Amplifier arrangement comprising two transistors
AssigneeU.S. Philips Corporation
InventorHermann Berger
Life of this patent
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Abstract
A symmetrical amplifier comprising two transistors having their emitters connected to ground via two resistors of equal value. An input signal is applied between the bases of the transistors and an output signal is available at the collectors of the transistors. This amplifier will provide improved linearity up to an input voltage of 200 mV if, for the emitter resistor, the relationship R.apprxeq.0.56 U.sub.T /I.sub.CO is satisfied, U.sub.T being the thermal voltage and I.sub.CO the collector quiescent current. The value of this resistor is very small so that the slope is reduced only slightly by the emitter resistors and the sensitivity of the circuit is hardly affected thereby.
Claims11
An amplifier arrangement comprising, first and second transistors each having an emitter, base and collector electrode, a pair of input terminals coupled to the base electrodes of the transistors for applying an input signal thereto in phase opposition, a pair of signal output terminals coupled to the collector electrodes of the first and second transistors, and a symmetrical resistor network connecting the emitter electrodes of the transistors to a point of constant potential, said resistor network being proportioned so that the slope of each of said first and second transistors is smaller than the value I.sub.CO /U.sub.T by a factor a, where I.sub.CO is the collector quiescent current of a transistor, U.sub.T is the thermal voltage, and a is a factor between 0.47 and 0.78.
Dependencies are inferred from the claim text.