High-Cx/Co Hollow Disk Resonators

Mass and stiffness reduction via hollowing out a ca-pacitive-gap transduced radial mode disk resonator while maintaining resonance frequency and transduction area has enabled a measured electromechanical coupling strength $(c_{x}/c_{o})$ of 0.56% at 123 MHz without electrode-to-resonator gap scaling. This is a more than $5\times$ improvement in $C_{x}/C_{o}$ compared with a conventional radial contour-mode disk at the same frequency. $c_{x}/c_{o}$ increases like this stand to improve the passbands of channel-select filters targeted for low power wireless transceivers, as well as lower the power of MEMS-based oscillators.