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

 

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.

 

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

 

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

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.