Contour-Mode Ring-Shaped AlN Microresonator on Si and Feasibility of Its Application in Series-Resonant Converter

Microelectromechanical systems (MEMS) resonators on Si have the potential to replace the discrete passive components in a power converter. The main intention of this paper is to present a ring-shaped aluminum nitride (AlN) piezoelectric microresonator that can be used as an energy-transferring device to replace inductors/capacitors in low-power resonant converters for biomedical applications. Finite-element simulation results have been provided, showing the mode of vibration at resonant frequency. The zero-voltage switching (ZVS) condition for a series-resonant converter incorporating the proposed MEMS resonator has been presented analytically and verified through experiment. This ZVS condition can be found in terms of the equivalent circuit parameters of the resonator. To the knowledge of the authors, ZVS analysis based on the equivalent electrical circuit model of the thin piezoelectric film resonators has not yet been reported in the literature. A CMOS-compatible fabrication process has been proposed and implemented. In addition, the fabricated devices have been characterized and experimental results are included in this paper. The first contour-mode AlN MEMS resonator with moderately low resonant frequency and motional resistance is reported in this paper with measured resonant frequency and motional resistance of 87.28 MHz and 36.728 Ω, respectively.