CN116953284A - High-precision silicon-based MEMS resonant accelerometer based on multistage differential output - Google Patents

High-precision silicon-based MEMS resonant accelerometer based on multistage differential output Download PDF

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Publication number
CN116953284A
CN116953284A CN202310734210.2A CN202310734210A CN116953284A CN 116953284 A CN116953284 A CN 116953284A CN 202310734210 A CN202310734210 A CN 202310734210A CN 116953284 A CN116953284 A CN 116953284A
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resonant
comb
resonator
differential output
silicon
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高乃坤
刘福民
高适萱
张乐民
吴浩越
张树伟
杨静
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Beijign Institute of Aerospace Control Devices
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Beijign Institute of Aerospace Control Devices
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/097—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by vibratory elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/097—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by vibratory elements
    • G01P15/0975—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by vibratory elements by acoustic surface wave resonators or delay lines

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pressure Sensors (AREA)

Abstract

The invention discloses a high-precision silicon-based MEMS resonant accelerometer based on multistage differential output. The middle-layer sensitive module comprises two same sensitive structures which are distributed in a bilateral symmetry mode and are isolated from each other, the sensitive structures comprise a mass block, a lever amplifying structure, a thermal stress releasing structure and a resonator, the resonator comprises a resonant beam and a sliding film comb tooth structure connected to the resonant beam, the sliding film comb tooth structure is connected with an external driving circuit to generate electrostatic force to drive the resonant beam to vibrate, and detection signals are output. According to the invention, through a multistage differential detection design, the precision interference of errors such as circuit noise, temperature drift and the like on the silicon-based MEMS resonant accelerometer is effectively reduced, and the silicon-based resonant MEMS accelerometer can maintain higher acceleration measurement precision in a full-temperature environment.

Description

High-precision silicon-based MEMS resonant accelerometer based on multistage differential output
Technical Field
The invention relates to a high-precision silicon-based MEMS resonant accelerometer based on multistage differential output, belonging to the technical field of micromechanical inertial instruments.
Background
The silicon-based MEMS resonant accelerometer is an inertial sensor which is processed based on MEMS technology and detects external acceleration according to the force frequency action principle, and generally consists of a mass block, a micro-lever mechanism and a resonator, wherein the inertial force of the mass block caused by acceleration is applied to the resonator through lever amplification, so that the natural frequency deviation of the resonator is caused, and the detected physical quantity can be detected by detecting the frequency deviation. The method is mainly characterized in that a frequency signal proportional to the input acceleration is output, the method is easy to detect, the anti-interference performance is good, the standard digital quantity is directly output, errors caused by A/D conversion are omitted, the limitation of the displacement detection limit precision of the traditional capacitance type instrument is avoided, and the method has strategic level precision potential. Meanwhile, the compatibility of the silicon material and the semiconductor process enables the silicon material to have the advantages of miniaturization, integration and mass production.
The resonators of the existing silicon-based MEMS resonant accelerometer all adopt a double-end fixed tuning fork structure, the structure consists of two parallel beams, and the tail ends of the beams are combined and connected with other structures. When the resonator works, the two parallel beams vibrate reversely, and the stress and moment generated in the merging area of the two beams are opposite in direction and offset each other, so that the whole structure is small in energy coupling with the outside through the fixed connecting end and has a higher Q value. However, due to the influence of errors such as temperature drift and circuit noise, the accuracy index of the silicon-based MEMS resonant accelerometer is difficult to further improve, and is difficult to adapt to engineering application in a full-temperature environment, and additional temperature compensation is needed to be performed on the silicon-based MEMS resonant accelerometer at a circuit end so as to improve the full-temperature zero bias stability of the silicon-based MEMS resonant accelerometer.
Disclosure of Invention
The invention solves the technical problems that: the defect of the prior art is overcome, and the high-precision silicon-based MEMS resonant accelerometer based on multi-stage differential output is provided, and through the design of a multi-stage differential detection structure, the precision interference of errors such as circuit noise, temperature drift and the like on the silicon-based MEMS resonant accelerometer is effectively reduced, so that the silicon-based resonant MEMS accelerometer can keep higher acceleration measurement precision in a full-temperature environment.
