MEMS resonant accelerometer based on coupling synchronization

Abstract

The invention discloses an MEMS (Micro Electro Mechanical System) resonant accelerometer based on coupling synchronization, which is characterized in that a tuning module is arranged around a mass block, and frequency and sensitivity matching of two accelerometers is realized through bias voltage, so that the two accelerometers still keep consistent frequency difference under different measurement inputs. In a mutual coupling electric synchronization state, the device using the method of the invention can maintain a synchronization state to a greater extent and has no sensitivity attenuation phenomenon. According to the invention, the problem that the synchronous bandwidth of the coupling synchronous accelerometer is narrow is effectively solved, and the measurement range of the whole machine is obviously widened. In addition, the noise in the oscillation circuit in the synchronous state is remarkably suppressed, so that the noise floor of the sensor is further reduced, and the zero offset instability is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-electro-mechanical systems (MEMS) sensors, and in particular relates to a MEMS resonant accelerometer based on coupling synchronization. Background Art

[0002] High-precision accelerometers play a key role in intelligent equipment, process industries, aerospace, and consumer electronics, providing systems with core functions such as positioning and navigation, vibration detection, and status monitoring, and have a wide range of application needs. With the continuous development of MEMS technology, MEMS resonant accelerometers have gradually become one of the most promising sensors due to their high sensitivity and quasi-digital output. However, the performance of traditional MEMS resonant accelerometers is gradually approaching a bottleneck, and the space for improving performance by relying solely on structural topology optimization is becoming increasingly limited. In recent years, 1:1 mutual coupling synchronization has been proven to significantly reduce the noise level of the core resonant element and improve system stability, which provides a new idea for further improving the performance of resonant sensors.

[0003] However, applying coupled synchronization to sensors faces the following technical challenges: First, processing errors can lead to frequency ratio misalignment. Due to the limitations of micro-nano manufacturing processes, non-ideal factors such as geometric errors and internal stress often appear in the resonator, making it difficult to achieve precise matching of the resonator frequency and hindering the realization of synchronization. Secondly, synchronization bandwidth is another key factor restricting the application of synchronization. As a key characteristic of synchronization, synchronization bandwidth is a core indicator for measuring the sustainable range of synchronization effects. Sensing effects can only be effectively enhanced within the synchronization bandwidth. However, due to limitations on coupling strength, synchronization bandwidth is often small, limiting the application scope of synchronized sensing technology. Furthermore, sensitivity degradation caused by mutual coupling synchronization further restricts its application.

[0004] Therefore, overcoming these factors is the key to improving the performance of synchronous accelerometers. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a MEMS resonant accelerometer based on coupled synchronization, so as to solve the technical problem of narrow synchronization bandwidth of the coupled synchronous accelerometer.

[0006] The present invention adopts the following technical solutions: A MEMS resonant accelerometer based on coupling synchronization includes two resonant sensing units with the same structure, each resonant sensing unit is configured with an independent oscillation circuit and a mutual injection synchronization circuit; The oscillation circuit includes a first oscillation circuit and a second oscillation circuit, which are used to drive the corresponding resonant tuning fork to self-oscillate near its resonant frequency and output an oscillation signal; The mutual injection synchronization circuit includes: A first signal processing branch connected to the output end of the first oscillation circuit; a second signal processing branch connected to the output end of the second oscillation circuit; a first adder, a first input end of which is connected to the output of the signal processing branch of the second oscillation loop, and an output end of which is connected to the feedback input end of the first oscillation loop; a second adder, a first input end of which is connected to the output of the signal processing branch of the first oscillation loop, and an output end of which is connected to the feedback input end of the second oscillation loop; By applying independent tuning bias voltages, the natural frequencies and sensitivities of the two resonant sensing units are matched. The oscillation signals output by the first oscillation circuit and the second oscillation circuit are processed by corresponding signal processing branches and then injected into each other's oscillation circuits through a first adder and a second adder, achieving 1:1 bidirectional electrical signal mutual injection coupling synchronization. After synchronization, the frequency offset of the system is output as an acceleration measurement, and there is no sensitivity attenuation in the synchronized state.

[0007] Preferably, the resonant sensing unit comprises: mass block; and a support structure for suspending and supporting the mass block; A resonant tuning fork comprising a resonant sensitive beam and a corresponding first fixed anchor point; a lever mechanism module, connecting the mass block and the resonant sensitive beam, for transmitting inertial force and amplifying strain; The first tuning module and the second tuning module are respectively arranged on the upper and lower sides of the mass block. Each tuning module includes at least one pair of variable-spacing comb-tooth capacitors consisting of a fixed comb-tooth electrode and a movable comb-tooth electrode connected to the mass block. The oscillation frequency and sensitivity of the two resonant tuning forks are adjusted by applying a tuning voltage.

[0008] Preferably, each of the tuning modules comprises two groups of variable-spacing comb-tooth capacitors, which are respectively arranged on the left and right sides of the corresponding mass block; when the first tuning module is loaded with a bias voltage, a downward electrostatic force is generated to cause the mass block to move downward; when the second tuning module is loaded with a bias voltage, an upward electrostatic force is generated to cause the mass block to move upward; the magnitude of the tuning bias voltage determines the sensitivity of the corresponding resonant sensing unit.

[0009] Preferably, the lever mechanism module includes a force input beam, a lever beam and a support beam; one end of the lever beam is connected to the mass block, and the other end is connected to the resonant sensitive beam through the force input beam, and the support beam is anchored to the base and provides a lever fulcrum.

[0010] Preferably, the resonant sensing unit further includes: The excitation module includes an excitation anchor point, an excitation electrode plate, and a second metal electrode layer. The excitation electrode plate and the first electrode plate provided on one side of the resonant sensitive beam form a driving capacitor with a gap of 2 to 5 μm. The detection module includes a detection anchor point, a detection electrode plate and a third metal electrode layer. The detection electrode plate and the second electrode plate arranged on the other side of the resonant sensitive beam form a detection capacitor with a gap of 2-5 μm.

[0011] Preferably, the resonant sensitive beam has a beam length of 300-1000 μm, a beam width of 3-10 μm, and a beam thickness of 40-60 μm.

[0012] Preferably, a single comb-tooth electrode in the tuning module has a length of 500-2000 μm and a width of 5-10 μm.

[0013] Preferably, the spacing between the fixed comb-tooth electrode and the movable comb-tooth electrode is 10-40 μm, and the overlapping length is 100-500 μm.

[0014] Preferably, the resonant tuning forks are arranged in the same direction, and when subjected to external acceleration, the natural frequencies of the resonant tuning forks will change in the same direction.

