Multi-axis sensing device based on frequency modulation and operation method thereof

Abstract

A MEMS device includes a first inertial mass system and a second inertial mass system. The first inertial mass system has a first driving mass block and a first sensing mass block that are elastically coupled to each other. The second inertial mass system has a second driving mass block and a second sensing mass block that are elastically coupled to each other. The first driving mass block and the second driving mass block undergo anti-phase driving motion along a first axis parallel to the surface of the substrate. The first sensing spring and the second sensing spring anchor and suspend the first sensing mass block and the second sensing mass block spaced apart from the surface of the substrate. The first sensing spring and the second sensing spring achieve anti-phase sensing motion of the first sensing mass block and the second sensing mass block along a second axis parallel to the surface in response to angular rotation about a third axis perpendicular to the surface. The first sensing spring and the second sensing spring additionally achieve in-phase sensing motion of the first sensing mass block and the second sensing mass block along the second axis in response to linear acceleration along the second axis.

Description

Technical Field

[0001] The present invention generally relates to microelectromechanical system (MEMS) multi-axis sensing devices. More specifically, the present invention relates to a frequency modulation-based MEMS multi-axis sensing device for simultaneously sensing linear acceleration and angular velocity. Background Art

[0002] In recent years, due to the fact that microelectromechanical system (MEMS) technology provides a way to fabricate very small mechanical structures using conventional batch semiconductor processing techniques and integrate these structures with electrical devices onto a single substrate, MEMS technology has achieved wide popularity. A common application of MEMS is the design and manufacture of sensor devices. MEMS sensor devices are widely used in various applications such as automotive, inertial guidance systems, household appliances, gaming devices, protection systems for various devices, and many other industrial systems, scientific systems, and engineering systems. Continuous efforts have been made in the conflicting goals of reducing the size of MEMS devices while enhancing the sensing capabilities of such MEMS devices. Summary of the Invention

[0003] Aspects of the present disclosure are defined in the appended claims.

[0004] In a first aspect, there is provided a microelectromechanical system (MEMS) multi-axis sensing device, the MEMS multi-axis sensing device comprising: a substrate having a surface; a first inertial mass system including a first driving mass block and a first sensing mass block elastically coupled to the first driving mass block; a second inertial mass system including a second driving mass block and a second sensing mass block elastically coupled to the second driving mass block, the first driving mass block and the second driving mass block being configured to undergo anti-phase driving motion along a first axis parallel to the surface of the substrate; a first sensing spring configured to anchor and suspend the first sensing mass block spaced apart from the surface of the substrate; and a second sensing spring configured to anchor and suspend the second sensing mass block spaced apart from the surface of the substrate, the first sensing spring and the second sensing spring effecting anti-phase sensing motion of the first sensing mass block and the second sensing mass block along a second axis parallel to the surface of the substrate and perpendicular to the first axis in response to angular rotation about a third axis perpendicular to the surface of the substrate, and the first sensing spring and the second sensing spring additionally effecting in-phase sensing motion of the first sensing mass block and the second sensing mass block along the second axis in response to linear acceleration along the second axis.

[0005] In a second aspect, a method is provided, the method comprising: providing a microelectromechanical system (MEMS) multi-axis sensing device, the MEMS multi-axis sensing device comprising: a substrate having a surface; a first inertial mass system comprising a first drive mass and a first sense mass elastically coupled to the first drive mass; a second inertial mass system comprising a second drive mass and a second sense mass elastically coupled to the second drive mass; a first sense spring configured to anchor and suspend the first sense mass spaced apart from the surface of the substrate; and a second sense spring configured to anchor and suspend the second sense mass spaced apart from the surface of the substrate; actuating the first drive mass and the second drive mass to undergo anti-phase drive motion along a first axis parallel to the surface of the substrate; sensing anti-phase sensing motion of the first sense mass and the second sense mass along a second axis parallel to the surface of the substrate and perpendicular to the first axis in response to an angular rotation about a third axis perpendicular to the surface of the substrate, wherein the first sense spring and the second sense spring effect the anti-phase sensing motion; sensing in-phase sensing motion of the first sense mass and the second sense mass along the second axis in response to a linear acceleration along the second axis, wherein the first sense spring and the second sense spring additionally effect the in-phase sensing motion; determining an angular rotation rate value of the angular rotation about the third axis in response to the anti-phase sensing motion; and determining a linear acceleration value of the linear acceleration along the second axis in response to the in-phase sensing motion.

[0006] In a third aspect, a microelectromechanical system (MEMS) multi-axis sensing device is provided. The MEMS multi-axis sensing device includes: a substrate having a surface; a first inertial mass system including a first driving mass and a first sensing mass elastically coupled to the first driving mass; a second inertial mass system including a second driving mass and a second sensing mass elastically coupled to the second driving mass, the first driving mass and the second driving mass being configured to undergo anti-phase driving motion along a first axis parallel to the surface of the substrate; a first sensing spring configured to anchor and suspend the first sensing mass spaced apart from the surface of the substrate; a second sensing spring configured to anchor and suspend the second sensing mass spaced apart from the surface of the substrate, the first sensing spring and the second sensing spring effecting anti-phase sensing motion of the first sensing mass and the second sensing mass along a second axis parallel to the surface of the substrate and perpendicular to the first axis in response to angular rotation about a third axis perpendicular to the surface of the substrate, and the first sensing spring and the second sensing spring additionally effecting in-phase sensing motion of the first sensing mass and the second sensing mass along the second axis in response to linear acceleration along the second axis; a first resonator beam elastically coupled to the first sensing mass by one of the first sensing springs, the first resonator beam being configured to undergo a first axial stress in response to movement of the first sensing mass along the second axis; a second resonator beam elastically coupled to the first sensing mass by the other of the first sensing springs, the second resonator beam being configured to undergo a second axial stress in response to the movement of the first sensing mass along the second axis; a third resonator beam elastically coupled to the second sensing mass by one of the second sensing springs, the third resonator beam being configured to undergo a third axial stress in response to movement of the second sensing mass along the second axis; and a fourth resonator beam elastically coupled to the second sensing mass by the other of the second sensing springs, the fourth resonator beam being configured to undergo a fourth axial stress in response to the movement of the second sensing mass along the second axis, wherein the substrate, the first inertial mass system and the second inertial mass system, the first sensing spring and the second sensing spring, and the first resonator beam, the second resonator beam, the third resonator beam, and the fourth resonator beam are juxtaposed in a cavity of a packaging device, and the cavity is in a vacuum. Description of the Drawings

[0007] The accompanying drawings are used to further illustrate the various embodiments and to explain all the principles and advantages in accordance with the present invention. In the separate views of the accompanying drawings, like reference numerals refer to the same or functionally similar elements. The accompanying drawings are not necessarily drawn to scale and are incorporated into and form a part of this specification together with the following detailed description.

