Design of High-Performance On-Chip Wideband Filter in Ceramic-Based Thin-Film IPD Technology

This paper presents a high-performance, wideband, ceramic-based thin-film integrated passive device (IPD) filter. By combining a transmission-line structure with a polyimide (PI) columnar structure, we have designed a fifth-order wideband thin-film IPD filter with a finite transmission zero. This design introduces transmission zeros and reduces parasitic capacitance without increasing the filter size, making it suitable for the development of miniaturized wideband thin-film IPD filters. Specifically, a commercial ceramic-based thin-film IPD (TF-IPD) process was used to fabricate a wideband thin-film IPD filter with a center frequency of $3 \mathbf{~ G H z}$. The filter’s dimensions are $2.5 \mathbf{~ m m}$ $\times 1.9 \mathrm{~mm}$, corresponding to $0.025 \lambda_{0} \times 0.019 \lambda_{0}$ at the center frequency ($f_{0}$). EM-simulated results using Ansys HFSS indicate that this filter exhibits a 3 dB fractional bandwidth of 109%, a return loss better than 14 dB, an insertion loss ranging from 1.39 to 2.06 dB, and a stopband suppression below 18 GHz exceeding 32.6 dB, thereby demonstrating superior overall performance.