Vibration Performance Analysis and Improvement of MEMS Resonant Accelerometers

In this article, the dynamic performance of microelectromechanical system (MEMS) resonant accelerometers when subjected to shock and vibration is meticulously analyzed and enhanced through optimization of the sensing structure, design of an active damping system and improvement of acceleration read-out method. A structure design strategy based on mechanical stiffness coordination (SC) is proposed to increase the overall structure stiffness with minimal cost of its sensitivity. The translational mode frequency of the prototype has been increased to 2765 Hz while the scale factor is maintained at 225 Hz/g. Subsequently, an active damping system is designed to enhance the damping of the proof mass near the translational mode so that it can recover from the impact quickly in less than 50 ms in a free-falling test. Besides, it has been observed that the active damping system can help the prototype free from external vibration noise and thus enhance the bias stability. To reduce the vibration rectification error (VRE) in a random vibration test, a proportional F-squared (PFS) method is adopted to mitigate the residual second-order nonlinearity of the scale factor which is verified to be the main source of the VRE. The compensation results show that the VRE has been reduced to less than 10 μg/g<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. The state-of-the-art result exhibits that our efforts in the structure optimization, active damping and VRE compensation can improve the micromachined resonant accelerometers (MRAs) performance greatly under the shock and vibration environment.