Pulse-width modulated oscillations in a nonlinear resonator under two-tone driving as a means for 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.Template for JJAP Regular Papers 2

Demonstration of Multiple Internal Resonances in a Microelectromechanical Self-Sustained Oscillator

“…The MEMS device used in this work is a AlGaAs/GaAs heterostructure piezoelectric clampedclamped beam. The structure, which is described in more detail in [18,19], is 150 µm long and possesses two electrically isolated actuation electrodes on each side of the beam's length near the anchoring points. A -1 V DC is applied to one of the electrodes while the other one is shorted, the dc is necessary to maintain a linear piezoelectric transduction and avoid the nonlinearities of the metal-semiconductor Schottky junction upon the application of an AC signal (see supplementary material).…”