Thin-film RF noise suppressor integrated onto a transmission line

We discuss the possibility of the integrated countermeasure of radio-frequency (RF) electromagnetic (EM) noise emission on a RF integrated transmission line by using the loss generation of ferromagnetic thin-films. The targeting frequency range is 1-10 GHz, where most of the bulk and the composite ferrite materials have only a small loss generation. A 3μm thick rf-sputter deposited Cu film was used form a thin coplanar transmission line on a soda glass substrate with a characteristic impedance of 50Ω. The co-planar line is most common in RF integrated circuits. An integrated magnetic thin-film countermeasure element was put on the transmission line with a 7μm thick polyimide layer in between. The magnetic film suppresses the high frequency noise by means of ferromagnetic resonance (FMR) losses. The 0.1μm thick Co₈₅Nb₁₂Zr₇ amorphous film was applied in narrow slit trains along the easy axis of magnetization in order to shift the FMR frequency toward the higher frequency range. The transmission characteristics were evaluated by the S₂₁ parameter.