BJT & FET Current Mirror

Discussion in 'General Electronics Chat' started by Mohammad Zahidul Haque, Nov 26, 2014.

  1. Mohammad Zahidul Haque

    Thread Starter New Member

    Nov 26, 2014
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    What is the difference in between BJT and FET current mirror circuit ?
     
  2. tindel

    Active Member

    Sep 16, 2012
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    The type of transistor that is used... What do I win?
     
  3. crutschow

    Expert

    Mar 14, 2008
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    Functionally it's more difficult to do accurate FET current mirrors because of the normal large manufacturing variation in their Vth voltages. The Vbe of a BJT is generally a much closer match between transistors.
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Mosfet current mirrors are a strange lot and difficult to control (poor compliance).
     
  5. #12

    Expert

    Nov 30, 2010
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    In addition, bjt current mirrors work well enough on a monolithic chip, but discrete transistors generally need resistors in the emitter side to get them to match better, and getting them to track with temperature change is yet another consideration.
     
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