Fabrication of an n77 Band-Pass Filter Using Advanced Glass-IPD Technology

In this paper, we design and implement an n77 band-pass filter with high attenuation characteristics using transmission zero and advanced glass-IPD technology. The n77 band is part of 5G NR and is adjacent to the n41 band and Wi-Fi 5 band, which can cause signal interference, thereby requiring a high-performance filter. Therefore, transmission zero can be utilized to design a filter with high attenuation characteristics. However, in real device implementation, the filter performance is degraded due to losses and reduced selectivity. To address this issue, it is essential to improve the Q-factor of the spiral inductor, which is a major source of loss. There are two approaches to improve the Q-factor of the spiral inductor. The first is by reducing the series resistance component of the conductor. The second is by reducing substrate losses. Through these two process improvements, the Q-factor of the inductor has been enhanced from 26.3 to 47.7 compared to conventional silicon. The designed transmission zero-based n77 band-pass filter was implemented and verified using advanced glass- IPD technology. The filter has dimensions of 1.57 × 1.27 ×0.2 mm³showing attenuation characteristics of 28-32 dB in the n41 band and 31-18 dB in the Wi-Fi 5 band. The insertion loss in the passband of the n77 band ranged from 1.72 to 1.16 dB.