A two-stage phononic crystal-based multi-output MEMS resonator and its frequency modulation method and system

Abstract

A two-stage phononic crystal-based multi-output MEMS resonator and its frequency modulation method and system, the multi-output MEMS resonator comprising a resonant structure body supported by a fixed anchor point and its functional accessory structure; the MEMS resonator reduces the anchor loss of modes in different frequency bands through two-stage phononic crystals, thereby achieving multi-frequency output with high frequency stability; the frequency modulation method and system utilize an integrated temperature measurement beam, an integrated joule heat heating beam and a suspended uniform heating frame, combined with a constant temperature control circuit, to achieve high-precision, low-cost, low-power and low-thermal hysteresis frequency modulation and constant temperature control.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of micro-electro-mechanical system, and particularly relates to a multi-output MEMS resonator based on two-stage phononic crystals and a frequency modulation method and system thereof. BACKGROUND

[0002] Clock is the heart of electronic system, which provides clock signal and reference frequency signal for electronic system, and determines the upper limit of performance of electronic system. Quartz oscillator has been widely used in various occasions requiring high-precision clock reference due to its excellent temperature frequency stability. With the development of technology, electronic system puts forward more and more strict requirements on the volume, power consumption and impact resistance of each subsystem, and in this background, MEMS oscillator emerges as the times require. Compared with quartz oscillator, MEMS oscillator manufactured by using semiconductor processing technology has higher integration, lower cost and lower power consumption, and has extremely high market value.

[0003] At present, in clock application occasions, frequency multiplication module is often used to up-convert the output frequency of MEMS oscillator to provide high-frequency clock signal, which will affect the stability of the output frequency. In order to adapt to the application demand of multi-band in future wireless communication system, it is urgent to make MEMS oscillator have the ability to output high-frequency and low-frequency signals at the same time. These application requirements increase the complexity and cost of the system.

[0004] For this, the patent application named "Frequency adjustable MEMS resonator" (CN103338022A) realizes the adjustment of resonant frequency by controlling the number, position and shape and size of the excitation electrode structure. In fact, continuous geometric entities all have infinite vibration modes, and according to the mode shape, the arrangement of excitation electrode can be matched, that is, the multi-frequency output function in the above patent application embodiment can be realized, which is a basic common sense, and researchers often do so. However, how to make the high-order mode with large dynamic impedance produce stable vibration through structure design is a systematic scientific problem, which cannot be realized by simple electrode matching, but needs to be realized by reasonably optimizing the resonant structure and reducing the energy loss of each mode.

[0005] The size of the quality factor is the key factor whether the high-order mode with high motion impedance can stabilize the vibration, and the quality factor also determines the output frequency stability of different order modes. The current mainstream quality factor improvement schemes include: optimizing the resonator structure and optimizing the resonator anchor structure. However, the existing literature ([1] Zhang Y, Bao J-F, Zhou X, et al. A 10MHz thin-film piezoelectric-on-silicon MEMS resonator with T-shaped tethers for Q enhancement [J]. Japanese Journal of Applied Physics, 2020, 59(1); [2] Hsu F-C, Hsu J-C, Huang T-C, et al. Design of lossless anchors for microacoustic-wave resonators utilizing phononic crystal strips [J]. Applied Physics Letters, 2011, 98(14).) can only improve the quality factor of a certain mode, cannot be compatible with multiple frequency band resonant working modes, and cannot realize the common improvement of multiple vibration mode quality factors, therefore, cannot be applied to occasions with multi-band application requirements; and at the same time of changing the resonator and its anchor structure, it is inevitable to affect the vibration frequency of the resonator itself, which introduces new difficulties for the resonator structure design.

[0006] Another key technology of MEMS resonator is the temperature compensation of the oscillator. Single crystal silicon has a larger temperature frequency coefficient (25ppm / ℃ to 60ppm / ℃) compared to quartz crystal. How to maintain the stable frequency output of MEMS resonator in a variable temperature environment is a key technical problem in the field of MEMS resonator technology. Active constant temperature control technology is expected to maintain the frequency stability of MEMS resonator at the ppb level, so it has been widely studied. Existing constant temperature control schemes ([3] Yang D, Woo J-K, Lee S, et al. A Micro Oven-Control System for Inertial Sensors [J]. Journal of Microelectromechanical Systems, 2017, 26(3): 507-518; [4] Fang Z, Yin Y, He X, et al. Temperature-drift characterization of a micromachined resonant accelerometer with a low-noise frequency readout [J]. Sensors and Actuators a-Physical, 2019, 300.) usually take discrete temperature measuring platinum resistance to read the temperature of MEMS resonator, and use discrete heating elements to control the temperature of MEMS resonator at a constant value, thereby realizing constant temperature control. However, this scheme has large thermal hysteresis, low control precision and high power consumption. In recent years, on-chip constant temperature control has attracted widespread attention. This constant temperature control scheme ([5] Xiao Y, Han J, Zhu K, et al. A Micro-Oven Controlled Dual-Mode Piezoelectric MEMS Resonator With ±190ppb Stability Over-40 to 105℃ Temperature Range [J]. IEEE Electron Device Letters, 2023, 44(8): 1340-1343; [6] Jia W, Chen W, Xiao Y, et al. A Micro-Oven-Controlled Dual-Mode Piezoelectric MEMS Resonator With + / -400PPB Stability Over-40 to 80 degrees C Temperature Range [J].Ieee Transactionson Electron Devices,2022,69(5):2597-2603.) utilizes the frequency offset of the MEMS resonator as a control signal to achieve high-precision, low-power, and low-thermal hysteresis constant temperature control by adjusting the heating resistor integrated in the MEMS resonator structure layer; the patent application entitled "MEMS oscillator" (CN 116545382A) also proposes the same constant temperature control scheme for controlling the frequency drift of the MEMS oscillator; however, the technical route of this scheme is complex, and a special high-frequency signal reading circuit needs to be designed, which poses a challenge to the development of on-chip constant temperature control technology, and the temperature stability of the built-in crystal oscillator in the frequency reading circuit in the variable temperature working environment also greatly limits the compensation accuracy of the MEMS resonator. SUMMARY

[0007] In view of the above-mentioned shortcomings in the prior art, the purpose of the present application is to provide a two-stage phononic crystal-based multi-output MEMS resonator and a frequency modulation method and system thereof. The MEMS resonator reduces the anchor loss of different frequency bands through two-stage phononic crystals, thereby achieving high-frequency stability and dual-frequency output. The integrated temperature measurement flexible support beam, integrated Joule heat heating flexible support beam, and suspended uniform heating frame, combined with a constant temperature control circuit, can achieve high-precision, low-cost, low-power, and low-thermal hysteresis frequency modulation and constant temperature control.

