Pade-Approximation-Based Behavioral Modeling

A new, nonlinear, frequency-domain behavioral model, based on Pade approximation theory, is presented in this paper. The new Pade model is similar in concept to the X-parameter method, but it uses a rational function instead of the X-parameter model's polynomial expression. The basic theory of the proposed Pade model and the model extraction methodology are provided. The proposed Pade approach increases the available modeling space beyond that available to the X-parameter method, and the performance of a selection of this family of models under various loading conditions is described in this paper. Along with the examples displaying the ability of the new model to predict fundamental frequency behavior, a second-harmonic example is also provided, with simulation results presented in both the frequency domain and the time domain. Based on the simulation studies and experimentally measured results, the new Pade model shows good accuracy and a high level of stability. All of these characteristics show that the proposed Pade model has high potential in RF design.