Over the past years, cutting-edge advances in electronics and microfabrication have allowed the integration of multiple sensors within integrated analog and digital circuits to design microelectromechanical systems. The multiple sensor integration or sensor fusion enables both cost and surface reduction, while maintaining high performances. This paper presents a new control system for an underdamped three-axis accelerometer, which allows the co-integration in the same cavity with a threeaxis Coriolis gyroscope to design a six degrees-of-freedom combo sensor. The accelerometer analog front end consumes 300 µA from a 1.6V power supply and is able to reach its steady state in 800 µs compared with a 400ms open loop and no damping configuration. The transducer control is implemented using a simultaneous multirate electrostatic damping method. To conclude on the closed-loop system stability, an innovative approach based on the multirate signal processing theory has been developed.

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.