| High-Q narrowband filters at ultra-high frequencies hold promise for reducing noise and suppressing interferers in wireless transceivers, yet research efforts confront a daunting challenge. So far, no existing resonator technology can provide the simultaneous high-Q, high electromechanical coupling ( k2eff), frequency tunability, low motional resistance (Rx), stopband rejection, self-switchability, frequency accuracy, and power handling desired to select individual channels or small portions of a band over a wide RF range. Indeed, each technology provides only a subset of the desired properties.;Recently introduced "capacitive-piezoelectric" resonators, i.e., piezoelectric resonators with non-contacting transduction electrodes, known for achieving very good Q's, have recently emerged (in the early 2010's) as a contender among existing technologies to address the needs of RF narrowband selection. Several reports of such devices, made from aluminum nitride (AlN), have demonstrated improved Q's over attached electrode counterparts at frequencies up to 1.2 GHz, albeit with reduced transduction efficiency due to the added capacitive gaps. Fabrication challenges, while still allowing for a glimpse of the promise of this technology, have, until now, hindered attempts at more complex devices than just simple resonators with improved Q's.;This thesis project demonstrates several key improvements to capacitive-piezo technology, which, taken together, further bolster its case for deployment for frequency control applications. (Abstract shortened by ProQuest.). |
