Impact of the closed-loop phase shift on the frequency stability of capacitive MEMS oscillators

Alexis Brenes (1, 2, 3) , Jérôme Juillard (1) , Filipe Vinci dos Santos (3)

1 GeePs - Laboratoire Génie électrique et électronique de Paris
2 TAES - THALES Avionics Electrical Systems
3 Chaire Conception Analogique Avancée Thales/Supélec

Phase noise is a clue performance indicator for MEMS-based resonant sensors. The optimal resolution achievable with these sensors is limited by the close-to-the-carrier phase noise resulting from the modulation of noise sources by the mechanical resonator. In this paper, we focus on the effect of a white noise input source on a one-sided capacitive MEMS resonator. We study how the closed-loop phase shift affects its frequency stability. Our study reveals the existence of optimal points, with phase noise minimization and SNR maximization, which cannot be predicted by a traditional third-order Taylor-Series approach. We reveal that, due to the modulation of the actuation force by the electrostatic nonlinearity, tuning the closed-loop phase shift to improve the oscillator frequency stability is especially relevant.

Mots clés: Electrostatic nonlinearity; closed-loop systems; oscillators; frequency stability; capacitive MEMS

Domaines: Micro et nanotechnologies/Microélectronique

Alexis Brenes, Jérôme Juillard, Filipe Vinci dos Santos. Impact of the closed-loop phase shift on the frequency stability of capacitive MEMS oscillators. 2016 Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS (DTIP) , May 2016, Budapest, Hungary. pp.169-172, ⟨10.1109/DTIP.2016.7514862⟩. ⟨hal-01357847⟩