New Stability Method of a Multirate Controller for a Three-Axis High-<inline-formula> <tex-math notation="LaTeX">$Q$ </tex-math> </inline-formula> MEMS Accelerometer With Simultaneous Electrostatic Damping

Abstract

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.

A Low-Noise Micromachined Accelerometer with Reconfigurable Electrodes for Resonance Suppression

“…The top and bottom electrodes ( and ) are to be used as actuators. A fixed DC voltage is added to the electrode, which causes the electrostatic actuator to behave linearly and generate a bidirectional force [ 23 ]. The net electrostatic force applied to the proof mass is [ 24 ]: where is the feedback voltage and is the fixed DC bias voltage, and is the capacitance of the actuator electrodes.…”

“…The appropriate controller should only impact the overall damping of the system around resonance. A derivative controller can provide sufficient damping to the system by increasing the damping factor in the velocity term as shown by the system’s equation of motion, given by where is the electrostatic damping coefficient [ 23 ].…”

“…x + kx = Ma ext (9) where β = 2ε 0 AV DC d −2 is the electrostatic damping coefficient [23]. The system's wide bandwidth, however, implies that a derivative controller could magnify noise and may cause instability.…”

Opto-Mechanical Photonic Crystal Cavities for Sensing Application

“…Inertial sensors are generally used to detect and measure acceleration, tilt, and vibration. In principle, the MEMS-based accelerometer works to measure the displacement of a mechanical mass, known as a proof mass [139,140]. In MEMS devices, displacement detection is electrically measured through the capacitance between proof mass and electrode.…”