Luca Falorni

This work presents a predictive model for the estimation of noise on the state variables of rate-integrating gyroscopes. Linearization of the state equations allows the design of an optimal control strategy and to analytically calculate the effect of noise on the control system. After cross-checking the model against behavioral noise simulations, the control system is implemented on FPGA and the model is validated on MEMS devices fabricated in a commercial process, employing an open-loop compensation of the stiffness asymmetry to enable a part-to-part repeatability of the scale-factor within 0.15%. Experimental results show a scale-factor linearity of 0.007%, a temperature stability of ±59.5 ppm, and a bias instability (BI) less than 0.2 °/h. An unprecedented angle white noise (AWN) floor of 100 $\mu ^{\circ }/\sqrt {\text {Hz}}$ is measured, matching the predictions of the proposed model.[2025-0207]

The research on high-end microelectromechanical system (MEMS) gyrosco-pes often ignores the possibility still offered by the well-known mode-split architecture. This letter analyses how a yaw MEMS gyroscope commercialized for automotive applications can be practically readapted, by changing specific operating parameters, and above all, the electronics and phase calibration settings, in order to achieve consistent improvements. While holding the same full-scale range, a factor 15 in noise (0.05 °/√hr) and a factor 50 in stability (0.18 °/hr) are obtained with respect to the initial values, closely in line with prediction of the theoretical analysis.

This work discusses and solves a relevant issue for Lissajous frequency modulated microelectromechanical system (MEMS) gyroscopes. Their working principle, under realistic control schemes, implies an undesired generation of spurious tones at twice the modulation frequency, which impairs system stability and band width. A novel sensor design is proposed and coupled to an integrated circuit including an oscillator and a frequency to digital converter. The system is designed such that operation can occur at much smaller motion (down to 300 nm displacement amplitude) without, nevertheless, impairing significantly noise performance. In operation, the system shows a 51-fold reduction of the spurious harmonic while holding sub-10-mdps/√Hz input referred noise.

The work demonstrates a setup for the accurate calibration of the relative phase drift between sense modulated output and drive demodulation reference in MEMS gyroscopes. The system enables to operate the sensor inside a climatic chamber, with all the electronics outside, reaching 2 µrad/√Hz short-term resolution in relative phase measurements. After a one-time calibration of parasitic electrical couplings, the setup enables to measure the phase drift in temperature with a sub-5-µrad long-term stability. On average, measurements over four samples, swept vs temperature in 18 different operating conditions, deviate from modeling by 12 µrad/K only.

In this paper a Cross Axis evaluation methodology is presented. The Cross Axis Sensitivity value depends on backend testing position tolerances as well as technological features and design properties of the MEMS gyroscope. A numerical model was developed to take into account the sources of cross axis related to the last two contributions, not considering backend tolerances. Given a specific structure for the AM gyroscope, the asymmetries in the MEMS structure are acknowledged as the main sources for the cross axis. The results of the harmonic FEM simulations were finally compared with real testing data, thus proving the validity of the developed FEM model.

In this work, the mechanical design and the experimental validation of a micro-electromechanical frequency-modulated (FM) pitch gyroscope are presented. The proposed device is fabricated through the ThELMA © surface micromachining process of STMicroelectronics and it represents, to the authors’ knowledge, the first small-footprint (690 µm × 946 µm) prototype of FM gyroscope able to measure an in-plane angular rate. The measured scale factor, defined as the mean angular gain, equals 0.973 Hz/Hz, in close agreement with theoretical predictions. It depends only on the mass distribution in the mechanical structure and is, consequently, not influenced by environmental fluctuations.