Performance-enhanced micro-machined resonant systems with two-degrees-of-freedom resonators

Two-degrees-of-freedom (2-DOF) resonant systems are employed to improve the resonating properties of micro-machined vibratory devices. Two mass-spring-damping units of identical natural frequency, are mechanically linked together to form a 2-DOF resonator. A great disparity was designed for the ratio of the two masses. Theoretical analysis and simulation both demonstrate that, under the condition of a low damping effect, the resonant amplitude of the small mass can be amplified and, becomes much higher than that of the big mass. This amplification effect can be used in applications of high mechanical sensitivity. On the other hand, the very broad resonant bandwidth of the small mass can be pursued by overlapping two split resonant modes together under certain damping conditions. Measurement results of a silicon micro-machined 2-DOF resonator in an atmospheric environment have verified the resonant amplification effect. As an application of the 2-DOF resonator, a silicon micro-machined vibratory gyroscope has been designed based on this amplification concept and has been fabricated using a bonded silicon-on-insulator wafer and a deep reactive-ion-etching process.