Temperature Compensation Using an In-Situ Gap-Based Temperature Sensor

By enabling precise measurement of temperature right on a micromechanical resonant structure, a new gap-based temperature sensor permits temperature compensation to reduce the resonance frequency excursion over a 100°C range of an 80-MHz polysilicon micromechanical ring resonator from an uncompensated 1882 ppm to a compensated 11.3 ppm, representing a more than 166× improvement. The key here is not only in-situ (i.e., localized) sensing, but also the fact that unlike other resonant temperature sensors this gap-based mechanism senses temperature in a manner decoupled from the Young's modulus temperature dependence that governs the temperature instability of the device-to-be-compensated (DTBC), where orthogonality of sensing and function is paramount. Since it requires just a few electrodes, this approach is applicable to a variety of applications, from resonator-based frequency references and sensors to non-resonant sensors using structures excitable to resonance without functional interference.