Analysis and stabilization tools for microwave amplifiers

In this paper, harmonic balance and envelope-transient tools are applied to the analysis and design of potentially unstable power amplifiers. The ranges of unstable behaviour are determined through bifurcation detection and the effects of odd-mode instability on the intermodulation distortion are investigated. The amplifier is stabilized using concepts from bifurcation control. Additionally, a feedback configuration for the amplifier stabilization is proposed and the results are compared with those obtained with previous methods, based on resistive loading. The techniques have been applied to a 4 GHz microwave amplifier.