Abstract
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 has been 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. To further improve the performance of the oscillator, a revised CMOS-MEMS oscillator with close-to-zero TCf of 0.17 ppm/˚C is achieved by the single-anchored (SA-) design for stress releasing with passive compensation by composite materials. The overall thermal stability of 4 ppm across 140˚C temperature span has been demonstrated by the constant resistance algorithm realized by the LabVIEW system, which is equivalent to 29 ppb/˚C. In addition, the Built-in Self-Test (BIST) has been designed for the rapid thermal-cycling test, which greatly reduces the testing time from hours to minutes.