[0008] Figure 1 A schematic plan view of a microelectromechanical system (MEMS) multi-axis sensing device according to an embodiment is shown;

[0009] Figure 2 Shows the inclusion of Figure 1 A highly simplified schematic side view of a MEMS sensor package of a MEMS device;

[0010] Figure 3 Shows Figure 1 A schematic plan view of a MEMS device showing an inverting drive motion;

[0011] Figure 4 Shows Figure 1 A schematic plan view of a MEMS device showing an inverting sensing motion;

[0012] Figure 5 Shows Figure 1 A schematic plan view of a MEMS device showing a non-inverting sensing motion;

[0013] Figure 6 Shows Figure 1 A block diagram of a signal processing circuit of a MEMS device; and

[0014] Figure 7 A schematic plan view of a microelectromechanical system (MEMS) multi-axis sensing device according to another embodiment is shown. Detailed Description of the Invention

[0015] In general, the present disclosure relates to a microelectromechanical system (MEMS) multi-axis sensing device and method of operation. More specifically, the MEMS multi-axis sensing device is based on frequency modulation (FM) to sense linear acceleration and angular rate (i.e., velocity) simultaneously using a single inertial mass detection structure. The FM resonant accelerometer and the FM vibrating gyroscope are co-fabricated as a single detection structure, wherein the detection of linear acceleration and angular rate is based on the change in the frequency (e.g., frequency modulation) of one or more elements set at resonance. The linear acceleration can be detected by a common-mode FM signal, and the angular rate can be detected by a differential-mode FM signal. Compared with other measurement techniques, resonant detection can produce a direct frequency output, high sensitivity, and a wide dynamic range. Additionally, a single FM-based detection structure enables the same cavity pressure for both the accelerometer and the gyroscope, which can thereby simplify the MEMS processing technology, reduce the MEMS die size, and decrease the number of MEMS dies in the sensor package.

[0016] The purpose of providing the present disclosure is to additionally explain at least one embodiment according to the present invention in an enabling manner. The present disclosure is additionally provided for enhancing the understanding and recognition of the inventive principles and advantages of the present disclosure, rather than limiting the present invention in any way. The present invention is defined only by the appended claims, which include any modifications made during the pendency of this application and all equivalents of those claims as published.

[0017] It should be understood that the use of relational terms such as first and second, top and bottom, etc. (if any) is only used to distinguish entities or actions from each other, and does not necessarily require or imply any actual such relationship or order between such entities or actions. Additionally, some of the figures in the drawings may be illustrated with various shadings and / or hatching to distinguish different elements generated within each structural layer. These different elements within the structural layer can be produced using current and upcoming microfabrication techniques such as deposition, patterning, etching, etc. Thus, although different shadings and / or hatching are utilized in the illustration, the different elements within the structural layer can be formed of the same material.

[0018] Reference Figure 1 , Figure 1 FIG. shows a schematic plan view of a microelectromechanical system (MEMS) multi-axis sensing device 20 according to an embodiment. The MEMS device 20 includes a substrate 22 having a generally planar surface 24, a first inertial mass system 26, a second inertial mass system 28, a first sensing spring 30, and a second sensing spring 32. The first inertial mass system 26 includes a first drive mass 34 and a first sensing mass 36 elastically coupled to the first drive mass 34. Similarly, the second inertial mass system 28 includes a second drive mass 38 and a second sensing mass 40 elastically coupled to the second drive mass 38.

[0019] The first sensing spring 30 is configured to anchor and suspend a first sensing mass 36 spaced apart from the surface 24 of the substrate 22, and the second sensing spring 32 is configured to anchor and suspend a second sensing mass 40 spaced apart from the surface 24 of the substrate 22. Accordingly, the first sensing spring 30 interconnects between the first sensing mass 36 and an anchor 42 fixed to the surface 24, and the second sensing spring 32 interconnects between the second sensing mass 40 and an anchor 44 fixed to the surface 24.

[0020] The first driving mass 34 includes a first frame 46 surrounding the first sensing mass 36, and the second driving mass 38 includes a second frame 48 surrounding the second sensing mass 40. The first driving spring 50 is configured to anchor and suspend the first frame 46 spaced apart from the surface 24 of the substrate 22, and the second driving spring 52 is configured to anchor and suspend the second frame 48 spaced apart from the surface 24 of the substrate 22. Accordingly, the first driving spring 50 interconnects between the first frame 46 and an anchor 54 fixed to the surface 24, and the second driving spring 52 interconnects between the second frame 48 and an anchor 56 fixed to the surface 24. The first driving spring 50 and the second driving spring 52 are interconnected at a joining element 58 spaced apart from the surface 24 of the substrate 22 such that the first driving spring 50 and the second driving spring 52 flexibly interconnect the first driving mass 34 and the second driving mass 38.

[0021] A third sensing spring 60 is coupled to the outer perimeter of the first frame 46 and the first driving spring 50. Similarly, a fourth sensing spring 62 is coupled to the outer perimeter of the second frame 48 and the second driving spring 52. Additionally, a third driving spring 64 is interposed between and interconnects the first sensing mass 36 and the first frame 46 of the first driving mass 34. A fourth driving spring 66 is interposed between and interconnects the second sensing mass 40 and the second frame 48 of the second driving mass 38. The third driving spring 64 and the fourth driving spring 66 can be of any convenient shape, size, and material.

[0022] Typically, the first sensing spring 30, the second sensing spring 32, the third sensing spring 60, and the fourth sensing spring 62 have a longitudinal extension (e.g., a longitudinal flexible dimension) parallel to the X-axis 68 in the three-dimensional coordinate system. The first driving spring 50, the second driving spring 52, the third driving spring 64, and the fourth driving spring 66 have a longitudinal extension (e.g., a longitudinal flexible dimension) parallel to the Y-axis 70 in the three-dimensional coordinate system. In this example, the X-axis 68 and the Y-axis 70 are parallel to the surface 24 of the substrate 22 and are perpendicular to each other. The three-dimensional coordinate system further includes a Z-axis 72 perpendicular to the surface 24 of the substrate 22 and thus perpendicular to the X-axis 68 and the Y-axis 70. The first driving spring 50, the second driving spring 52, the third driving spring 64, and the fourth driving spring 66 can be of any convenient shape, size, and material to allow large oscillatory linear motion of the first driving mass 34 and the second driving mass 38 along the X-axis 68 (e.g., the driving axis) while preventing the transmission of this oscillatory linear motion to the first sensing mass 36 and the second sensing mass 40, and these driving springs are still rigid enough to transfer the Coriolis force from the first driving mass 34 and the second driving mass 38 to the first sensing mass 36 and the second sensing mass 40 along the Y-axis 70 (e.g., the sensing axis) in response to rotation of the MEMS device 20 about the Z-axis 72 (e.g., the input axis).

[0023] The MEMS multi-axis sensing device 20 further includes a first resonator beam 74, a second resonator beam 76, a third resonator beam 78, and a fourth resonator beam 80. The first resonator beam 74 has one end elastically coupled to the first sensing mass 36 through one of the first sensing springs 30, and the opposite end of the first resonator beam is fixed to the surface 24 of the substrate 22 through an anchor 82. The second resonator beam 76 has one end elastically coupled to the first sensing mass 36 through another of the first springs 30, and the opposite end of the second resonator beam is fixed to the surface 24 through an anchor 84. The third resonator beam 78 has one end elastically coupled to the second sensing mass 40 through one of the second sensing springs 32, and the opposite end of the third resonator beam is fixed to the surface 24 through an anchor 86. The fourth resonator beam 80 has one end elastically coupled to the second sensing mass 40 through another of the second sensing springs 32, and the opposite end of the fourth resonator beam is fixed to the surface 24 through an anchor 88.

[0024] The first driving electrode 90 and the first sensing electrode 92 are aligned with the first resonator beam 74. The second driving electrode 94 and the second sensing electrode 96 are aligned with the second resonator beam 76. The third driving electrode 98 and the third sensing electrode 100 are aligned with the third resonator beam 78. The fourth driving electrode 102 and the fourth sensing electrode 104 are aligned with the fourth resonator beam 80.

