Port Parameter Extraction Based Self Consistent Coupled EM-Circuit FEM Solvers

TL;DR

This paper introduces a novel port parameter extraction method for self-consistent EM-circuit coupling using FEM, enabling efficient and accurate analysis of linear and non-linear circuit-EM systems in the frequency domain.

Contribution

It extends a recent time domain integral equation approach to FEM for stable port parameter extraction, matching fully coupled solutions in accuracy.

Findings

Port extraction reduces computational cost compared to full coupling.

The method accurately reproduces self-consistent solutions for non-linear circuits.

Integration with device physics models is demonstrated.

Abstract

Self consistent solution to electromagnetic (EM)-circuit systems is of significant interest for a number of applications. This has resulted in exhaustive research on means to couple them. In time domain, this typically involves a tight integration (or coupling) with field and non-linear circuit solvers. This is in stark contrast to coupled analysis of linear/weakly non-linear circuits and EM systems in frequency domain. Here, one typically extracts equivalent port parameters that are then fed into the circuit solver. Such an approach has several advantages; (a) the number of ports is typically smaller than the number of degrees of freedom, resulting in cost savings; (b) is circuit agnostic; (c) can be integrated with a variety of device models. Port extraction is tantamount to obtaining impulse response of the linear EM system. In time domain, the deconvolution required to effect this is unstable. Recently, a novel approach was developed for time domain integral equations to overcome this bottleneck. We extend this approach to time domain finite element method, and demonstrate its utility via a number of examples; significantly, we demonstrate that self consistent solutions obtained using either a fully coupled or port extraction is identical to the desired precision for non-linear circuit systems. This is shown within a nodal network. We also demonstrate integration of port extracted data directly with drift diffusion equation to model device physics.