An ovenized CMOS-MEMS oscillator with isothermal resonator and sub-mW heating power

This work reports an ultra-low-power temperature-compensated CMOS-MEMS oscillator based on an uniform temperature design that ensures low temperature gradient of the proposed resonator to attain high frequency stability. The oven heating efficiency greater than 140°C/mW is achieved in this work by a proper thermal isolation design. In addition, the lowest temperature coefficient of frequency (TCf) of 2.84 ppm/°C is also accomplished through a passive temperature compensation scheme. The performance of the ovenized oscillator is evaluated by Allan deviation where the frequency instability of 95 ppb / 32 ppb is characterized for the oven on/off conditions, respectively, which is on par with state-of-the-art silicon-based MEMS oscillators.