[0008] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0009] A two-stage phononic crystal-based multi-output MEMS resonator, comprising a MEMS resonator structure body 1 and its functional accessory structure supported by a first fixed support anchor 5-1, a second fixed support anchor 5-2, a third fixed support anchor 5-3, a fourth fixed support anchor 5-4, a fifth fixed support anchor 5-5, a sixth fixed support anchor 5-6, a seventh fixed support anchor 5-7, and an eighth fixed support anchor 5-8. The structure form of the MEMS resonator structure body 1 is one of a disc type, a ring type, a thin film type, or a beam type.

[0010] The functional accessory structure includes: a first-stage phononic crystal A2-1 connected with the MEMS resonator structure body 1, a first-stage phononic crystal B2-2, a first-stage phononic crystal C2-3, a first-stage phononic crystal D2-4; the other ends of the first-stage phononic crystal A2-1, the first-stage phononic crystal B2-2, the first-stage phononic crystal C2-3, and the first-stage phononic crystal D2-4 are connected with a second-stage phononic crystal A3-1, a second-stage phononic crystal B3-2, a second-stage phononic crystal C3-3, and a second-stage phononic crystal D3-4 respectively, and the other ends of the second-stage phononic crystal A3-1, the second-stage phononic crystal B3-2, the second-stage phononic crystal C3-3, and the second-stage phononic crystal D3-4 are connected in the floating uniform heating frame 7;

[0011] The first fixed support anchor point 5-1, the second fixed support anchor point 5-2, the third fixed support anchor point 5-3, the fourth fixed support anchor point 5-4, the fifth fixed support anchor point 5-5, the sixth fixed support anchor point 5-6, the seventh fixed support anchor point 5-7, and the eighth fixed support anchor point 5-8 are connected with the flexible support beam A6-1, the flexible support beam B6-2, the flexible support beam C6-3, the flexible support beam D6-4, the flexible support beam E6-5, the flexible support beam F6-6, the flexible support beam G6-7, and the flexible support beam H6-8 respectively; wherein the flexible support beam C6-3, the flexible support beam D6-4, the flexible support beam G6-7, and the flexible support beam H6-8 are temperature measuring beams; and the flexible support beam A6-1, the flexible support beam B6-2, the flexible support beam E6-5, and the flexible support beam F6-6 are joule heat heating beams.

[0012] All the flexible support beams are connected with the floating uniform heating frame 7.

[0013] The structure form of the flexible support beam is one of a folded beam, a snake-shaped beam, or a straight beam.

[0014] The MEMS resonator body 1, the first-stage phononic crystal A2-1, the first-stage phononic crystal B2-2, the first-stage phononic crystal C2-3, the first-stage phononic crystal D2-4, the second-stage phononic crystal A3-1, the second-stage phononic crystal B3-2, the second-stage phononic crystal C3-3, and the second-stage phononic crystal D3-4 are collectively anchored in the floating uniform heating frame 7, and the floating uniform heating frame 7 is anchored on the substrate through the flexible support beam A6-1, the flexible support beam B6-2, the flexible support beam C6-3, the flexible support beam D6-4, the flexible support beam E6-5, the flexible support beam F6-6, the flexible support beam G6-7, the flexible support beam H6-8, and the first fixed support anchor point 5-1, the second fixed support anchor point 5-2, the third fixed support anchor point 5-3, the fourth fixed support anchor point 5-4, the fifth fixed support anchor point 5-5, the sixth fixed support anchor point 5-6, the seventh fixed support anchor point 5-7, and the eighth fixed support anchor point 5-8.

[0015] The MEMS resonator structure body 1, the phononic crystal, the suspended uniform heat frame 7, and the flexible support beam are all suspended on the structure substrate.

[0016] The first-level phononic crystal A2-1, the first-level phononic crystal B2-2, the first-level phononic crystal C2-3, the first-level phononic crystal D2-4, the second-level phononic crystal A3-1, the second-level phononic crystal B3-2, the second-level phononic crystal C3-3, and the second-level phononic crystal D3-4 generate different frequency bands of phononic band gaps, respectively.

[0017] The frequency range of the phononic band gap includes the resonant frequencies of different orders of the working mode of the MEMS resonator structure body 1, for reducing the vibration energy of the working mode dissipated to the substrate through the clamped anchor point, and realizing the improvement of the Q value of the working mode.

[0018] The MEMS resonator structure body 1 is provided with an excitation and detection structure outside, for exciting and detecting the resonant motion of the MEMS resonator; the excitation and detection mode is electrostatic, piezoresistive, electromagnetic or electrothermal; the excitation signal type adopts direct harmonic excitation, degenerate parameter excitation, non-degenerate parameter excitation or internal resonance excitation.

[0019] The frequency modulation method of the multi-output MEMS resonator based on the two-level phononic crystal comprises the following steps:

[0020] Step 1, the MEMS resonator is powered on and works, and the modes in different frequency bands generate stable closed-loop oscillations in the respective maintaining oscillation systems;

[0021] Step 2, according to the current change of the temperature measurement flexible support beam in the integrated temperature measurement system, the temperature change of the MEMS resonator body 1 is monitored in real time, and the temperature change quantity after analog-to-digital conversion is transmitted to the control system;

[0022] Step 3, the error current signal is calculated by the error value calculation module in the control system, and the Joule heat heating voltage required for compensating the temperature change is calculated by the PID control module using the control algorithm;

[0023] Step 4, the integrated Joule heat heating system outputs the Joule heat heating voltage, and the constant temperature of the MEMS resonator is realized by using the Joule heat effect;

[0024] Step 5, return to step 2, and repeat the above steps to maintain the constant temperature of the MEMS resonator and the stable multi-output frequency of the MEMS resonator.

