Abstract
This paper reports on the design, fabrication, and measurement of a novel radio frequency (RF) microelectromechanical systems (MEMS) tunable all-silicon evanescent-mode cavity-based resonator that simultaneously achieves high quality factor and fast response speed. The resonator is based on a 1.5-mm-deep silicon-etched cavity attached to a gold-coated silicon substrate with an array of 75 185-mu m-long 20-mu m-wide 1-mu m-thick gold beams. The 54-mm(3) resonator is tunable from 15.2 GHz up to 16.5 GHz (analog tuning range) and up to 17.8-GHz range (digital tuning range) with an array of 75 MEMS fixed-fixed beams. The MEMS beams are biased against their own silicon substrate. This helps keep RF leakage at a minimum and permits high quality factors of 500-735 for the all-silicon configuration. By applying dynamic biasing waveforms, the MEMS tuners respond within 9 mu s (actuation time) and 60 mu s (release including settling time). To the best of the authors' knowledge, the presented resonator is more than 3x smaller, achieves nearly 30% higher average quality factor, and is at least 10-100x faster than state-of-the-art resonators based on similar technology, implemented in similar frequency ranges.