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.

A physical quantity sensor includes a first plate, and a second plate opposed to the first plate via a gap, wherein a sensing area in which the gap between the first plate and the second plate changing with a physical quantity is detected based on a change of a capacitance is disposed in an area where the first plate and the second plate overlap each other in a plan view, the first plate is provided with a through hole in the sensing area, and in a part of the second plate where the second plate overlaps the through hole of the first plate in the plan view, a distance from the second plate to an imaginary plane extending in a same plane as a surface of the first plate opposed to the second plate via the gap is longer than a distance of the gap.

An inertial sensor includes a movable mass spaced apart from a surface of the substrate. The movable mass is adapted for motion about a rotational axis positioned between first and second ends of the movable mass in response to a first force imposed upon the movable mass in a first direction that is perpendicular to the surface of the substrate. The inertial sensor further includes a damping system configured to limit motion of the movable mass in a second direction perpendicular to the first direction. The damping system includes a first damping structure coupled to the movable mass, a second damping structure adjacent to the first damping structure, the first and second damping structures being spaced apart from the surface of the substrate, and a spring structure interconnected between the movable mass and the second damping structure.

The present invention relates to capacitive micromechanical accelerometers, and in particular to acceleration sensors with movable rotors which may rotate out of a substrate plane when the accelerometer undergoes movement with an acceleration component perpendicular to the substrate plane. The capacitive micromechanical accelerometer includes additional damping springs to reduce unwanted movement of the rotor in the substrate plane, thereby reducing the parasitic capacitance that results from motion of the rotor in the substrate plane. The damping springs are vertically recessed with respect to other components of the accelerometer in order to minimise the effect of the damping springs on movement of the rotor out of the substrate plane.

Microelectronic structure comprising a mobile mass mechanically linked to a first and to a second mechanical element by first and second mechanical linking device respectively, a polarisation source for the second mechanical linking device. The second mechanical linking means comprises two linking elements and a thermal reservoir placed between the linking elements, where at least one of the linking elements is made of piezoresistive material, where at least one of the first and second linking elements exhibit thermoelasticity properties. The thermal reservoir exhibits a thermal capacity which is different from those of the linking elements. The second linking device and the mobile mass are arranged relative to each other such that displacement of the mobile mass applies a mechanical stress to the second linking means.

An audio system including an accelerometer positioned to produce an accelerometer signal representative of road noise within a vehicle cabin; a microphone operably positioned within the vehicle to receive the road noise and to produce a microphone signal having a road-noise component; and a cabin road-noise canceler, comprising a cabin road-noise cancellation filter, configured to receive the accelerometer signal and to produce a cabin road-noise cancellation signal, wherein the cabin road-noise cancellation signal is provided to an acoustic transducer for transduction of an acoustic road-noise cancellation signal, the acoustic road-noise cancellation signal minimizing the road noise within at least one cancellation zone in the vehicle cabin; a microphone road-noise canceler, comprising a microphone road-noise cancellation filter, configured to receive the cabin road-noise signal and the microphone signal and to minimize the road-noise component of the microphone signal according to the cabin road-noise cancellation signal, to produce an estimated microphone signal.

This disclosure describes a capacitive micromechanical accelerometer with at least a first sensor which comprises a rotor which is a two-sided seesaw frame. The rotor comprises one or more first damping plates on the first side of its rotation axis and one or more first damping plates on the second side of its rotation axis. One or more second damping plates are fixed to the inner package plane above or below at least some of the one or more first damping plates, so that at least one first damping plate overlaps with the projection of a second damping plate on each side of the axis. The frame-shaped rotor may surround second and third acceleration sensors located in the substrate plane.

An inertial sensor for sensing an external acceleration includes: a first and a second proof mass; a first and a second capacitor formed between first and second fixed electrodes and the first proof mass; a third and a fourth capacitor formed between third and fourth fixed electrodes and the second proof mass; a driving assembly configured to cause an antiphase oscillation of the first and second proof masses; a biasing circuit configured to bias the first and third capacitors, thus generating first variation of the oscillation frequency in a first time interval, and to bias the second and fourth capacitors, thus generating first variation of the oscillation frequency in a second time interval; a sensing assembly, configured to generate an differential output signal which is a function of a difference between a value of the oscillating frequency during the first time interval and a value of the oscillating frequency during the second time interval. Such differential output signal can be correlated to the value and direction of the external acceleration.

Accelerometer including a decoupling structure for fixing the accelerometer on a package and a MEMS sensor chip for measuring an acceleration. The chip is supported by the decoupling structure and includes a sensor wafer layer of a semiconductor material. The decoupling structure forms a bottom portion for fixing the decoupling structure on the package and a top portion fixed to the sensor wafer layer so that the chip is arranged above the decoupling structure. A width of the top portion in a planar direction is smaller than a width of the bottom portion and/or the sensor wafer layer in the planar direction. The decoupling structure is made of the same semiconductor material as the sensor wafer layer. The centre point of the top portion is arranged in a central region of the bottom portion. The chip includes a hermetically closed cavity which includes a seismic mass of the chip.