DIFFERENTIAL AMPLIFIERS HAVING BETA COMPENSATION BIASING CIRCUITS THEREIN

摘要

Differential amplifiers include biasing circuits therein that can automatically account for process and/or temperature induced variations in &bgr; and thereby more uniformly maintain the voltage gain of the differential amplifier at a desired level. A differential amplifier is provided that comprises first and second bipolar transistors electrically coupled together as an emitter-coupled pair (ECP) and a biasing circuit that is electrically connected to first and second emitters of the first and second≤ bipolar transistors, respectively. This biasing circuit includes a current mirror that sets a magnitude of an emitter bias current in the first emitter at a value proportional to ( beta +Z+1)/( beta +1), where beta is the gain of the first bipolar transistor and 1+2 beta )/( beta <2>+2 beta 1) which is a relatively weak function of beta , even for small beta .