Statistical characterizaton of a CMOS-MEMS resonator for monolithic ovenized oscillator applications

A statistical study on the resonance frequency, Q-factor, electrostatic frequency tuning coefficient, and thermal resistance (R_th) of a CMOS-MEMS resonator is carried out in this work to evaluate the practical utility for ovenized MEMS oscillator applications. The mean frequency of 1.195 MHz, Q of 1,190, and R_th of 295 K/mW are obtained from 12 resonator chips. The measured 1-σ frequency tolerance of 7,560 ppm not only comes from random etching bias but also attributes to variations in electrical tuning coefficients. The 1-R_th error on R_th less than 4.08% is satisfactory to allow the implementation of ultra-low-power ovenized MEMS oscillators. Moreover, the monolithic CMOS-MEMS oscillator is also characterized through 6 individual chips, and the maximum phase noise difference <; 3 dB is measured at 1-kHz offset. In conclusion, this study confirms the fabrication yield, uniformity of geometry/material properties, and performance reproducibility of CMOS-MEMS resonators for monolithic ovenized oscillator applications.