What happens if the base current goes out of the base of an NPN BJT?

  • \$\begingroup\$ You end up reverse-biasing both junctions. \$\endgroup\$ Jun 26, 2016 at 8:02
  • \$\begingroup\$ I suppose such a question (misconception?) can arise only because one thinks that a base current could be "injected" into a node like the base. But this is not the case. The base current IB is always the RESULT of an applied B-E voltage. \$\endgroup\$
    – LvW
    Jun 26, 2016 at 16:57
  • 1
    \$\begingroup\$ The transistor gets switched off faster. \$\endgroup\$
    – CL.
    Jun 26, 2016 at 17:55

1 Answer 1


you just reverse biased both diode(B-E & B-C) . Now question about the magnitude of the current.

If you have very little amount of current like micro ampere , then you just reverse biased both diode, on the other hand emitter and collector voltages are higher then base voltage.

If current is high like mA or more, you not only biased them reverse but also reverse bias voltage is more then break down voltage. And most likely your transistor is going to burn.


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