Multi-output MEMS resonator based on two-stage photonic crystal and frequency modulation method and system thereof

Abstract

The invention discloses a multi-output MEMS resonator based on two-stage photonic crystals and a frequency modulation method and system thereof. The multi-output MEMS resonator comprises a resonant structure body supported by clamped anchor points and a functional accessory structure of the resonant structure body. The MEMS resonator simultaneously reduces anchoring loss of modals in different frequency bands through two stages of photonic crystals, so that multi-path frequency output with high frequency stability is realized; according to the frequency modulation method and system, high-precision, low-cost, low-power-consumption and low-heat-hysteresis frequency modulation and constant-temperature control can be realized by utilizing the integrated temperature measurement beam, the integrated Joule heat heating beam and the suspension soaking frame and combining the constant-temperature control circuit.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-electromechanical systems, and in particular relates to a multi-channel output MEMS resonator based on two-stage phononic crystals and a frequency modulation method and system thereof. Background Art

[0002] The clock is the heart of the electronic system, providing the clock signal and reference frequency signal for the electronic system, and determining the upper limit of the performance of the electronic system. Quartz oscillators have been widely used in various occasions requiring high-precision clock references due to their excellent temperature and frequency stability. With the development of technology, electronic systems have put forward increasingly stringent requirements on the volume, power consumption and impact resistance of each subsystem. Against this background, MEMS oscillators came into being. Compared with quartz oscillators, MEMS oscillators manufactured using semiconductor processing technology have higher integration, lower cost and lower power consumption, and have extremely high market value.

[0003] At present, in clock applications, it is often necessary to use a frequency multiplication module to up-convert the output frequency of the MEMS oscillator to provide a high-frequency clock signal, which will affect the stability of the output frequency; and in order to adapt to the future wireless communication systems and other multi-band application requirements, MEMS oscillators are urgently required to 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] In this regard, the patent application named "Frequency-Adjustable MEMS Resonator" (CN103338022A) achieves the adjustment of the resonant frequency by controlling the number, position, shape and size of the excitation electrode structure. In fact, continuous geometric entities have an infinite number of vibration modes. It is basic common sense to match the arrangement of the excitation electrodes according to the modal vibration type, so as to achieve the multi-frequency output function in the above patent application embodiment, and R&D personnel often do so. However, how to use structural design to make high-order modes with large dynamic impedance produce stable vibrations is a systematic scientific problem, which cannot be achieved through simple electrode matching, but needs to be achieved by reasonably optimizing the resonant structure and reducing the energy loss of each order mode.

[0005] The size of the quality factor is a key factor in whether high-order modes with high motion impedance can stably vibrate, and the quality factor also determines the output frequency stability of different-order modes. The current mainstream solutions to improve the quality factor include: optimizing the resonator structure and optimizing the resonator anchor point structure. However, existing literature ([1] Zhang Y, Bao JF, 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 FC, Hsu JC, Huang TC, 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, but cannot be compatible with resonant working modes of multiple frequency bands, and cannot achieve the joint improvement of the quality factors of multiple vibration modes. Therefore, it cannot be applied to occasions with multi-band application requirements; and while changing the structure of the resonator and its anchor point, it will inevitably affect the vibration frequency of the resonator itself, which introduces new difficulties to the resonator structure design.