[0025] The frequency modulation system for realizing the frequency modulation method of the multi-output MEMS resonator based on the two-level phononic crystal comprises:

[0026] Maintain the oscillation system: for the different frequency band within the mode is simultaneously excited to closed loop oscillation state, output multi-channel frequency different frequency signal;

[0027] Integrated temperature measurement system: for the integrated temperature measurement resistance both ends to apply constant temperature measurement voltage, and real-time monitoring temperature measurement beam temperature measurement current changes, temperature measurement current transmission to the control system;

[0028] Control system: with the above integrated temperature measurement system, the temperature measurement current into digital quantity, according to the difference between the current measurement value and the current preset value, using control algorithm to calculate the heating voltage required to compensate the difference, and the heating voltage control signal transmission to the integrated joule heat heating system;

[0029] Integrated joule heat heating system: with the above control system, for the heating voltage control signal into voltage, and joule heat voltage transmission to the integrated joule heat heating beam both ends located with the suspension frame 7 connected to the frame 7, realize the temperature control of MEMS resonator structure body 1, so as to realize the MEMS resonator structure body 1 temperature constant.

[0030] The maintain the oscillation system includes:

[0031] And the first electrode plate 4-1, the second electrode plate 4-2 connected with the first signal amplification module 8-1, the second signal amplification module 9-1, respectively for amplifying the first working mode and the second working mode of the movement signal;

[0032] And the first signal amplification module 8-1, the second signal amplification module 9-1 connected with the first band pass filter module 8-2, the second band pass filter module 9-2, respectively for filtering the first working mode and the second working mode of the movement signal in the stray signal;

[0033] And the first band pass filter module 8-2, the second band pass filter module 9-2 connected with the first phase shift module 8-3, the second phase shift module 9-3, respectively for adjusting the first working mode and the second working mode of the phase difference value in the closed loop oscillation circuit, so that the two closed loop oscillation circuit respectively meet the phase difference condition of the Barkhausen closed loop start, realize stable closed loop oscillation;

[0034] And the first phase shift module 8-3, the second phase shift module 9-3 connected with the first limiting module 8-4, the second limiting module 9-4, respectively for stabilizing the first working mode and the second working mode of the amplitude of the excitation signal in the closed loop oscillation circuit; the first limiting module 8-4 and the second limiting module 9-4 are reserved with signal output interface respectively, for outputting the vibration signal of MEMS resonator.

[0035] The number of closed loop oscillation circuit in the maintain the oscillation system is adjusted according to the number of required output frequency.

[0036] The control system comprises:

[0037] An analog / digital conversion module 10-1 is connected with the integrated temperature measurement system, and converts the temperature measurement current into a digital quantity.

[0038] An error value calculation module 10-2 is output-connected with the analog / digital conversion module 10-1, receives the temperature measurement current signal of the analog / digital conversion module 10-1, compares the temperature measurement current signal with a preset current value, and outputs an error current signal.

[0039] A PID control module 10-3 is output-connected with the error value calculation module 10-2, and is used for executing a temperature control program, and outputs a corresponding Joule heat voltage control signal according to the error current signal.

[0040] A heating voltage control module 10-4 is output-connected with the PID control module 10-3, and the heating voltage control module 10-4 is connected with the integrated Joule heat heating system, and is used for transmitting the Joule heat voltage control signal generated by the PID control module 10-3 to the integrated Joule heat heating system, so as to control the heating power of the Joule heat heating beam, and realize the temperature constant of the MEMS resonator.

[0041] The integrated Joule heat heating system comprises:

[0042] A first digital / analog conversion module 11-1 and a second digital / analog conversion module 11-2 are connected with the heating voltage control module of the control system, and are used for the Joule heat voltage control signal, and real-time adjust the heating power of the Joule heat heating beam.

[0043] A Joule heat heating beam (flexible support beam A 6-1, flexible support beam B 6-2, flexible support beam E 6-5, flexible support beam F 6-6) is used for executing a heating instruction, and transmitting heat to the suspended uniform heating frame 7 through four connecting rods connected with the suspended uniform heating frame 7.

[0044] The suspended uniform heating frame 7 is connected with the Joule heat heating beam, generates uniform temperature change under the action of the heat generated by the Joule heat heating beam, and transmits the heat to the MEMS resonator structure body 1 through four transmission paths through four groups of series phononic crystals, so as to ensure the uniformity of the temperature distribution of the MEMS resonator structure body 1, and make the MEMS resonator structure body 1 maintain stable oscillation under the action of the Joule heat system.

[0045] Compared with the prior art, the present application has the following beneficial effects:

[0046] The MEMS resonator of the application adopts a two-stage phononic crystal structure, can simultaneously generate phonon band gaps corresponding to multiple modal resonance frequencies, and has the innovative points and advantages of simultaneously improving the frequency stability of multiple frequency point outputs.

[0047] The MEMS resonator of the application adopts a suspended uniform heating frame to anchor the MEMS resonator and the phononic crystal connected thereto on a flexible support beam, can uniformly transmit the temperature of the MEMS resonator to the temperature measuring point and uniformly transmit the heating power to the MEMS resonator on the premise of ensuring effective support, has the innovative points and advantages of accurate temperature reading and rapid compensation.

[0048] The heating structure of the MEMS resonator of the application adopts the structure form of a flexible support beam, can realize further suppression of energy transmission on the premise of realizing high-efficiency heating power output, has the innovative points and advantages of improving heating efficiency and increasing the quality factor of the MEMS resonator.

