Broadband 3D Modeling and Simulation of DC-Biased SMT Ferrite Beads for EMI Filters

Electromagnetic interference (EMI) within electronic based systems (EBS) became a fundamental issue that requires dedicated countermeasures e.g. filter structures to avoid unintended system behavior. The sefilters comprise several components including surface-mounted(SMT) devices to suppress unwanted electromagnetic emissions. However, these devices change their behavior due to dispersion-and saturation-effects (ferroelectric-and ferromagnetic-effect), hence applying a DC bias current might lead to a significantly different behavior than intended. The presented methodology allows a broadband characterization of ferrite core materials used in SMT ferrite bead to predict the impact of dispersion-and saturation-effects on impedance behavior of device. The proposed modeling strategy is based on the Kramers-Kronig relation, vector network analyzer (VNA) measurements, and full-wave finite element simulations.The Extracted Material Models are validated for a frequency range from 100 kHz - 1 GHz and DC bias current levels up to 5A.