Suppression of parasitic resonance in piezoresistively transduced longitudinal mode MEMS resonators

This paper demonstrates the suppression of parasitic resonance in a piezoresistively transduced longitudinal mode MEMS resonator, wherein beams are electrostatically excited in a combined extensional mode with an associated frequency-Q product of 3.28 × 10¹². The response of the beam is sensed using both capacitive and piezoresistive transduction principles. The resonator consists of six parallel beams linked to a central anchor and a pair of symmetrical parallel beams that force the beams to vibrate in-phase. The mode suppression in the resonator is compared with other structures by finite element analysis (FEA). The relative distribution of strain energies in both the resonant structure and anchors and in both primary and secondary directions of vibration are proposed as figures of merit to compare this device to previously reported longitudinal mode beam resonators. The design optimization of longitudinal mode beam resonators is also discussed.