Measurement Techniques for Capacitively-Transduced VHF-to-UHF Micromechanical Resonators

Abstract

An electromechanical mixing technique has been demonstrated for accuratelymeasuring the performance of sub-optimal (e.g., insufficiently smallcapacitive gap, limited dc-bias), high-frequency, high-Q micromechanicalresonators under conditions where parasitic effects could otherwisemask motional output currents. The technique employs the nonlinearvoltage-to-force transfer function inherent in capacitive transducers,allowing an off-resonance input signal to mix down to a force atthe resonance frequency and drive a resonator into vibration. Usingthis technique, a Q of 9,400 was measured for a non-optimal 156MHzdisk resonator - 3X higher than the false 3,090 obtained when parasiticfeedthrough is allowed to influence the frequency response. (9 References)