A Tunable Miniaturized RF MEMS Resonator With Simultaneous High $Q$ (500–735) and Fast Response Speed $(<\hbox{10}-\hbox{60}\ \mu\hbox{s})$

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-μm-long 20-μm-wide 1- μm-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 μs (actuation time) and 60 μs (release including settling time). To the best of the authors' knowledge, the presented resonator is more than 3 × smaller, achieves nearly 30% higher average quality factor, and is at least 10-100 × faster than state-of-the-art resonators based on similar technology, implemented in similar frequency ranges.