The technical scheme of the invention is as follows:
a high-precision silicon-based MEMS resonant accelerometer based on multistage differential output comprises an upper cover layer, a middle sensitive module and a lower substrate layer; the upper cover cap layer and the lower substrate layer are connected to form an internal vacuum structure, and the middle sensitive module is arranged in the internal vacuum structure; the middle-layer sensitive module comprises two identical sensitive structures which are distributed symmetrically left and right and are isolated from each other, and the sensitive structures comprise a mass block, a lever amplifying structure, a thermal stress releasing structure and a resonator;
the mass block is fixed between the upper cover cap layer and the lower substrate layer; the lever amplifying structure is vertically arranged at the outer side of the mass block, and two ends of the lever amplifying structure are connected with the mass block;
the resonator comprises a resonance beam and a sliding film comb tooth structure connected to the resonance beam, wherein the sliding film comb tooth structure is connected with an external driving circuit to generate electrostatic force to drive the resonance beam to vibrate, and a detection signal is output;
the two thermal stress release structures are respectively arranged above and below the resonator.
Preferably, the sliding film comb tooth structure comprises a driving comb tooth and a detecting comb tooth, wherein the driving comb tooth is driven by electrostatic force, and the detecting comb tooth is capacitive detection output;
three driving comb teeth are longitudinally arranged along the central axis of the resonator, and each row of driving comb teeth is one;
two sides of each driving comb tooth are respectively provided with a detection comb tooth in parallel;
the output signals of the detection comb teeth positioned at the two sides of the upper end part and the lower end part driving comb teeth are connected, the output signals of the remaining detection comb teeth are connected, and the two signals are differentiated to form detection signals.
Preferably, the detection signals output by the resonators in the two sensitive structures are subjected to differential processing, and the differential signal frequency is obtained.
Preferably, one end of the resonance beam is connected with the lever amplifying structure, and the other end of the resonance beam is fixed on the mass block through the straight beam.
Preferably, the frequency difference between the working frequency of the resonator and the anti-phase resonance mode frequency is changed by adjusting the rigidity of the straight beam.
Preferably, an anchor region is arranged between the upper cover cap layer and the lower substrate layer, and two ends of each mass block are respectively fixed on the anchor region through a folding beam; the stiffness of the folded beam in the length direction is much smaller than the stiffness in the width direction and the vertical direction.
Preferably, the transverse vibration mode resonance frequency of the mass block is determined by the elasticity coefficient and the self mass of the connected folding beam group.
Preferably, the upper cover cap layer and the lower substrate layer are connected to form an internal vacuum structure, and the middle sensitive module is bonded in the internal vacuum structure through anchor points.
Preferably, the two ends of the lever amplifying structure are connected to the mass block through a folding beam respectively.
A high-precision silicon-based MEMS resonance acceleration measurement method based on multistage differential output comprises the following steps:
applying in-phase alternating current signals to driving comb teeth at the upper end and the lower end of each of the two resonators through an external driving circuit, and applying another alternating current signal which is opposite to the alternating current signals to the rest driving comb teeth, so that two resonant beams on each resonator do reverse push-pull vibration, and signal frequency after difference of output signals of the two resonators is obtained;
when acceleration in the length direction of the resonant beam acts on the resonant accelerometer, the two mass blocks are sensitive to acceleration, and inertial force and displacement in the length direction of the resonant beam are generated, the inertial force respectively generates push-pull loads in the axial directions of the two resonators through the two lever amplifying structures, and signal frequency after the output signals of the two resonators are differentiated is acquired again;
and obtaining a frequency change amount according to the signal frequencies obtained in the front and back steps, and calculating to obtain an acceleration value.
Compared with the prior art, the invention has the advantages that:
(1) According to the invention, by means of the design of the double-mass symmetrical differential structure, compared with a single-mass structure, the mechanical sensitivity of the silicon-based MEMS resonant accelerometer can be effectively improved, and the instrument precision is greatly improved.
(2) According to the invention, through the design of the mutually isolated double-mass block structure, the dead zone of the silicon-based MEMS resonant accelerometer can be effectively reduced, and the threshold value is lowered.
(3) According to the invention, through the design of the single resonator detection output differential structure, the circuit common mode noise interference can be effectively reduced, and the detection precision of the silicon-based MEMS resonant accelerometer is improved.
