Device for coupling transistors operated in I2 L to a transistor operated at a higher bias-current

Claim 1

A coupling device within a semiconductor body having a region containing transistors operating in accordance with I 2 L technology including a driver transistor, said driver transistor being coupled to a transistor operated at a higher bias current, said coupling device comprising: an island of a first conductivity type on said semiconductor body; said island being electrically isolated from the rest of said semiconductor body; said island being connected to a fixed potential; said semiconductor body having a plurality of zones of a second conductivity type opposed to said first conductivity type; a lateral transistor formed on said semiconductor body, its base being said island of said first conductivity type, its collector being a first zone of said second opposite conductivity type and its emitter being a second zone of said second opposite conductivity type; a vertical transistor formed on said semiconductor body, said vertical transistor having said island and said first zone in common with said lateral transistor, said vertical transistor having said island as its collector; said first zone as its base and a third zone within said first zone of said first conductivity type as its emitter; said first zone common to said lateral transistor and said vertical transistor being connected to said driver transistor; said third zone, being the emitter of said vertical transistor and being connected to said transistor operated at a higher bias current; said second zone of said lateral transistor, being its emitter, which zone is not common to said vertical transistor, and being connected to a voltage supply such that the current from said second zone is larger than the current with which said I 2 L transistors are operated.