Glass-Integrated Single- and Dual-Band Bandpass Filters

A new class of bandpass filters (BPFs) using a commercially available glass-integrated manufacturing platform is presented. The proposed BPFs are designed to create single-band and dual-band quasi-elliptic transfer functions by incorporating multi-resonant stages that create transmission zeros (TZs) in the out-of-band response. The BPFs are implemented using a compact scheme of series resonators that create wide out-of-band spurious-free response. For proof-of-concept validation purposes, two prototypes were designed, manufactured and measured at S-band. The single-band BPF exhibited the following RF measured characteristics: center frequency: 3.1 GHz, 3-dB fractional bandwidth: 12.8%, minimum in-band insertion loss: 2.6 dB, and a 2.34:1 spurious-free out-of-band bandwidth with > 21 dB of isolation. The dual-band BPF exhibited the following RF measured characteristics: center frequencies: 2.6 GHz and 3.3 GHz, 3-dB fractional bandwidth: 8.5% and 7.8%, minimum in-band insertion loss: 3.6 dB and 4.5 dB, and a 2.17:1 spurious-free bandwidth with> 18 dB of isolation.