(4) According to the invention, through further differential design of the detection output signals of the left resonator and the right resonator, the detection precision is improved, the influence of temperature drift on the full-temperature performance of the silicon-based MEMS resonant accelerometer can be effectively reduced, and the full-temperature environmental stability index of the instrument is improved.
(5) Compared with the traditional wing-shaped comb tooth structure scheme, the capacitive driving and detecting comb tooth structure scheme has the advantages that the capacitive driving and detecting comb tooth structure scheme is adopted, the stress state of the resonant beam is relatively good, and the influence of the asymmetry of the additional mass on the resonant characteristic of the resonator in the processing process can be effectively reduced;
(6) The driving and detecting sliding film comb tooth structure adopted by the invention has the advantages that the second-order derivative of the driving capacitance and the amplitude is 0, namely the static stiffness is 0, and compared with the film pressing comb tooth structure scheme, the influence of static negative stiffness is not required to be considered.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a diagram of a differential high-precision silicon-based MEMS resonant accelerometer according to an embodiment of the invention;
FIG. 2 is a schematic diagram of a cross-sectional structure of a differential high-precision silicon-based MEMS resonant accelerometer according to an embodiment of the invention;
FIG. 3 is a diagram of the operating mode of a differential high-precision silicon-based MEMS resonant accelerometer resonator according to an embodiment of the invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.
The invention provides a high-precision silicon-based MEMS resonant accelerometer based on multistage differential output, which is used for measuring acceleration of a carrier relative to an inertial space. The accelerometer is shown in fig. 1 and includes an upper capping layer 17, a middle sensitive module 18, and a lower substrate layer 19. The upper cap layer 17 and the lower substrate layer 19 are connected to form an internal vacuum structure, and the middle sensitive module 18 is arranged in the internal vacuum structure and is bonded between the upper cap layer 17 and the lower substrate layer 19 through anchor points. The bonding process reduces the anchor points in the structure as much as possible and avoids the area with the largest vibration stress.
As shown in fig. 2, the middle sensitive module 18 is composed of a first sensitive structure 1 and a second sensitive structure 2 which are symmetrical left and right, and the two sensitive structures are isolated, have gaps, and increase the threshold value.
The first sensitive structure 1 comprises a first mass 101, a first lever amplifying structure 102, a first thermal stress relief structure 103, a first resonator 104, a first folded beam group 105, a first anchor group 106, a folded beam 107, a folded beam 108, a straight beam 1025, an anchor area 1020, an anchor area 1021, an anchor area 1022, a straight beam 1023, a straight beam 1024, a straight beam 1026.
The first mass 101 is fixed to the first anchor block group 106 by the first folding beam group 105, and is respectively a folding beam 1051 connected to the anchor block 1061, a folding beam 1052 connected to the anchor block 1062, a folding beam 1053 connected to the anchor block 1063, and a folding beam 1054 connected to the anchor block 1064. The first anchor region is located between the cap layer 17 and the substrate layer 19. The transverse vibration mode resonance frequency of the first mass block is determined by the elastic coefficient of the first folding beam group 105 and the mass of the first mass block, and the transverse vibration mode resonance frequency of the mass block is greater than 3000Hz so as to improve the mechanical property of the accelerometer. The stiffness of the group of folded beams 105 in the X direction is much less than the stiffness in the Y and Z directions, so that the mass can be driven in the X direction.