[0049] In summary, the application provides a two-stage phononic crystal-based multi-output MEMS resonator and a frequency modulation method and system thereof, through the structure form of double-stage series connection of the phononic crystal, the anchor loss of the vibration mode in different frequency bands is simultaneously reduced on the basis of not affecting the resonance frequency of the MEMS resonator, the short-time frequency stability of the vibration mode is improved, and high-stability multi-oscillation frequency output is realized; at the same time, in order to realize temperature compensation of the MEMS resonator, the application proposes a miniaturized, high-precision and low-power frequency modulation method and system of an integrated temperature measuring beam and an integrated Joule heat heating beam, which reduces the thermal hysteresis of the traditional constant temperature control method, does not need to additionally design a high-precision frequency reading circuit, and does not introduce additional frequency reading error, thereby improving the accuracy of constant temperature control; in addition, the frequency modulation method and system improve the temperature uniformity of the MEMS resonator through the structural design of the suspended uniform heating frame, ensure the accuracy of temperature measurement, and improve the temperature stability of the output frequency of the MEMS resonator. Ultimately, the overall performance of the MEMS resonator is greatly improved through the above three aspects. The application provides a new idea for the design of high-performance MEMS oscillators, can be easily integrated into various sensing and timing systems, and has extremely high theoretical and engineering application value. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a basic structure schematic diagram of a two-stage phononic crystal-based multi-output MEMS resonator of the application.

[0051] Figure 2 It is a structure schematic diagram of an embodiment MEMS resonator of the application.

[0052] Figure 3 It is a structure schematic diagram of an embodiment phononic crystal of the application, wherein (a) is an elevation view, and (b) is a three-dimensional view.

[0053] Figure 4 The schematic diagram of phononic band gap of two-stage phononic crystal calculated by finite element simulation for the embodiment of the present application, wherein (a) is the first phononic band gap (corresponding to the second order lame mode), the second phononic band gap (corresponding to the breathing mode), and the third phononic band gap (corresponding to the fifth order lame mode) generated by the first stage phononic crystal; (b) is the fourth phononic band gap (corresponding to the fourth order lame mode) and the fifth phononic band gap (corresponding to the eighth order lame mode) generated by the second stage phononic crystal.

[0054] Figure 5 The vibration modes of five different frequency bands for the embodiment of the present application, wherein (a) is the second order lame mode with a design frequency of about 5MHz; (b) is the breathing mode with a design frequency of about 7.4MHz; (c) is the fifth order lame mode with a design frequency of about 13MHz, (d) is the fourth order lame mode with a design frequency of about 10MHz, and (e) is the eighth order lame mode with a design frequency of about 20MHz.

[0055] Figure 6 The flow chart of the frequency regulation method for the embodiment of the present application.

[0056] Figure 7 The logic framework schematic diagram of the frequency regulation system for the embodiment of the present application.

[0057] In the figure: 1. MEMS resonator structure body; 2-1. First-stage phononic crystal A; 2-2. First-stage phononic crystal B; 2-3. First-stage phononic crystal C; 2-4. First-stage phononic crystal D; 3-1. Second-stage phononic crystal A; 3-2. Second-stage phononic crystal B; 3-3. Second-stage phononic crystal C; 3-4. Second-stage phononic crystal D; 4-1. First electrode plate; 4-2. Second electrode plate; 4-3. Third electrode plate; 4-4. Fourth electrode plate; 4-5. Fifth electrode plate; 4-6. Sixth electrode plate; 4-7. Seventh electrode plate; 4-8. Eighth electrode plate; 4-9. Ninth electrode plate; 4-10. Tenth electrode plate; 4-11. Eleventh electrode plate; 4-12. Twelfth electrode plate; 5-1. First fixed support anchor point; 5-2. Second fixed support anchor point; 5-3. Third fixed support anchor point; 5-4. Fourth fixed support anchor point; 5-5. Fifth fixed support anchor point; 5-6. Sixth fixed support anchor point; 5-7. Seventh fixed support anchor point; 5-8. Eighth fixed support anchor point; 6-1. Flexible support beam A; 6-2. Flexible support beam B; 6-3. Flexible support beam C; 6-4. Flexible support beam D; 6-5. Flexible support beam E; 6-6. Flexible support beam F; 6-7. Flexible support beam G; 6-8. Flexible support beam H; 7. Suspended uniform heating frame; 8-1. First signal amplification module; 8-2. First band-pass filter module; 8-3. First phase shift module; 8-4. First limiting module; 9-1. Second signal amplification module; 9-2. Second band-pass filter module; 9-3. Second phase shift module; 9-4. Second limiting module; 10-1. Analog / digital conversion module; 10-2. Error value calculation module; 10-3. PID control module; 10-4. Heating voltage control module; 11-1. First digital / analog conversion module; 11-2. Second digital / analog conversion module. DETAILED DESCRIPTION

[0058] The application will be described in detail below with reference to the embodiments and the accompanying drawings.

[0059] Reference Figure 1 A multi-output MEMS resonator based on two-stage phononic crystals, comprising a MEMS resonator structure body 1 and its functional accessory structures supported by a first fixed support anchor point 5-1, a second fixed support anchor point 5-2, a third fixed support anchor point 5-3, a fourth fixed support anchor point 5-4, a fifth fixed support anchor point 5-5, a sixth fixed support anchor point 5-6, a seventh fixed support anchor point 5-7, and an eighth fixed support anchor point 5-8.

[0060] The structure of the MEMS resonator structure body 1 is one of a disc type, a ring type, a thin film type, or a beam type.

