We report a newly developed equivalent electrical circuit for microelectromechanical systems (MEMS) based on a circuit simulator Qucs (Quite Universal Circuit Simulator). An analog computing solver for the equation of motion (EOM) has been interpreted to an electrical equivalent circuit by using an electrical capacitor as an ideal mathematic integrator. Viscoelastic suspension and electrostatic parallel‐plate actuator are modeled as equivalent subcircuits that can be cosolved with the EOM module. Those subcircuit models are used as building blocks to numerically simulate the behavior of various types of MEMS actuators. Thanks to the well‐prepared simulation toolbox of Qucs, multiphysics analysis of micromechanical and electrical quantities has become straightforward on a single platform. Equivalent circuit models for coupled oscillator and parallel‐plate electrostatic actuator (including mechanical contact after electrostatic pull‐in) are presented as a verification program to examine the simulation accuracy. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

No 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.

The silicon MOSFET and single-electron-transistor (SET) with a movable gate electrode (MGE) are reported. For the first time, the modulation of the pull-in voltage, where subthreshold swing (SS) is much steeper than 60mV/dec, is experimentally demonstrated in MGE MOSFET using an additional electrode. The modulation of FWHM and peak position of Coulomb blockade oscillation (CBO) by tuning capacitance of SET is also experimentally demonstrated for the first time.