[0015] Preferably, the structures of the two resonant sensing units are bilaterally symmetrical along the Y-axis, and the second accelerometer is obtained by translating the first accelerometer downward along the X-axis.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: A MEMS resonant accelerometer based on coupled synchronization, based on the principle of 1:1 bidirectional electrical signal mutual injection coupled synchronization, achieves phase lock by mutually injecting the oscillating signals of two resonant units, significantly reducing phase noise. Theoretical and experimental results show that in the synchronized state, the noise power spectral density can be further reduced, and the signal-to-noise ratio can be further improved. The independent tuning bias voltage dynamically compensates for resonant frequency deviations caused by the manufacturing process, solving the frequency mismatch problem caused by processing errors in traditional resonant accelerometers. It ensures that the two resonators have the same frequency in the absence of acceleration, creating conditions for synchronization. By synchronizing two oscillators, both sensitive to acceleration, it eliminates sensitivity degradation in the synchronized state, avoiding the sensitivity loss and reduced sensor accuracy caused by traditional coupled synchronization schemes.

[0017] Furthermore, the lever mechanism converts the tiny displacement of the mass block into strain of the resonant beam, thereby amplifying the resonant frequency offset.

[0018] Furthermore, the bias voltage is tuned to control the magnitude of the electrostatic force, change the equilibrium position of the mass block, and thus adjust the frequency of the resonant beam to meet the synchronization requirements.

[0019] Furthermore, the electrostatic stiffness generated by tuning the bias voltage can adjust the frequency of the resonant beam to meet the synchronization requirements.

[0020] Furthermore, under the action of acceleration, the two resonant tuning forks are simultaneously pulled / compressed, and the frequencies change in the same direction. The two oscillators will always maintain synchronization, solving the problem that the synchronization range limits the measurement range of the sensor.

[0021] In summary, the present invention realizes the mutual coupling synchronization of two resonant accelerometers for the first time, and as a universal method, it helps to significantly improve the performance of traditional MEMS resonant accelerometers.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is the overall structure diagram of the coupled synchronous MEMS resonant accelerometer of the present invention; Figure 2 This is a detailed diagram of the resonant sensing module; Figure 3 This is a detailed diagram of the tuning module; Figure 4 This is a schematic diagram of the measurement circuit structure of the present invention.

[0025] Among them: 1-1. Resonant sensitive beam; 1-2. First fixed anchor point; 1-3. First metal electrode layer; 1-4. First connecting beam; 1-5. First electrode plate; 1-6. Second electrode plate; 2-1. Excitation anchor point; 2-2. Second metal electrode layer; 2-3. Excitation electrode plate; 3-1. Detection anchor point; 3-2. Third metal electrode layer; 3-3. Detection electrode plate; 4-1. Force input beam; 4-2. Force output beam; 4-3. Lever beam; 4-4. Support beam; 4-5. First support anchor point; 4-6. Fourth metal electrode layer; 5-1. Mass block; 5-2. Mass block support beam ; 5-3. Mass block support anchor point; 6-1. Fixed comb electrode; 6-2. Movable comb electrode; 6-3. Fixed anchor end; 6-4. Metal electrode layer sputtered on the anchor point; 7-1. First amplifier; 7-2. First phase detector; 7-3. First PI controller; 7-4. First numerically controlled oscillator; 7-5. First limiter; 7-6. First phase shifter; 7-7. Second amplifier; 7-8. Second phase detector; 7-9. Second PI controller; 7-10. Second numerically controlled oscillator; 7-11. Second limiter; 7-12. First adder; 7-13. Second adder. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0028] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0029] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0030] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0031] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0032] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0033] This invention provides a MEMS resonant accelerometer based on coupled synchronization. This approach leverages the electrostatic softening effect to adjust the bias voltage to match the natural frequencies and sensitivities of two accelerometers, achieving a 1:1 frequency ratio of coupled synchronization. This effectively addresses the problem of excessive frequency deviation and inability to maintain synchronization due to sensitivity mismatch, significantly broadening the sensor's detection range. Furthermore, in the synchronized state, the overall system sensitivity is maintained without attenuation.

[0034] The present invention provides a MEMS resonant accelerometer based on coupling synchronization and its resonant sensing unit, oscillation circuit and mutual injection synchronization circuit. The mutual injection synchronization circuit realizes bidirectional electrical signal coupling synchronization, and the tuning module is combined to accurately match the resonant frequency, effectively solving the problems of frequency mismatch, limited synchronization bandwidth and sensitivity attenuation in traditional designs. It has the advantages of improving frequency matching accuracy, expanding synchronization bandwidth and avoiding sensitivity attenuation.

[0035] See also Figure 1 、 Figure 2 and Figure 3 The present invention provides a MEMS resonant accelerometer based on coupling synchronization, comprising a resonant sensing module, a lever amplification module, a mass block module and a comb tuning module; The structure of the MEMS resonant accelerometer is bilaterally symmetrical along the Y-axis. The first accelerometer is translated downward along the X-axis to obtain the second accelerometer. The following description only takes one side of the first accelerometer as an example.

[0036] The resonant sensing module includes a sensitive beam module, an excitation module, and a detection module.

[0037] The sensitive beam module includes a resonant sensitive beam 1-1, a first fixed anchor point 1-2 and a first connecting beam 1-4. The first fixed anchor point 1-2 provides fixed support for the resonant sensitive beam 1-1.

[0038] The first electrode plate 1-5 and the second electrode plate 1-6 are located on both sides of the resonant sensitive beam 1-1 and are connected to the resonant sensitive beam 1-1 by short beams.

[0039] A metal electrode layer 1-3 is uniformly sputtered on the first fixed anchor point 1-2 for inputting and outputting electrical signals.

[0040] The resonant sensitive beam 1 - 1 has a beam length of 300 to 1000 μm, a beam width of 3 to 10 μm, and a beam thickness of 40 to 60 μm.

[0041] The excitation module includes an excitation anchor point 2-1, a second metal electrode layer 2-2 sputtered on the excitation anchor point, and an excitation electrode plate 2-3.

[0042] The detection module includes a detection anchor point 3-1, a third metal electrode layer 3-2 sputtered on the detection anchor point, and a detection electrode plate 3-3.

[0043] The first fixed anchor point 1-2, the excitation anchor point 2-1, and the detection anchor point 3-1 are all rectangular in shape, and their size range is .

[0044] The first metal electrode layer 1-3, the second metal electrode layer 2-2, and the third metal electrode layer 3-2 are all rectangular in shape, and their dimensions are .

[0045] A certain gap exists between the first electrode plate 1 - 5 and the excitation electrode plate 2 - 3 to form a parallel plate capacitor for providing a reciprocating excitation force.

[0046] There is a gap between the second electrode plate 1-6 and the detection electrode plate 3-3 for electrostatic detection. The gap size is 2~5 .

[0047] The lever mechanism module includes a force input beam 4-1, a force output beam 4-2, and a lever beam 4-3.

[0048] The lever beam 4 - 3 connects the mass block 5 - 1 and the resonant sensing module.

