US 8,516,889 B2Granted

MEMS resonant accelerometer having improved electrical characteristics

AssigneeSTMicroelectronics S.r.l.

InventorsBarbara Simoni, Claudia Comi, Alberto Corigliano

Life of this patent

Estimating the term…

Loading patent…

Abstract

A MEMS resonant accelerometer is disclosed, having: a proof mass coupled to a first anchoring region via a first elastic element so as to be free to move along a sensing axis in response to an external acceleration; and a first resonant element mechanically coupled to the proof mass through the first elastic element so as to be subject to a first axial stress when the proof mass moves along the sensing axis and thus to a first variation of a resonant frequency. The MEMS resonant accelerometer is further provided with a second resonant element mechanically coupled to the proof mass through a second elastic element so as to be subject to a second axial stress when the proof mass moves along the sensing axis, substantially opposite to the first axial stress, and thus to a second variation of a resonant frequency, opposite to the first variation.

Claims30

Dependent claims

A MEMS resonant accelerometer, comprising:

a substrate;
a proof mass;
a first anchoring region coupled to the substrate;
a first elastic element coupled to the first anchoring region and the proof mass, the first elastic element configured to allow movement along a sensing axis in response to an external acceleration;
a second anchoring region coupled to the substrate;
a second elastic element coupled to the second anchoring region and to the proof mass, the second elastic element configured to allow movement along the sensing axis in response to the external acceleration;
a third anchoring region coupled to the substrate;
a first resonating element having a resonant frequency and a longitudinal extension along the sensing axis with a first end and a second end, the first end coupled to the third anchoring region and the second end coupled to a first coupling point on the first elastic element, the first resonating element being coupled to the proof mass via the first elastic element, and configured to generate a first variation of the resonant frequency in response to a first axial stress when the proof mass moves along the sensing axis;
a fourth anchoring region coupled to the substrate;
and
a second resonating element having the resonant frequency and a longitudinal extension along the sensing axis with a respective first end and a respective second end, the respective first end coupled to the fourth anchoring region and the respective second end coupled to a second coupling point on the second elastic element, the second resonating element being coupled to the proof mass via the second elastic element, and being configured to generate a second variation of the resonant frequency in response to a second axial stress when the proof mass moves along the sensing axis, the second axial stress being substantially opposite to the first axial stress, and the second variation being substantially opposite to the first variation.

8 more elements

An electronic device, comprising:

a microprocessor;
a detection circuit coupled to the microprocessor;
and
a MEMS resonant accelerometer coupled to the detection circuit, the accelerometer comprising:
a substrate;
a proof mass;
a first, a second, a third, and a fourth anchoring region coupled to the substrate;
a first elastic element coupled to the first anchoring region and the proof mass;
a second elastic element coupled to the second anchoring region and to the proof mass, the first and second elastic elements configured to allow movement along a sensing axis in response to an external acceleration;
a first resonating element having a resonant frequency and a longitudinal extension along the sensing axis with a first end and a second end, the first end coupled to the third anchoring region and the second end coupled to a first coupling point on the first elastic element, the first resonating element being coupled to the proof mass via the first elastic element, and configured to generate a first variation of the resonant frequency in response to a first axial stress when the proof mass moves along the sensing axis;
and
a second resonating element having the resonant frequency and a longitudinal extension along the sensing axis with a respective first end and a respective second end, the respective first end coupled to the fourth anchoring region and the respective second end coupled to a second coupling point on the second elastic element, the second resonating element being coupled to the proof mass via the second elastic element, and configured to generate a second variation of the resonant frequency in response to a second axial stress when the proof mass moves along the sensing axis, the second axial stress being substantially opposite to the first axial stress, and the second variation being substantially opposite to the first variation;
and
wherein the detection circuit is configured to detect a value of the external acceleration as a function of a difference between the first and second variations of the resonant frequency.

11 more elements

A MEMS resonant accelerometer, comprising:

a substrate;
a proof mass;
a first anchoring region coupled to the substrate;
a first elastic element coupled to the first anchoring region and the proof mass, the first elastic element configured to allow movement along a sensing axis in response to an external acceleration;
a second anchoring region coupled to the substrate;
a second elastic element coupled to the second anchoring region and to the proof mass, the second elastic element configured to allow movement along the sensing axis in response to the external acceleration;
a first resonating element having a resonant frequency and a longitudinal extension along the sensing axis, the first resonating element being coupled to the proof mass via the first elastic element, and configured to generate a first variation of the resonant frequency in response to a first axial stress when the proof mass moves along the sensing axis;
and
a second resonating element having the resonant frequency and a longitudinal extension along the sensing axis, the second resonating element being coupled to the proof mass via the second elastic element, and being configured to generate a second variation of the resonant frequency in response to a second axial stress when the proof mass moves along the sensing axis, the second axial stress being substantially opposite to the first axial stress, and the second variation being substantially opposite to the first variation.

6 more elements

A MEMS resonant accelerometer, comprising:

a substrate;
a proof mass, having a first and a second projecting portion;
a first anchoring region coupled to the substrate;
a first elastic element coupled to the first anchoring region and the first projecting portion of the proof mass, the first elastic element configured to allow movement along a sensing axis in response to an external acceleration;
a second anchoring region coupled to the substrate;
a second elastic element coupled to the second anchoring region and to the second projecting portion of the proof mass, the second elastic element configured to allow movement along the sensing axis in response to the external acceleration, wherein the first and second projecting portions and the first and second anchoring regions are positioned so that the first and second elastic elements are substantially parallel to each other and are transverse to the sensing axis;
a first resonating element having a resonant frequency and a longitudinal extension along the sensing axis, the first resonating element being coupled to the proof mass via the first elastic element, and configured to generate a first variation of the resonant frequency in response to a first axial stress when the proof mass moves along the sensing axis;
a second resonating element having the resonant frequency and a longitudinal extension along the sensing axis, the second resonating element being coupled to the proof mass via the second elastic element, and being configured to generate a second variation of the resonant frequency in response to a second axial stress when the proof mass moves along the sensing axis, the second axial stress being substantially opposite to the first axial stress, and the second variation being substantially opposite to the first variation;
and
wherein the first and second resonating elements extend transverse to the first and second elastic elements at opposite sides of the proof mass.

7 more elements

Dependencies are inferred from the claim text.