Tapping Bandwidth Widening of CMOS-MEMS Vibro-Impacting Resonators Based on Double-Sided Stopper Structures

A CMOS-MEMS based vibro-impacting resonator with double sided stopper structures has been demonstrated that exhibits a wider tapping bandwidth up to 2.3× compared to the conventional single sided counterpart. In particular, a folded-beam capacitive-comb transduced resonator fabricated using a
$0.35-\mu \mathrm{m}$
CMOS process is driven impacts the stopper structure on either side of the shuttle with an air gap of
$0.6\ \mu \mathrm{m}$
and results in a flat region in the frequency transmission response, where the tapping occurs, around the resonance frequency of 125 kHz. The effective stiffness of the system and therefore the resonance frequency abruptly increase during tapping, leading to duffed transmission response curves towards higher frequency. Conceptually, the addition stopper in the doubled-sided impacting resonator effects additional stiffness hardening that in turn pushes the impact induced resonance frequency even further. A numerical model established here arrives the same trend about tapping bandwidth widening in the structure with double-sided stoppers.