Design and Comparison of Filter Structures in the Millimeter Wave Frequency Range on Outer- and Inner-Layers of Organic Circuit Boards

This paper contains the design, simulation and measurement of two shuntstub bandpass filters, realized on the outer- and inner-layer of a printed circuit board (PCB). First, the influence of the prepreg on the RF transmission properties is analyzed. The necessary steps and special designs for realizing a functional inner layer filter are described as well. Especially the copper roughness has strong influence on inner layer structures. Therefore, the influence on simulation and measurement is discussed in detail. In addition, the robustness against production tolerances of the developed inner layer filter is compared to the outer layer filter. RF measurements up to 110 GHz from both filter implementations are used for comparison.