Multi emitter transistors

Discussion in 'General Electronics Chat' started by Sparky49, Jun 19, 2012.

  1. Sparky49

    Thread Starter Well-Known Member

    Jul 16, 2011
    836
    417
    Hi all,

    Studying one of my bargain books, I come across an interesting (but brief) portion which mentions multi-emitter transistors.

    A quick Google search reveals that they are used in logic designs, but what is their actual construction?

    I presume that each emitter leg does not use the same bit of silicon, but wouldn't having multiple bits of p silicon, (or indeed n type) affect the operation of the overall transistor?

    Many thanks,

    Sparky
     
  2. jwd217

    New Member

    Jun 19, 2012
    5
    1
    Multi-emitter transistiors are used extensively in 7400 series of digital integrated circuits. Each emitter would be a seperate bit of silicon. They function exactly like several diodes connected together in the correct polarity. The only difference is that the transistors could operate at a higher frequency than the diodes could. As digital integrated circuits it made 2 to 8 input nand gates possible.
     
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  3. chuckey

    Well-Known Member

    Jun 4, 2007
    75
    10
    The emitters do all go to the same base junction. The 2n3866 VHF medium power transistor ( circs 1966) had over 110 emitters which were all connected together to give a really low inductance lead from the die.
    Frank
     
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  4. WBahn

    Moderator

    Mar 31, 2012
    20,237
    5,758

    Are you sure these were separate emitters and not simply a multi-bonded node? If they were separate emitters, then you could apply different voltages to them without causing any problems.
     
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