Ku-band bandpass filters using novel micromachined substrate integrated waveguide structure with embedded silicon vias in benzocyclobutene dielectrics

In this paper, Ku-band bandpass filters (BPFs) based on a novel micromachined substrate integrated waveguide (SIW) platform with square complementary split-ring resonators (CSRRs) have been demonstrated. The proposed SIW platform adopts embedded metal-coated silicon vias in benzocyclobutene (BCB) dielectric substrate filled into a silicon trench. Unlike conventional SIW BPFs using classical microwave substrates, the proposed BPFs can be integrated with silicon-based circuits or RF MEMS devices since the fabrication process is fully compatible with the silicon process while providing low-loss properties of the waveguide. Three types of BPFs using CPW and microstrip feeding configurations have been designed and fabricated. The microstrip-fed BPF using the same CSRRs shows an improved insertion loss of 1.39 dB at 13.8 GHz with reduced device size compared to the CPW-fed BPF which has an insertion loss of 2.27 dB at 14.1 GHz. The microstrip-fed BPF with different CSRR configurations designed to improve shape factor shows an attenuation factor of 124 dB/GHz, with an insertion loss of 2.3 dB at 21.2 GHz.