Thin-film inductor for gigahertz band with CoFeSiO-Si[O.sub.2] multilayer granular films and its application for power amplifier module

The thin-film power amplifier module for wide-band code division multiple access was designed and fabricated using the magnetic thin film as magnetic core of choke inductors. CoFeSiO--Si[O.sub.2] multilayer granular films showing high resistivity and good magnetic properties were applied to the module. Inductance value increased about 30% by application of magnetic films, and occupation area and series resistance were also reduced by 20%. The obtained module size was 3.0 mm x 3.5 mm, which was much smaller than the conventional power amplifier module, since the bias circuit was formed on the same silicon substrate. Index Terms--Choke inductor, magnetic film, power amplifier module, thin-film inductor.