Five Low-Noise Stable Oscillators Referenced to the Same Multimode AlN/Si MEMS Resonator

Area of Science:

• Electrical Engineering
• Materials Science
• Physics

Background:

• Microelectromechanical systems (MEMS) resonators offer high quality (Q) factors for frequency control.
• Piezoelectric materials like aluminum nitride on silicon (AlN/Si) enable efficient transduction in MEMS devices.
• Multimode resonators can support multiple stable oscillation frequencies, but their integrated use in oscillators is challenging.

Purpose of the Study:

• To experimentally demonstrate multiple self-sustaining feedback oscillators referenced to a single AlN/Si MEMS resonator.
• To characterize the phase noise and frequency stability of these oscillators across different resonance modes.
• To investigate the mode dependency of oscillator performance for potential applications.

Main Methods:

• Fabrication of AlN/Si MEMS resonator capable of supporting multiple resonance modes.
• Integration of piezoelectric transduction for efficient readout of resonance modes at 10, 30, 65, 95, and 233 MHz.
• Construction and testing of five self-sustaining oscillators, each locked to a distinct high-Q resonance mode.
• Measurement and analysis of phase noise and Allan deviation for each oscillator.

Main Results:

• Successful demonstration of five stable, self-sustaining oscillators operating at 10, 30, 65, 95, and 233 MHz.
• Achieved high Q factors for the resonance modes (up to 18,600 at 10 MHz).
• Measured low phase noise (e.g., -116 dBc/Hz at 1 kHz offset for 10 MHz oscillator) and good frequency stability (e.g., Allan deviation of 4x10^-9 at 1s for 65 MHz oscillator).

Conclusions:

• The AlN/Si MEMS technology enables the creation of multiple stable oscillators from a single resonator.
• The demonstrated oscillators exhibit promising performance for clock, timing, and sensing applications.
• This work provides insights into mode-dependent noise and stability in multimode resonators, crucial for future device engineering.