A micromachined voltage controlled oscillator using the pull-in mechanism of electrostatic actuation

Abstract

This study presents a microelectromechanical voltage controlled oscillator based on the pull-in electromechanical contact of an electrostatic actuator. Micromachining process of nickel electroplating on a silicon substrate was used to develop an electrostatic torsion plate mechanism (200 µm × 200 µm in area, 15 µm in thickness) that could be mechanically movable (0.1 rad) by the electrostatic torque of applied voltage. An electromechanical stopper was designed underneath the movable plate such that the effective drive voltage was discharged upon the electrostatic pull-in contact. Peripheral electrical circuits were designed to compose a ring oscillator, in which the temporal response of electrostatic mechanism determined the oscillation frequency. The frequency became tunable as a function of the drive voltage. Frequency tuning range of 4.39∼9.6 kHz was experimentally observed using the control voltage of 7.4∼10.6 V.

Discharging-phototransistor-integrated high-voltage Si photovoltaic cells for fast driving demonstration of an electrostatic MEMS actuator by wavelength modulation

“…Self-oscillation is a method using a pull-in mechanism of electrostatic actuation. 34) This method releases the charge by letting the actuator touch an electrode. However, this method is intended to be used for a resonant actuator; it is difficult to release the charge at an arbitrary timing.…”