A 60GHz stripline BPF for LTCC system-in-package applications

We present a new LTCC stripline (SL) structured 60 GHz bandpass filter (BPF) composed of transitions to CPW pads for MMIC integration. The possible loss through the SL-CPW transition has been minimized by adopting air-cavities below the via and by gradual approaching the height of the ground planes. The fabricated transition reveals an insertion loss of 1.6dB and a S11/S22 below -20dB at the pass band of the filter. The dual-mode four-pole BPF shows a center frequency of 60.4GHz, 3.5% bandwidth, and S11/S22 below -15dB at the pass band. Excluding the insertion loss of the transitions, the filter insertion loss reveals 3.67dB.