Abstract
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.
Highlights
M ICROELECTROMECHANICAL systems (MEMS) have become a technological solution of choice for many advanced applications and currently are a roughly $20B/year industry
This paper investigates the use of pulse width modulation (PWM) to control three different analog electrostatic MEMS systems, (1) a single parallel plate mass sensor, (2) a comb-drive actuator used for writing with atomic beams, and (3) a commerical deformable mirror (DM) that can be reshaped dynamically using an array of parallel plate actuators
In this paper we discussed the use of a PWM signal to control analog MEMS devices compared to the conventional method
Summary
M ICROELECTROMECHANICAL systems (MEMS) have become a technological solution of choice for many advanced applications and currently are a roughly $20B/year industry. There is a digital control system (usually a microprocessor), a high precision Digital to Analog converter (DAC) and a linear, high voltage (HV) amplifier These drive circuits need high precision and modest speeds. With a 1 kHz MEMS device and a 1 GHz processor, one can use a 10 kHz PWM drive with nanosecond timing control to provide the equivalent of a 17 bit DAC. Another advantage, as we show below, is that PWM linearizes the response of the system. While this paper focuses on electrostatic drives, the PWM approach is general and works well with any type of drive (e.g. thermal, piezoelectric, magnetic)
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