Detailed investigation of fundamental instability mechanisms in power amplifiers

Advances in the understanding and prediction of instability phenomena in power amplifiers are presented. The effects of the input signal on the circuit natural frequencies are analyzed from an insightful viewpoint, combining pole-zero identification with bifurcation detection versus bias voltage and input power. The impact of gain expansion and parametric effects on the stability properties are studied using this combined approach, which also takes into account the relationship between poles and Floquet multipliers. Multi-valued power transfer curves are demonstrated to be caused by a parametric resonance at the fundamental frequency.