[0025] Typically, each of the first drive electrode 90, the second drive electrode 94, the third drive electrode 98, and the fourth drive electrode 102 is used to send one of the associated first resonator beam 74, second resonator beam 76, third resonator beam 78, and fourth resonator beam 80 into resonance condition by applying an appropriate potential difference. Each of the first sensing electrode 92, the second sensing electrode 96, the third sensing electrode 100, and the fourth sensing electrode 104 serves as a detection electrode for detecting a change in the corresponding resonance frequency by means of a change in the capacitive coupling with one of the associated first resonator beam 74, second resonator beam 76, third resonator beam 78, and fourth resonator beam 80. As will be discussed in connection with Figure 6 As discussed, suitable electrical connections can be provided for the electrical connections of the drive electrodes 90, 94, 98, 102 and the sensing electrodes 92, 96, 100, 104 to the electronic circuit. The electronic circuit is configured to supply actuation electrical signals to the first drive electrode 90, the second drive electrode 94, the third drive electrode 98, and the fourth drive electrode 102, and to receive and process the electrical detection signals provided by the first sensing electrode 92, the second sensing electrode 96, the third sensing electrode 100, and the fourth sensing electrode 104.

[0026] For the sake of consistency in the description throughout the following figures, any anchoring structures that connect the suspension elements of the MEMS device 20 to the underlying surface 24 of the substrate 22, such as the anchors 42, 44, 54, 56, 82, 84, 86, 88, are shown with an "X" through them. Elements suspended above the surface 24 of the substrate 22 are represented by a dotted pattern. Spring elements suspended above the surface 24 are generally represented by solid lines. Elements that are directly fixed to the surface 24 of the substrate 22 but do not connect the elements of the MEMS device 20 to the underlying surface 24 are shown with wide hatch lines angled up and to the right, or alternatively with wide hatch lines angled down and to the right.

[0027] The drive actuation and measurement unit, referred to herein as the drive system 106, resides in the openings of each of the first drive mass 34 and the second drive mass 38 and is operatively in communication with the first drive mass 34 and the second drive mass 38. More specifically, the drive system 106 includes drive elements configured to linearly oscillate the first drive mass 34 and drive elements configured to linearly oscillate the second drive mass 38. Each of the drive elements includes electrodes referred to as movable fingers 108 and fixed fingers 110 that are spaced apart from each other and positioned in an alternating arrangement. For clarity of illustration, only a few movable fingers 108 and fixed fingers 110 are shown. Those skilled in the art will readily recognize that the number and structure of the movable fingers and fixed fingers will vary according to design requirements.

[0028] The first drive mass 34 and the second drive mass 38 are configured to undergo oscillatory motion in a plane parallel to the surface 24 of the substrate 22. For example, an alternating current (AC) voltage can be applied to the fixed fingers 110 through a drive circuit (not shown) to cause the movable fingers 108 (and thus the first drive mass 34 and the second drive mass 38) to move generally parallel to the fixed fingers 110. The connection of the first drive mass 34 and the second drive mass 38 through the first drive spring 50, the second drive spring 52, and the engagement element 58 enables the drive motion of the first drive mass 34 and the second drive mass 38 in opposite directions (i.e., out of phase) along a first axis (e.g., the X-axis 68 in this configuration) that is parallel to the surface 24 of the substrate 22. This out-of-phase drive motion is referred to herein as anti-phase drive motion. However, the third drive spring 64 and the fourth drive spring 66 that interconnect the first sensing mass 36 and the second sensing mass 40 with the first frame 46 and the second frame 48 associated with the first drive mass 34 and the second drive mass 38 are deformed appropriately to largely prevent the transfer of the anti-phase drive motion from the first drive mass 34 and the second drive mass 38 to the first sensing mass 36 and the second sensing mass 40. In other words, the first sensing mass 36 and the second sensing mass 40 are generally immovable along the X-axis 68 relative to the first drive mass 34 and the second drive mass 38.

[0029] The first sensing spring 30 and the second sensing spring 32 are configured to effect in-phase sensing motion of the first sensing mass 36 and the second sensing mass 40 along a second axis that is parallel to the surface 24 of the substrate 22 and perpendicular to the first axis in response to a linear acceleration along the second axis. Additionally, the first sensing spring 30 and the second sensing spring 32 are configured to effect out-of-phase sensing motion of the first sensing mass 36 and the second sensing mass 40 along the second axis in response to an angular rotation about a third axis that is perpendicular to the surface 24 of the substrate 22. Similarly, the third sensing spring 60 and the fourth sensing spring 62 are configured to cause the first drive mass 34 and the second drive mass 38 to move together with the first sensing mass 36 and the second sensing mass 40.

[0030] In this example, in the defined three-dimensional coordinate system, the first axis is the X-axis 68, the second axis is the Y-axis 70, and the third axis is the Z-axis 72. Thus, the linear acceleration is the Y-axis linear acceleration 112, A Y , and the angular rotation is the Z-axis angular rotation 114, Ω ZTherefore, the Y-axis linear acceleration 112 will cause both the first sensing mass 36 and the second sensing mass 40 to move together along the Y-axis 70, which is referred to as the common mode. The Coriolis force generated by the Z-axis angular rotation 114 will cause the first sensing mass 36 and the second sensing mass 40 to move in opposite directions, which is referred to as the differential mode. Of course, it should be understood that the sensing mass and the driving mass can be rotated 90° in a plane parallel to the surface 24 of the substrate 22 to appropriately detect the X-axis linear acceleration instead of the Y-axis linear acceleration 112. Additionally, configurations for detecting both the X-axis linear acceleration and the Y-axis linear acceleration will be discussed in conjunction with Figure 7 the configuration for detecting both the X-axis linear acceleration and the Y-axis linear acceleration will be discussed.

[0031] The first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 will experience tension or compression, referred to as axial stress, in response to the movement of the first sensing mass 36 and the second sensing mass 40. Thus, the first resonator beam 74 is configured to experience a first axial stress in response to the movement of the first sensing mass 36 along the Y-axis 70, and the second resonator beam 76 is configured to experience a second axial stress in response to the movement of the first sensing mass 36 along the Y-axis 70. The third resonator beam 78 is configured to experience a third axial stress in response to the movement of the second sensing mass 40 along the Y-axis 70, and the fourth resonator beam 80 is configured to experience a fourth axial stress in response to the movement of the second sensing mass 40 along the Y-axis 70. The corresponding axial stresses will cause a frequency shift in the resonance frequencies of the resonator beams 74, 76, 78, 80, which can be appropriately processed at an electronic circuit (e.g., a signal processing circuit, Figure 6 ) to obtain a common mode signal representing the Y-axis linear acceleration 112 and a differential mode signal representing the Z-axis angular rotation 114.

[0032] In conjunction with reference to Figure 1 and 2 , Figure 2 FIG. shows a highly simplified schematic side view of a MEMS sensor package 116 including the MEMS multi-axis device 20. The MEMS sensor package 116 includes the MEMS multi-axis device 20 (represented by a box for simplicity), which resides in a single cavity 118 formed between the substrate 22 and the housing 120. Thus, the first inertial mass system 26 and the second inertial mass system 28, various sensing springs 30, 32, 60, 62, and various driving springs 50, 52, 64, 66 are juxtaposed in the cavity 118 of the MEMS sensor package 116. In some embodiments, the cavity 118 can be in a vacuum.

[0033] Many prior art MEMS gyroscopes and accelerometers rely on amplitude modulation (AM) of an input excitation, where an inertial input produces a proportional change in the sensor output voltage. In other words, the inertial input is amplitude modulated such that the final output signal of the sensor is proportional to the true input as well as to a number of device parameters (e.g., stiffness of a spring, pick-up electronics gain, etc.).

