A Miniaturized On-Chip Bandpass Filter With Mixed Coupling Using TGV Technology

Abstract

This letter presents a glass-based on-chip filter in which coupling between adjacent resonators generates two transmission zeros (TZs) on both sides of the passband, significantly enhancing out-of-band rejection. The design employs wafer-level through-glass-via (TGV) fabrication to ensure low dielectric loss and miniaturization. Experimental results demonstrate a center frequency of 24.384 GHz with a fractional bandwidth (FBW) of 7.76%, insertion loss (IL) of 1.44 dB, and return loss (RL) greater than 13 dB. The compact footprint of $5.1\times 2.8$ mm ( $0.41\lambda ~\times 0.23\lambda $ ) highlights the effectiveness of the mixed coupling mechanism and TGV-based implementation. Measured responses align closely with simulations, validating the design for millimeter-wave (mmW) applications.