[0061] The functional accessory structure includes: a first-stage phononic crystal A2-1 connected with the MEMS resonant structure body 1, a first-stage phononic crystal B2-2, a first-stage phononic crystal C2-3, a first-stage phononic crystal D2-4; the other end of the first-stage phononic crystal A2-1, the first-stage phononic crystal B2-2, the first-stage phononic crystal C2-3, and the first-stage phononic crystal D2-4 is connected with a second-stage phononic crystal A3-1, a second-stage phononic crystal B3-2, a second-stage phononic crystal C3-3, and a second-stage phononic crystal D3-4 respectively, and the other end of the second-stage phononic crystal A3-1, the second-stage phononic crystal B3-2, the second-stage phononic crystal C3-3, and the second-stage phononic crystal D3-4 is connected in the suspended uniform heating frame 7;

[0062] The first fixed support anchor point 5-1, the second fixed support anchor point 5-2, the third fixed support anchor point 5-3, the fourth fixed support anchor point 5-4, the fifth fixed support anchor point 5-5, the sixth fixed support anchor point 5-6, the seventh fixed support anchor point 5-7, and the eighth fixed support anchor point 5-8 are connected with the flexible support beam A6-1, the flexible support beam B6-2, the flexible support beam C6-3, the flexible support beam D6-4, the flexible support beam E6-5, the flexible support beam F6-6, the flexible support beam G6-7, and the flexible support beam H6-8 respectively; wherein the flexible support beam C6-3, the flexible support beam D6-4, the flexible support beam G6-7, and the flexible support beam H6-8 are temperature measuring beams, which are used to generate a current reflecting the temperature change of the MEMS resonator under the action of a constant voltage through the resistance temperature dependence of single crystal silicon, so as to determine the direction and size of the temperature change of the MEMS resonator; the flexible support beam A6-1, the flexible support beam B6-2, the flexible support beam E6-5, and the flexible support beam F6-6 are joule heat heating beams, which are used to generate heat through the joule heat effect under the action of a heating voltage, so as to maintain the temperature of the MEMS resonator body 1 constant;

[0063] All the flexible support beams and the suspended uniform heating frame 7 are connected, which is used to uniformly transmit the heat generated by the joule heat heating beams to the MEMS resonator structure body 1, and improve the frequency stability of the MEMS resonator.

[0064] The MEMS resonator structure body 1 and the first-level phononic crystal A2-1, the first-level phononic crystal B2-2, the first-level phononic crystal C2-3, the first-level phononic crystal D2-4, and the second-level phononic crystal A3-1, the second-level phononic crystal B3-2, the second-level phononic crystal C3-3, and the second-level phononic crystal D3-4 are anchored in the suspended uniform heat frame 7, and the suspended uniform heat frame 7 is anchored on the substrate through the flexible support beam A6-1, the flexible support beam B6-2, the flexible support beam C6-3, the flexible support beam D6-4, the flexible support beam E6-5, the flexible support beam F6-6, the flexible support beam G6-7, the flexible support beam H6-8, and the first fixed support anchor 5-1, the second fixed support anchor 5-2, the third fixed support anchor 5-3, the fourth fixed support anchor 5-4, the fifth fixed support anchor 5-5, the sixth fixed support anchor 5-6, the seventh fixed support anchor 5-7, and the eighth fixed support anchor 5-8.

[0065] The flexible support beam has one of a folded beam, a serpentine beam, or a straight beam; the MEMS resonator structure body 1, the phononic crystal, the suspended uniform heat frame 7, and the flexible support beam are all suspended on the structural substrate.

[0066] The first-level phononic crystal A2-1, the first-level phononic crystal B2-2, the first-level phononic crystal C2-3, the first-level phononic crystal D2-4, and the second-level phononic crystal A3-1, the second-level phononic crystal B3-2, the second-level phononic crystal C3-3, and the second-level phononic crystal D3-4 generate different frequency bands of phononic band gaps, respectively.

[0067] The frequency range of the phononic band gap includes the resonant frequencies of different order working modes of the MEMS resonator structure body 1, for reducing the vibration energy of the working mode dissipated to the substrate through the fixed support anchor, and achieving the improvement of the working mode Q value.

[0068] The excitation and detection method of the multi-output MEMS resonator based on the two-level phononic crystal includes electrostatic, piezoresistive, electromagnetic, or electrothermal.

[0069] The MEMS resonator structure body 1 is provided with an excitation and detection structure on the outside, for exciting and detecting the resonant motion of the MEMS resonator; the excitation signal type adopts direct harmonic excitation, degenerate parameter excitation, non-degenerate parameter excitation, or internal resonance excitation.

[0070] Reference Figure 2The embodiment is a multi-output MEMS resonator based on two-stage phononic crystals, comprising: a disc-shaped MEMS resonator structure body 1, a first-stage phononic crystal A 2-1, a first-stage phononic crystal B 2-2, a first-stage phononic crystal C 2-3, a first-stage phononic crystal D 2-4, a second-stage phononic crystal A 3-1, a second-stage phononic crystal B 3-2, a second-stage phononic crystal C 3-3, a second-stage phononic crystal D 3-4, a flexible support beam A 6-1 in the form of a folded beam, a flexible support beam B 6-2, a flexible support beam C 6-3, a flexible support beam D 6-4, a flexible support beam E 6-5, a flexible support beam F 6-6, a flexible support beam G 6-7, a flexible support beam H 6-8, and a square-shaped suspended uniform heating frame 7 placed at 45°; the disc-shaped MEMS resonator structure body 1 is provided with a first electrode plate 4-1, a second electrode plate 4-2, a third electrode plate 4-3, a fourth electrode plate 4-4, a fifth electrode plate 4-5, a sixth electrode plate 4-6, a seventh electrode plate 4-7, an eighth electrode plate 4-8, a ninth electrode plate 4-9, a tenth electrode plate 4-10, an eleventh electrode plate 4-11, and a twelfth electrode plate 4-12, which form capacitors with the MEMS resonator structure body 1 and excite and detect the resonant motion of the MEMS resonator.

