Dual-operating accelerometer
AssigneeSTMicroelectronics S.r.l.
InventorsFrancesco Rizzini, Nicolo' Manca, Cristian Dall'Oglio
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Abstract
The present disclosure is directed to micro-electromechanical system (MEMS) accelerometers that are configured for a user interface mode and a true wireless stereo (TWS) mode of an audio device. The accelerometers are fabricated with specific electromechanical parameters, such as mass, stiffness, active capacitance, and bonding pressure. As a result of the specific electromechanical parameters, the accelerometers have a resonance frequency, quality factor, sensitivity, and Brownian noise density that are suitable for both the user interface mode and the TWS mode.
Claims20
An accelerometer, comprising:
- a substrate having a surface;
- a sensing mass overlying the surface of the substrate, the sensing mass configured to move in a direction extending along the surface of the substrate, the sensing mass having a mass between 12 and 13 microgram;
- a plurality of electrodes on the surface of the substrate, the plurality of electrodes configured to be capacitively coupled to the sensing mass with an active capacitance between 250 and 450 femtofarad;
- and
- a plurality of folded springs that couple the sensing mass to the substrate, the plurality of folded springs having a stiffness between 1.5 and 6.3 Newton/meter.
An accelerometer, comprising:
- a substrate having a surface extending in a first direction and a second direction;
- a sensing mass overlying the surface of the substrate, the sensing mass configured to move in a third direction transverse to the first and second directions, the sensing mass having a mass between 24 and 28 microgram;
- a plurality of electrodes on the surface of the substrate, the plurality of electrodes configured to be capacitively coupled to the sensing mass with an active capacitance between 330 and 570 femtofarad;
- and
- a plurality of torsional springs that couple the sensing mass to the substrate, the plurality of torsional springs having a stiffness between 170e-9 and 370e-9 Newton/meter.
A device, comprising:
- a substrate;
- first and second accelerometers, each of the first and second accelerometers including:
- a first sensing mass overlying the substrate, the first sensing mass configured to move in a first direction, the first sensing mass having a mass between 12 and 13 microgram;
- a first plurality of electrodes on the substrate, the first plurality of electrodes configured to be capacitively coupled to the first sensing mass with an active capacitance between 250 and 450 femtofarad;
- and
- a plurality of folded springs that couple the first sensing mass to the substrate, the plurality of folded springs having a stiffness between 1.5 and 6.3 Newton/meter;
- and
- a third accelerometer including:
- a second sensing mass overlying the substrate, the second sensing mass configured to move in a second direction transverse to the first direction, the second sensing mass having a mass between 24 and 28 microgram;
- a second plurality of electrodes on the substrate, the second plurality of electrodes configured to be capacitively coupled to the second sensing mass with an active capacitance between 330 and 570 femtofarad;
- and
- a plurality of torsional springs that couple the second sensing mass to the substrate, each of the plurality of torsional springs having a stiffness between 170e-9 and 370e-9 Newton/meter.
Dependencies are inferred from the claim text.