[0049] The inertial force generated by the mass block 5-1 is transmitted to the lever beam 4-3 through the force input beam 4-1, and then transmitted to the resonant sensing module through the force output beam 4-2.

[0050] The mass block module includes a mass block 5 - 1 and a mass block supporting structure 5 - 2 .

[0051] The mass block module is bilaterally symmetrical, with four identical mass block support structures. Mass block 5-1 is suspended on a silicon micro-substrate, with a hollowed-out bottom and connected to mass block support structure 5-2.

[0052] The comb tuning module consists of four sets of movable comb electrodes directly connected to the proof mass and fixed comb electrodes connected to the surrounding anchors. These electrodes are located on either side of the proof mass. Each set of comb electrodes consists of 10 parallel electrode plates (the number of comb teeth can be customized to n). The fixed comb electrodes are mated to the corresponding movable comb electrodes using a fork-like arrangement. A single comb electrode ranges from 500 to 2000 μm in length and 5 to 10 μm in width.

[0053] The two sets of comb-tooth electrodes arranged at the top are called the first tuning module, which provides an upward electrostatic force to pull the resonant sensing module. The two sets of comb-tooth electrodes arranged at the bottom are called the second tuning module, which provides a downward electrostatic force to compress the resonant sensing module.

[0054] Each comb module group includes a fixed anchor end 6-3, a metal electrode layer 6-4 sputtered on the anchor point, a fixed comb electrode 6-1 connected to the fixed anchor end, and a movable comb electrode 6-2 connected to the mass block. The length of the fixed comb electrode and the movable comb electrode is the same, ranging from 200 to 600 mm. The distance between two adjacent fixed comb electrodes and movable comb electrodes is 10~40 The overlapping length between the fixed comb electrode and the movable comb electrode is 100~500 .

[0055] See also Figure 4 The resonant accelerometer uses a closed-loop oscillator circuit to form a first oscillation loop and a second oscillation loop. This closed-loop oscillator circuit includes an amplifier, a phase detector, a PI controller, a numerically controlled oscillator, and a phase shifter. By adjusting the various loop parameters, the resonator is able to self-oscillate near its resonant frequency. The signal from the first oscillation loop passes through a limiter and a phase shifter before being injected into the second oscillation loop via an adder. The signal from the second oscillation loop passes through a limiter and then is injected into the first oscillation loop via an adder, achieving mutual synchronization.

[0056] The first oscillation circuit includes a first amplifier 7-1, a first phase detector 7-2, a first PI controller 7-3, and a first numerically controlled oscillator 7-4. By adjusting the various control circuit parameters, the first oscillation circuit is ensured to self-oscillate near the resonant frequency. The oscillation signal from the closed-loop feedback of the resonant beam is input into the first limiter 7-5 and the first phase shifter 7-6, generating harmonics with equal frequency and adjustable amplitude. These harmonics act as a synchronization signal and are injected into the second adder 7-13 in the form of electrostatic disturbance force, influencing the second oscillation circuit.

[0057] The second oscillation circuit includes a second amplifier 7-7, a second phase detector 7-8, a second PI controller 7-9, and a second numerically controlled oscillator 7-10, connected in sequence. Similarly, the oscillation signal from the closed-loop feedback of the resonant beam is input into a second limiter 7-11, generating harmonics with equal frequency and adjustable amplitude. These harmonics act as a synchronization signal and are injected into the first adder 7-12 in the form of electrostatic disturbance force, influencing the first oscillation circuit. The mutual injection of the harmonic signals of the first and second oscillation circuits achieves mutual injection synchronization.

[0058] This invention achieves 1:1 synchronization between two accelerometers for the first time through bidirectional electrical signal injection. Using electrostatic tuning, the frequencies and sensitivities of the two oscillation signals are aligned. The oscillation frequencies of Oscillator Signal 1 and Oscillator Signal 2 are injected into each other as electrical signals, achieving synchronization. After synchronization, the two frequencies match and change in sync with external acceleration.

[0059] Compared with the traditional electrostatic weak coupling method, the design of the present invention fundamentally solves the problem of sensitivity reduction caused by the interaction between coupled resonators through mutual injection synchronization of two oscillators that are both sensitive to acceleration, giving full play to the role of 1:1 synchronization in improving overall performance. Adjusting the sensitivity of the two accelerometers to remain consistent can ensure that the frequency difference between the two oscillators is constant under external input acceleration, greatly widening the measurement range. In addition, in the synchronized state, the noise in the accelerometer oscillation circuit is significantly suppressed and the frequency stability is significantly improved. In summary, this method comprehensively optimizes the performance of the resonant accelerometer in terms of sensitivity, resolution, and noise control.

[0060] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0061] See also Figure 4 The working principle of the coupling synchronization-based resonant accelerometer of the present invention is as follows: When the accelerometer is subjected to external acceleration, the mass block undergoes displacement and deformation under the action of gravity acceleration; the lever mechanism at one end of the mass block amplifies the tensile or compressive strain it receives by a certain proportion, causing the sensitive beams at both ends of the mass block to produce greater tensile strain or compressive strain.

[0062] The accelerometer's tuning fork's resonant frequency changes under the influence of tensile and compressive stresses. When the tuning fork is subjected to tensile stress, the resonant frequency increases; conversely, when the tuning fork is subjected to compressive stress, the resonant frequency decreases. By measuring this change in the resonant frequency of the tuning fork, the magnitude of the input acceleration can be inverted.

[0063] The frequency of the accelerometer's sensitive resonator can be adjusted through a tuning module; when the first tuning module of the resonant tuning fork is loaded with a bias voltage, its tensile stress frequency increases; conversely, when the second tuning module of the resonant tuning fork is loaded with a bias voltage, its compressive stress frequency decreases.

[0064] The tuning voltage can generate electrostatic stiffness, so the sensitivity of the accelerometer can be adjusted by adjusting the bias voltage loaded on the first tuning module and the second tuning module to make the sensitivities of the first accelerometer and the second accelerometer consistent.

[0065] The accelerometer is built into an oscillation loop through a closed-loop oscillation circuit. The vibration signal of the first accelerometer is detected by the electrostatic detection of the parallel electrode plate and then enters the first amplifier, the first phase detector, the first PI controller, and the first numerically controlled oscillator to form a first oscillation loop.

[0066] Similarly, the vibration signal of the second accelerometer enters the second amplifier, the second phase detector, the second PI controller, and the second digital controlled oscillator after being electrostatically detected by the parallel electrode plates, forming a second oscillation loop.

[0067] By applying a bias voltage to the tuning module, the oscillation frequencies of the two oscillation circuits are adjusted to match each other.

[0068] Subsequently, the oscillation signal of the first oscillation circuit is injected into the second oscillation circuit through the first limiter, the first phase shifter and the first adder; the oscillation signal of the second oscillation circuit is injected into the first oscillation circuit through the second limiter and the second adder to achieve mutual coupling synchronization.