[0006] Another key technology of MEMS resonators is the temperature compensation of the oscillator. Compared with quartz crystals, single-crystal silicon has a larger temperature frequency coefficient (25ppm / ℃ to 60ppm / ℃). How to maintain the stable frequency output of the MEMS resonator in a variable temperature environment is a key technical problem that needs to be solved in the field of MEMS resonator technology. Active constant temperature control technology is expected to maintain the frequency stability of the MEMS resonator at the ppb level, so it has been widely studied. Existing constant temperature control schemes ([3] Yang D, Woo JK, 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 use discrete temperature measuring platinum resistors to read the temperature of the MEMS resonator, and use discrete heating elements to control the temperature of the MEMS resonator at a constant value, thereby achieving constant temperature control. However, this scheme has large thermal hysteresis, low control accuracy, 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 PiezoelectricMEMS Resonator With±190ppb Stability Over-40to 105℃Temperature Range[J].IEEE Electron Device Letters,2023,44(8):1340-1343;[6]Jia W,Chen W,Xiao Y,etal.A Micro-Oven-Controlled Dual-Mode Piezoelectric MEMS ResonatorWith+ / -400PPB Stability Over-40to 80degrees C Temperature Range[J].Ieee Transactions on Electron Devices, 2022, 69(5): 2597-2603.) The frequency offset of the MEMS resonator is used as the control signal to adjust the heating resistor integrated in the MEMS resonator structure layer to achieve high-precision, low-power, and low-thermal hysteresis constant temperature control; the patent application named "MEMS oscillator" (CN 116545382A) also proposed 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 requires the design of a dedicated high-frequency signal reading circuit, which poses a challenge to the development of on-chip constant temperature control technology. At the same time, the temperature stability of the built-in crystal oscillator in the frequency reading circuit in a variable temperature working environment also greatly limits the compensation accuracy of the MEMS resonator. . Summary of the invention

[0007] In view of the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a multi-channel output MEMS resonator based on two-stage phononic crystals and its frequency modulation method and system. The MEMS resonator uses two-stage phononic crystals to simultaneously reduce the anchoring loss of modes in different frequency bands, thereby achieving dual-channel frequency output with high frequency stability; by utilizing an integrated temperature-measuring flexible support beam, an integrated Joule heat heating flexible support beam, and a suspended heat-averaging frame, combined with a constant temperature control circuit, high-precision, low-cost, low-power consumption, and low thermal hysteresis frequency modulation and constant temperature control can be achieved.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

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

[0010] The functional auxiliary structure includes: a first-level phononic crystal A2-1, a first-level phononic crystal B2-2, a first-level phononic crystal C2-3, and a first-level phononic crystal D2-4 connected to the MEMS resonator structure body 1; the other ends of the first-level phononic crystal A2-1, the first-level phononic crystal B2-2, the first-level phononic crystal C2-3, and the first-level phononic crystal D2-4 are respectively connected to 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, and the other ends of 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 connected to the suspended heat-saturating 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 respectively connected to 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; among them, 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; 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 flexible support beams are connected to the suspended heat soaking frame 7 .

[0013] The structure of the flexible support beam is one of a folded beam, a serpentine beam or a straight beam.

[0014] The MEMS resonator 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 together in a suspended heat-averaging frame 7, and the suspended heat-averaging frame 7 is anchored on the substrate through flexible support beams A6-1, B6-2, C6-3, D6-4, E6-5, F6-6, G6-7, H6-8 and 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.

[0015] The MEMS resonator structure body 1, the phononic crystal, the suspended heat-saturating 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 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 respectively generate phonon band gaps of different frequency bands.

[0017] The frequency range of the phonon bandgap includes the resonant frequencies of working modes of different orders of the MEMS resonator structure body 1, and is used to reduce the vibration energy of the working mode dissipated to the substrate through the fixed support anchor point, thereby improving the Q value of the working mode.

[0018] 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 and detection methods are 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 a multi-output MEMS resonator based on a two-stage phononic crystal comprises the following steps:

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

[0021] 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 body 1 is monitored in real time, and the temperature change after analog-to-digital conversion is transmitted to the control system;

[0022] Step 3, the error value calculation module in the control system calculates the error current signal, and the PID control module uses the control algorithm to calculate the Joule heat heating voltage required to compensate for the temperature change;

[0023] Step 4, the integrated Joule heat heating system outputs a Joule heat heating voltage, and utilizes the Joule heat effect to achieve a constant temperature of the MEMS resonator;

[0024] Step 5, return to step 2, and repeat this process to maintain the constant temperature of the MEMS resonator and the stability of the multi-channel output frequency of the MEMS resonator.

