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When we talk about an n-p-n transistor in common emitter configuration, we often say that emitter-collector circuit (the one towards right) is reverse biased. In what sense it is reverse biased? Here, both terminals are n-type, for such a thing to be reverse biased must not we put positive voltages across both the n-type terminals?

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    \$\begingroup\$ Look at the C-B pn junction and Vcc>Vbb. \$\endgroup\$ – LvW Feb 13 '15 at 15:30
  • \$\begingroup\$ That would mean C-B pn junction is reverse biased. I am confused about C-E. \$\endgroup\$ – Swami Feb 13 '15 at 15:33
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A BJT has two PN junctions:

  1. The Emitter-Base Junction or Emitter junction.
  2. The Collector-Base Junction or Collector junction.

So you can say something like "Emitter junction is forward biased" or "collector junction is reverse biased". You can not say that the collector-emitter circuit is reverse biased since there is no 'collector-emitter' junction.

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