Abstract: A high gain RF amplifier comprises first and second common-emitter transistor amplifier stages coupled in cascade between an RF input terminal to which RF signals to be amplified are applied and an RF output terminal from which amplified RF signals are derived. A first RF signal feedback path is coupled between the emitter of the second common-emitter transistor amplifier stage and the RF input terminal. A directional coupler is connected to provide a second, high reverse isolation RF signal feedback path between the output terminal and the emitter of the first common-emitter transistor amplifier stage. The first RF signal feedback path preferably comprises a resistor-capacitor circuit coupled in series between the emitter of the second common-emitter transistor amplifier stage and the base of the first common-emitter transistor amplifier stage.

Abstract: A linear attenuator using a dc control current to change the rf resistance of PIN diodes in series and parallel with the load. As the control current changes, the rf resistance of the series diode varies inversely and the parallel diode varies directly providing attenuation which changes linearly as a function of the control current through the series diode.