Long-term frequency stabilization of MEMS oscillators based on axial force feedback control

The frequency stability of MEMS oscillators is critical for delivering precise and reliable reference signals in electronic devices. This paper proposes a long-term frequency stabilization method for MEMS oscillators based on axial force feedback control. A symmetric diamond-shaped MEMS oscillator with an integrated axial force amplifier is designed and a PID-based frequency controller is employed to implement the strategy. The controller generates a control voltage based on the measured frequency, which, in turn, produces an electrostatic force via the end-capacitor to dynamically adjust the resonator’s axial force, ensuring frequency stability. Experimental results reveal that the proposed method achieves a significant enhancement in long-term frequency stability, improving it by over 27,000 times over a period of 7200 seconds. Additionally, the controller compensates for frequency fluctuations caused by environmental temperature variations in real time, achieving a frequency stability improvement of five orders of magnitude.