Frequency Selection in a MEMS Flexural Beam Resonator by Electrostatic Actuation

The utilization of MEMS resonators in microelectronics has garnered significant attention, given their crucial role in a multitude of applications, including timing and sensing. Among the various types of resonators, tunable resonators are particularly noteworthy, as they possess the capability of dynamically adjusting their resonant frequency. Accordingly, this work presents an innovative method for tuning the resonant frequency of beam resonators that are resonating out-of-plane by using a pair of electrostatic actuators. The proposed mechanism focuses on increasing the stiffness of the anchoring structure, which ultimately results in a significant increase in the resonant frequency of the beam resonator. This approach relies on the use of electrostatic actuators which are positioned in close proximity to the anchors and are pulled into the device from a distance of $\mathrm {2 ~\mu \text {m} }$ . The method is investigated using finite element simulation and measurement results from fabricated devices. The results indicate significant frequency tuning that reaches 27% and 51% of the initial resonant frequency by activation of one and both electrostatic actuators, respectively. [2023-0095]