Communications
Revolution 		Communications
Networks 		Optical
Fibres 		Photonic
Devices 		Future of
Communications 		Credits

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Principle of The Transistor
Symbol of Transistor The basic transistor is a sandwich of two types of semiconductor: n-type and p-type.

An n-type semiconductor is for instance a piece of silicon doped with phosphorus atoms. This material has more free electrons in its conduction band.
A p-type semiconductor is for instance a piece of silicon doped with boron atoms. This material has more holes in its valence band.
The transistor has a base, a collector, and an emitter.
For instance, in the case of an p-n-p transistor:
  • the emittor and collector are p-type.
  • the base is n-type.

  • The collector is connected to a power source;
  • the emittor is the output, and
  • the base controls how much power is applied to the output.

    The collector current flows when sufficient bias is applied on the base.
    As the base current increases, current flows from the collector to the emitter. 
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