Enhancement of temperature stability via constant-structural-resistance control for MEMS resonators

In this work, we proposed a methodology to enhance thermal stability of MEMS resonators by the use of a constant-structural-resistance control where temperature coefficient of resistivity (TC_R) of the MEMS resonator serves as an instrinsic temperature sensor, thus leading to a constant structural temperature to greatly alleviate the frequency drifts due to change of ambient temperature. As a proof of concept, the effective temperature coefficient of frequency (TC_f) was measured under a manual control of bias power with one-point calibration to maintain constant structural resistance, ultimately demonstrating up to 46 times improvement of temperature stability as compared to uncompensated counterparts. This technology prevents the use of external temperature sensors or reference resonators with which errors occur due to indirect temperature measurement of the active MEMS resonator. Notably, this technology is well suited for all kinds of MEMS resonators featuring proper temperature-dependent structural resistance, such as capacitive, piezoresistive, piezoelectric, and thermal-piezoresistive silicon-based resonators.