Design and Experiment of Push–Pull MEMS Resonant Accelerometers
Yunbo Shi, Jieyu Zhang, Fei Li, Yiwei Chen, Yuntian Qu, Huiliang Cao
Abstract
This article presents a new push–pull resonant accelerometer. The vibration equation of the resonator is derived, the natural frequency of the resonator and the change of the resonant frequency under the action of inertia force are calculated, and the finite-element simulation analysis is carried out for the working mode and interference mode of the structure. Then, the preparation process of the sensor was designed, and the sensor structure was prepared by silicon on glass (SOG) process. The structure of the sensor chip was characterized by microscopy analysis. The chip is vacuum-packed by a gold-tin welding process, and the driving circuit is designed for the driving response test and scale factor test. The resonant frequency of resonator I is 21.443 kHz, and the quality factor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> is 3063; the resonant frequency of resonator II is 21.455 kHz, and the quality factor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> is 3065. The maximum relative error between the actual value and the simulation value (21.708 kHz) and the theoretical value (22.275 kHz) is 1.22% and 3.74%, respectively. At room temperature, the scale factor of the accelerometer is 204.42 Hz/g in the range of ±1-g acceleration.