A model for impedance of planar RF inductors based on magnetic films

An electromagnetic model is presented for planar stripe inductors based on thin metallic magnetic films. The model solves Maxwell's equations analytically, allowing eddy currents in both the conductor and the magnetic film, for an inductor structure in which the magnetic film completely encloses a stripe conductor. For typical inductor geometries, eddy currents in the magnetic film are the main factor limiting the efficiency of the device. We find, however, that stripe inductors with significantly enhanced inductance characteristics and high efficiencies (Q/spl sim/10) up to 1 GHz range are feasible.