Nonlinear Stability Analysis of MMIC Power Amplifiers

Any correction of the manufactured MSIC circuits is obviously not possible. Moreover designers do not have efficient and rigorous tools to detect and localize the possible instbilities of their circuits using standard CAD packages. This is particularly true in the case of very complex circuits such as power amplifiers where oscillations can appear under constant bias conditions or under the application of a microwave signal. In this paper, we introduce the HB formalism to predict linear stability but above al nonlinear stability with local and global analysis. This method relying on the general Harmonic Balance formulation has been developed in our laboratory on the software L.I.S.A. [4]. Finally, an MMIC example of non linear local investigation and instability localization demonstrates the importance of non-linear stability checking during the circuit design.