The first lever amplifying structure 102 is connected to the first mass 101 at both ends thereof by a folding beam 107 and a folding beam 108. First resonator
The first resonator 104 is located in the middle of the first sensitive structure 1, and one end is connected to the U-beam 109 of the first lever amplifying structure 102 through a straight beam 1025, and the other end is fixed to the anchor area 1020 through a straight beam 1026. The first resonator 104 adopts a sliding film comb structure, has a larger scale factor and a higher resonant frequency, and can avoid the influence of static negative stiffness, and specifically comprises two resonant beams 1010 with fixed two ends, and the sliding film comb structure is connected on the resonant beams. The sliding film comb structure comprises first one-to-one detection comb 1011, first two-driving comb 1012, first three detection comb 1013, first four detection comb 1014, first five-driving comb 1015, first six detection comb 1016, first seven detection comb 1017, first eight-driving comb 1018, and first nine detection comb 1019. Wherein the first one-to-one detection comb 1011, the first two-to-one drive comb 1012 and the first three detection comb 1013 are arranged side by side at equal intervals in the X direction; the first four detecting comb teeth 1014, the first five driving comb teeth 1015 and the first six detecting comb teeth 1016 are arranged side by side at equal intervals in the X direction; the first seven detection combs 1017, the first eight drive combs 1018, and the first nine detection combs 1019 are equally spaced side by side in the X-direction. The first detection comb 1011, the first four driving comb 1014 and the first seven detection comb 1017 are arranged in parallel at equal intervals in the Y direction; the first two detection comb teeth 1012, the first five driving comb teeth 1015 and the first eight detection comb teeth 1018 are arranged in parallel at equal intervals in the Y direction and are positioned at the center of the resonator in the horizontal direction; the first three detecting comb teeth 1013, the first six driving comb teeth 1016, and the first nine detecting comb teeth 1019 are arranged in parallel at equal intervals in the Y direction. The X direction is the length direction of the resonance beam, the Y direction is the width direction of the resonance beam, and the Z direction is determined according to the right hand rule.
The first thermal stress release structures 1031 of the first thermal stress release structures 103 are arranged above the first detection comb teeth 1011, and one end of each first thermal stress release structure is connected with the first lever amplifying structure 102 through the straight beam 1023, and the other end of each first thermal stress release structure is fixed through the anchor area 1021; the first two-thermal stress relief structure 1032 of the first thermal stress relief structure 103 is disposed above the first seven sense combs 1017 and is connected at one end to the first lever amplifying structure 102 by a straight beam 1024 and at the other end to the anchor region 1022.
The second sensitive structure 2 comprises a second mass 201, a second lever amplifying structure 202, a second thermal stress relief structure 203, a second resonator 204, a second folded beam group 205, a second anchor group 206, a folded beam 207, a folded beam 208, a straight beam 2025, a U-beam 209, an anchor region 2020, an anchor region 2021, an anchor region 2022, a straight beam 2023, a straight beam 2024, a straight beam 2026.
The second mass 201 is secured to a second anchor group 206 by a second folded beam group 205, the second anchor group 206 being located between the cap layer 17 and the substrate layer 19. The transverse vibration mode resonance frequency of the second mass is determined by the elastic coefficient of the second folded beam group 205 and the mass of the second mass itself. The second lever amplifying structure 202 is connected to the second mass 201 at both ends thereof by a folding beam 207 and a folding beam 208.
The second resonator 204 is located in the middle of the second sensitive structure 2, and is connected at one end to the U-beam 209 of the second lever amplifying structure 202 by a straight beam 2025, and is fixed at the other end to the anchor 2020 by a straight beam 2026. The second resonator 204 specifically includes two resonant beams 2010 with two fixed ends, and a sliding film comb structure connected to the resonant beams. The sliding film comb structure includes a second first detecting comb 2011, a second driving comb 2012, a second third detecting comb 2013, a second fourth detecting comb 2014, a second fifth driving comb 2015, a second sixth detecting comb 2016, a second seventh detecting comb 2017, a second eighth driving comb 2018, and a second ninth detecting comb 2019. Wherein the second first detection comb 2011, the second driving comb 2012, and the second third detection comb 2013 are disposed at equal intervals in the X direction; the second four detecting comb teeth 2014, the second five driving comb teeth 2015, and the second six detecting comb teeth 2016 are arranged side by side at equal intervals in the X direction; the second seven detection comb teeth 2017, the second eight driving comb teeth 2018 and the second nine detection comb teeth 2019 are arranged side by side at equal intervals in the X direction. The second first detection comb 2011, the second fourth driving comb 2014 and the second seventh detection comb 2017 are arranged in parallel at equal intervals in the Y direction; the second detection comb 2012, the second five driving comb 2015 and the second eight detection comb 2018 are arranged in parallel at equal intervals in the Y direction and are positioned at the center of the resonator in the horizontal direction; the second three detecting comb teeth 2013, the second six driving comb teeth 2016 and the second nine detecting comb teeth 2019 are arranged in parallel at equal intervals in the Y direction.
