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, |Γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> |, 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 |Γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> |-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.