• second harmonic
• high-Q polysilicon micromechanical flexural resona
• RF MEMS
• fully-differential topology
• finite-element simulations
• lumped-parameters equivalent circuit

The present work deals with the design and characterization of microelectromechanical resonators from theoretic, simulative and experimental perspectives. We introduce for the first time the concept of differential actuation and sensing for flexural type microresonators as a viable solution to improve linearity and parasitic signal rejection properties of the devices as compared with the single-ended one. Three novel mechanical structures of fully-differential flexural resonators are presented, and a theoretical analysis is conducted based on Bernoulli’s beam theory and the equivalent circuit approach developed by Tilmans. Moreover, some features of flexural free-free resonators made with the THELMA process by STMicroelectronics are investigated. We propose a new lumped-parameters equivalent circuit for the description of the main electrical and mechanical properties, and an analytic model for the temperature dependence of the resonance frequency. Both models are verified by means of numerical, finite-element simulations performed with FEMLAB. Finally, two set-ups for electrical characteristic measurement of flexural free-free resonators were developed. Measurement techniques based on differential driving and second-harmonic sensing are proposed, and we describe the design and realization of the discrete-components, PCB board-built electronic circuits required for the implementation of these techniques. The results of preliminary experimental measurements are discussed.