Multi emitter transistors

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

  1. Sparky49

    Thread Starter Active Member

    Jul 16, 2011
    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,

  2. jwd217

    New Member

    Jun 19, 2012
    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.
    Sparky49 likes this.
  3. chuckey

    Well-Known Member

    Jun 4, 2007
    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.
    Sparky49 likes this.
  4. WBahn


    Mar 31, 2012

    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.