The second thermal stress release structure 2031 of the second thermal stress release structure 203 is disposed above the second first detection comb 2011, and one end is connected to the second lever amplification structure 202 through the straight beam 2023, and the other end is fixed through the anchor region 2021; the second thermal stress relief structure 2032 of the second thermal stress relief structure 203 is disposed above the second seven detecting comb teeth 2017, and is connected to the second lever amplifying structure 202 at one end via a straight beam 2024 and fixed at the other end via an anchor region 2022.
Fig. 3 shows working modes of the first resonator 104 and the second resonator 204, which are resonance Liang Fanxiang vibration modes, and stresses generated by vibration of the resonance beam can be offset at the end, so that the thermal elasticity quality factor is high, and mechanical thermal noise in a high vacuum environment is small. The operating frequencies of the first resonator 104 and the second resonator 204 may be adjusted by sizing the resonant beams 1010 and 2010, respectively, with the operating frequency of this embodiment being about 20 KHz. The frequency difference between the operating frequency of the first resonator 104 and the second resonator 204 and the anti-phase resonant mode frequency is determined by the stiffness of the straight beam 1026 and the straight beam 2026, respectively, and the frequency difference is greater than 1000Hz in this embodiment.
The in-phase ac signal generated by the external driving circuit is applied to the first two-driving comb teeth 1012 and the first eight-driving comb teeth 1018, and is inverted with the ac signal applied to the first five-driving comb teeth 1015 by the external driving circuit, so that the two resonant beams of the first resonator 104 perform inverse push-pull vibration. Similarly, the ac signals applied to the second driving comb 2012 and the second eighth driving comb 2018 by the external driving circuit are in phase and opposite to the ac signals applied to the second fifth driving comb 2015 by the external driving circuit, so that the two resonant beams of the second resonator 204 perform inverse push-pull vibration.
The resonator is driven in the Y-axis direction, and simple harmonic driving of the resonator in the Y-axis direction is realized. Under the acceleration in the X direction, the first mass 101 and the second mass 201 generate an inertial force in the X direction, and the inertial force generates a push-pull load in the axial direction of the first resonator 104 and the second resonator 204 through the first lever amplifying structure 102 and the second lever amplifying structure 202, respectively. Wherein one resonator is subjected to axial tension and the resonance frequency is increased, and the other resonator is subjected to axial compression and the resonance frequency is decreased. Two individual resonators form a push-pull differential structure to compensate common mode errors such as temperature.
The output signals of the first one-to-one detection comb 1011, the first three detection comb 1013, the first seven detection comb 1017 and the first nine detection comb 1019 are connected, the output signals of the first four detection comb 1014 and the first six detection comb 1016 are connected, and the two output signals are subjected to differential processing. Similarly, the output signals of the second first detection comb 2011, the second third detection comb 2013, the second seventh detection comb 2017 and the second ninth detection comb 2019 are connected, the output signals of the second fourth detection comb 2014 and the second sixth detection comb 2016 are connected, and the two output signals are subjected to differential processing. The output signals of the first resonator 104 and the output signals of the second resonator 204 obtained by difference are further subjected to difference processing, and the frequency change amount of the output signals is in direct proportion to the external acceleration, so that the detection of the acceleration is realized, the interference of common mode noise is reduced, the signal detection precision is improved, and the sensitivity of the silicon-based MEMS resonant accelerometer is improved.
The invention relates to a multistage differential silicon-based MEMS resonant accelerometer which can be widely applied to military and civil fields such as guided bombs, portable air-defense missiles, microsatellites, intelligent wearing, intelligent driving, unmanned aerial vehicles and the like and is used for measuring carrier acceleration. The invention can also effectively reduce the volume of the inertial measurement unit, and has important military and commercial application values.
The above examples are only preferred embodiments of the present invention, and ordinary changes and substitutions made by those skilled in the art within the scope of the present invention are intended to be included in the scope of the present invention.

