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 (200µm × 200µm in area, 15µm in thickness) that could be mechanically movable (0.1rad) 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∼9.6kHz was experimentally observed using the control voltage of 7.4∼10.6V.