Electrostatic Tuning to Achieve Higher Stability Microelectromechanical Composite Resonators

Electrostatic tuning of the frequency in micromachined Si-SiO
₂
composite resonators for temperature compensation is demonstrated and analyzed. Electrostatic tuning exploits the bias voltage dependence of frequency for the compensation. Si-SiO
₂
composite resonators have intrinsically small frequency variation over temperature, thus being appropriate for electrostatic tuning. We developed a tuning procedure and applied it to a flexural-mode composite resonator. Experimental results show ±2.5-ppm stability over a 90°C-wide temperature range.