Efficient nonlinear Stability Analysis of Microwave Circuits using Commercially Available Tools

In this paper, two techniques for checking stability of multi-transistor MMIC circuits are analyzed. The two approaches allow both linear and nonlinear stability analysis of any complex circuit fed by small or large signals. The agreement found gives a unified way to propose a fast and efficient tool to ensure stability of a design during the design step using commercially available software. An example is given to evidence the suitability of the approach. It concerns a MMIC HBT power amplifier, which exhibited a frequency division phenomena that has been detected by simulations and confirmed by measurements.