Equivalent circuit analysis of an RF integrated ferromagnetic inductor

Abstract

An RF integrated air-core inductor and a ferromagnetic thin-film inductor having a ferromagnetic film on top of the spiral have been microfabricated. An equivalent circuit of the RF integrated spiral inductor with ferromagnetic film has been derived to analyze the contribution of the permeability of the magnetic film to the inductance of the inductor. The scattering parameters (S-parameters) have been measured to derive the equivalent circuit parameters of the inductors. Using the amorphous Co/sub 85/Nb/sub 12/Zr/sub 3/ film with slots, the inductance increased and the capacitance between the magnetic film and the coil and between the magnetic film and the ground could be neglected up to 5 GHz.