ACTIVE TEMPERATURE COMPENSATION FOR MICROMACHINED RESONATORS

Abstract

Encapsulated micromechanical resonators have been fabricated from single crystal silicon and a method for stabilizing their resonant frequency over temperature has been demonstrated. The method uses high-frequency AC signals applied directly to the resonant structure in order to heat it. By adjusting the power of the heating signal, varying amounts of heat could be added to the resonant structure in order to compensate for the effects of changing external temperature and the variation in resonant frequency was reduced significantly. This method requires minimal changes to existing resonator designs and is applicable to any resonator with a current path through its structure. The resonators examined here exhibited temperature coefficients of resonant frequency of over 210 Hz/C (170 ppm/C) without temperature compensation. With compensation, the temperature coefficient was reduced to less than 5 Hz/C (4 ppm/C).