[0025] A frequency modulation system for implementing the frequency modulation method of a multi-channel output MEMS resonator based on a two-stage phononic crystal comprises:

[0026] Maintaining oscillation system: used to simultaneously excite modes in different frequency bands to a closed-loop oscillation state and output multiple frequency signals with different frequencies;

[0027] Integrated temperature measurement system: used to apply a constant temperature measurement voltage across the integrated temperature measurement resistor, monitor the temperature measurement current changes of the temperature measurement beam in real time, and transmit the temperature measurement current to the control system;

[0028] Control system: connected to the above-mentioned integrated temperature measurement system, converting the temperature measurement current into a digital quantity, calculating the heating voltage required to compensate for the difference between the current measurement value and the current preset value using a control algorithm, and transmitting the heating voltage control signal to the integrated Joule heat heating system;

[0029] Integrated Joule heat heating system: connected to the above-mentioned control system, used to convert the heating voltage control signal into voltage, and transmit the Joule heat voltage to the two ends of the integrated Joule heat heating beam connected to the suspended heat equalization frame 7, to achieve temperature control of the MEMS resonator structure body 1, thereby achieving constant temperature of the MEMS resonator structure body 1.

[0030] The oscillation-maintaining system comprises:

[0031] A first signal amplification module 8-1 and a second signal amplification module 9-1 connected to the first electrode plate 4-1 and the second electrode plate 4-2, respectively used to amplify motion signals of the first working mode and the second working mode;

[0032] The first band-pass filtering module 8-2 and the second band-pass filtering module 9-2 connected to the first signal amplifying module 8-1 and the second signal amplifying module 9-1 are used to filter out stray signals in the motion signals of the first working mode and the second working mode respectively;

[0033] The first phase shift module 8-3 and the second phase shift module 9-3 connected to the first band-pass filter module 8-2 and the second band-pass filter module 9-2 are respectively used to adjust the phase difference between the first working mode and the second working mode closed-loop oscillation circuits, so that the two closed-loop oscillation circuits respectively meet the phase difference conditions for Barkhausen closed-loop oscillation, and achieve stable closed-loop oscillation;

[0034] The first limiting module 8-4 and the second limiting module 9-4 connected to the first phase shifting module 8-3 and the second phase shifting module 9-3 are respectively used to stabilize the amplitude of the excitation signal in the closed-loop oscillation circuit of the first working mode and the second working mode; the first limiting module 8-4 and the second limiting module 9-4 are respectively reserved with signal output interfaces for outputting the vibration signal of the MEMS resonator.

[0035] The number of closed-loop oscillation circuits in the sustaining oscillation system is adjusted according to the number of required output frequencies.

[0036] The control system comprises:

[0037] Analog / digital conversion module 10-1: The analog / digital conversion module 10-1 is connected to the integrated temperature measurement system and converts the temperature measurement current into a digital quantity;

[0038] Error value calculation module 10-2: The error value calculation module 10-2 is connected to the output of 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] PID control module 10 - 3: The PID control module 10 - 3 is connected to the output of the error value calculation module 10 - 2 and is used to execute the temperature control program and output a corresponding Joule thermal voltage control signal according to the error current signal;

[0040] Heating voltage control module 10-4: The heating voltage control module 10-4 is connected to the output of the PID control module 10-3, and the output of the heating voltage control module 10-4 is connected to the integrated Joule heat heating system, and is used to transmit the Joule heat voltage control signal generated by the PID control module 10-3 to the integrated Joule heat heating system, thereby controlling the heating power of the Joule heat heating beam and achieving constant temperature of the MEMS resonator.