[0069] The synchronized first and second oscillator circuits, due to their consistent sensitivity, maintain a similar frequency difference, ensuring the sensors remain synchronized even under large acceleration inputs, significantly broadening the measurement range of the synchronized accelerometer. Furthermore, due to the high frequency stability of the electrical signal, when the two oscillators are synchronized, the noise of the sensitive beam oscillator circuit in the resonant sensing module is significantly suppressed, improving frequency stability and significantly improving the noise level and bias instability of the synchronized accelerometer.

[0070] Example 1 High-precision accelerometers play a vital role in several key areas. However, traditional MEMS resonant accelerometers face performance bottlenecks. Manufacturing errors make it difficult to match resonator frequencies, limited synchronization bandwidth affects the sustainability of synchronization, and sensitivity degradation further restricts the application of the technology. Existing solutions rely on structural optimization, making it difficult to resolve the conflict between frequency misalignment and synchronization stability.

[0071] To address these issues, active adjustment mechanisms were considered to compensate for process errors in frequency misalignment. Bidirectional signal coupling was explored to enhance system stability, addressing synchronization bandwidth limitations. Furthermore, mechanisms to maintain output signals under synchronization were investigated to address sensitivity degradation. Inherent errors were reduced through structural symmetry, and dynamic balance was achieved through the introduction of electrical signal mutual injection, ultimately resulting in a solution based on bidirectional coupling synchronization.

[0072] Therefore, this application proposes a MEMS resonant accelerometer based on coupled synchronization, comprising two resonant sensing units of identical structure, each equipped with an independent oscillation circuit and a mutual injection synchronization circuit. The oscillation circuit drives the corresponding resonant tuning fork into self-oscillation, and the mutual injection synchronization circuit includes a first signal processing branch and a second signal processing branch connecting the two oscillation circuits, and bidirectional signal mutual injection is achieved through a first adder and a second adder. The bias voltage is tuned to match the natural frequency and sensitivity of the two units. After synchronization, the frequency offset of the system is output as the acceleration measurement.

[0073] Among them, the resonant sensing unit refers to a vibration system with the same mechanical structure, which can be implemented by a symmetrically arranged resonant tuning fork structure, and the initial frequency deviation is reduced by geometric symmetry. The oscillation circuit refers to a circuit system that maintains the continuous vibration of the resonator, which can be implemented by a closed-loop circuit including an amplifier and a feedback network to ensure that the resonator operates stably near the natural frequency. The mutual injection synchronization circuit refers to a circuit module that realizes the interaction of signals between two independent systems, which can be implemented by a combination structure of a signal processing branch and an adder, and a dynamic coupling relationship is established by cross-injection signals. The tuning bias voltage refers to a DC voltage signal used to adjust the system parameters, which can be implemented by applying electrostatic force through a variable-pitch comb capacitor structure to compensate for the frequency deviation caused by manufacturing errors.

[0074] Specifically, the two resonant sensing units initially have a slight frequency difference. A bias voltage is applied through a tuning module to bring the natural frequencies closer together. The signal output from the oscillation circuit is converted by a processing branch and then cross-injected into the other feedback loop via an adder, forming a bidirectional coupling path. When the system reaches a synchronized state, the vibration frequencies of the two resonators converge, and the frequency offset caused by external acceleration is converted into a synchronous frequency change for the entire system. This operating method replaces mechanical coupling with electrical signal coupling, avoiding the energy loss associated with traditional mechanical coupling while maintaining the independent detection capabilities of the two sensing channels.

[0075] Compared with existing technologies, traditional solutions use a single resonator or a mechanically coupled dual-resonator structure, which presents challenges in balancing sensitivity and stability. This solution achieves dynamic synchronization through bidirectional mutual injection of electrical signals, retaining the differential detection advantages of dual resonators while overcoming the influence of manufacturing errors through an active tuning mechanism. While existing synchronization technologies often rely on unidirectional coupling or open-loop control, this solution's bidirectional closed-loop coupling significantly improves the system's anti-interference capabilities.

[0076] Through the above technical solutions, this application effectively solves the resonator frequency matching problem, expands the synchronization bandwidth range, and improves system stability while maintaining detection sensitivity. The mutual injection mechanism of electrical signals reduces the impact of process errors on the synchronization effect. The bidirectional coupling structure enhances the consistency of the system's response to external acceleration. The active control function of the tuning voltage achieves dynamic parameter matching, providing a reliable solution for high-precision acceleration detection.

[0077] Example 2 This application further proposes a MEMS resonant accelerometer based on coupled synchronization, comprising a mass block, a support structure that suspends and supports the mass block, a resonant tuning fork containing a resonant sensitive beam and a first fixed anchor point, a lever mechanism module connecting the mass block and the resonant sensitive beam, and a first tuning module and a second tuning module disposed on the upper and lower sides of the mass block, respectively. Each tuning module includes at least one pair of variable-pitch comb-tooth capacitors consisting of a fixed comb-tooth electrode and a movable comb-tooth electrode connected to the mass block. The oscillation frequency and sensitivity of the two resonant tuning forks are adjusted by applying a tuning voltage.

[0078] The mass block refers to an inertial mass structure used to sense external acceleration. It can be formed using silicon-based materials through micromachining processes and converts acceleration into inertial force. The support structure is a mechanical framework that suspends the mass block using elastic beams or cantilever beams. Specifically, it can be implemented using multiple cross-arranged support beams. It constrains the mass block's freedom of movement and transmits inertial force. The resonant tuning fork is a vibration-sensing element consisting of a resonant sensitive beam and a fixed anchor point. Specifically, it can be a double-clamped beam structure, achieving frequency response through the beam's bending vibration. The lever mechanism module is a mechanical amplification structure consisting of a force input beam, a lever beam, and a support beam. Specifically, it can be a lever design with one end connected to the mass block and the other to the sensitive beam. It converts the displacement of the mass block into strain amplification of the sensitive beam. The tuning module is a capacitive structure consisting of fixed and movable comb electrodes. Specifically, it can be a layout where the comb spacing varies with the displacement of the mass block. Applying a bias voltage generates an electrostatic force to adjust the resonant frequency and sensitivity.

[0079] Specifically, when the mass block is subjected to external acceleration, it generates inertial displacement, which is transmitted to the resonant sensitive beam through a lever mechanism, causing it to deform and change its natural frequency. The tuning module generates electrostatic forces in opposite directions on the upper and lower sides of the mass block by loading independent bias voltages, thereby adjusting the preload and stiffness of the sensitive beam and achieving dynamic matching of the resonant frequency and sensitivity. For example, when the upper tuning module is loaded with voltage, the movable comb electrode is subjected to a downward electrostatic force, which drives the mass block downward, thereby changing the stress distribution of the sensitive beam; when the lower tuning module is loaded with voltage, a reverse regulation effect is generated. By adjusting the ratio of the tuning voltages on both sides, the frequency mismatch caused by processing errors can be compensated, while optimizing the sensitivity consistency.

