Si-MMIC用GHz帯磁性薄膜インダクタの低損失化  [in Japanese] Reduction of the Loss of a Magnetic Thin-Film Inductor of a GHz-Drive Si-MMIC  [in Japanese]

We microfabricated magnetic thin-film inductors for use as rf front-end receiver impedance matchers in 1-GHz-drive mobile commutication handsets. This is the first practical application of soft magnetic in the 1-GHz range. Fe-Al-O high-resistivity thin films were used for the inductors. The purpose of this paper is to demonstrate a method of reducing the loss of magnetic thin films. Thin Cr films were used as underlayers for the Fe-Al-O films in order to solve the problem. We slit the magnetic thin films in order to reduce eddy current losses. The resistance of the inductor by 40% at 1 GHz. A quality factor of Q=7.4 was achieved by using a Cr underlayer and slits at 1 GHz.