PWM as a Low Cost Method for the Analog Control of MEMS Devices

• Published in: Journal of microelectromechanical systems Vol. 28; no. 2; pp. 245 - 253
• Main Authors: Pollock, Corey, Barrett, Lawrence K., del Corro, Pablo G., Stange, Alexander, Bifano, Thomas G., Bishop, David J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuators; Capacitors; Deformation; Electric potential; Electronics; electrostatic actuator; Electrostatics; Force; Formability; High voltages; Linear amplifiers; linearize; Low cost; Microelectromechanical systems; Micromechanical devices; Parallel plates; Product design; Pulse duration modulation; Pulse width modulation; Resonant frequencies; Voltage control
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2019.2891205

In this paper, we discuss the use of pulse width modulation (PWM) to control analog MEMS devices. We achieve a precise linear analog control of MEMS by applying PWM signal with a frequency well above the system's mechanical natural frequency. We first demonstrate this using a parallel plate actuator and comb-drive, and then extend the technique to control a commercial deformable mirror. Such an approach allows the system designer to replace expensive drive electronics such as the high precision DACs and high voltage, linear amplifiers with a simple on-off switch. The advancements in the electronics industry tend to make precise timing cheaper and faster; our approach exploits these long-term trends to create low-cost control circuits. We also show how PWM control can linearize the positional response of the devices, where typically the position would depend quadratically on the applied analog voltage.