Multi emitter transistors

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

  1. Sparky49

    Thread Starter Well-Known 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.