A Methodology for Finite-Element Modeling of Magnetic Inductive Devices with In-Plane Multidomain Pattern

Incorporating magnetic materials into integrated-circuit inductors is an active area of research, offering higher inductance devices with smaller area. However, eddy current and spin dynamic losses in magnetic materials can hurt their performance. Here we analyze magnetic toroids as one candidate for IC inductors, utilizing a commercially available 3D electromagnetic FEM solver (Ansoft HFSS) that accounts for eddy currents and spin-dynamics. We verify our results obtained from HFSS using both the NIST OOMMF program and by directly calculating the toroid magnetic eigenmodes. Previous workers have considered toroid behavior assuming a single-domain (SD) toroid, with in-plane anisotropy parallel to the excitation current. However, this is the first analysis of the toroid dynamic behavior assuming a multi-domain (MD) pattern.