FEM analysis on the effects of soft magnetic film as a noise suppressor at GHz range

To investigate the rf electromagnetic noise attenuation properties by soft magnetic films, the finite element method is applied to analyze electromagnetic field and loss generation in a coplanar transmission line with soft magnetic thin film at GHz range. The coplanar transmission line is with the total width of 400 μm and 50 μm width of signal line, 3 μm thickness, respectively, and has 50 Ω characteristic impedance. The change of the magnetic field distribution, the induced surface current density on the coplanar transmission line and hence the rf noise suppression by magnetic films are significant as a function of the magnetic film width/slit width (10/3, 20/3, and 50/3 μm) and magnetic film thickness (0.1, 0.3, 0.5, and 1 μm).