[0071] Referring to Figure 3 The structure of the phononic crystal in the embodiment is as follows: in a square with a horizontal D+2R and a vertical W+2R, four quarter circles are removed from four corners as the centers and with R as the radius, as shown in (a) of the drawings; for the first-stage phononic crystal: D is equal to 90 microns, R is equal to 70 microns, and W is equal to 8 microns; for the second-stage phononic crystal: D is equal to 120 microns, R is equal to 110 microns, and W is equal to 8 microns. Figure 3

[0072] Referring to Figure 4 The first-stage phononic crystal A 2-1, the first-stage phononic crystal B 2-2, the first-stage phononic crystal C 2-3, the first-stage phononic crystal D 2-4, the second-stage phononic crystal A 3-1, the second-stage phononic crystal B 3-2, the second-stage phononic crystal C 3-3, and the second-stage phononic crystal D 3-4 respectively generate different frequency bands of phononic band gaps, wherein the first-stage phononic crystal A 2-1, the first-stage phononic crystal B 2-2, the first-stage phononic crystal C 2-3, and the first-stage phononic crystal D 2-4 generate a first phononic band gap (corresponding to a second-order lame mode), a second phononic band gap (corresponding to a breathing mode), and a third phononic band gap (corresponding to a fifth-order lame mode); the second-stage phononic crystal A 3-1, the second-stage phononic crystal B 3-2, the second-stage phononic crystal C 3-3, and the second-stage phononic crystal D 3-4 generate a fourth phononic band gap (corresponding to a fourth-order lame mode) and a fifth phononic band gap (corresponding to an eighth-order lame mode), respectively reduce the anchoring loss of the corresponding mode vibration energy, and realize the improvement of the output frequency stability.​

[0073] Referring to Figure 5 The MEMS resonator in the embodiment works in modes of multiple different base frequencies simultaneously, which are respectively: a second-order lame mode with a design frequency of about 5MHz, a breathing mode with a design frequency of about 7.4MHz, a fifth-order lame mode with a design frequency of about 13MHz, a fourth-order lame mode with a design frequency of about 10MHz, and an eighth-order lame mode with a design frequency of about 20MHz. The vibration frequencies of the modes are located in the phonon band gap generated by the two-level phononic crystal.

[0074] Referring to Figure 6 A frequency modulation method of a multi-output MEMS resonator based on a two-level phononic crystal, comprising the following steps:

[0075] Step 1: power on the MEMS resonator to work, and the modes in different frequency bands are respectively in a stable closed-loop oscillation in the respective maintained oscillation system;

[0076] Step 2: according to the current change of the temperature measuring beam in the integrated temperature measuring system, the temperature change of the MEMS resonator structure body 1 is monitored in real time, and the temperature change after analog-to-digital conversion is transmitted to the control system;

[0077] Step 3: the error current signal is calculated by the error value calculation module in the control system, and the joule heat heating voltage required for compensating the temperature change is calculated by the PID control module using a control algorithm;

[0078] Step 4: the integrated joule heat heating system outputs the joule heat heating voltage, and the temperature of the MEMS resonator is kept constant by using the joule heat effect;

[0079] Step 5: return to step 2, and repeat the above steps to maintain the constant temperature of the MEMS resonator and the stable multi-output frequency of the MEMS resonator.

[0080] A frequency modulation system for implementing the frequency modulation method of the multi-output MEMS resonator based on the two-level phononic crystal, comprising:

[0081] The maintained oscillation system is used for simultaneously exciting the modes in different frequency bands to a closed-loop oscillation state, and outputting frequency signals with different frequencies;

[0082] The integrated temperature measuring system is used for applying a constant temperature measuring voltage across the integrated temperature measuring resistor, and monitoring the temperature measuring current change of the temperature measuring beam in real time, and transmitting the temperature measuring current to the control system;

[0083] Control system: connected with the above-mentioned integrated temperature measurement system, converts the temperature measurement current into digital quantity, calculates the heating voltage required for compensating the difference value according to the difference value between the current measurement value and the preset current value, and transmits the heating voltage control signal to the integrated Joule heat heating system;

[0084] Integrated Joule heat heating system: connected with the above-mentioned control system, used for converting the heating voltage control signal into voltage, and transmitting the Joule heat voltage to the two ends of the integrated Joule heat heating beam connected with the suspended uniform heating frame 7, realizing the temperature control of the MEMS resonator structure body 1, so as to realize the constant temperature of the MEMS resonator structure body 1.

[0085] Selecting two reference signals with output frequencies of 5MHz and 10MHz respectively, Figure 7 The maintenance oscillation system for realizing double frequency output includes:

[0086] The first signal amplification module 8-1 and the second signal amplification module 9-1 connected with the first electrode plate 4-1 and the second electrode plate 4-2 are respectively used for amplifying the motion signals of the first working mode (second order lame mode) and the second working mode (fourth order lame mode), facilitating the subsequent signal processing;

[0087] The first band-pass filter module 8-2 and the second band-pass filter module 9-2 connected with the first signal amplification module 8-1 and the second signal amplification module 9-1 are respectively used for filtering out the stray signals in the motion signals of the first working mode (second order lame mode) and the second working mode (fourth order lame mode);

[0088] The first phase shift module 8-3 and the second phase shift module 9-3 connected with the first band-pass filter module 8-2 and the second band-pass filter module 9-2 are respectively used for adjusting the phase difference value in the closed loop oscillation circuit of the first working mode (second order lame mode) and the second working mode (fourth order lame mode), so that the two closed loop oscillation circuits respectively meet the phase difference condition of the Barkhausen closed loop starting, and realize stable closed loop oscillation.

[0089] The first limiting amplitude module 8-4 and the second limiting amplitude module 9-4 connected with the first phase shift module 8-3 and the second phase shift module 9-3 are respectively used for stabilizing the amplitude of the excitation signal in the closed loop oscillation circuit of the first working mode (second order lame mode) and the second working mode (fourth order lame mode), so as to maintain the stability of the output signal; the first limiting amplitude module 8-4 and the second limiting amplitude module 9-4 respectively reserve signal output interfaces for outputting the vibration signal of the MEMS resonator.

