Common emitter BJT transistor circuit

Discussion in 'General Electronics Chat' started by mghg13, Oct 5, 2014.

  1. mghg13

    Thread Starter Member

    Jul 17, 2013
    63
    0
    Hello guys,

    In a simple CE npn BJT circuit, is it possible to have some leakage current flowing from ground through the emitter terminal to the base IF a negative voltage is applied as input to the base?

    thanks
     
  2. ramancini8

    Member

    Jul 18, 2012
    442
    118
    Yes, the B-E junction acts like a diode, so there is reverse leakage current. In fast switching circuits high negative voltage was applied through current limiting resistors to the base to suck charge out of the junction fast. If the applied negative voltage exceeded the B-E breakdown spec the junction would zener. Later it was proved that repeated reverse breakdown caused a beta degradation.
     
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  3. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    As said the reverse voltage breakdown is given in the datasheet as Veb0.
    See the picture for an example:

    [​IMG]

    Bertus
     
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  4. mghg13

    Thread Starter Member

    Jul 17, 2013
    63
    0

    Thanks ramancini8 and bertus. Exactly what I wanted to know.
     
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