[0080] Compared with existing technologies, traditional resonant accelerometers typically rely on a single resonator structure and lack an active tuning mechanism, making it difficult to eliminate frequency mismatches caused by process deviations. However, this solution achieves bidirectional dynamic adjustment of resonant frequency and sensitivity by symmetrically arranging tuning modules on the upper and lower sides of the mass block, combined with the mechanical amplification effect of a lever mechanism, significantly improving frequency matching accuracy. Furthermore, the tuning structures in existing technologies often use a single-directional electrostatic force design, resulting in a limited adjustment range. However, the bidirectional tuning modules in this solution expand the dynamic range of frequency adjustment by synergizing opposing electrostatic forces.

[0081] Through the above technical solution, this application can effectively compensate for the resonator dimensional errors caused by the micromachining process, reduce the risk of frequency mismatch, and thus provide a stable frequency matching foundation for mutual injection synchronization. At the same time, through the synergy between the lever mechanism and the tuning module, precise control of the resonant frequency is achieved while ensuring sensitivity consistency, solving the problem of limited synchronization bandwidth caused by process deviations in traditional solutions.

[0082] Example 3 The present application further proposes a MEMS resonant accelerometer based on coupled synchronization, in which each tuning module includes two sets of variable-spacing comb-tooth capacitors, which are arranged on the left and right sides of the corresponding mass block respectively; when the first tuning module is loaded with a bias voltage, a downward electrostatic force is generated to cause the mass block to move downward; when the second tuning module is loaded with a bias voltage, an upward electrostatic force is generated to cause the mass block to move upward; the size of the tuning bias voltage determines the resonant frequency and sensor sensitivity of the corresponding resonant sensing unit.

[0083] Among them, the variable-spacing comb-tooth capacitor refers to a capacitor structure composed of a fixed comb-tooth electrode and a movable comb-tooth electrode connected to a mass block. Specifically, it can be implemented by using a comb-tooth pair whose electrode spacing changes with the displacement of the mass block. The capacitance value is adjusted by changing the spacing to generate electrostatic force.

[0084] Among them, arranging on the left and right sides of the mass block means that two groups of comb-tooth capacitors are symmetrically distributed on both sides of the mass block. Specifically, this can be achieved by adopting a mirror-symmetrical layout method. The linearity and balance of the electrostatic force regulation are improved through the double-sided arrangement.

[0085] The downward or upward electrostatic force refers to the electric field force formed between the comb capacitors by loading bias voltages of different polarities. Specifically, the direction of the electrostatic force can be controlled by adjusting the voltage polarity, thereby driving the mass block to generate displacement.

[0086] Among them, tuning the bias voltage to determine the resonant frequency and sensitivity means changing the displacement of the mass block by adjusting the voltage amplitude, thereby adjusting the strain state of the resonant tuning fork, and ultimately achieving dynamic matching of frequency and sensitivity.

[0087] Specifically, when the first tuning module is loaded with a bias voltage, the comb capacitors on the left and right sides simultaneously generate a downward electrostatic force, driving the mass block to move downward, causing the axial stress of the resonant sensitive beam to increase and the resonant frequency to increase accordingly; when the second tuning module is loaded with a reverse voltage, the comb capacitors on both sides generate an upward electrostatic force, causing the mass block to move upward, reducing the stress on the sensitive beam and lowering the resonant frequency. Through the symmetrical arrangement of the comb capacitors on both sides, the direction and amplitude of the electrostatic force can be precisely controlled, thereby compensating for the frequency mismatch caused by processing errors. The amplitude adjustment range of the tuning voltage determines the accuracy of the frequency matching, and the bilateral layout avoids the nonlinear error caused by unilateral drive, ensuring that the natural frequency and sensitivity of the two resonant sensing units meet the matching conditions required for synchronization.

[0088] Compared with existing technologies, traditional tuning modules typically use a single set of comb-tooth capacitors or an asymmetric layout. This limits the range of electrostatic force and easily introduces lateral interference, resulting in insufficient frequency adjustment precision. This solution expands the electrostatic force adjustment range by symmetrically arranging two sets of comb-tooth capacitors on both sides. It also utilizes bidirectional drive to offset lateral displacement deviations, significantly improving the linearity and stability of frequency matching and providing a reliable basis for frequency consistency for mutual injection synchronization.

[0089] Through the above technical solution, the present application solves the problem of resonator frequency mismatch caused by processing errors, realizes high-precision dynamic adjustment of the resonant frequency through the symmetrical drive of the double-sided comb capacitors, effectively expands the synchronization bandwidth, and avoids sensitivity attenuation at the same time, ensuring that the accelerometer maintains a stable synchronization state within a wide dynamic range.

[0090] Example 4 The present application further proposes a MEMS resonant accelerometer based on coupled synchronization, wherein the lever mechanism module includes a force input beam, a lever beam and a support beam; one end of the lever beam is connected to a mass block, and the other end is connected to a resonant sensitive beam through a force input beam; the support beam is anchored to a substrate and provides a lever fulcrum.

[0091] Among them, the force input beam refers to a structural component used to transmit the inertial force generated by the movement of the mass block. Specifically, it can be implemented by a cantilever beam or a straight beam structure. Its function is to convert the displacement of the mass block into the input force of the lever mechanism.

[0092] Among them, the lever beam refers to a mechanical structure used to amplify the input force, which can be implemented in the form of a single-arm or double-arm lever. Its function is to amplify the tiny inertial force into a measurable strain signal through the lever principle.

[0093] Among them, the support beam refers to a rigid anchoring structure that fixes the fulcrum of the lever. Specifically, it can be implemented in the form of a double-end fixed beam or a cross beam. Its function is to provide a stable fulcrum for the lever movement to avoid energy loss.

[0094] Specifically, when an external acceleration acts on the mass, the inertial force generated by the mass is transmitted via a force input beam to the input end of the lever beam. The lever beam amplifies the input force based on the position of the fulcrum and then drives the resonant sensitive beam to deform through its other end. A support beam secures the lever fulcrum to the substrate via an anchoring structure, creating a stable force transmission path. This structure enhances the strain response of the resonant sensitive beam through mechanical amplification while maintaining the overall compactness of the structure and avoiding energy dissipation caused by redundant degrees of freedom in the lever mechanism.

[0095] Compared to existing technologies, the lever mechanism of traditional accelerometers typically uses a single beam structure directly connecting the proof mass and sensitive beam. This force transmission path suffers from high mechanical losses and low strain amplification efficiency. This solution, however, forms a three-stage transmission structure with separate force input beams, lever beams, and support beams. While maintaining high force amplification, this solution utilizes the rigid constraints of the support beam to suppress parasitic vibrations, thereby improving force-strain conversion efficiency.

