Patent ID: 8610484

Claim:
A circuit comprising: (a) a main output stage including a main output transistor having a base coupled to operate in response to a first input signal, an emitter coupled to a first reference voltage, and a collector coupled to an output conductor; (b) an auxiliary output stage including an auxiliary output transistor having a base coupled to operate in response to the first input signal, an emitter coupled to the first reference voltage, and a collector coupled to the output conductor; (c) a clamping transistor having a control electrode coupled to the base of the auxiliary output transistor, a first electrode coupled to provide feedback via a first gain circuit to the base of the main output transistor and to also provide feedback to the base of the auxiliary output transistor, and a second electrode coupled to the collector of the auxiliary output transistor; and (d) wherein the auxiliary output stage supplies an amount of drive to the base of the auxiliary output transistor corresponding to an amount of drive supplied by the main output stage to the base of the main output transistor such that the auxiliary output transistor goes into deep saturation and causes the clamping transistor to generate negative feedback that limits drive to the base of the main output transistor so as to prevent the main output transistor from going into deep saturation, a current boost circuit, an additional output transistor having a base coupled to the base of the auxiliary output transistor, an emitter coupled to the first reference voltage, and a collector coupled to an input of the current boost circuit, an output of the current boost circuit being coupled to the base of the main output transistor.