Pulse-width modulated oscillations in a nonlinear resonator under two-tone driving as a means for MEMS sensor readout

TL;DR

This paper demonstrates how two-tone driven nonlinear MEMS resonators exhibit bistable oscillations that can be modulated for sensitive pulse-width modulation sensor readout, with tunable cycle periods influenced by drive parameters.

Contribution

It introduces a novel method for MEMS sensor readout using pulse-width modulated oscillations induced by two-tone driving in a nonlinear resonator.

Findings

Oscillations are modulated by bistable response and relaxation cycles.

Cycle period depends on drive amplitude, detuning, and tension.

Method enables sensitive PWM-based MEMS sensor readout.

Abstract

A MEMS Duffing resonator is driven by two adjacent frequency tones into the nonlinear regime. We show that if the two-tone drive is applied at a frequency where a bistable response of the nonlinear oscillator exists, then the system output will be modulated by a relaxation cycle caused by periodically jumping between the two solution-branches of the bistable response. Although the jumps are caused by the beating of the drives, the existence and period of this relaxation or hysteresis cycle is not solely dictated by the beat frequency between the two driving tones, but also by their amplitude and detuning with respect to the device resonance frequency. We equally demonstrate how the period of the cycles can be tuned via added tension in the device and how these oscillations can be used as a means of sensitive pulse-width modulated (PWM) readout of MEMS sensors.