Patent ID: 7489196

Claim:
A control circuit for controlling an output current from an output bipolar power transistor comprising: a sense network comprising a sense transistor coupled as an emitter-follower to a base of the output bipolar power transistor for sensing a base current thereof; an error amplifier for comparing an input bias voltage with a power control signal for generating an output signal; an input biasing network being controlled by the output signal from said error amplifier for biasing the output bipolar power transistor; a control current generator for generating a control current; a current-scaling circuit coupled to said control current generator and comprising a bipolar transistor of a same type as said output bipolar power transistor, and through which the control current generated by said control current generator generates a current-scaled control current to be compared with the sensed base current of said output bipolar power transistor; a first current-to-voltage converting network coupled to an output of said current-scaling circuit; and a second current-to-voltage converting network coupled to a collector of said emitter-follower sense transistor; said error amplifier having a first input coupled to said first current-to-voltage converting network, and a second input coupled to said second current-to-voltage converting network.