Monolithic CMOS-MEMS oscillators with micro-degree temperature resolution in air conditions

This paper reports the thermal characterization of MEMS resonator-based oscillators fabricated using a conventional 0.35-mum CMOS process. The MEMS resonators are sub-micrometer scale metal beams which resonance frequency is highly dependent on temperature (up to -2055 ppm/degC). Thanks to the monolithic integration of the oscillator electronics, the oscillator frequency stability is better than 1 ppm allowing temperature resolutions up to 0.00019degC for 0.1 s averaging time, which is at least one order of magnitude better than the best previously reported.