RF-integrated noise suppressor using spin-sprayed ferrite films

We demonstrated the RF-integrated noise suppressor on a coplanar transmission line using spin-sprayed ferrite films. The magnetic film was integrated on top of the transmission line by micro-lithography process with 2-μm-thick polyimide and without polyimide layer as an insulator between magnetic film and transmission line. These devices were composed of a 1.5-μm-thick ferrite film/insulator (or non-insulator)/transmission line/glass substrate. The NiZn-ferrite films were deposited by spin-sprayed ferrite plating, where magnetic films were patterned with a variation in length (15-2 mm) and width (2000-50 μm). The magnitudes of signal attenuation of the noise suppressor were changed from about -5 to -30 dB at 20 GHz. The power loss was enhanced up to 50% than that of non-integrated type at 5 GHz (stop-band frequency). The signal attenuations in pass-band frequency region were observed at about-3 dB at around 1 GHz, where signal attenuation can be reduced by design for considering characteristic impedance of transmission line along with the magnetic film.