A High-Stability MEMS Frequency Reference

Silicon MEMS resonators with high levels of frequency stability are demonstrated in an oscillator system suitable for use as a frequency reference. The use of resonator quality factor (Q) as a temperature sensor allows us to control the temperature of the resonator with milli-degree precision, thus stabilizing the output frequency of the resonator to ~0.1 ppm. Composite Si/SiO₂ resonator design has reduced the inherent frequency sensitivity of the resonator. The combination of Q(T) temperature stabilization and composite resonator design has reduced the frequency variation to ~0.01 ppm, a level that is competitive with high-performance commercial devices.