A POWER-CONSERVING LINEAR BROADBAND RF AMPLIFIER

摘要

A power-conserving, linear and broadband RF amplifier, suitable for use at more than one band in the ultra-high frequency regions allotted to radiotelephone transceivers, employs an emitter-follower output transistor to deliver the nominal 1.0 milliwatt RF power to a single-ended load from a low voltage battery, typically 2.7 v. dc, without the use of output coupling transformers. The amplifier receives only a small differential input signal from the preceding mixer or multiplier stage having a typical peak-to-peak magnitude of 0.3 v. The differential input signal is applied to the emitters of a pair of transistors whose bases are interconnected, one transistor of which is diode-connected in a current-mirror configuration and the other of which is configured in a common-base connection with emitter degeneration. The signals are summed at the collector of the common-base transistor to deliver a substantial voltage swing, illustratively 1.7 volts peak to peak, which is large enough to drive the base of the emitter-follower output transistor without requiring the high standby current in the emitter-follower normally required to maintain an emitter-follower in class A operation.