[0041] The integrated Joule heat heating system comprises:

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

[0043] Joule heat heating beams (flexible support beam A6-1, flexible support beam B6-2, flexible support beam E6-5, flexible support beam F6-6): used to execute heating instructions and transfer heat to the suspended heat soaking frame 7 through four connecting rods connected to the suspended heat soaking frame 7;

[0044] Suspended heat-averaging frame 7: connected to the Joule heat heating beam, produces uniform temperature change under the action of the heat generated by the Joule heat heating beam, and transfers heat to the MEMS resonator structure body 1 through four transmission paths through four groups of evenly distributed series phononic crystals, thereby ensuring the uniformity of 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.

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

[0046] The MEMS resonator of the present invention adopts a two-stage phononic crystal structure, which can simultaneously generate phonon band gaps corresponding to multiple modal resonance frequencies, and has the innovation and advantage of simultaneously improving the stability of multi-frequency output frequencies.

[0047] The MEMS resonator of the present invention uses a suspended heat-averaging frame to anchor the MEMS resonator and the phononic crystal connected in series on a flexible support beam. Under the premise of ensuring effective support, the temperature of the MEMS resonator can be evenly transferred to the temperature measurement point and the heating power can be evenly transferred to the MEMS resonator. It has the innovation points and advantages of accurate temperature reading and fast compensation.

[0048] The MEMS resonator heating structure of the present invention adopts a flexible support beam structure, which can achieve further suppression of energy transfer under the premise of efficient heating power output, and has the innovation and advantage of improving heating efficiency and increasing the quality factor of the MEMS resonator.

[0049] In summary, the present invention provides a multi-channel output MEMS resonator based on two-stage phononic crystals and its frequency modulation method and system. Through the structural form of the two-stage series phononic crystal, the anchoring loss of the vibration mode in different frequency bands is reduced without affecting the resonant frequency of the MEMS resonator, the short-term frequency stability of the vibration mode is improved, and a high-stability multi-channel oscillation frequency output is achieved; at the same time, in order to achieve temperature compensation of the MEMS resonator, the present invention proposes a miniaturized, high-precision, low-power frequency modulation method and system of an integrated temperature measurement beam and an integrated Joule heat heating beam, while reducing the thermal hysteresis of the traditional constant temperature control method, without the need to additionally design a high-precision frequency reading circuit, and without introducing additional frequency reading errors, the accuracy of the constant temperature control is improved; in addition, the frequency modulation method and system improve the temperature uniformity of the MEMS resonator through the structural design of the suspended heat-averaging frame, ensure the accuracy of temperature measurement, and improve the temperature stability of the output frequency of the MEMS resonator. Finally, the overall performance of the MEMS resonator is greatly improved through the above three aspects. The present invention 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 THE DRAWINGS

[0050] Figure 1 The schematic diagram is a basic structural diagram of a multi-channel output MEMS resonator based on two-stage phononic crystals of the present invention.

[0051] Figure 2 Schematic diagram of the structure of a MEMS resonator according to an embodiment of the present invention.

[0052] Figure 3 Schematic diagram of the structure of the phononic crystal according to an embodiment of the present invention, wherein (a) is a front view and (b) is a three-dimensional view.

[0053] Figure 4 Schematic diagram of the phonon bandgap of the two-level phononic crystal obtained by finite element simulation calculation according to an embodiment of the present invention, wherein (a) is the first phonon bandgap (corresponding to the second-order lame mode), the second phonon bandgap (corresponding to the breathing mode), and the third phonon bandgap (corresponding to the fifth-order lame mode) generated by the first-level phononic crystal; (b) is the fourth phonon bandgap (corresponding to the fourth-order lame mode) and the fifth phonon bandgap (corresponding to the eighth-order lame mode) generated by the second-level phononic crystal.

[0054] Figure 5 These are vibration modes of five different frequency bands of an embodiment of the present invention, where (a) is a second-order lame mode with a design frequency of approximately 5 MHz; (b) is a breathing mode with a design frequency of approximately 7.4 MHz; (c) is a fifth-order lame mode with a design frequency of approximately 13 MHz; (d) is a fourth-order lame mode with a design frequency of approximately 10 MHz; and (e) is an eighth-order lame mode with a design frequency of approximately 20 MHz.

