

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