Spherical Wave Based Macromodels for Efficient System-Level EMC Analysis in Circuit Simulators Part I: Optimized Derivation and Truncation Criteria

This work presents a general framework that enables one to compute near- and far-field interactions inside a circuit simulator environment, aimed at efficient system-level electromagnetic compatibility (EMC) analysis. For readability, the paper is subdivided in two parts. Part I focuses on deriving (high-order) spherical wave based macromodels in optimal time and describes two truncation criteria which define the maximum complexity of the models. The latter is generally a compromise between the accuracy of reconstructed near-fields and the computation time for evaluating interactions between these models, and is therefore a crucial parameter when such models are to be applied in fast circuit solvers. Existing guidelines on truncating spherical wave expansions are held against the newly derived criteria. In part II, the framework is extended with optimized routines that enable one to compute efficiently near- and far-field interactions between the macromodels discussed in part I. It will be shown that by extensive understanding of spherical wave expansions, the underlying computations only add negligible computational cost compared to traditional S-parameter simulations, partially contributed to correctly chosen truncations of the applied models.