Multi-layer coupled band-pass filter for 60 GHz LTCC system-on-package

We have developed a design method for space-saving and wide passband band-pass filter (BPF) for 60-GHz band applications. The BPF comprises multilayer-coupled stripline resonators on a multilayer low temperature co-fired ceramic (LTCC) substrate and can be highly integrated into a millimeter-wave system-on-package that is suitable for 60 GHz-band wireless communication applications. The proposed design method provides compactness and wide passband characteristics under fabrication accuracy limitation. The prototype filter is fabricated on a six-layer 50-m LTCC substrate. A fabricated prototype BPF circuit achieves a passband of 5466 GHz, which is suitable for 60 GHz channels. We also clarified that the displacements between layers of the LTCC multilayer substrate caused during its fabrication degraded its characteristics only slightly.