A Mode-Localized Mems Accelerometer in the Modal Overlap Regime Employing Parametric Pump

The principle of vibration mode localization has been been researched in recent years as an approach towards the high accuracy transduction of inertial forces. This transduction scheme comprises of two or more weakly coupled resonators and a low coupling factor is critical in order to enhance parametric sensitivity and consequently resolution. In this paper, we report a new mode-localized accelerometer topology which enables a high amplitude ratio scale factor using a differential acceleration perturbation method. Further, by employing a parametric pump, an adjustable ultra-weak virtual coupling factor is realized where the coupled resonators can operate in the weak coupling regime. In this regime, modal overlap is apparent and the amplitude ratio sensitivity is much improved, by decreasing the pump strength. The experiments show that the amplitude ratio sensitivity of the proposed accelerometer is 9.2/g, and it can be enlarged to as high as 6300/g by employing a parametric pump signal with 100 mV strength, indicating a scale-factor improvement factor of 684. Consequently, the input-referred bias instability is improved from 6.7 µg for the case of no parametric pump to 420 ng while employing a parametric pump for operation in the modal-overlap regime, showing an improvement by a factor of ~16.