Development of an oscillation loop for a micromachined differential type resonant accelerometer and its performance

This paper presents a surface micro-machined differential resonant accelerometer (DRXL) by using the epitaxially grown thick polysilicon process. The proposed DRXL utilizes the electrostatic stiffness changing effect of an electrostatic torsional actuator. This device produces a differential digital output proportional to an applied acceleration. For a self-generated and self-sustained oscillation of the resonator, a feedback oscillation loop is designed, implemented, and applied to the DRXL chip. The oscillation loop is designed using an analytical result based on the describing function method. Using the implemented self-sustaining oscillation loop, specifications of sensor performance are obtained by various performance tests. These results show quite an improved quality factor and resolution compared to that of the sensing device only. And we obtained more stable output frequency responses.