Claims (10)

1. A high-precision silicon-based MEMS resonant accelerometer based on multistage differential output is characterized by comprising an upper layer cap layer, a middle layer sensitive module and a lower layer substrate layer; the upper cover cap layer and the lower substrate layer are connected to form an internal vacuum structure, and the middle sensitive module is arranged in the internal vacuum structure; the middle-layer sensitive module comprises two identical sensitive structures which are distributed symmetrically left and right and are isolated from each other, and the sensitive structures comprise a mass block, a lever amplifying structure, a thermal stress releasing structure and a resonator;
the mass block is fixed between the upper cover cap layer and the lower substrate layer; the lever amplifying structure is vertically arranged at the outer side of the mass block, and two ends of the lever amplifying structure are connected with the mass block;
the resonator comprises a resonance beam and a sliding film comb tooth structure connected to the resonance beam, wherein the sliding film comb tooth structure is connected with an external driving circuit to generate electrostatic force to drive the resonance beam to vibrate, and a detection signal is output;
the two thermal stress release structures are respectively arranged above and below the resonator.
2. The high-precision silicon-based MEMS resonant accelerometer based on multistage differential output as claimed in claim 1, wherein the sliding film comb structure comprises a driving comb and a detecting comb, the driving comb is driven by electrostatic force, and the detecting comb is a capacitance detecting output;
three driving comb teeth are longitudinally arranged along the central axis of the resonator, and each row of driving comb teeth is one;
two sides of each driving comb tooth are respectively provided with a detection comb tooth in parallel;
the output signals of the detection comb teeth positioned at the two sides of the upper end part and the lower end part driving comb teeth are connected, the output signals of the remaining detection comb teeth are connected, and the two signals are differentiated to form detection signals.
3. The high-precision silicon-based MEMS resonant accelerometer based on multi-level differential output according to claim 1 or 2, wherein detection signals output by respective resonators in two sensitive structures are subjected to differential processing to obtain differential signal frequencies.
4. The high-precision silicon-based MEMS resonant accelerometer based on multistage differential output according to claim 1, wherein one end of the resonant beam is connected with the lever amplifying structure, and the other end of the resonant beam is fixed on the mass block through a straight beam.
5. The high-precision silicon-based MEMS resonant accelerometer based on multistage differential output according to claim 4, wherein the frequency difference between the working frequency of the resonator and the anti-phase resonant mode frequency is changed by adjusting the rigidity of the straight beam.
6. The high-precision silicon-based MEMS resonant accelerometer based on multistage differential output according to claim 1, wherein an anchor region is arranged between an upper cover layer and a lower substrate layer, and two ends of each mass block are respectively fixed on the anchor region through a folding beam; the stiffness of the folded beam in the length direction is much smaller than the stiffness in the width direction and the vertical direction.
7. The high-precision silicon-based MEMS resonant accelerometer based on multistage differential output according to claim 6, wherein the transverse vibration mode resonant frequency of the mass block is determined by the elastic coefficient of the connected folding beam group and the self mass.
8. The high-precision silicon-based MEMS resonant accelerometer based on multistage differential output according to claim 1, wherein the upper cover cap layer and the lower substrate layer are connected to form an internal vacuum structure, and the middle sensitive module is bonded in the internal vacuum structure through anchor points.
9. The high-precision silicon-based MEMS resonant accelerometer based on multistage differential output according to claim 1, wherein two ends of the lever amplifying structure are connected to the mass block through a folded beam.
10. A high-precision silicon-based MEMS resonance acceleration measurement method based on multistage differential output is characterized by comprising the following steps:
applying in-phase alternating current signals to driving comb teeth at the upper end and the lower end of each of the two resonators through an external driving circuit, and applying another alternating current signal which is opposite to the alternating current signals to the rest driving comb teeth, so that two resonant beams on each resonator do reverse push-pull vibration, and signal frequency after difference of output signals of the two resonators is obtained;
when acceleration in the length direction of the resonant beam acts on the resonant accelerometer, the two mass blocks are sensitive to acceleration, and inertial force and displacement in the length direction of the resonant beam are generated, the inertial force respectively generates push-pull loads in the axial directions of the two resonators through the two lever amplifying structures, and signal frequency after the output signals of the two resonators are differentiated is acquired again;
and obtaining a frequency change amount according to the signal frequencies obtained in the front and back steps, and calculating to obtain an acceleration value.
CN202310734210.2A 2023-06-20 2023-06-20 High-precision silicon-based MEMS resonant accelerometer based on multistage differential output Pending CN116953284A (en)

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