A fully embedded 60-GHz novel BPF for LTCC system-in-package applications

In this paper, a novel LTCC stripline (SL) 60-GHz band-pass filter (BPF) composed of transitions to coplanar waveguide (CPW) pads for monolithic microwave integrated circuit integration is presented. For low-loss interconnection with active devices, a CPW-to-SL vertical via transition integrating air cavities and a CPW-to-CPW planar transition using internal ground planes are proposed and implemented. The fabricated transition shows an insertion loss of 1.6 dB and a reflection loss below -20 dB at the passband of the filter. The implemented SL BPF using dual-mode patch resonators shows a center frequency of 60.4 GHz, 3.5 % bandwidth, and reflection losses below -15 dB at the passband. Excluding the insertion loss of the transitions, the filter insertion loss reveals 4.0 dB.