[0055] Figure 6 The figure is a flow chart of a frequency control method according to an embodiment of the present invention.

[0056] Figure 7 It is a schematic diagram of the logical framework of the frequency control system according to an embodiment of the present invention.

[0057] In the figure: 1. MEMS resonator structure body; 2-1. First-level phononic crystal A; 2-2. First-level phononic crystal B; 2-3. First-level phononic crystal C; 2-4. First-level phononic crystal D; 3-1. Second-level phononic crystal A; 3-2. Second-level phononic crystal B; 3-3. Second-level phononic crystal C; 3-4. Second-level phononic crystal D; 4-1. First electrode plate; 4-2. Second electrode plate; 4-3. Third electrode plate; 4 -4. The fourth electrode plate; 4-5. The fifth electrode plate; 4-6. The sixth electrode plate; 4-7. The seventh electrode plate; 4-8. The eighth electrode plate; 4-9. The ninth electrode plate; 4-10. The tenth electrode plate; 4-11. The eleventh electrode plate; 4-12. The twelfth electrode plate; 5-1. The first anchor point; 5-2. The second anchor point; 5-3. The third anchor point; 5-4. The fourth anchor point; 5-5. The fifth anchor point; 5-6. The sixth fixed anchor point; 5-7. The seventh fixed anchor point; 5-8. The eighth fixed 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 heat-averaging frame; 8-1. The first signal amplification module; 8-2. The first band-pass filter module; 8-3. The first phase shift module; 8-4. The first limiting module; 9-1. The second signal amplification module; 9-2. The second band-pass filter module; 9-3. The second phase shift module; 9-4. The second limiting module; 10-1. The analog / digital conversion module; 10-2. The error value calculation module; 10-3. The PID control module; 10-4. The heating voltage control module; 11-1. The first digital / analog conversion module; 11-2. The second digital / analog conversion module. DETAILED DESCRIPTION

[0058] The present invention is described in detail below in conjunction with embodiments and drawings.

[0059] Reference Figure 1 , a multi-channel output MEMS resonator based on a two-stage phononic crystal, comprising a MEMS resonant structure body 1 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, and its functional subsidiary structures;

[0060] The structure of the MEMS resonator structure body 1 is one of disk type, ring type, film type or beam type;

[0061] The functional auxiliary structure includes: a first-level phononic crystal A2-1, a first-level phononic crystal B2-2, a first-level phononic crystal C2-3, and a first-level phononic crystal D2-4 connected to the MEMS resonant structure body 1; the other ends of the first-level phononic crystal A2-1, the first-level phononic crystal B2-2, the first-level phononic crystal C2-3, and the first-level phononic crystal D2-4 are respectively connected to 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, and the other ends of 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 connected in the suspended heat-saturating 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 respectively connected to 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; among which the flexible support beams C6-3, D6-4, E6-5, F6-6, G6-7, and H6-8 are respectively connected; 4. The flexible support beams G6-7 and H6-8 are temperature measuring beams, which are used to generate a current reflecting the temperature change of the MEMS resonator through the temperature dependence of the resistance of single crystal silicon under the action of a constant voltage, so as to judge the direction and magnitude of the temperature change of the MEMS resonator; the flexible support beams A6-1, B6-2, E6-5 and 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 are connected to the suspended heat-saturating frame 7 to uniformly transfer the heat generated by the Joule heat heating beams to the MEMS resonator structure body 1, thereby improving 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 together in the suspended heat-saturating frame 7, and the suspended heat-saturating frame 7 is anchored together by the flexible support beam A6-1 and the flexible support beam B6-2, flexible support beam C6-3, flexible support beam D6-4, flexible support beam E6-5, flexible support beam F6-6, flexible support beam G6-7, 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 are anchored on the substrate.

