3-axis high Q MEMS accelerometer with simultaneous damping control

The increasing demand of consumer market sensors involves a continuous development for the die size, cost and performances. In this context, the integration of both a 3-axis MEMS accelerometer and a gyroscope within the same low pressure cavity becomes attractive. Such a packaging results in MEMS with high quality factor Q, which reduces Brownian noise, thereby improving the achievable precision. However, contrary to gyroscopes, in such a configuration, the MEMS accelerometers need to be damped prior to measurement. Therefore, this paper presents a new damping control architecture for such high Q capacitive accelerometers. Damping is ensured by inserting electrostatic force feedback (EFF) phases between measurement phases. By simultaneously damping 3 axis of acceleration, the transducer settling time is improved. Model simulations results prove damping efficiency and figure out a tradeoff between system sampling frequency and circuit complexity.