Analysis of Odd-Mode Parametric Oscillations in HBT Multi-Stage Power Amplifiers

Abstract

In this paper a technique for predicting odd-mode parametric oscillations from the analysis of exact pole-zero cancellations that take place in the frequency response obtained at some specific nodes of power amplifiers is presented. By using this technique the nature of parametric oscillations can be determined, which allows establishing a suitable strategy for circuit stabilization. The proposed methodology has been applied to the analysis and elimination of parametric odd-mode oscillations in an X- band two-stage MMIC power amplifier. The analysis has been complemented with the harmonic-balance calculation of the odd-mode frequency-divided steady-state solution.