[0096] Through the above technical solution, this application solves the energy loss problem caused by the unstable fulcrum of the traditional lever mechanism, significantly improves the inertial force amplification efficiency by optimizing the force transmission path, and makes the strain response of the resonant sensitive beam and the acceleration signal show higher linearity, providing a reliable input signal for subsequent frequency detection.

[0097] Example 5 This application further proposes a MEMS resonant accelerometer based on coupled synchronization, whose resonant sensing unit also includes an excitation module and a detection module. The excitation module includes an excitation anchor point, an excitation electrode plate, and a second metal electrode layer. The excitation electrode plate forms a driving capacitor with a first electrode plate arranged on one side of the resonant sensitive beam, with a gap of 2-5μm. The detection module includes a detection anchor point, a detection electrode plate, and a third metal electrode layer. The detection electrode plate forms a detection capacitor with a second electrode plate arranged on the other side of the resonant sensitive beam, with a gap of 2-5μm.

[0098] The excitation anchor refers to the mechanical support structure used to secure the excitation module. It can be fabricated using silicon-based materials through micromachining, providing a stable anchor point for the electrodes. The excitation electrode plate is a conductive component that forms a drive capacitor with the first electrode plate on the resonant sensing beam. It can be fabricated using a metal thin film deposition process and is used to drive the sensing beam to vibrate via electrostatic force. The second metal electrode layer is a conductive layer covering the surface of the excitation electrode plate. It can be made of aluminum or copper to reduce contact resistance and enhance signal transmission stability. The detection anchor is a support structure that secures the detection module. Made of the same material as the excitation anchor, it ensures the positional accuracy of the detection electrodes. The detection electrode plate forms a detection capacitor with the second electrode plate on the sensing beam. Changes in the detection capacitance indicate the vibration state of the sensing beam. The third metal electrode layer functions similarly to the second metal electrode layer, optimizing the transmission quality of the detection signal. The gap between the drive and detection capacitors is set to 2-5μm, controlled through photolithography and etching processes. This range ensures sufficient electric field strength while minimizing the risk of short circuits between the electrodes.

[0099] Specifically, the excitation module generates electrostatic force in the driving capacitor by applying an alternating voltage, driving the resonant sensitive beam to vibrate near its resonant frequency. The detection module obtains the vibration signal of the sensitive beam by detecting the gap change of the capacitor and converts it into an electrical signal for output. The driving capacitor and the detection capacitor are arranged on both sides of the sensitive beam, forming a symmetrical structure, which can effectively suppress common-mode interference. The introduction of the second metal electrode layer and the third metal electrode layer reduces the contact resistance of the electrode surface and improves the signal-to-noise ratio of the signal. The gap between the driving and detection capacitors is controlled in the range of 2-5μm, which not only ensures the electric field strength and sensitivity, but also avoids electrode contact problems caused by process errors.

[0100] Compared to existing technologies, existing MEMS resonant accelerometers typically use a single electrode layer, making the drive and detection signals susceptible to parasitic capacitance interference, and the electrode gap design lacks process tolerance. This solution reduces signal transmission loss by providing independent second and third metal electrode layers, while limiting the gap between the drive and detection capacitors to a process-controllable range, achieving a balance between sensitivity and manufacturing feasibility.

[0101] Through the above technical solution, this application solves the signal attenuation problem caused by poor electrode contact or excessive gaps in traditional resonant accelerometers, improving the stability and reliability of vibration detection. The symmetrical arrangement of the drive and detection capacitors effectively offsets external interference, while the optimized electrode gap design reduces process complexity while maintaining sensitivity, providing a foundation for high-precision acceleration measurement.

[0102] Example 6 The present application further proposes that the beam length of the resonant sensitive beam is 300 to 1000 microns, the beam width is 3 to 10 microns, and the beam thickness is 40 to 60 microns.

[0103] A resonant sensitive beam is a vibrating structural element used to sense changes in acceleration. It can be fabricated using single-crystal silicon through micromachining. Its geometric parameters directly influence the resonant frequency and mechanical quality factor. Beam length controls the effective mass distribution of the vibration mode, beam width determines the lateral stiffness, and beam thickness influences the longitudinal bending resistance. By limiting the three-dimensional dimensions, the target frequency response can be achieved while maintaining structural stability.

[0104] Specifically, during the MEMS manufacturing process, the beam length is set to be above 300 microns to reduce the impact of process errors on the resonant frequency, while not exceeding 1000 microns to avoid the risk of structural instability. The beam width is controlled in the range of 3 to 10 microns, which not only meets the lateral stiffness requirements but also avoids the decrease in sensitivity caused by excessive width. The beam thickness is limited to the range of 40 to 60 microns. This thickness value has been verified by finite element simulation to balance bending strength and processing feasibility. Through this size combination, the sensitive beams of the two resonant sensing units are easier to achieve geometric parameter matching during the processing process.

[0105] Compared to existing technologies, traditional resonant beam designs often use a single fixed dimension or a wider parameter range, resulting in significant frequency deviation in the actual device after fabrication. This solution significantly reduces the impact of process fluctuations on frequency matching by precisely defining the upper and lower limits of the three-dimensional dimensions, making it easier to achieve the frequency consistency required for mutual injection synchronization.

[0106] Through the above technical solution, this application effectively solves the problem of resonator frequency mismatch caused by processing errors, allowing the two resonant sensing units to achieve a high degree of frequency consistency during the manufacturing process, creating favorable conditions for subsequent precise synchronization through electrical tuning. At the same time, this size combination not only ensures structural reliability but also takes into account the feasibility of the processing technology, which is conducive to quality control in mass production.

[0107] Example 7 The present application further proposes that the length of a single comb-tooth electrode in the tuning module is 500-2000 μm and the width is 5-10 μm.

[0108] The length of a single comb-tooth electrode refers to its overall dimension along the electrode's extension direction, which can be achieved by using a photolithography process to form a linear or segmented structure. This size range can balance the range of electrostatic force action and structural rigidity, avoiding mechanical deformation caused by excessive length or insufficient driving force caused by excessive shortness. The width of a single comb-tooth electrode refers to the lateral dimension perpendicular to the length direction, which can be achieved by using a deep reactive ion etching process to form a rectangular or trapezoidal cross-section. This size range can optimize the match between the capacitance change rate and processing accuracy, reducing the impact of process errors on tuning performance.

[0109] Specifically, when the length of the comb-tooth electrode in the tuning module is controlled within the range of 500-2000μm, sufficient electrostatic force can be generated when the tuning voltage is applied to drive the displacement of the mass block, while avoiding the decrease in the structural resonance frequency or weakening of the impact resistance due to excessive electrode length. When the comb-tooth electrode width is limited to the range of 5-10μm, it can ensure that the electrode gap remains uniform within the process error range. For example, when there is a ±1μm deviation in the photolithography process, this width range can effectively suppress the nonlinear fluctuation of the capacitance value. Through the above-mentioned size combination, a linear mapping relationship between the tuning voltage and the frequency offset can be achieved without increasing the process complexity.

