Methodology for Characterization and Modelling of DC-Biased Surface-Mount Ferrite Power Inductors

A methodology for frequency-domain impedance characterization of DC-biased surface-mounted inductive components is proposed. The test structure based on a bias tee is designed to allow the S-parameter measurements of the inductive components under different DC current levels. The equivalent circuit model of a power inductor is extracted to validate the proposed methodology. The values of the circuit model elements are optimized at each DC current level to fit the impedance characteristics of the circuit model to the measured data. The normalized root-mean-square error of the equivalent circuit model compared to the measurements is calculated and found to be less than 10^-3.