Automatic pole-zero identification for multivariable large-signal stability analysis of RF and microwave circuits

Current methods for stability analysis through pole-zero identification rely on a quality assessment based on visual inspection. This implies a manual approach that limits in practice the identification of large amount of data. Here, an automated methodology for large-signal stability analysis through pole-zero identification is proposed. The methodology is based on an algorithm that prevents the adverse effects due to undermodeling and overmodeling on the stability criteria. The automatic routine enables the use of pole-zero identification for multivariable large-signal stability analyses in which a large amount of individual identifications have to be performed and evaluated. The proposed methodology is illustrated through its application to a RF LDMOS distributed power amplifier. A multivariable stability analysis reveals two different kinds of parametric oscillations depending on the load and input drive conditions.