Fully-differential poly-SiC Lame mode resonator and checkerboard filter

In this paper, we report the first fully-differential, electrostatically transduced RF MEMS resonator. The fully-differential electrode configuration not only cancels capacitive feedthrough between the drive and sense terminals but also eliminates the reduction in electromechanical quality factor (Q) from the large ohmic resistance of the polycrystalline silicon carbide (poly-SiC) suspension and anchor. Using this configuration, we have demonstrated a 173 MHz poly-SiC Lame-mode resonator with a Q of 9,300 in air. By mechanically coupling five Lame-mode resonators into a 2-D checkerboard, we have realized a 173 MHz center frequency band-pass filter with 110 kHz bandwidth and < 2 dB pass-band ripple.