Demonstration of 28GHz Band Pass Filter Toward 5G Using Ultra Low Loss and High Accuracy Through Quartz Vias

Synthetic fused quartz is an ideal material for devices in millimeter wave (mm-wave) band, particularly suited for devices and infrastructure in the 5G arena due to its excellent low loss, ultra low roughness, and low coefficient of thermal expansion. To realize such devices utilizing synthetic fused quartz, the accurate micromachining technology specialized for the material coupled with the material technology is essential. This paper discusses the dielectric characteristics of synthetic fused quartz and the high accuracy through quartz glass via formation (TQV) technology. The metallization technology for synthetic fused quartz is also discussed, which is also a key technology to make optimum use of the material. Finally, to validate the superiority of the ultra-low loss synthetic fused quartz and high accuracy TQVs, a 28 GHz band pass filter based on substrate integrated waveguide (SIW) is demonstrated and characterized. The measurement results corroborated well with the simulated results and showed extremely high efficiency, proving that AGC's material and the TQV formation technology are extremely useful for the 5G devices.