Patent ID: 6577195
Filing Date: 2003-06-10
Classification: H03F

Abstract:
A bipolar differential amplifier, comprising:first and second transistors having respective emitters, bases and collectors and connected to respond differentially to a varying input signal to produce an amplifier current signal; a common resistor connected to the emitters of said first and second transistors for receiving said amplifier current signal; a third transistor having an emitter, a base and a collector, said emitter being connected to the common resistor, the third transistor provides only DC bias and provides no signal amplification; and DC bias means for biasing the bases of the first, second and third transistors, whereby the first, second and third transistors apply DC operating currents to said common resistor, wherein the value of the common resistor is arranged relative to the DC operating currents flowing therein so that the gain of said amplifier current signal of the differential amplifier relative to said input signal is substantially constant over a wide range.