[0034] In many applications, it may be desirable to produce a multi-axis sensing device on a single die. However, producing conventional gyroscopes and accelerometers on a single chip has significant drawbacks. Specifically, producing conventional gyroscopes and accelerometers requires very different packaging parameters. MEMS gyroscope chips are typically packaged at a specific vacuum level to obtain a desired quality factor (Q-factor). The Q-factor is a dimensionless parameter that describes the degree of under-damping of an oscillator and thus characterizes the bandwidth of the oscillator relative to its center frequency. A higher Q-factor indicates a lower rate of energy loss relative to the stored energy of the oscillator (i.e., the oscillation dies out more slowly). Thus, MEMS gyroscopes typically have a very high Q-factor and thus low damping, resulting in a longer ring or vibration time. In contrast, the Q-factor of a conventional AM-based accelerometer must be very low. That is, a conventional AM-based accelerometer must be damped to provide bandwidth, which requires the accelerometer to be packaged at or above atmospheric pressure to provide the necessary bandwidth.

[0035] High-precision gyroscopes require a vacuum cavity to operate, and at the same time, AM-based accelerometers operate at or above atmospheric pressure to provide the necessary bandwidth. The fundamental difference between the packaging of prior art MEMS gyroscopes and accelerometers makes co-fabrication and co-packaging infeasible. According to the embodiments described herein, a single sensing structure that combines a resonant accelerometer (e.g., an FM accelerometer) and an FM gyroscope can allow for a reduction in the overall footprint of the system relative to configurations implementing multiple single-axis sensors, since a single structure can be housed in a single cavity (e.g., cavity 118 of MEMS sensor package 116). Thus, a single sensing structure configuration can result in a significantly reduced silicon die size and a simplified process technology with a correspondingly reduced cost and simplified assembly process.

[0036] Figure 3 A simplified schematic plan view of a MEMS multi-axis sensing device 20 is shown that exhibits anti-phase drive motion 122 represented by oppositely directed arrows. In this simplified schematic plan view, for simplicity, the drive system 106 having movable fingers 108 and fixed fingers 110 is not shown. However, a Figure 1For reference. Generally, an AC voltage can be applied to the fixed fingers 110 through a driving circuit (not shown) to move the movable fingers 108 (and thus the first driving mass 34 and the second driving mass 38) generally parallel to the fixed fingers 110.

[0037] The connection of the first driving mass 34 and the second driving mass 38 through the first driving spring 50, the second driving spring 52, and the engaging element 58 enables the driving movement of the first driving mass 34 and the second driving mass 38 in opposite directions (i.e., out of phase) along the driving axis (e.g., the X-axis 68 in this example). This driving movement is called the out-of-phase driving movement 122. The out-of-phase driving movement 122 of the first driving mass 34 and the second driving mass 38 can be kept constant to maintain the constant sensitivity of the MEMS multi-axis sensing device 20. Additionally or alternatively, the oscillation frequency can be locked to the mechanical resonance of the first inertial mass 26 and the second inertial mass 28 to minimize the driving power.

[0038] The third driving spring 64 interconnecting the first sensing mass 36 and the first frame 46 of the first driving mass 34 and the fourth driving spring 66 interconnecting the second sensing mass 40 and the second frame 48 of the second driving mass 38 are appropriately bent or deformed to largely prevent the transmission of the out-of-phase driving movement 122 from the first driving mass 34 and the second driving mass 38 to the first sensing mass 36 and the second sensing mass 40. Therefore, the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 will not be force-stressed due to the out-of-phase driving movement 122 and thus will not provide an output signal with a signal error component that is a function of the out-of-phase driving movement 122.

[0039] Figure 4A simplified schematic plan view of a MEMS multi-axis sensing device 20 is shown that demonstrates an in-phase sensing motion 124 represented by arrows pointing in opposite directions. Again, in this simplified schematic plan view, for simplicity, the drive system 106 with movable fingers 108 and fixed fingers 110 is not shown. Once the first drive mass 34 and the second drive mass 38 are placed in an in-phase drive motion 122 parallel to the drive axis (e.g., the X-axis 68), and the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 are actuated to resonate at their resonant frequencies, the first inertial mass system 26 and the second inertial mass system 28 are capable of detecting the angular rate (e.g., the Z-axis angular rotation 114) caused by the rotation of the MEMS device 20 about the axis of rotation (commonly referred to as the input axis (e.g., the Z-axis 72)). When the MEMS device 20 undergoes a Z-axis angular rotation 114 about the Z-axis 72, the first inertial mass system 26 and the second inertial mass system 28 undergo an oscillatory sensing motion in opposite directions (i.e., out of phase) along the sensing axis (e.g., the Y-axis 70). This sensing motion is referred to as the in-phase sensing motion 124.

[0040] Specifically, the Coriolis force occurs with respect to the Y-axis 70 that is perpendicular to the X-axis 68 and the Z-axis 72. The Coriolis force generally causes an in-plane linear in-phase sensing motion 124 of the inertial mass systems 26, 28. This in-phase sensing motion 124 has an amplitude that is proportional to the Z-axis angular rotation 114 of the MEMS device 20 about the Z-axis 72. The in-phase sensing motion 124 can be detected as a change in the corresponding resonant frequencies of the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80.

[0041] Figure 5FIG. 20 shows a simplified schematic plan view of a MEMS multi-axis sensing device 20 showing in-phase sensing motion 126 represented by arrows pointing in the same direction. Again, in this simplified schematic plan view, for simplicity, the drive system 106 with movable fingers 108 and fixed fingers 110 is not shown. Once the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 are actuated to resonate at the resonant frequency, when the MEMS device 20 experiences a Y-axis linear acceleration 112 along the Y-axis 70, the first inertial mass system 26 and the second inertial mass system 28 can detect the linear acceleration (e.g., the Y-axis linear acceleration 112). When the MEMS device 20 experiences a Y-axis linear acceleration 112 parallel to the Y-axis 70, the first inertial mass system 26 and the second inertial mass system 28 experience sensing motion in the same direction along the sensing axis (e.g., the Y-axis 70). This sensing motion is referred to as in-phase sensing motion 126. The magnitude of this in-phase sensing motion 126 is proportional to the Y-axis linear acceleration 112 of the MEMS device 20 along the Y-axis 70. The in-phase sensing motion 126 can be detected as a change in the corresponding resonant frequencies of the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80.

[0042] Figure 6 FIG. 21 shows a block diagram of a signal processing circuit 130 of the MEMS multi-axis sensing device 20. Generally, the signal processing circuit 130 is configured to receive output signals from the sensing electrodes 92, 96, 100, 104 and generate a linear acceleration value representing the Y-axis linear acceleration 112 and / or an angular rotation rate value representing the Z-axis angular rotation 114.

[0043] It should be recalled that the first resonator beam 74 and the second resonator beam 76 are elastically coupled to the first sensing mass 36 Figure 1 ) via respective first sensing springs 30 ( Figure 1 ), and the third resonator beam 78 and the fourth resonator beam 80 are elastically coupled to the second sensing mass 40 Figure 1 ) via respective second sensing springs 32. The first drive electrode 90 and the first sensing electrode 92 are aligned with the first resonator beam 74. The second drive electrode 94 and the second sensing electrode 96 are aligned with the second resonator beam 76. The third drive electrode 98 and the third sensing electrode 100 are aligned with the third resonator beam 78. The fourth drive electrode 102 and the fourth sensing electrode 104 are aligned with the fourth resonator beam 80.

