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.
Claims23
A device, comprising:
- a first accelerometer including:
- a first sensing mass having a mass between 12 and 13 microgram;
- and
- a first plurality of electrodes configured to be capacitively coupled to the first sensing mass with a capacitance between 250 and 450 femtofarad;
- and
- a second accelerometer including:
- a second sensing mass having a mass between 24 and 28 microgram;
- and
- a second plurality of electrodes configured to be capacitively coupled to the second sensing mass with a capacitance between 330 and 570 femtofarad.
An accelerometer, comprising:
- a sensing mass having a mass between 12 and 13 microgram;
- and
- a plurality of electrodes configured to be capacitively coupled to the sensing mass with a capacitance between 250 and 450 femtofarad,
- each of the plurality of electrodes having a thickness between 20 and 30 micrometers, having a length between 100 and 120 micrometers, and being spaced from the sensing mass by a distance between 1.8 and 2 micrometers.
An accelerometer, comprising:
- a sensing mass having a mass between 24 and 28 microgram, a width between 570 and 590 micrometers, and a length between 950 and 1050 micrometers, the sensing mass having a center of mass and a tilting axis that are spaced from each other by a distance between 150 and 170 micrometers;
- and
- a plurality of electrodes configured to be capacitively coupled to the sensing mass with a capacitance between 330 and 570 femtofarad.
An accelerometer, comprising:
- a substrate;
- a sensing mass having a mass between 12 and 13 microgram;
- a plurality of springs coupled between the sensing mass and the substrate, each of the plurality of springs having a stiffness between 1.5 and 6.3 Newton/meter, each of the springs including 3 to 5 folds, each of the folds has a width between 2.2 and 2.6 micrometers and has a length between 180 and 200 micrometers;
- and
- a plurality of electrodes configured to be capacitively coupled to the sensing mass with a capacitance between 250 and 450 femtofarad.
An accelerometer, comprising:
- a sensing mass having a mass between 12 and 13 microgram;
- and
- a plurality of electrodes configured to be capacitively coupled to the sensing mass with a capacitance between 250 and 450 femtofarad,
- wherein the accelerometer has a resonance frequency between 2 and 3.6 kilohertz, a quality factor between 3 and 7, a sensitivity between 10 and 12 femtofarad/g, and a Brownian noise density between 5 and 9 micro-g/square root hertz (μg/√Hz).
An accelerometer, comprising:
- a substrate;
- a sensing mass having a mass between 24 and 28 microgram;
- a plurality of springs coupled between the sensing mass and the substrate, each of the plurality of springs having a stiffness between 170e-9 and 370e-9 Newton/meter;
- and
- a plurality of electrodes configured to be capacitively coupled to the sensing mass with a capacitance between 330 and 570 femtofarad.
An accelerometer, comprising:
- a sensing mass having a mass between 24 and 28 microgram;
- and
- a plurality of electrodes configured to be capacitively coupled to the sensing mass with a capacitance between 330 and 570 femtofarad,
- wherein each of the plurality of electrodes has an area between 65e3 and 67e3 micrometer2, and is spaced from the sensing mass by a distance between 1 and 1.2 micrometers.
An accelerometer, comprising:
- a sensing mass having a mass between 24 and 28 microgram;
- and
- a plurality of electrodes configured to be capacitively coupled to the sensing mass with a capacitance between 330 and 570 femtofarad,
- wherein the accelerometer has a resonance frequency between 1.9 and 2.6 kilohertz, a quality factor between 1.5 and 4, a sensitivity between 6 and 16 femtofarad/g, and a Brownian noise density between 7 and 11 micro-g/square root hertz (μg/√Hz).
Dependencies are inferred from the claim text.