Fundamental Study on Tunable RF Magnetic Devices Using DC Bias Magnetic Field Generated by Permanent Magnet Film

A tunable coplanar resonator using a combination of high-permeability soft magnetic thin film/permanent magnet film was fabricated and evaluated. The magnetic pole based on the remanent magnetization of permanent magnet film, which is controlled by a pulse-current magnetization scheme, generates a dc bias magnetic field in the soft magnetic film. Consequently, the permeability of the soft magnetic film can be controlled by changing the pulse-current magnetization for the permanent magnet film. A scheme to control the permeability of the soft magnetic film is described here, and fabrication and evaluation of the tunable coplanar-resonator are also explained.