Miniaturized bandpass filters based on multilayer substrate technologies

Novel concept of bandpass filters focused on their miniaturization, cost-effectiveness and high integration in a chip-package system has been discussed in the paper. This concept is based on a three-dimensional architecture, in which both a vertical transition and a planar transmission line disposed in a multilayer substrate, are used as building blocks of the filters. Here, the vertical transition is formed as a specific coaxial wave guiding structure by a signal via, being inner conductive boundary, and ground vias, serving in the role of an outer conducive boundary.