Time-invariant behavioral modeling for harmonic balance simulation based on waveform shape maps

A new time-domain time-invariant periodic nonlinear behavioral model for multi-port systems is formulated from first principles in this paper. Unlike frequency-domain behavioral models like the Poly-Harmonic Distortion (PHD) model that describe the output frequency spectral components of the system, this black-box approach provides a time-invariant map of the discrete-time representation of the input waveform shape to the discrete-time representation of the output waveform shape, resulting in a reduction of the number of describing functions compared to a frequency domain description of the system. A two-port transistor behavioural model implementation for harmonic balance simulation is presented. The validation results show that the proposed model is capable of modeling the steady-state periodic output of multi-port nonlinear time-invariant systems and has potential to assist in the computer-aided design of RF systems with nonlinear components.