Basic electronics doubt: What is a bipolar device?

Replies

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  skipper

  It's called a bipolar device because there are two kinds of differently polarized material elements in the device.
  A bipolar transistor has two main sections which are n-type or p-type semiconductors. A third section is the base which straddles the two main sections. The idea is that the bipolarity is a kind of "stretch" in a membrane (made of charge) which biasing the device changes the size of.
  
  When a transistor (or a diode) is biased and the bias oscillates, the charge "stretches" and "compresses" inside the device (actually across the junction called the depletion region). This is like stretching and relaxing an elastic membrane, any "particles" on it will bounce around.
  
  So that, forward-bias gives electrons a kick in a certain direction; if they're in the +ve section of the device they see either a +ve boost (so they stay put) or a -ve boost (which repels them). The base in a transistor "injects" electrons as a signal, which the forward bias "carries". Hence, carrier + signal carried.
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  Anil Jain

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• 

  jvivin1990

  crazyboy

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  Sriman44

  the name "Bipolar" device says about it ..
  bi-two polar device..
  means two polar device + and - are two polars
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