Low-voltage, high-noise immunity I2 L interface

Claim 1

An improved integrated injection logic (I 2 L) interface adapted for switching associated I 2 L logic circuitry by selective grounding of an associated bonding pad, including in combination: first and second transistors forming a differential pair, each transistor being of a first conductivity type and having base emitter and collector electrodes; a constant current source for providing an injector current to said emitter electrodes of said differential transistor pair; third and fourth transistors of a second conductivity type and having base emitter and collector electrodes; and means for connecting said base of said first transistor and said emitter of said third transistor to the associated bonding pad, for connecting said collector electrode of said first transistor to said base electrode of said third transistor, for interconnecting said collector electrode of said third transistor to said collector electrode of said second transistor and to said base electrode of said fourth transistor, and for connecting and permanently maintaining said base electrode of said second transistor and said emitter electrode of said fourth transistor at ground reference potential, said collector electrode of said fourth transistor being connected to the associated I 2 L logic circuitry for control thereof.