Parallel-Plate Driven Oscillations and Resonant Pull-In

Abstract

This work characterizes parallel-plate actuators for oscillations near the mechanical resonant frequency and amplitudes comparable to the actuator gap. Specifically, we show that at resonance, the structure can move beyond the well-known pull-in-limit but is instead limited to 56% of the gap by "resonant pull-in." Above the resonant frequency, the structure is not limited by pull-in and can theoretically oscillate across the entire gap. We develop a describing function model, which includes an amplitudedependent model for electrostatic spring tuning, to predict the steady-state frequency response. These results are verified experimentally.