Monolithic integrable constant current source for transistors connected as current stabilizing elements

Claim 1

A monolithic integrable constant current source comprising: a source of supply voltage having a voltage conducting pole and a zero voltage pole; a plurality of current stabilizing transistors of one conductivity type having base-emitter sections connected in parallel and in the same direction; a control transistor having a base-emitter section connected in the same direction and parallel to the base-emitter section of one of said plurality of current stabilizing transistors; a resistor coupled between the collector of said control transistor and said second pole; and a DC regulating amplifier receiving at its input a fraction of the common base current and delivering at its output the total common base current, said amplifier coupled between the junction of said resistor and collector of said control transistor and the junction of the bases of said plurality of current stabilizing transistors for comparing a reference voltage with the voltage at the junction of said resistor and control transistor collector for adjusting the difference to equal the potential at a common reference point, said regulating amplifier comprising: a first transistor having an emitter coupled to the voltage conducting pole of said reference voltage, and a base coupled to the junction of said resistor and the collector of said control transistor, the voltage across said voltage conducting pole and said base establishing said reference voltage; and a second transistor having a base coupled to the collector of said first transistor, and emitter coupled to the zero pole of said supply voltage and a collector coupled to the junction of the bases of said plurality of current stabilizing transistors.