[0090] Referring to Figure 7 The control system includes:

[0091] Analog / digital conversion module 10-1: The analog / digital conversion module 10-1 is connected with the integrated temperature measurement system, and converts the temperature measurement current into a digital quantity;

[0092] Error value calculation module 10-2: The error value calculation module 10-2 is connected with the analog / digital conversion module 10-1, receives the temperature measurement current signal of the analog / digital conversion module 10-1, compares the temperature measurement current signal with a preset current value, and outputs an error current signal;

[0093] PID control module 10-3: The PID control module 10-3 is connected with the error value calculation module 10-2, and is used for executing a temperature control program, and outputs a corresponding Joule heat voltage control signal according to the error current signal;

[0094] Heating voltage control module 10-4: The heating voltage control module 10-4 is connected with the PID control module 10-3, and the heating voltage control module 10-4 is connected with the integrated Joule heat heating system, and is used for transmitting the Joule heat voltage control signal generated by the PID control module 10-3 to the integrated Joule heat heating system, so as to control the heating power of the Joule heat heating beam, and realize the temperature constant of the MEMS resonator.

[0095] The integrated Joule heat heating system comprises:

[0096] First digital / analog conversion module 11-1 and second digital / analog conversion module 11-2: The first digital / analog conversion module 11-1 and the second digital / analog conversion module 11-2 are connected with the heating voltage control module of the control system, and are used for the Joule heat voltage control signal, and real-time adjustment of the heating power of the Joule heat heating beam;

[0097] Joule heat heating beam (flexible support beam A6-1, flexible support beam B6-2, flexible support beam E6-5, flexible support beam F6-6): The Joule heat heating beam is used for executing a heating instruction, and transmitting heat to the suspended uniform heating frame 7 through four connecting rods connected with the suspended uniform heating frame 7;

[0098] Suspended uniform heating frame 7: The suspended uniform heating frame 7 is connected with the Joule heat heating beam, generates uniform temperature change under the action of the heat generated by the Joule heat heating beam, and transmits the heat to the MEMS resonator structure body 1 through four transmission paths through four groups of series phononic crystals, so as to ensure the uniformity of the temperature distribution of the MEMS resonator structure body 1, and enable the MEMS resonator structure body 1 to maintain stable oscillation under the action of the Joule heat system.

[0099] The above content is only for illustrating the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A two-stage phononic crystal based multi-output MEMS resonator, characterized in that: The application relates to a MEMS resonator structure body (1) and its functional accessory structure which are supported by a first fixed anchor point (5-1), a second fixed anchor point (5-2), a third fixed anchor point (5-3), a fourth fixed anchor point (5-4), a fifth fixed anchor point (5-5), a sixth fixed anchor point (5-6), a seventh fixed anchor point (5-7) and an eighth fixed anchor point (5-8); the structure form of the MEMS resonator structure body is one of a disc type, a ring type, a thin film type or a beam type; The functional accessory structure comprises a first-level phononic crystal A (2-1), a first-level phononic crystal B (2-2), a first-level phononic crystal C (2-3) and a first-level phononic crystal D (2-4) which are connected with the MEMS resonator structure body (1); the other ends of the first-level phononic crystal A (2-1), the first-level phononic crystal B (2-2), the first-level phononic crystal C (2-3) and the first-level phononic crystal D (2-4) are respectively connected with a second-level phononic crystal A (3-1), a second-level phononic crystal B (3-2), a second-level phononic crystal C (3-3) and a second-level phononic crystal D (3-4); the other ends of the second-level phononic crystal A (3-1), the second-level phononic crystal B (3-2), the second-level phononic crystal C (3-3) and the second-level phononic crystal D (3-4) are connected in a suspended uniform heating frame (7); the first fixed anchor point (5-1), the second fixed anchor point (5-2), the third fixed anchor point (5-3), the fourth fixed anchor point (5-4), the fifth fixed anchor point (5-5), the sixth fixed anchor point (5-6), the seventh fixed anchor point (5-7) and the eighth fixed anchor point (5-8) are respectively connected with a flexible support beam A (6-1), a flexible support beam B (6-2), a flexible support beam C (6-3), a flexible support beam D (6-4), a flexible support beam E (6-5), a flexible support beam F (6-6), a flexible support beam G (6-7) and a flexible support beam H (6-8); wherein the flexible support beam C (6-3), the flexible support beam D (6-4), the flexible support beam G (6-7) and the flexible support beam H (6-8) are temperature measuring beams; the flexible support beam A (6-1), the flexible support beam B (6-2), the flexible support beam E (6-5) and the flexible support beam F (6-6) are joule heat heating beams; All the flexible support beams are connected with the suspended uniform heating frame (7); the structure form of the flexible support beam is one of a folded beam, a snake-shaped beam or a straight beam. The MEMS resonator structure body (1) is anchored in the suspended uniform heat frame (7) together with the first level phononic crystal A (2-1), the first level phononic crystal B (2-2), the first level phononic crystal C (2-3), the first level phononic crystal D (2-4), and the second level phononic crystal A (3-1), the second level phononic crystal B (3-2), the second level phononic crystal C (3-3), and the second level phononic crystal D (3-4), and the suspended uniform heat frame (7) is anchored on the substrate through the flexible support beam A (6-1), the flexible support beam B (6-2), the flexible support beam C (6-3), the flexible support beam D (6-4), the flexible support beam E (6-5), the flexible support beam F (6-6), the flexible support beam G (6-7), the flexible support beam H (6-8), and the first fixed support anchor point (5-1), the second fixed support anchor point (5-2), the third fixed support anchor point (5-3), the fourth fixed support anchor point (5-4), the fifth fixed support anchor point (5-5), the sixth fixed support anchor point (5-6), the seventh fixed support anchor point (5-7), and the eighth fixed support anchor point (5-8); The MEMS resonator structure body (1), the phononic crystal, the suspended uniform heat frame (7), and the flexible support beam are all suspended on the structural substrate.

2. The multi-output MEMS resonator of claim 1, wherein, The first level phononic crystal A (2-1), the first level phononic crystal B (2-2), the first level phononic crystal C (2-3), the first level phononic crystal D (2-4), the second level phononic crystal A (3-1), the second level phononic crystal B (3-2), the second level phononic crystal C (3-3), and the second level phononic crystal D (3-4) respectively generate different frequency bands of phonon band gaps; the frequency range of the phonon band gap includes the resonant frequencies of different order working modes of the MEMS resonator structure body (1), is used for reducing the vibration energy of the working mode dissipated to the substrate through the fixed support anchor point, and realizes the improvement of the working mode Q value.

