Implementation of X-parameter models in harmonic-balance simulators

X-parameter modeling paradigm constitutes a major advancement in circuit and system simulation and design. However being a frequency domain defined nonlinear model, its implementation in harmonic-balance simulators is not trivial. The implementation available in commercial simulators does not fully respond to the needs. In particular, the multi-tone simulations and the prediction of the dynamic effects remain challenges. This paper presents a method to implement such behavioral models into the RF engines. Despite the fact that this paper covers the implementation of X-parameter model, it's perfectly applicable to any behavioral models describing the relations between complex envelope signals.