All-Silicon Technology for High-Q Evanescent Mode Cavity Tunable Resonators and Filters

This paper presents a new fabrication technology and the associated design parameters for realizing compact and widely-tunable cavity filters with a high unloaded quality factor (Qu) maintained throughout the analog tuning range. This all-silicon technology has been successfully employed to demonstrate tunable resonators in mobile form factors in the C, X, Ku, and K bands with simultaneous high unloaded quality factors (≥500) and tuning ratios (≥1:2). It is shown that by employing high-precision micro-fabrication techniques and careful modeling, the measured RF and tuning performance of the fabricated device closely match the simulated results. The capability of monolithic (system-on-chip) integration, low-cost batch processing, and compatibility with CMOS processing is some of the key advantages of this 3-D tunable filter fabrication technology over conventional approaches. This technology also has the potential to be extended to produce tunable resonators and filters in the millimeter wave region.