[0044] Each of the first drive electrode 90 and the first sense electrode 92 is electrically connected to a first oscillator circuit 132. The first oscillator circuit 132 is configured to generate a periodic oscillating electrical signal 134, for example, at a resonant frequency, and the periodic oscillating electrical signal 134 is provided to the first drive electrode 90 to cause the first resonator beam 74 to resonate. The first resonator beam 74 is configured to experience a first axial stress (e.g., tension or compression) in response to an inertial force 136 (linear acceleration and / or Coriolis force) that moves the first sensing mass 36. The first sense electrode 92 is configured to detect a change in the resonant frequency of the first resonator beam 74 in response to the first axial stress (e.g., tension or compression) and provide a first output signal 138 corresponding to the first axial stress, which is applied to the first resonator beam 74 in response to the inertial force 136. The first phase-locked loop circuit 140 is configured to receive the first output signal 138 and generate a first frequency signal 142, f1, the phase of the first frequency signal 142, f1 being related to the first output signal 138.

[0045] Each of the second drive electrode 94 and the second sense electrode 96 is electrically connected to a second oscillator circuit 144. The second oscillator circuit 144 is configured to generate a periodic oscillating electrical signal 146, for example, at a resonant frequency, and the periodic oscillating electrical signal 146 is provided to the second drive electrode 94 to cause the second resonator beam 76 to resonate. The second resonator beam 76 is configured to experience a second axial stress (e.g., tension or compression) in response to an inertial force 136 (linear acceleration and / or Coriolis force) that moves the first sensing mass 36. The second sense electrode 96 is configured to detect a change in the resonant frequency of the second resonator beam 76 in response to the second axial stress (e.g., tension or compression) and provide a second output signal 148 corresponding to the second axial stress, which is applied to the second resonator beam 76 in response to the inertial force 136. The second phase-locked loop circuit 150 is configured to receive the second output signal 148 and generate a second frequency signal 152, f2, the phase of the second frequency signal 152, f2 being related to the second output signal 148.

[0046] Each of the third drive electrode 98 and the third sense electrode 100 is electrically connected to the third oscillator circuit 154. The third oscillator circuit 154 is configured to generate a periodic oscillating electrical signal 156, for example, at a resonant frequency, and the periodic oscillating electrical signal 156 is provided to the third drive electrode 98 to cause the third resonator beam 78 to resonate. The third resonator beam 78 is configured to experience a third axial stress (e.g., tension or compression) in response to an inertial force 136 (linear acceleration and / or Coriolis force) that moves the second sensing mass 40. The third sense electrode 100 is configured to detect a change in the resonant frequency of the third resonator beam 78 in response to the third axial stress (e.g., tension or compression), and provide a third output signal 158 corresponding to the third axial stress, where the third axial stress is applied to the third resonator beam 78 in response to the inertial force 136. The third phase-locked loop circuit 160 is configured to receive the third output signal 158 and generate a third frequency signal 162, f3, where the phase of the third frequency signal 162, f3 is related to the third output signal 158.

[0047] Each of the fourth drive electrode 102 and the fourth sense electrode 104 is electrically connected to the fourth oscillator circuit 164. The fourth oscillator circuit 164 is configured to generate a periodic oscillating electrical signal 166, for example, at a resonant frequency, and the periodic oscillating electrical signal 166 is provided to the fourth drive electrode 102 to cause the fourth resonator beam 80 to resonate. The fourth resonator beam 80 is configured to experience a fourth axial stress (e.g., tension or compression) in response to an inertial force 136 (linear acceleration and / or Coriolis force) that moves the fourth sensing mass 40. The fourth sense electrode 104 is configured to detect a change in the resonant frequency of the fourth resonator beam 80 in response to the fourth axial stress (e.g., tension or compression), and provide a fourth output signal 168 corresponding to the fourth axial stress, where the fourth axial stress is applied to the fourth resonator beam 80 in response to the inertial force 136. The fourth phase-locked loop circuit 170 is configured to receive the fourth output signal 168 and generate a fourth frequency signal 172, f4, where the phase of the fourth frequency signal 172, f4 is related to the fourth output signal 168.

[0048] The first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 remain in resonance in a plane along the Y-axis 70. In the absence of the inertial force 136, the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 have the same nominal bending oscillation frequency f0. When the inertial force 136 (which can be the Y-axis linear acceleration 112 or the Coriolis force corresponding to the Z-axis angular rotation 114) is applied, the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 experience an axial action (e.g., axial stress). In the illustrated configuration, the first resonator beam 74 and the second resonator beam 76 will experience opposite axial stresses (e.g., one resonator beam will experience compressive stress and the other resonator beam will experience tensile stress simultaneously). Similarly, the third resonator beam 78 and the fourth resonator beam 80 will experience opposite axial stresses.

[0049] The fundamental frequency of a single resonator beam without an axial load can be characterized as follows:

[0050]

[0051] The axial action exerted on the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 due to the inertial force 136 (e.g., the linear acceleration 112 and / or the Coriolis force associated with the angular rotation 114) determines the change in the natural resonance frequency (commonly designated as f n ) of the resonator beam (e.g., any one of the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80). The change in the natural resonance frequency (e.g., the fundamental frequency f0) can be characterized as follows:

[0052]

[0053] In Expressions (1) and (2), c and α are coefficients based on the resonator beam, L is the length of the resonator beam, E is the modulus of elasticity, I is the moment of inertia, ρ is the mass density of the resonator beam material, A is the area of the resonator beam cross-section, and N is the axial action or axial force. In Expression (2), n = 1 - 4. Thus, in this example, f n corresponds to the change in the natural resonance frequency of any one of the first resonator beam 74, the second resonator beam 76, the third resonator beam 78, and the fourth resonator beam 80 (e.g., f1, f2, f3, f4).

[0054] The signal processing circuit 130 includes a first combining circuit 174 (e.g., a differential frequency circuit) that is electrically connected to the outputs of the first phase-locked loop circuit 140 and the second phase-locked loop circuit 150. The first combining circuit 174 provides a first differential output signal 176, Δf, based on the difference between the measured resonance frequency of the first resonator beam 74 and the measured resonance frequency of the second resonator beam 76 (e.g., the difference between the first frequency signal 142 and the second frequency signal 152). M1 Taking into account linearization and the first resonator beam 74 and the second resonator beam 76 that experience a first axial stress and a second axial stress due to the movement of the first sensing mass 36, the change in the bending resonance frequency (e.g., the first differential output signal 176) proportional to the inertial force 136 applied to the first sensing mass 36 can be characterized as follows:

[0055]

[0056] Additionally, the signal processing circuit 130 includes a second combining circuit 178 (e.g., a differential frequency circuit) that is electrically connected to the outputs of the third phase-locked loop circuit 160 and the fourth phase-locked loop circuit 170. The second combining circuit 178 provides a second differential output signal 180, Δf, based on the difference between the measured resonance frequency of the third resonator beam 78 and the measured resonance frequency of the fourth resonator beam 80 (e.g., the difference between the third frequency signal 162 and the fourth frequency signal 172). M2 Taking into account linearization and the third resonator beam 78 and the fourth resonator beam 80 that experience a third axial stress and a fourth axial stress due to the movement of the second sensing mass 38, the change in the bending resonance frequency (e.g., the second differential output signal 180) proportional to the inertial force 136 applied to the second sensing mass 40 can be characterized as follows:

[0057]

[0058] Thus, the relative change in the resonance frequency will manifest as a change in the combined differential output of each pair of resonator beams associated with a particular sensing mass (e.g., Δf M1 and Δf M2 ). Generally, the relationship between the axial action and the change in the resonance frequency can be expressed in Hz / G (where G is the G-force) for linear acceleration and in Hz / dps (where dps is degrees per second) for angular rotation rate. In some embodiments, in the illustrated tuning fork design, the sensitivity of the MEMS multi-axis sensing device 20 to linear acceleration can be, for example, 400 Hz / G, and the sensitivity of the MEMS multi-axis sensing device 20 to angular rotation can be, for example, 0.54 Hz / dps. However, it should be understood that other sensitivity values for linear acceleration and angular rotation can alternatively be implemented.

