On/Off Micro-electromechanical Switching of AlN Piezoelectric Resonators

We report the first switchable piezoelectric resonator as a building block for a new class of adaptive and reconfigurable filters. The resonator integrates AlN contour-mode resonator and RF MEMS capacitive switch technologies to change the coupling between the RF signal electrodes and the AlN piezoelectric film. Modeling reveals that a 1.5 mu m gap minimizes coupling, while a 10 nm gap couples nearly as efficiently as an electrode in intimate contact, suggesting that high contrast can be achieved using this approach. Measurements of a 400 mu m x 150 mu m two-port resonator demonstrate a switching ratio of 13 dB, a Q of 170, and a center frequency of 240 MHz. Research is continuing with goals of improving the device Q and switching ratio, extending the device operation to other frequencies, and extending the approach to adaptive and reconfigurable filters.