[0110] Compared to existing technologies, existing tuning electrodes often adopt a single size design, such as a fixed length of 1000μm or a width of 8μm, which results in a limited tuning range or excessive sensitivity to processing errors. This solution, by limiting the coordinated range of electrode length and width, expands the dynamic range of frequency adjustment and improves process tolerance, ensuring that devices manufactured from different batches maintain consistent tuning characteristics.

[0111] Through the above technical solution, this application can effectively compensate for resonant frequency deviations caused by manufacturing errors, achieving more accurate frequency matching during the tuning process, thereby improving the stability of mutual injection synchronization. At the same time, this size range can reduce the risk of electrode breakage, ensuring that the tuning module can continue to operate reliably in long-term vibration environments.

[0112] Example 8 The present application further proposes that the spacing between the fixed comb-tooth electrode and the movable comb-tooth electrode is 10-40 μm, and the overlapping length is 100-500 μm.

[0113] The spacing between the fixed and movable comb electrodes refers to the vertical distance between the parallel surfaces of the two electrodes. This can be achieved by controlling the electrode positioning precision using photolithography. This spacing range balances the strength of the electrostatic force with the safety margin of the breakdown voltage between the electrodes. The overlap length refers to the effective contact area between the two electrodes in the direction of motion. This can be achieved by adjusting the longitudinal layout dimensions of the electrodes. This length range ensures that the electrostatic force adjustment range covers the tuning requirements of the resonant frequency.

[0114] Specifically, when a tuning voltage is applied to the fixed comb electrode, the movable comb electrode is displaced by the electrostatic force. The displacement is determined by the combined parameters of the electrode spacing and the overlap length. A smaller electrode spacing enhances the electrostatic force per unit voltage, while a larger overlap length expands the linear adjustment range of the electrode displacement. By controlling the proportional relationship between spacing and overlap length, the resonant frequency can be precisely adjusted without increasing the driving voltage, thereby compensating for frequency mismatches caused by machining errors.

[0115] Compared to existing technologies, conventional tuning electrodes often use a uniformly distributed comb-teeth structure, where the spacing and overlap lengths are not designed in concert with frequency tuning requirements, resulting in limited tuning sensitivity and linear range. This solution, by limiting the spacing and overlap lengths to specific numerical ranges, creates a nonlinear coupling relationship between the electrostatic force and displacement, achieving a wider frequency tuning range under the same process conditions.

[0116] Through the above technical solution, this application effectively solves the resonator frequency mismatch problem caused by machining errors, allowing the natural frequencies of the two resonant sensing units to quickly converge to a synchronized state. This design significantly improves the sensitivity and linearity of frequency tuning while ensuring a safe electrode spacing, thereby expanding the synchronization bandwidth and suppressing sensitivity degradation.

[0117] Example 9 The present application further proposes that the resonant tuning forks are arranged in the same direction, and when subjected to external acceleration, the frequencies of the resonant tuning forks will increase or decrease simultaneously.

[0118] The unidirectional arrangement means that the vibration directions of the two resonant tuning forks are configured to be consistent, which can be achieved by adopting a symmetrical structural design or the same material orientation, so that the strain direction caused by acceleration produces a synergistic effect in the tuning fork structure.

[0119] The simultaneous increase or decrease in frequency means that when acceleration is applied, the resonant frequencies of the two tuning forks change in the same direction. This is achieved by transmitting the inertial force and amplifying the strain through a lever mechanism, so that the stiffness of the tuning forks changes in the same direction, thereby avoiding synchronous instability caused by frequency response differences.

[0120] Specifically, when an external acceleration acts on the mass, the lever mechanism converts the inertial force into axial strain in the resonant sensitive beam. Because the resonant tuning forks are arranged in the same direction, the strain caused by acceleration remains consistent in both sets of tuning forks, resulting in the same change in stiffness for both sets. At this point, the resonant frequency increases or decreases synchronously with the direction of acceleration. This consistency eliminates the need to compensate for frequency differences in the signal processing of the mutually injected synchronization circuit, enabling bidirectional coupling via an adder, thereby simplifying the synchronization control logic.

[0121] In some embodiments, the co-directional arrangement can be achieved by aligning the sensitive beams of the two sets of resonant tuning forks parallel to the same axis, or by adjusting the connection direction between the mass block and the lever mechanism to ensure consistent strain transmission. Furthermore, the tuning module can further coordinate the stiffness variation range of the tuning forks by applying bias voltages of the same polarity.

[0122] Compared to existing technologies, the resonant tuning forks in existing accelerometers often use out-of-phase arrangements or independent response designs, resulting in opposite or random frequency changes under acceleration. This requires additional circuitry to compensate for frequency differences and increases signal processing complexity. This solution, however, uses a co-directional arrangement to align frequency changes. This not only reduces the impact of machining errors on frequency matching, but also expands the synchronization bandwidth and enhances system stability under dynamic acceleration.

[0123] Through the above technical solution, the present application solves the frequency response mismatch problem of the resonant tuning fork caused by processing errors or acceleration direction, ensures the coordination of frequency changes through unidirectional arrangement, reduces the need for compensation of frequency differences by the synchronization circuit, thereby improving the synchronization bandwidth and sensitivity stability, and avoiding sensitivity attenuation.

[0124] Example 10 The present application further proposes a coupled and synchronized MEMS resonant accelerometer in which the structures of the two resonant sensing units are bilaterally symmetrical along the Y-axis, and the second accelerometer is obtained by translating the first accelerometer downward along the X-axis.

[0125] Among them, the left-right symmetry of the Y-axis means that the two resonant sensing units form a geometrically symmetrical layout with the Y-axis as the mirror symmetry axis. Specifically, the silicon-based micromachining process can be used to achieve a symmetrical design of the photolithography mask, and the symmetrical layout can reduce the impact of processing errors on the resonant frequency matching.

[0126] The downward translation of the X-axis refers to the vertical movement of the overall structure of the second accelerometer relative to the first accelerometer along the X-axis by a certain distance. This can be achieved by adjusting the position offset of the mask pattern. The spatial staggered arrangement avoids mechanical coupling interference and optimizes the density of the sensitive structure.