[0059] The signal processing circuit 130 includes a third combinational circuit 182 (e.g., a frequency summing circuit) that is electrically connected to the outputs of the first combinational circuit 174 and the second combinational circuit 178. The third combinational circuit 182 generates a linear acceleration value 184, A Y as the sum of the first differential output signal 176 and the second differential output signal 180 (i.e., Δf M1 +Δf M2 ), and this sum represents the Y-axis linear acceleration 112. The linear acceleration value 184 can be received at a low-pass filter 186, where the signal is appropriately filtered to obtain a linear acceleration output value 188, A T(OUT) . Thus, the linear acceleration output value 188 is based on frequency modulation, and due to the summing that occurs at the third combinational circuit 182, the linear acceleration output value 188 is common mode. Therefore, a common-mode frequency-modulated acceleration signal is generated as the linear acceleration output value 188.

[0060] The signal processing circuit 130 further includes a fourth combinational circuit 190 (e.g., a differential frequency circuit) that is also electrically connected to the outputs of the first combinational circuit 174 and the second combinational circuit 176. The fourth combinational circuit 190 generates an angular rotation rate value 192, Ω Z(MOD) as the difference between the first differential output signal 176 and the second differential output signal 180 (i.e., Δf M1 -Δf M2 ), and this difference represents the Z-axis angular rotation 114. The angular rotation rate value 192 is modulated by a drive frequency (e.g., 20 kHz) that causes the first drive mass 32 and the second drive mass 36 to be in an anti-phase drive motion 122 ( Figure 3 ). Thus, the angular rotation rate value 192 can be received at an amplitude demodulator 194, where the signal is appropriately demodulated to obtain a demodulated angular rotation rate value 196, Ω Z(DEMOD) . Thereafter, the demodulated angular rotation rate value 196 can be received at a low-pass filter 198, where the signal is appropriately filtered to obtain an angular rotation rate output value 200, Ω Z(OUT) . Thus, the angular rotation rate output value 200 is also based on frequency modulation, and due to the subtraction that occurs at the fourth combinational circuit 190, the angular rotation rate output value 200 is differential mode. Therefore, a differential-mode frequency-modulated angular rotation rate signal is generated as the angular rotation rate output value 200.

[0061] Thus, the MEMS multi-axis sensing device 20 having the signal processing circuit 130 is configured to perform the following functions: actuating the first drive mass 34 and the second drive mass 38 to undergo an anti-phase drive motion 122 along a first axis (e.g., the X-axis 68) that is parallel to the surface 24 of the substrate 22 ( Figure 3); sensing an out-of-phase sensing motion 124 of the first sensing mass 36 and the second sensing mass 40 along a second axis (e.g., Y-axis 70) that is parallel to the surface 24 of the substrate 22 and perpendicular to the first axis in response to an angular rotation (e.g., Z-axis angular rotation 114) about a third axis (e.g., Z-axis 72) that is perpendicular to the surface 24 of the substrate 22 Figure 4 ); and sensing an in-phase sensing motion 126 of the first sensing mass 36 and the second sensing mass 40 along the second axis in response to a linear acceleration along the second axis (e.g., Y-axis linear acceleration 112) Figure 5 ). Additional functionality requires determining an angular rotation rate value (e.g., angular rotation rate output value 200) about the third axis in response to the out-of-phase sensing motion and determining a linear acceleration value (e.g., linear acceleration output value) in response to the out-of-phase sensing motion.

[0062] For illustrative purposes, a simplified block diagram of the signal processing circuit 130 is provided. Those skilled in the art will recognize that the specific processing blocks of the signal processing circuit may differ from those shown while still performing the following functions: generating a first differential signal from the output signals associated with the first resonator beam and the second resonator beam; generating a second differential signal from the output signals associated with the third resonator beam and the fourth resonator beam; summing the first differential signal and the second differential signal to generate a linear acceleration value; and determining the difference between the first differential signal and the second differential signal to generate an angular rotation rate value.

[0063] Figure 7 A schematic plan view of a microelectromechanical system (MEMS) multi-axis sensing device 202 according to another embodiment is shown. The MEMS multi-axis sensing device 202 can be configured to sense a Y-axis linear acceleration 112, a Z-axis angular rotation 114, and an X-axis linear acceleration 204. By way of example, the MEMS multi-axis sensing device 202 can include a first inertial mass system 26 and a second inertial mass system 28 as discussed in detail above. The first inertial mass system 26 and the second inertial mass system 28 are anchored to and spaced apart from the surface 206 of the substrate 208. The MEMS device 202 further includes a third inertial mass system 210 and a fourth inertial mass system 212 that are anchored to and spaced apart from the surface 206 of the substrate 208. The third inertial mass system 210 and the fourth inertial mass system 212 include the same components as the first inertial mass system 26 and the second inertial mass system 28 and thus operate in a similar manner to the first inertial mass system 26 and the second inertial mass system 28. As such, for the sake of brevity, a detailed description of the third inertial mass system 206 and the fourth inertial mass system 208 will not be provided herein.

[0064] Of particular interest in this example is that the third inertial mass system 210 and the fourth inertial mass system 212 are rotated 90° relative to the first inertial mass system 26 and the second inertial mass system 28. Additionally, the first inertial mass system 26, the second inertial mass system 28, the third inertial mass system 210, and the fourth inertial mass system 212 are interconnected by a spring system 214. The spring system 214 is coupled to the bottom surface 206 of the substrate 208. The spring system 214 can be of any convenient shape, size, and material for effecting an anti-phase drive movement of the first drive mass 34 and the second drive mass 38 of the first inertial mass system and the second inertial mass system along the X-axis 68 (e.g., the drive axis) and for effecting an anti-phase drive movement of the third drive mass 216 and the fourth drive mass 218 of the third inertial mass system 210 and the fourth inertial mass system 212 along the Y-axis 70. In this way, and as discussed in detail above, the resonant frequencies of the resonator beams associated with the third sensing mass 220 and the fourth sensing mass 222 of the third inertial mass system 210 and the fourth inertial mass system 212 will vary in response to a linear acceleration aligned with the X-axis 68 (e.g., the X-axis linear acceleration 204) and / or in response to a Coriolis force transferred from the third drive mass 216 and the fourth drive mass 218 to the third sensing mass 220 and the fourth sensing mass 222, the Coriolis force being responsive to a rotation of the MEMS device 202 about the Z-axis 72.

[0065] The embodiments disclosed herein require a microelectromechanical system (MEMS) multi-axis sensing device and method of operation. More specifically, the MEMS multi-axis sensing device is based on frequency modulation (FM) to sense linear acceleration and angular rate (i.e., velocity) simultaneously using a single inertial mass detection structure. The FM resonant accelerometer and the FM vibrating gyroscope are co-fabricated as a single detection structure, where the detection of linear acceleration and angular rate is based on a change in the frequency (e.g., frequency modulation) of one or more elements set at resonance. The linear acceleration can be detected by a common-mode FM signal, and the angular rate can be detected by a differential-mode FM signal. Compared to other measurement techniques, resonant detection can produce a direct frequency output, high sensitivity, and a wide dynamic range. Additionally, a single FM-based detection structure enables the same cavity pressure for both the accelerometer and the gyroscope, which can thereby simplify MEMS processing technology, reduce the MEMS die size, and reduce the number of MEMS dies in the sensor package.

