Nonlinear Behavioral Modeling Dependent on Load Reflection Coefficient Magnitude

Abstract

A new frequency-domain nonlinear behavioral modeling technique is presented and validated in this paper. This technique extends existing Padé and poly-harmonic distortion models by including the load reflection magnitude, ΓL, as a parameter. Although a rigorous approach requires a full 2-D load-pull model to cover the entire Smith chart, simulation and experimental evidence have shown that such a 1-D model - that retains only amplitude information of the load reflection coefficient - can give accuracy close to that of a full 2-D load-pull model. Consequently, neglecting the phase constitutes an approximation that provides large benefits without appearing to lead to a severe compromise in accuracy. Furthermore, compared with traditional load-independent models, the new ΓL-dependent models provide a major improvement in model accuracy. After a discussion of the model extraction methodology, examples are provided comparing traditional load-pull X-parameter models with the model presented in this paper. The new model not only provides consistently good accuracy, but also has a much smaller model file size. Along with the examples that display the ability of the new modeling technique to predict fundamental frequency behavioral, a second harmonic example is also provided. The modeling approach is also validated using measurements results.