[0065] The structural form of the flexible support beam is one of a folded beam, a serpentine beam or a straight beam; the MEMS resonator structure body 1, the phononic crystal, the suspended heat-saturating 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 respectively generate phonon band gaps of different frequency bands.

[0067] The frequency range of the phonon bandgap includes the resonant frequencies of working modes of different orders of the MEMS resonator structure body 1, and is used to reduce the vibration energy of the working mode dissipated to the substrate through the fixed support anchor point, thereby improving the Q value of the working mode.

[0068] The excitation and detection methods of the multi-channel output MEMS resonator based on the two-stage phononic crystal include: electrostatic, piezoresistive, electromagnetic or electrothermal.

[0069] 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 signal type adopts direct harmonic excitation, degenerate parameter excitation, non-degenerate parameter excitation or internal resonance excitation.

[0070] Reference Figure 2, this embodiment is a multi-channel output MEMS resonator based on two-stage phononic crystals, including: a disc-type MEMS resonator structure body 1, a first-stage phononic crystal A2-1, a first-stage phononic crystal B2-2, a first-stage phononic crystal C2-3, a first-stage phononic crystal D2-4, a second-stage phononic crystal A3-1, a second-stage phononic crystal B3-2, a second-stage phononic crystal C3-3, a second-stage phononic crystal D3-4, a folded beam-shaped flexible support beam A6-1, a flexible support beam B6-2, a flexible support beam C6-3, a flexible support beam D6-4, a flexible support beam E6-5, a flexible support beam F6-6, Flexible support beams G6-7 and H6-8, and a suspended heat-averaging frame 7 of a square structure placed at 45 degrees; 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 are provided on the outside of the disc-type MEMS resonator structure body 1, forming a capacitor with the MEMS resonator structure body 1 to excite and detect the resonant motion of the MEMS resonator.

[0071] Reference Figure 3 In this embodiment, the structure of the phononic crystal is as follows: in a square of horizontal D+2R and vertical W+2R, four quarter circles are dug out with four corners as the center and R as the radius, such as Figure 3 As shown in (a); for the first-level phononic crystal: D is equal to 90 microns, R is equal to 70 microns, and W is equal to 8 microns; for the second-level phononic crystal: D is equal to 120 microns, R is equal to 110 microns, and W is equal to 8 microns.

[0072] Reference Figure 4 , 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 respectively generate phononic bandgap of different frequency bands, among which the first-level phononic crystal A2-1, the first-level phononic crystal B2-2, the first-level phononic crystal C2-3, and the first-level phononic crystal D2-4 generate the first phononic bandgap ( 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 the fourth phonon bandgap (corresponding to the fourth-order lame mode) and the fifth phonon bandgap (corresponding to the eighth-order lame mode), which respectively reduce the anchoring loss of the corresponding modal vibration energy and improve the output frequency stability.

[0073] Reference Figure 5 The MEMS resonator described in this embodiment works simultaneously in multiple modes with different fundamental frequencies, namely: a second-order lame mode with a design frequency of approximately 5 MHz, a breathing mode with a design frequency of approximately 7.4 MHz, a fifth-order lame mode with a design frequency of approximately 13 MHz, a fourth-order lame mode with a design frequency of approximately 10 MHz, and an eighth-order lame mode with a design frequency of approximately 20 MHz. The vibration frequency of each mode is within the phonon bandgap generated by the two-stage phononic crystal.

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

[0075] Step 1, the MEMS resonator is powered on and works, and the modes in different frequency bands respectively generate stable closed-loop oscillations in their respective oscillation-maintaining systems;

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

[0077] Step 3, the error value calculation module in the control system calculates the error current signal, and the PID control module uses the control algorithm to calculate the Joule heat heating voltage required to compensate for the temperature change;

[0078] Step 4, the integrated Joule heat heating system outputs a Joule heat heating voltage, and utilizes the Joule heat effect to achieve a constant temperature of the MEMS resonator;

[0079] Step 5, return to step 2, and repeat this process to maintain the constant temperature of the MEMS resonator and the stability of the multi-channel output frequency of the MEMS resonator.

