Radio-frequency variable attenuator

摘要

A variable attenuator comprises bipolar transistors Q1 and Q2 connected in reverse parallel between a point 1 and ground potential G. The base electrodes of the transistors Q1 and Q2 are biased independently by a control circuit 3. The collector of transistor Q1 and the emitter of transistor Q2 are commonly connected to a bias voltage provided by resistor R2 and voltage source Vr. The attenuator provides means by which the linearity, gain, power handling capabilities and noise figure of a front-end receiver can be altered. The attenuator is susceptible to integration in, for example, a radio receiver front-end.