[0066] This disclosure is intended to explain how to shape and use various embodiments in accordance with the present invention, rather than to limit the true, intended, and reasonable scope and spirit of the present invention. The foregoing description is not intended to be exhaustive or to limit the invention to the exact forms disclosed. Modifications or variations are possible in light of the above teachings. One or more embodiments have been selected and described to provide the best illustration of the principles of the invention and its practical application and to enable those skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular uses contemplated. All such modifications and variations fall within the scope of the invention as determined by the appended claims and their full equivalents, which may be amended during the pendency of this patent application, when interpreted in accordance with the scope of fair, legal, and reasonable authorization.

[0067] Reference numeral

[0068] 20 MEMS multi-axis sensing device

[0069] 22 Substrate

[0070] 24 Flat surface

[0071] 26 First inertial mass system

[0072] 28 Second inertial mass system

[0073] 30 First sensing spring

[0074] 32 Second sensing spring

[0075] 34 First drive mass block

[0076] 36 First sensing mass block

[0077] 38 Second drive mass block

[0078] 40 Second sensing mass block

[0079] 42 Anchor

[0080] 44 Anchor

[0081] 46 First frame

[0082] 48 Second frame

[0083] 50 First drive spring

[0084] 52 Second drive spring

[0085] 54 Anchor

[0086] 56 Anchor

[0087] 58 Joining element

[0088] 60 Third sensing spring

[0089] 62 Fourth sensing spring

[0090] 64 Third driving spring

[0091] 66 Fourth driving spring

[0092] 68 X-axis

[0093] 70 Y-axis

[0094] 72 Z-axis

[0095] 74 First resonator beam

[0096] 76 Second resonator beam

[0097] 78 Third resonator beam

[0098] 80 Fourth resonator beam

[0099] 82 Anchor

[0100] 84 Anchor

[0101] 86 Anchor

[0102] 88 Anchor

[0103] 90 First driving electrode

[0104] 92 First sensing electrode

[0105] 94 Second driving electrode

[0106] 96 Second sensing electrode

[0107] 98 Third driving electrode

[0108] 100 Third sensing electrode

[0109] 102 Fourth driving electrode

[0110] 104 Fourth sensing electrode

[0111] 106 Driving system

[0112] 108 Movable finger

[0113] 110 Fixed finger

[0114] 112 Y-axis linear acceleration, A Y

[0115] 114 Z-axis angular rotation, Ω Z

[0116] 116 MEMS sensor package

[0117] 118 Cavity

[0118] 120 Housing

[0119] 122 Arrow / Inverted drive motion

[0120] 124 Arrow / Inverted sensing motion

[0121] 126 Arrow / In-phase sensing motion

[0122] 130 Signal processing circuit

[0123] 132 First oscillator circuit

[0124] 134 Oscillating electronic signal

[0125] 136 Inertial force

[0126] 138 First output signal

[0127] 140 First PLL

[0128] 142 First frequency signal, f1

[0129] 144 Second oscillator circuit

[0130] 146 Oscillating electronic signal

[0131] 148 Second output signal

[0132] 150 Second PLL

[0133] 152 Second frequency signal, f2

[0134] 154 Third oscillator circuit

[0135] 156 Oscillating electronic signal

[0136] 158 Third output signal

[0137] 160 Third PLL

[0138] 162 Third frequency signal, f3

[0139] 164 Fourth oscillator circuit

[0140] 166 Oscillating electronic signal

[0141] 168 Fourth output signal

[0142] 170 Fourth PLL

[0143] 172 Fourth frequency signal, f4

[0144] 174 First combinational circuit / differential frequency circuit

[0145] 176 First differential output signal, Δf m1

[0146] 178 Second combinational circuit / differential frequency circuit

[0147] 180 Second differential output signal, Δf m2

[0148] 182 Third combinational circuit / frequency summing circuit

[0149] 184 Linear acceleration value, A Y

[0150] 186 Low - pass filter

[0151] 188 Linear acceleration output value, A T(OUT)

[0152] 190 Fourth combinational circuit

[0153] 192 Angular rotation rate value, Ω Z(MOD)

[0154] 194 Amplitude demodulator

[0155] 196 Demodulated angular rotation rate value, Ω Z(DEMOD)

[0156] 198 Low - pass filter

[0157] 200 Angular rotation rate output value

[0158] 202 MEMS multi - axis sensing device

[0159] 204 X - axis linear acceleration

[0160] 206 Surface

[0161] 208 Substrate

[0162] 210 Third inertial mass system

[0163] 212 Fourth inertial mass system

[0164] 214 Spring system

[0165] 216 Third driving mass block

[0166] 218 Fourth driving mass block

[0167] 220 Third sensing mass block

[0168] 222 Fourth sensing mass block.

Claims

1. A microelectromechanical system multi-axis sensing device, characterized in that, Comprising: A substrate having a surface; A first inertial mass system including a first driving mass block and a first sensing mass block elastically coupled to the first driving mass block; A second inertial mass system including a second driving mass block and a second sensing mass block elastically coupled to the second driving mass block, wherein the first driving mass block and the second driving mass block are configured to undergo anti-phase driving motion along a first axis parallel to the surface of the substrate; A first sensing spring configured to be anchored and suspended from the first sensing mass block spaced apart from the surface of the substrate; And A second sensing spring configured to be anchored and suspended from the second sensing mass block spaced apart from the surface of the substrate, wherein the first sensing spring and the second sensing spring effect anti-phase sensing motion of the first sensing mass block and the second sensing mass block along a second axis parallel to the surface of the substrate and perpendicular to the first axis in response to angular rotation about a third axis perpendicular to the surface of the substrate, and the first sensing spring and the second sensing spring additionally effect in-phase sensing motion of the first sensing mass block and the second sensing mass block along the second axis in response to linear acceleration along the second axis; A first resonator beam elastically coupled to the first sensing mass block by one of the first sensing springs, the first resonator beam being configured to undergo a first axial stress in response to movement of the first sensing mass block along the second axis; A second resonator beam elastically coupled to the first sensing mass block by the other of the first sensing springs, the second resonator beam being configured to undergo a second axial stress in response to the movement of the first sensing mass block along the second axis; A third resonator beam elastically coupled to the second sensing mass block by one of the second sensing springs, the third resonator beam being configured to undergo a third axial stress in response to movement of the second sensing mass block along the second axis; And A fourth resonator beam elastically coupled to the second sensing mass block by the other of the second sensing springs, the fourth resonator beam being configured to undergo a fourth axial stress in response to the movement of the second sensing mass block along the second axis.

2. The microelectromechanical system multi-axis sensing device according to claim 1, wherein The substrate, the first inertial mass system, the second inertial mass system, the first sensing spring, and the second sensing spring are juxtaposed in a cavity of a packaging device, and the cavity is in a vacuum.

3. The MEMS multi-axis sensing device according to claim 1, wherein: The first driving mass block includes a first frame surrounding the first sensing mass block; The second driving mass block includes a second frame surrounding the second sensing mass block; And The MEMS multi-axis sensing device further includes: A first driving spring configured to be anchored and suspended from the first frame spaced from the surface of the substrate; and A second driving spring configured to be anchored and suspended from the second frame spaced from the surface of the substrate, the first driving spring and the second driving spring flexibly interconnecting the first driving mass and the second driving mass.

4. The MEMS multi-axis sensing device according to claim 3, characterized in that, Further comprising: A third sensing spring coupled to the first frame and the first driving spring of the first driving mass; and A fourth sensing spring coupled to the second frame and the second driving spring of the second driving mass, each of the third sensing spring and the fourth sensing spring having a longitudinal extension parallel to the first axis, the longitudinal extension being configured to deform in response to the in-phase sensing motion or the anti-phase sensing motion of the first inertial mass system and the second inertial mass system.