[0080] A frequency modulation system for implementing the frequency modulation method of a multi-channel output MEMS resonator based on a two-stage phononic crystal comprises:

[0081] Maintaining oscillation system: used to simultaneously excite modes in different frequency bands to a closed-loop oscillation state and output multiple frequency signals with different frequencies;

[0082] Integrated temperature measurement system: used to apply a constant temperature measurement voltage across the integrated temperature measurement resistor, monitor the temperature measurement current changes of the temperature measurement beam in real time, and transmit the temperature measurement current to the control system;

[0083] Control system: connected to the above-mentioned integrated temperature measurement system, converting the temperature measurement current into a digital quantity, calculating the heating voltage required to compensate for the difference between the current measurement value and the current preset value using a control algorithm, and transmitting the heating voltage control signal to the integrated Joule heat heating system;

[0084] Integrated Joule heat heating system: connected to the above-mentioned control system, used to convert the heating voltage control signal into voltage, and transmit the Joule heat voltage to the two ends of the integrated Joule heat heating beam connected to the suspended heat equalization frame 7, to achieve temperature control of the MEMS resonator structure body 1, thereby achieving constant temperature of the MEMS resonator structure body 1.

[0085] Select two reference signals with output frequencies of 5MHz and 10MHz respectively, refer to Figure 7 , the oscillation system for achieving dual-frequency output includes:

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

[0087] The first band-pass filtering module 8-2 and the second band-pass filtering module 9-2 connected to the first signal amplifying module 8-1 and the second signal amplifying module 9-1 are used to filter 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) respectively;

[0088] The first phase shift module 8-3 and the second phase shift module 9-3 connected to the first band-pass filter module 8-2 and the second band-pass filter module 9-2 are respectively used to adjust the phase difference in the closed-loop oscillation circuits 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 conditions of the Barkhausen closed-loop oscillation, and achieve stable closed-loop oscillation;

[0089] The first limiting module 8-4 and the second limiting module 9-4 connected to the first phase shifting module 8-3 and the second phase shifting module 9-3 are respectively used to stabilize 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 module 8-4 and the second limiting module 9-4 are respectively reserved with signal output interfaces for outputting the vibration signal of the MEMS resonator.

[0090] Reference Figure 7 , the control system comprises:

[0091] Analog / digital conversion module 10-1: The analog / digital conversion module 10-1 is connected to 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 to the output of 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 to the output of the error value calculation module 10 - 2 and is used to execute the temperature control program and output a corresponding Joule thermal 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 to the output of the PID control module 10-3, and the output of the heating voltage control module 10-4 is connected to the integrated Joule heat heating system, and is used to transmit the Joule heat voltage control signal generated by the PID control module 10-3 to the integrated Joule heat heating system, thereby controlling the heating power of the Joule heat heating beam and achieving constant temperature of the MEMS resonator.

[0095] The integrated Joule heat heating system comprises:

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

[0097] Joule heat heating beams (flexible support beam A6-1, flexible support beam B6-2, flexible support beam E6-5, flexible support beam F6-6): used to execute heating instructions and transfer heat to the suspended heat soaking frame 7 through four connecting rods connected to the suspended heat soaking frame 7;

[0098] Suspended heat-averaging frame 7: connected to the Joule heat heating beam, produces uniform temperature change under the action of the heat generated by the Joule heat heating beam, and transfers heat to the MEMS resonator structure body 1 through four transmission paths through four groups of evenly distributed series phononic crystals, thereby ensuring the uniformity of 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.

