Analysis of optimum sheet resistance for integrated electromagnetic noise suppressors

This paper discusses the physical nature of the optimum sheet resistance of noise suppression sheets/films based on three-dimensional (3-D) finite-element method (FEM) electromagnetic field simulation. Co-Al-O films with sheet resistance of10(-1) - 10(5) Omega/square were deposited on top of a micro strip-line. It was revealed that inline loss generation was maximized with the film's sheet resistance of nominally 100 Omega/square, which explains well the earlier experimental results. The ratio of loss generation to the input power reached 0.96 in the experimental results and 0.97 in the simulation results at 6 GHz. A certain balance of eddy current generation and a material resistivity allowed the Co-Al-O film to dissipate the inline noise power effectively. The simulation results also showed that the inline power was not radiated from the Co-Al-O film but was lost in the film. Ferromagnetic resonance losses were found around 1-2 GHz combined with the eddy current losses. These two electric and magnetic losses enhanced total inline loss generation effectively.