3. The multiple output MEMS resonator of claim 1, wherein, The outside of the MEMS resonator structure body (1) is provided with an excitation and detection structure for exciting and detecting the resonant motion of the MEMS resonator; The excitation and detection mode is electrostatic, piezoresistive, electromagnetic or electrothermal; the excitation signal type adopts direct harmonic excitation, degenerate parameter excitation, non-degenerate parameter excitation or internal resonance excitation.

4. A method of frequency modulation of a two-stage phononic crystal based multi-output MEMS resonator according to any one of claims 1-3, characterized in that, Including the following steps: Step 1, the MEMS resonator is powered on and works, and the modes in different frequency bands respectively generate stable closed loop oscillation in the respective maintaining oscillation system; Step 2, according to the current change of the temperature measuring flexible support beam in the integrated temperature measuring system, the temperature change of the MEMS resonator structure body (1) is monitored in real time, and the temperature change quantity after analog-to-digital conversion is transmitted to the control system; Step 3, the error current signal is calculated by the error value calculation module in the control system, and the joule heat heating voltage required for compensating the temperature change is calculated by the PID control module using the control algorithm; Step 4, the integrated joule heat heating system outputs the joule heat heating voltage, and the constant temperature of the MEMS resonator is realized by using the joule heat effect; Step 5, return to step 2, and repeat the above steps to maintain the constant temperature of the MEMS resonator and the stability of the multi-output frequency of the MEMS resonator.

5. A frequency modulation system for implementing the frequency modulation method of the multi-output MEMS resonator based on two-level phononic crystals according to claim 4, characterized in that, Including: Maintain the oscillation system: for the different frequency band within the mode to be excited to the closed loop oscillation state, output multi-channel frequency different frequency signal; Integrated temperature measurement system: for the integrated temperature measurement resistance to apply a constant temperature measurement voltage, and real-time monitoring of temperature measurement beam temperature measurement current changes, temperature measurement current transmission to the control system; Control system: connected with the above-mentioned integrated temperature measurement system, the temperature measurement current into a digital quantity, according to the difference between the current measurement value and the current preset value, using control algorithm to calculate the heating voltage required to compensate for the difference, and the heating voltage control signal transmission to the integrated joule heat heating system; Integrated joule heat heating system: connected with the above-mentioned control system, for the heating voltage control signal into voltage, and the joule heat voltage transmission to the integrated joule heat heating beam located in the suspension frame (7) connected to the MEMS resonator structure body (1), realize the temperature control, so as to realize the MEMS resonator structure body (1) temperature constant.

6. The frequency modulation system of claim 5, wherein, The maintain the oscillation system includes: And the first electrode plate (4-1), the second electrode plate (4-2) connected with the first signal amplification module (8-1), the second signal amplification module (9-1), respectively for amplifying the first working mode and the second working mode movement signal; And the first signal amplification module (8-1), the second signal amplification module (9-1) connected with the first band pass filter module (8-2), the second band pass filter module (9-2), respectively for filtering the first working mode and the second working mode movement signal in the stray signal; And the first band pass filter module (8-2), the second band pass filter module (9-2) connected with the first phase shift module (8-3), the second phase shift module (9-3), respectively for adjusting the first working mode and the second working mode closed loop oscillation circuit in the phase difference value, so that two closed loop oscillation circuit respectively meet the phase difference condition of the Barkhausen closed loop start, realize stable closed loop oscillation; And the first phase shift module (8-3), the second phase shift module (9-3) connected with the first limiting module (8-4), the second limiting module (9-4), respectively for stabilizing the first working mode and the second working mode closed loop oscillation circuit in the amplitude of the excitation signal; The first limiting module (8-4) and the second limiting module (9-4) are respectively reserved with signal output interface, for outputting the vibration signal of MEMS resonator; The number of closed loop oscillation circuit in the maintain the oscillation system is adjusted according to the number of required output frequency.

7. The frequency modulation system of claim 5, wherein, The control system includes: Analog / digital conversion module (10-1): analog / digital conversion module (10-1) is connected with the integrated temperature measurement system, and the temperature measurement current is converted into a digital quantity; Error value calculation module (10-2): error value calculation module (10-2) and analog / digital conversion module (10-1) output connection, receive the temperature measurement current signal of analog / digital conversion module (10-1), and compare the temperature measurement current signal with the preset current value, output error current signal; PID control module (10-3): the PID control module (10-3) and error value calculation module (10-2) output connection, for executing temperature control program, according to error current signal output corresponding joule heat voltage control signal; Heating voltage control module (10-4): heating voltage control module (10-4) and PID control module (10-3) output connection, heating voltage control module (10-4) output and the integrated joule heat heating system is connected, for the joule heat voltage control signal generated by PID control module (10-3) is transmitted to the integrated joule heat heating system, so as to control the heating power of joule heat heating beam, realize the temperature constant of MEMS resonator.

8. The frequency modulation system of claim 5, wherein, The integrated joule heat heating system comprises: First digital / analog conversion module (11-1), second digital / analog conversion module (11-2): connected with the heating voltage control module of the control system, for joule heat voltage control signal, real-time adjustment of the heating power of joule heat heating beam; Joule heat heating beam (flexible support beam A6-1, flexible support beam B6-2, flexible support beam E6-5, flexible support beam F6-6): for executing heating instruction, and transmitting heat to the suspended uniform heating frame (7) through four connecting rods connected with the suspended uniform heating frame (7); Suspended uniform heating frame (7): connected with the joule heat heating beam, under the action of the heat generated by the joule heat heating beam, generates uniform temperature change, and transmits heat to the MEMS resonator structure body (1) through four transmission paths through four groups of series phononic crystals, so as to ensure the uniformity of the temperature distribution of the MEMS resonator structure body (1), so that the MEMS resonator structure body (1) can maintain stable oscillation under the action of the joule heat system.

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