Patent ID: 7649417

Claim:
A circuit for audio amplification, comprising: an input differential pair including a first bipolar transistor having at least a base, a collector, and an emitter; and a second bipolar transistor having at least a base, a collector, and an emitter; a bias current duplicator transistor having at least a base, a collector, and an emitter; a plurality of translinear elements that are arranged such that a voltage between the collector and the emitter of the bias current duplicator transistor is substantially the same as a voltage between the collector and the emitter of the first bipolar transistor; and a current mirror having at least an input that is coupled to the base of the bias current duplicator transistor, a first output that is coupled to the base of the first bipolar transistor, and a second output that is coupled to the base of the second bipolar transistor, wherein the plurality of translinear elements include: N translinear elements arranged to provide N diode drops down from the emitter of the first transistor to a first node; N translinear elements arranged to provide N diode drops up from the first node to the emitter of the bias current duplicator transistor; M translinear elements arranged to provide M diode drops down from the collector of the first transistor to a second node; and M translinear elements arranged to provide M diode drops up from the second node to the collector of the bias current duplicator transistor.