[0127] Specifically, the two resonant sensing units form a symmetrical structure in the Y-axis direction, so that the dimensional deviations generated during the processing show complementary characteristics under the symmetrical layout. For example, the positive deviation of the beam width of the left unit can offset the negative deviation of the beam width of the right unit, thereby reducing the probability of natural frequency mismatch. After the second accelerometer is translated along the X-axis, the two sensing units form a non-overlapping arrangement in the plane space, avoiding the intersection of mechanical vibration transmission paths, and providing independent signal transmission channels for the mutual injection circuit. When acceleration is applied, the symmetrical structure causes the stress distribution of the two resonant tuning forks to show regular changes, and the translational arrangement ensures the spatial isolation of the detection signal, and ultimately achieves bidirectional synchronization through mutual injection of electrical signals while maintaining sensitivity without attenuation.

[0128] Compared to existing technologies, traditional resonant accelerometers employ densely arranged structures in the same plane, which can easily lead to frequency mismatch and mechanical crosstalk due to manufacturing errors. This solution compensates for these process variations through a Y-axis symmetrical structure, aligning the natural frequencies of the two resonant units. The X-axis translational arrangement eliminates mechanical coupling paths, creating an independent operating environment for mutual electrical signal injection, thereby expanding synchronization bandwidth and improving system stability.

[0129] Through the above technical solution, the present application solves the frequency mismatch problem caused by processing errors, reduces mechanical interference in the synchronous state, enables the mutual injection coupling synchronization to be stably maintained in a wider acceleration range, and ultimately achieves high-precision acceleration measurement.

[0130] In summary, the present invention proposes a coupled-synchronized MEMS resonant accelerometer that addresses the core conflict between frequency mismatch and sensitivity degradation through a bidirectional mutual injection synchronization circuit. Comb tuning achieves matching of sensor sensitivity to frequency. This overall solution will further enhance the comprehensive performance of MEMS accelerometers, meeting the demands of cutting-edge fields such as aerospace and microgravity measurement.

[0131] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A MEMS resonant accelerometer based on coupling synchronization, characterized in that: It includes two resonant sensing units with the same structure, each resonant sensing unit is configured with an independent oscillation circuit and a mutual injection synchronization circuit; The oscillation circuit includes a first oscillation circuit and a second oscillation circuit, which are used to drive the corresponding resonant tuning fork to self-oscillate near its resonant frequency and output an oscillation signal; The mutual injection synchronization circuit includes: A first signal processing branch connected to the output end of the first oscillation circuit; a second signal processing branch connected to the output end of the second oscillation circuit; A first adder (7-12), a first input end of which is connected to the output of the signal processing branch of the second oscillation circuit, and an output end of which is connected to the feedback input end of the first oscillation circuit; A second adder (7-13), a first input end of which is connected to the output of the signal processing branch of the first oscillation loop, and an output end of which is connected to the feedback input end of the second oscillation loop; By applying independent tuning bias voltages, the natural frequencies and sensitivities of the two resonant sensing units are matched; the oscillation signals output by the first oscillation circuit and the second oscillation circuit are processed by corresponding signal processing branches respectively, and then injected into each other's oscillation circuits through a first adder (7-12) and a second adder (7-13), thereby achieving 1:1 bidirectional electrical signal mutual injection coupling synchronization; after synchronization, the frequency offset of the system is output as an acceleration measurement, and there is no sensitivity attenuation in the synchronized state.

2. The MEMS resonant accelerometer based on coupling synchronization according to claim 1, characterized in that: The resonant sensing unit includes: Mass (5-1); and a supporting structure for suspending and supporting the mass block (5-1); A resonant tuning fork comprising a resonant sensitive beam (1-1) and a corresponding first fixed anchor point (1-2); A lever mechanism module, connecting the mass block (5-1) and the resonant sensitive beam (1-1), for transmitting inertial force and amplifying strain; The first tuning module and the second tuning module are respectively arranged on the upper side and the lower side of the mass block (5-1); each tuning module comprises at least one pair of variable-pitch comb-tooth capacitors consisting of a fixed comb-tooth electrode (6-1) and a movable comb-tooth electrode (6-2) connected to the mass block; and the oscillation frequency and sensitivity of the two resonant tuning forks are adjusted by loading a tuning voltage.

3. The MEMS resonant accelerometer based on coupling synchronization according to claim 2, characterized in that: Each tuning module comprises two groups of variable-spacing comb-tooth capacitors, which are respectively arranged on the left and right sides of the corresponding mass block (5-1); when the first tuning module is loaded with a bias voltage, a downward electrostatic force is generated to cause the mass block (5-1) to move downward; When the second tuning module is loaded with a bias voltage, an upward electrostatic force is generated to cause the mass block (5-1) to move upward; The magnitude of the tuning bias voltage determines the resonant frequency and sensor sensitivity of the corresponding resonant sensing unit.

4. The MEMS resonant accelerometer based on coupling synchronization according to claim 2, characterized in that: The lever mechanism module comprises a force input beam (4-1), a lever beam (4-3) and a support beam (4-4); one end of the lever beam (4-3) is connected to the mass block (5-1), and the other end is connected to the resonant sensitive beam (1-1) through the force input beam (4-1); the support beam (4-4) is anchored to a base and provides a lever fulcrum.

5. The MEMS resonant accelerometer based on coupling synchronization according to claim 1, characterized in that: The resonant sensing unit also includes: An excitation module comprises an excitation anchor point (2-1), an excitation electrode plate (2-3) and a second metal electrode layer (2-2), wherein the excitation electrode plate (2-3) and a first electrode plate (1-5) arranged on one side of the resonant sensitive beam (1-1) form a driving capacitor, with a gap of 2 to 5 μm; The detection module comprises a detection anchor point (3-1), a detection electrode plate (3-3) and a third metal electrode layer (3-2); the detection electrode plate (3-3) and a second electrode plate (1-6) arranged on the other side of the resonant sensitive beam (1-1) form a detection capacitor, with a gap of 2-5 μm.

6. The MEMS resonant accelerometer based on coupling synchronization according to claim 2, characterized in that: The resonant sensitive beam (1-1) has a beam length of 300-1000 μm, a beam width of 3-10 μm, and a beam thickness of 40-60 μm.

7. The MEMS resonant accelerometer based on coupling synchronization according to claim 2, characterized in that: The length of a single comb-tooth electrode in the tuning module is 500-2000 μm, and the width is 5-10 μm.

8. The MEMS resonant accelerometer based on coupling synchronization according to claim 2, characterized in that: The spacing between the fixed comb-tooth electrode (6-1) and the movable comb-tooth electrode (6-2) is 10-40 μm, and the overlapping length is 100-500 μm.

9. The MEMS resonant accelerometer based on coupling synchronization according to claim 2, characterized in that: The resonant tuning forks are arranged in the same direction. When subjected to external acceleration, the frequencies of the resonant tuning forks will increase or decrease at the same time.

10. The MEMS resonant accelerometer based on coupling synchronization according to claim 1, characterized in that: The structures of the two resonant sensing units are bilaterally symmetrical along the Y axis, and the second accelerometer is obtained by translating the first accelerometer downward along the X axis.

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