Design of multilayer spiral inductor resonator filter and diplexer for system-in-a-package

A compact L-shaped multilayer spiral inductor resonator filter and diplexer using inductor type resonators are proposed. The design is based on the self-resonant frequency of the spiral inductors and electromagnetic coupling between the resonators. The filter was built, and measurement results show good agreement with the simulation data. A multilayer structure can be used to significantly reduce the footprint and enhance the electromagnetic coupling effects between the resonators. The center frequency and bandwidth of the inductor resonator filter can be directly optimized by the physical arrangement of resonators. Finally, this new filter topology is applied to the design of a diplexer.