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Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators
Published on: August 15, 2014
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A Fast-Switching (1.35-μs) Low-Control-Voltage (2.5-V) MEMS T/R Switch Monolithically Integrated With a Capacitive
Xiao Zhang1, Oluwafemi Joel Adelegan1, Feysel Yalçın Yamaner1
1Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC 27695, USA.
Journal of Microelectromechanical Systems : a Joint IEEE and ASME Publication on Microstructures, Microactuators, Microsensors, and Microsystems
|March 22, 2021
Summary
This study presents a novel electrostatic microelectromechanical systems (MEMS) switch designed for capacitive micromachined ultrasonic transducer (CMUT) applications. The MEMS switch offers efficient transmit/receive (T/R) functionality, potentially reducing the need for high-voltage electronics in ultrasound imaging systems.
Area of Science:
- Microelectromechanical Systems (MEMS)
- Ultrasonic Transducer Technology
- RF Switching Applications
Background:
- Capacitive micromachined ultrasonic transducers (CMUTs) are crucial for ultrasound imaging.
- Existing CMUT systems often require high-voltage front-end electronics for transmit/receive (T/R) switching.
- Integration of efficient T/R switches directly with CMUTs can improve system efficiency and reduce complexity.
Purpose of the Study:
- To design and fabricate an electrostatic MEMS switch co-processable with CMUTs.
- To characterize the static and dynamic performance of the MEMS switch for T/R applications.
- To evaluate the potential of the MEMS switch to eliminate high-voltage requirements in CMUT-based systems.
Main Methods:
- Design of a modified CMUT cell structure incorporating an interrupted transmission line and electrostatic pull-down electrodes.
- Finite-element modeling (FEM) for switch design optimization.
- Fabrication on a glass substrate using anodic bonding, followed by static and dynamic characterization.
Main Results:
- Demonstrated a MEMS switch with a DC switching voltage of 68 V and an on-resistance of 50 Ω.
- Achieved RF isolation of approximately 66 dB and insertion loss of 4.5 dB within medical ultrasound frequency ranges.
- Operated the switch dynamically with a low control voltage (2.5 V) and measured minimum switching/release times of 1.34 μs and 80 ns, respectively.
Conclusions:
- The developed electrostatic MEMS switch is suitable for co-fabrication with CMUTs as a T/R switch.
- The switch exhibits promising RF performance and can operate effectively with low control voltages.
- This technology has the potential to significantly reduce the high-voltage process requirements for CMUT-based ultrasound imaging systems, enhancing overall efficiency.
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