Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

PNP versus NPN bipolar transistors

  1. Aug 1, 2014 #1
    Hi,

    Could anybody explain me why the base current of a pnp is higher than a npn for the same collector current?

    Regards,
    David
     
  2. jcsd
  3. Aug 5, 2014 #2
    It depends a great deal on the particular transistors. Some are designed for high current, some for low, and the current gain varies with many different influences: current, voltage, temperature for starters.
    Some manufacturers do make complementary pairs of transistors in NPN and PNP which are designed to match each other reasonably well, for push-pull applications.
     
  4. Sep 7, 2014 #3
    The simple reason traces to hole mobility - which translates to a lower beta - which translates to a higher Ib for the same Ic value compared to an NPN.
     
  5. Sep 7, 2014 #4

    vk6kro

    User Avatar
    Science Advisor

    A transistor which has less current gain than another will require more base current for the same collector current.

    PNP and NPN transistors come in a variety of current gain versions, so you couldn't claim PNP types have lower gain without producing some evidence that this is true.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook