High frequency filters based on piezoelectrically transduced micromechanical resonators

The paper presents the design, simulation, fabrication, and preliminary test results of a novel micromechanical filter based on coupled piezoelectrically transduced resonators. This is the first report of two identical microfabricated free-free beam resonators coupled with two torsional beams forming a second-order mechanical filter. Piezoelectric transducers from thin-film ZnO were used to drive anti sense resonance, eliminating the need for precision fabrication of nanometer-scale gaps in contrast to electrostatic transduction. Fabrication was done with a four-mask process on SOI wafers with maximum temperature capped at 250°C, allowing post-CMOS integration. Preliminary tests showed a resonant peak of 10.83 MHz and a quality factor of 41 under atmospheric pressure.