5. The MEMS multi-axis sensing device according to claim 3, characterized in that, Each of the first driving spring and the second driving spring has a longitudinal extension parallel to the second axis, the longitudinal extension being configured to deform to effect the anti-phase driving motion of the first inertial mass system and the second inertial mass system along the first axis.

6. The MEMS multi-axis sensing device according to claim 3, wherein, Further comprising: A third driving spring interposed between and interconnecting the first sensing mass and the first frame of the first driving mass; and A fourth driving spring interposed between and interconnecting the second sensing mass and the second frame of the second driving mass, wherein the third driving spring and the fourth driving spring are configured to deform to prevent transmission of the anti-phase driving motion from the first driving mass and the second driving mass to the first sensing mass and the second sensing mass.

7. The microelectromechanical system multi-axis sensing device according to claim 1, characterized in that, Further comprising: A first driving electrode and a first sensing electrode aligned with the first resonator beam, the first driving electrode being configured to resonate the first resonator beam, and the first sensing electrode being configured to detect a change in the resonant frequency of the first resonator beam in response to the first axial stress; A second driving electrode and a second sensing electrode aligned with the second resonator beam, the first driving electrode being configured to resonate the second resonator beam, and the second sensing electrode being configured to detect a change in the resonant frequency of the second resonator beam in response to the second axial stress; A third driving electrode and a third sensing electrode aligned with the third resonator beam, the third driving electrode being configured to resonate the third resonator beam, and the third sensing electrode being configured to detect a change in the resonant frequency of the third resonator beam in response to the third axial stress; and A fourth drive electrode and a fourth sense electrode, the fourth drive electrode and the fourth sense electrode being aligned with a fourth resonator beam, the fourth drive electrode being configured to cause the fourth resonator beam to resonate, and the fourth sense electrode being configured to detect a change in the resonant frequency of the fourth resonator beam in response to the fourth axial stress.

8. A method for operating a microelectromechanical system, characterized in that, Comprising: Provided is a microelectromechanical system multi-axis sensing device, the microelectromechanical system multi-axis sensing device comprising: a substrate having a surface; a first inertial mass system including a first drive mass and a first sense mass elastically coupled to the first drive mass; a second inertial mass system including a second drive mass and a second sense mass elastically coupled to the second drive mass; a first sense spring configured to be anchored and suspended from the first sense mass spaced apart from the surface of the substrate; and a second sense spring configured to be anchored and suspended from the second sense mass spaced apart from the surface of the substrate; Actuating the first drive mass and the second drive mass to undergo out-of-phase drive motion along a first axis parallel to the surface of the substrate; Actuating a first resonator beam to resonate, the first resonator beam being elastically coupled to the first sense mass by one of the first sense springs; Actuating a second resonator beam to resonate, the second resonator beam being elastically coupled to the first sense mass by the other of the first sense springs; Actuating a third resonator beam to resonate, the third resonator beam being elastically coupled to the second sense mass by one of the second sense springs; Actuating a fourth resonator beam to resonate, the fourth resonator beam being elastically coupled to the second sense mass by the other of the second sense springs; Sensing out-of-phase sensing motion of the first sense mass and the second sense mass along a second axis parallel to the surface of the substrate and perpendicular to the first axis in response to an angular rotation about a third axis perpendicular to the surface of the substrate, wherein the first sense spring and the second sense spring effect the out-of-phase sensing motion; Sensing in-phase sensing motion of the first sense mass and the second sense mass along the second axis in response to a linear acceleration along the second axis, wherein the first sense spring and the second sense spring additionally effect the in-phase sensing motion; Wherein sensing the in-phase sensing motion and sensing the out-of-phase sensing motion includes: Detecting a change in the resonant frequency of the first resonator beam in response to a first axial stress, the first resonator beam being configured to undergo the first axial stress in response to movement of the first sense mass along the second axis; Detecting a change in the resonant frequency of the second resonator beam in response to a second axial stress, the second resonator beam being configured to undergo the second axial stress in response to the movement of the first sense mass along the second axis; Detecting a change in the resonant frequency of the third resonator beam in response to a third axial stress, the second resonator beam being configured to experience the third axial stress in response to movement of the second sensing mass along the second axis; and Detecting a change in the resonant frequency of the fourth resonator beam in response to a fourth axial stress, the fourth resonator beam being configured to experience the fourth axial stress in response to the movement of the second sensing mass along the second axis; Determining an angular rotation rate value of the angular rotation about the third axis in response to the out-of-phase sensing movement; and Determining a linear acceleration value of the linear acceleration along the second axis in response to the in-phase sensing movement.

9. A microelectromechanical system multi-axis sensing device, characterized in that, Comprising: A substrate having a surface; A first inertial mass system including a first drive mass and a first sensing mass elastically coupled to the first drive mass; A second inertial mass system including a second drive mass and a second sensing mass elastically coupled to the second drive mass, the first drive mass and the second drive mass being configured to undergo out-of-phase drive movement along a first axis toward being parallel to the surface of the substrate; A first sensing spring configured to anchor and suspend the first sensing mass spaced apart from the surface of the substrate; A second sensing spring configured to anchor and suspend the second sensing mass spaced apart from the surface of the substrate, the first sensing spring and the second sensing spring effecting out-of-phase sensing movement of the first sensing mass and the second sensing mass along a second axis parallel to the surface of the substrate and perpendicular to the first axis in response to an angular rotation about a third axis perpendicular to the surface of the substrate, and the first sensing spring and the second sensing spring additionally effecting in-phase sensing movement of the first sensing mass and the second sensing mass along the second axis in response to a linear acceleration along the second axis; A first resonator beam elastically coupled to the first sensing mass by one of the first sensing springs, the first resonator beam being configured to experience a first axial stress in response to movement of the first sensing mass along the second axis; A second resonator beam elastically coupled to the first sensing mass by the other of the first sensing springs, the second resonator beam being configured to experience a second axial stress in response to the movement of the first sensing mass along the second axis; A third resonator beam elastically coupled to the second sensing mass by one of the second sensing springs, the third resonator beam being configured to experience a third axial stress in response to movement of the second sensing mass along the second axis; And A fourth resonator beam, which is elastically coupled to the second sensing mass block by another second sensing spring among the second sensing springs, and is configured to experience a fourth axial stress in response to the movement of the second sensing mass block along the second axis, wherein the substrate, the first inertial mass system and the second inertial mass system, the first sensing spring and the second sensing spring, and the first resonator beam, the second resonator beam, the third resonator beam and the fourth resonator beam are juxtaposed in a cavity of a packaging device, and the cavity is in a vacuum; wherein the sense in-phase sensing motion and the sense anti-phase sensing motion include: detecting a change in the resonant frequency of the first resonator beam in response to a first axial stress, the first resonator beam being configured to experience the first axial stress in response to the movement of the first sensing mass block along the second axis; detecting a change in the resonant frequency of the second resonator beam in response to a second axial stress, the second resonator beam being configured to experience the second axial stress in response to the movement of the first sensing mass block along the second axis; detecting a change in the resonant frequency of the third resonator beam in response to a third axial stress, the second resonator beam being configured to experience the third axial stress in response to the movement of the second sensing mass block along the second axis; and detecting a change in the resonant frequency of the fourth resonator beam in response to a fourth axial stress, the fourth resonator beam being configured to experience the fourth axial stress in response to the movement of the second sensing mass block along the second axis.

Images