On the Generation of SPICE-Compatible Nonlinear Behavioral Macromodels

This article presents a complete framework for the generation of behavioral macromodels of a wide class of nonlinear components, devices, and systems. The model structure and related identification algorithms are based on the Volterra series formulated in the frequency domain through multivariate generalized transfer functions (GTFs). A multivariate rational model is first estimated in pole-residue form from sampled responses and then converted to a bilinear state-space form. The main novel contribution of this work is the SPICE-compatible circuit synthesis, which enables the usage of nonlinear macromodels within circuit simulation environments as part of more complex system-level simulations. Examples are provided for a low dropout voltage regulator and a system-level power distribution network embedding integrated regulators. For such examples, the proposed SPICE equivalents offer speedup factors ranging from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12\times $ </tex-math></inline-formula> up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$650\times $ </tex-math></inline-formula> with negligible loss in accuracy.