Temperature compensation mechanism for a micromechanical ring resonator

摘要

There is described a time base comprising a resonator (4) and an integrated electronic circuit (3) for driving the resonator into oscillation and for producing, in response to the oscillation, a signal having a determined frequency. The resonator is an integrated micromechanical ring resonator supported above a substrate (2) and adapted to oscillate around an axis of rotation (O) substantially perpendicular to the substrate, the ring resonator comprising a central post (5) extending from the substrate along the axis of rotation, a free-standing oscillating structure (6) connected to the central post and including an outer ring (60) coaxial with the axis of rotation and connected to the central post by means of a plurality of spring elements (62), and electrode structures (9; 9*) disposed around the outer ring and connected to the integrated electronic circuit. The free-standing oscillating structure further comprises a plurality of thermally compensating members (65) which are adapted to alter a mass moment of inertia of the free-standing oscillating structure as a function of temperature so as to compensate for the effect of temperature on the resonant frequency of the ring resonator.