This disclosure is related to devices, systems, and techniques for determining an acceleration of a vibrating beam accelerometer (VBA). For example, a system includes processing circuitry configured to receive, from a first resonator, one or more electrical signals indicative of a frequency of a first mechanical beam and a frequency of a second mechanical beam, determine, based on the one or more electrical signals, the frequency of the first mechanical beam and the frequency of the second mechanical beam, and calculate, based on the frequency of the first mechanical beam and the frequency of the second mechanical beam, an acceleration of a proof mass assembly.

Described herein are accelerometers, apparatus and systems incorporating accelerometers, and techniques for controlling sensing operations in an accelerometer. In certain embodiments, an accelerometer is a microelectromechanical systems (MEMS) device including a proof mass, an anchor, a spring between the proof mass and the anchor, a drive electrode, and a sense beam. The anchor is located in an opening defined by a body of the proof mass. The spring and the proof mass form a spring system suspended from the anchor. The sense beam is configured to oscillate at a particular resonance frequency that changes according to a force generated by movement of the proof mass in response to acceleration. In some embodiments, a support structure couples the anchor to the spring and operates as a stress decoupling area that prevents or limits propagation of stress from the anchor to the sense beam and the spring system.

Piezoresistive detection resonant device comprising a substrate, a mobile par configured to move with respect the substrate, suspension elements suspending the mobile part to the substrate, a piezoresistive detection device to detect the motions of the mobile part, said piezoresistive detection device comprising at least one strain gauge, wherein the piezoresistive detection resonant device also comprises a folded spring with at least two spring arms, connected to the mobile part and configured to be deformed by the motion of the mobile part, the at least one gauge being suspended between the substrate and the folded spring in such manner that the deformation of the gauge is reduced compared to the motion of the mobile part.

An MEMS or NEMS accelerometer adapted to measure an acceleration along a sensing axis includes a substrate featuring a plane; a mass having a central zone and suspended relative to the substrate; a single lever arm comprising: a first end connected to the substrate by means of a first connection adapted to allow rotation of the lever arm about a rotation axis perpendicular to the sensing axis, and a second end connected to the mass by means of a second connection adapted to transmit movement in translation of the mass to the lever arm whilst allowing rotation of the lever arm about the rotation axis; the second end of the lever arm being disposed at the level of the central zone of the mass; at least one strain gauge comprising: a first end connected to the substrate, and a second end connected to the lever arm.

The disclosure describes a magnetic circuit assembly that includes a magnet assembly and an excitation ring. The magnet assembly defines a central axis and includes a pole piece and a magnet underlying the pole piece. The excitation ring includes a base and an outer ring positioned around the magnet assembly. The base includes a platform layer underlying the magnet, an upper base layer underlying the platform layer, and a lower base layer underlying the upper base layer. The outer ring overlies the upper base layer and is configured to couple to an outer radial portion of a proof mass assembly. The platform layer and lower base layer are made from high coefficient of thermal expansion (CTE) materials, while the upper base layer and outer ring are made from low CTE materials. Each relatively high CTE material has a higher CTE than each relatively low CTE material.

Microelectromechanical accelerometer comprising a support (2) and a mobile portion (4) able to be vibrated, means for measuring (10) the amplitude of the vibration of said mobile portion (4) in at least one detection direction of the plane of the accelerometer. The accelerometer comprises at least one foot (6) anchored on the support (2) by a first end and fixed to the mobile portion (4) by a second end, and allowing the mobile portion (4) to vibrate at least along said at least one detection direction under the effect of an acceleration force.

This disclosure is related to devices, systems, and techniques for determining an acceleration of a vibrating beam accelerometer (VBA). For example, a system includes processing circuitry configured to receive, from a first resonator, one or more electrical signals indicative of a frequency of a first mechanical beam and a frequency of a second mechanical beam, determine, based on the one or more electrical signals, the frequency of the first mechanical beam and the frequency of the second mechanical beam, and calculate, based on the frequency of the first mechanical beam and the frequency of the second mechanical beam, an acceleration of a proof mass assembly.

The disclosure describes techniques to adjust the geometry of a pendulous proof mass VBA to operate with sufficient signal-to-noise performance while avoiding nonlinear mechanical coupling at specified frequencies. The techniques of this disclosure include adding anchor support flexures to a resonator connection structure, adjusting shape, thickness, and the material of VBA components and of the VBA support structure to both control the frequency of any mechanical resonant modes and to adjust the mechanical mode frequencies away from desired operating frequencies and, in some examples, away from harmonics of desired operating frequencies.

This disclosure describes techniques of configuring capacitive comb fingers of an accelerometer resonator into discreet electrodes with drive electrodes and at least two sense electrodes. The routing of electrical signals is configured to produce parasitic feedthrough capacitances that are approximately equal. The sense electrodes may be placed on opposite sides of the moving resonator beams such that the changes in capacitance with respect to displacement (e.g. dC/dx) are approximately equal in magnitude and opposite in sign. The arrangement may result in sense currents that are also opposite in sign and result in feedthrough currents of the same sign. The sense outputs from the resonators may be connected to a differential amplifier, such that the difference in output currents may mitigate the effect of the feedthrough currents and cancel parasitic feedthrough capacitance. Parasitic feedthrough capacitance may cause increased accelerometer noise and reduced bias stability.

The disclosure describes techniques to damp the proof mass motion of an accelerometer while achieving an underdamped resonator. In an example of an in-plane micro-electromechanical systems (MEMS) VBA, the proof mass may contain one or more damping combs that include one or more banks of rotor comb fingers attached to the proof mass. The rotor comb fingers may be interdigitated with stator comb fingers that are attached to fixed geometry. These damping comb fingers may provide air damping for the proof mass when the MEMS die is placed into a package containing a pressure above a vacuum. The geometry of the damping combs with a reduced air gap and large overlap area between the rotor comb fingers and stator comb fingers. The geometry of resonator of the VBA of this disclosure may be configured to avoid air damping.