Spurious mode suppression in UHF micromechanical extensional wine-glass ring resonators

A geometry-specific excitation configuration has been used to suppress all undesired spurious modes around the center frequencies of stand-alone micromechanical extensional wine-glass ring ("ext. WGR") resonators, previously demonstrated at frequencies up to 1.47-GHz with Q's > 2,000 as stated in Y. Xie et al. (2003). Using this technique, spurious modes at 406.7, 418, and 419 MHz, normally observed near the resonance of a 415-MHz ext. WGR, have been removed, as have all spurious modes within at least a 50% bandwidth region around the resonance. In removing unwanted modes, this technique solves one of the most encumbering issues with ring-type (as opposed to disk-type in J. Wang et al. (2004)) GHz resonators, and paves the way for their use in the micromechanical oscillator and filter circuits targeted for future wireless transceivers based on C. T.-C. Nguyen (2004).