Mechanical Synchronization of MEMS Electrostatically Driven Coupled Beam Filters.

Area of Science:

• Electrical Engineering
• Mechanical Engineering
• Materials Science

Background:

• Micro-electromechanical systems (MEMS) bandpass filters utilize electrostatically driven coupled beams for MHz frequency operation.
• High Q-factor mechanical resonators and electrostatic transduction enable tuning, matching, and actuation in MEMS filters.
• A conflict exists in high-order filters between electrostatic tuning and dynamic synchronization using a single voltage.

Purpose of the Study:

• To propose a general solution to enable simultaneous tuning and synchronization in MEMS bandpass filters.
• To overcome the limitations of achieving both dynamic synchronization and electrostatic tuning concurrently in complex filter designs.

Main Methods:

• Introduction of mass-loaded beams at the ends of the coupled beam array.
• Utilizing direct current (DC) voltages for electrostatic tuning via mass-loaded beams, while preserving alternating current (AC) in-band synchronization.
• Modeling and verification using lumped element, stiffness matrix, and finite element models for in-plane arrays with parallel plate drives.

Main Results:

• The proposed mass-loaded beam approach allows for electrostatic tuning without interfering with in-band AC synchronization.
• Spurious modes generated by the mass-loaded beams can be effectively damped, approximating the desired filter response.
• The method is shown to be tolerant of variations in the added mass, indicating robustness.

Conclusions:

• The developed technique provides a general solution for simultaneous tuning and synchronization in MEMS bandpass filters.
• This approach offers potential for compensating fabrication-induced variations in complex MEMS filter designs.
• Enables the design of higher-order, more sophisticated MEMS filters with enhanced performance and tunability.