High-Q Support Transducer MEMS Resonators Enabled Low-Phase-Noise Oscillators

Area of Science:

• Materials Science
• Electrical Engineering
• Acoustic Engineering

Background:

• Resonators are critical components in electronic systems, particularly for oscillators.
• Enhancing the quality factor (Q-factor) of resonators is essential for improving oscillator performance and reducing phase noise.
• Existing resonator designs face limitations in achieving high Q-factors and spurious-free operation.

Purpose of the Study:

• To demonstrate a methodology for enhancing the quality factor of support transducer-enabled Wine-glass and Lamé mode resonators.
• To investigate the impact of structural and electrode material engineering on resonator performance.
• To develop high-performance oscillators meeting Global System for Mobile (GSM) communication requirements.

Main Methods:

• Utilizing short mechanical couplers to link the resonant structure with piezoelectric transducer arms.
• Investigating two different top electrode materials and their metal loading effects on aluminum nitride (AlN)-on-Si resonators.
• Optimizing an oscillation system with a low-noise amplifier and careful passive component positioning for closed-loop operation.

Main Results:

• Achieved a quality factor enhancement for the Wine-glass resonator from 9800 to 16 300.
• Maintained a spurious-free spectrum over a 200-MHz span, crucial for oscillator applications.
• Developed Wine-glass and Lamé mode resonator-based oscillators with low phase noise (-133.6 dBc/Hz at 1-kHz offset and -153.7 dBc/Hz at 1-MHz offset for Wine-glass mode).

Conclusions:

• The proposed resonator design strategy significantly improves the quality factor and maintains spectral purity.
• The developed high-performance oscillators meet stringent Global System for Mobile (GSM) communication requirements.
• This work provides a viable methodology for advancing resonator technology for next-generation communication systems.