Carlo Caminada

A low-power 3-axis digital-output MEMS gyroscope with single drive and multiplexed angular rate readout

Motivated by the increasing demand of integrated inertial-sensing solutions for motion processing and dead-reckoning navigation in handheld devices and low-cost GPS navigators, this paper reports the details of a 3-axis silicon MEMS vibratory gyroscope that fulfills the pressing market requirements for low power consumption, small size and low cost. Thanks to a compact mechanical design that combines a triple tuning-fork structure within a single vibrating element, our solution achieves satisfactory performance in terms of thermal stability, cross-axis error, and acoustic noise immunity by using a small die size. Furthermore, the presence of a single primary vibration mode for the excitation of the 3 tuning-forks, together with the possibility of sensing the pickoff modes in a multiplexing fashion, allows to design a small-area, low-power ASIC.

Open loop compensation of the quadrature error in MEMS vibrating gyroscopes

This paper presents a simple, yet effective approach for rejecting the quadrature error in MEMS vibratory gyroscopes. The proposed solution consists of an open loop compensation that is performed on the proof-mass displacement readout signal provided by a standard capacitive sensing interface based on parallel-plate capacitors. The compensating signal is generated and calibrated according to the nominal quadrature error to reject, and is injected into the system by means of a compensation circuit based on a dynamically reconfigurable capacitor bank. The compensation scheme described in the paper has been implemented on ASIC and experimentally tested on a real MEMS vibratory gyroscope. Experimental results show that the proposed solution assures good rejection capabilities, even for very large quadrature errors that unavoidably saturates the sensor readout interface.