An Ultra-Stable MEMS Oscillator Based on High-Q Micromechanical Resonator and a Two-Stage Temperature Compensation System

MEMS resonators are the core elements in precision clocks and sensitive resonant detectors. However, due to the large temperature coefficient of frequency (TCF) of single-crystal silicon, MEMS resonators suffer from frequency stability degradation caused by temperature drift. Here, we developed a two-stage temperature compensation system for highly stable oscillators' application based on the fuzzy PID control. Additionally, a MEMS disk resonator with quality factor approaching the limits from Akhiezer damping was designed and microfabricated. After packaging with the compensation system, the frequency drift of the developed MEMS oscillator was maintained within $\pm 0.063 \text{ppm}$ over 1800s, and its Allan deviation reached 0.225 ppb.