Detecting and avoiding odd-mode parametric oscillations in microwave power amplifiers

Abstract

Multistage power amplifiers are prone to parametric oscillations of an odd-mode nature. In this article, a technique for detecting and avoiding odd-mode parametric oscillations in microwave power amplifiers under large-signal excitations is extended and improved. For that, two monolithic amplifiers, having different topology and different oscillation mode, are extensively analyzed. A previously analyzed X-band two-stage power amplifier is used as a first example. Then, the technique is applied to a novel L-band one-stage power amplifier exhibiting a different oscillation mode. The success in determining the oscillation nature of these two different examples and the strategies used for their stabilization clearly illustrate the potential of this technique to address the complex problem of parametric oscillations in microwave amplifiers. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE 15, 2005.