This paper presents a biaxial silicon resonant microaccelerometer characterized by a high sensitivity and a low cross-axis sensitivity. The device has a detection structure with a single inertial mass and two pairs of resonating beams allowing for the simultaneous differential measurement of acceleration acting along two different axes. The design of the accelerometer and in particular the geometrical configuration of the resonating elements is analytically optimized and finalized through finite element simulations. Experimental results on a fabricated device demonstrate a mean differential sensitivity of 250 Hz g−1 at a polarization voltage of 4 V, around a resonance frequency of 84 kHz.

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Two methods for limiting the oscillation amplitude in micromechanical resonators, typically used in many kinds of MEMS sensors, are discussed and compared. First, it is shown how the presence of parasitic capacitances sets several constraints on the design of the oscillating circuit gain and bandwidth. The paper specifically focuses on the case of a transimpedance based oscillator coupled to a clamped-clamped beam, that forms the sensing element of a resonant accelerometer. Experimental results then show that the oscillating amplitude can be limited either using an electronic limiting stage, or exploiting the mechanical nonlinearities of the beam for large displacements. Though the latter approach is advantageous in terms of power dissipation, it is shown that the sensitivity of the resonant accelerometer is strongly compromised.

resonators, labeled A and B in figure 1, consisting of a square mass and two folded torsional springs attached to the proof mass, allow for the differential sensing of the acceleration. Driving and sensing of the resonators is obtained through two parallel electrodes attached to the substrate, as shown by dashed lines in figure 2 and also represented in figure 3. When an external out-of-plane acceleration is applied, the proof mass tilts and the frequency of the resonators change due to the variation of the electric stiffness induced by the gap variation.To obtain a high sensitivity the mechanical torsional stiffness of the resonators should be low but this can result in nonlinear dynamic behavior which is studied in this paper.The paper is organized as follows. In section 2, Hamilton's principle is formulated for the mechanical description of nonlinear oscillations of an electrostatically actuated torsional resonator. In section 3, Hamilton's principle is used as a basis for a one-degree-of-freedom formulation and analytical solutions are obtained. Section 4 discusses the influence of the geometry of the resonator and of the fabrication imperfections on the nonlinear behavior. The experimental results obtained both in the linear and nonlinear regimes on the resonators of the resonant out-of-plane accelerometer [3] are presented and discussed in section 5. The experimental data concerning the