[0099] The above contents are 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 multi-output MEMS resonator based on a two-stage phononic crystal, characterized in that: The invention comprises a MEMS resonator structure body (1) and its functional accessory structures supported by a first fixing anchor point (5-1), a second fixing anchor point (5-2), a third fixing anchor point (5-3), a fourth fixing anchor point (5-4), a fifth fixing anchor point (5-5), a sixth fixing anchor point (5-6), a seventh fixing anchor point (5-7) and an eighth fixing anchor point (5-8); the structure of the MEMS resonator structure body is one of a disk type, a ring type, a film type or a beam type.

2. The multi-output MEMS resonator according to claim 1, characterized in that: The functional auxiliary 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) connected to 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 to 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); 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 heat-saturating frame (7); the first fixed support anchor point (5-1), the first fixed support anchor point (5-2), the first fixed support anchor point (5 ... 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 to 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), and the 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; and 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 to the suspended heat soaking frame (7); the structural form of the flexible support beams is one of a folded beam, a serpentine beam or a straight beam.

3. The multi-output MEMS resonator according to claim 2, characterized in that: The MEMS resonator structure body (1) and 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) are anchored together in a suspended heat-saturating frame (7), and the suspended heat-saturating frame (7) is anchored by a flexible support beam A (6-1), a flexible support beam B (6-2), a first-level phononic crystal C (2-3), and a first-level phononic crystal D (2-4). -2), flexible support beam C (6-3), flexible support beam D (6-4), flexible support beam E (6-5), flexible support beam F (6-6), flexible support beam G (6-7), 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) are anchored on the substrate; The MEMS resonator structure body (1), the phononic crystal, the suspended heat-saturating frame (7), and the flexible support beam are all suspended on the structure substrate.

4. The multi-output MEMS resonator according to claim 2, characterized in that: 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) respectively generate phonon bandgap of different frequency bands; the frequency range of the phonon bandgap includes the resonant frequency of working modes of different orders of the MEMS resonator structure body (1), and is used to reduce the vibration energy dissipated by the working mode to the substrate through the fixed support anchor point, thereby achieving an improvement in the Q value of the working mode.

5. The multi-output MEMS resonator according to claim 2, characterized in that: The MEMS resonator structure body (1) is provided with an excitation and detection structure on the outside thereof, which is used to excite and detect the resonant motion of the MEMS resonator; The excitation and detection methods are electrostatic, piezoresistive, electromagnetic or electrothermal; the excitation signal type adopts direct harmonic excitation, degenerate parameter excitation, non-degenerate parameter excitation or internal resonance excitation.

6. A frequency modulation method for a multi-output MEMS resonator based on a two-stage phononic crystal according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, the MEMS resonator is powered on and works, and the modes in different frequency bands respectively generate stable closed-loop oscillations in their respective oscillation-maintaining systems; 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 after analog-to-digital conversion is transmitted to the control system; Step 3, the error value calculation module in the control system calculates the error current signal, and the PID control module uses the control algorithm to calculate the Joule heat heating voltage required to compensate for the temperature change; Step 4, the integrated Joule heat heating system outputs a Joule heat heating voltage, and utilizes the Joule heat effect to achieve a constant temperature of the MEMS resonator; Step 5, return to step 2, and repeat this process to maintain the constant temperature of the MEMS resonator and the stability of the multi-channel output frequency of the MEMS resonator.

7. A frequency modulation system for implementing the frequency modulation method of a multi-output MEMS resonator based on two-stage phononic crystals as described in claim 6, characterized in that: include: Maintaining oscillation system: used to simultaneously excite modes in different frequency bands to a closed-loop oscillation state and output multiple frequency signals with different frequencies; Integrated temperature measurement system: used to apply a constant temperature measurement voltage across the integrated temperature measurement resistor, monitor the temperature measurement current changes of the temperature measurement beam in real time, and transmit the temperature measurement current to the control system; Control system: connected to the above-mentioned integrated temperature measurement system, converting the temperature measurement current into a digital quantity, calculating the heating voltage required to compensate for the difference between the current measurement value and the current preset value using a control algorithm, and transmitting the heating voltage control signal to the integrated Joule heat heating system; An integrated Joule heat heating system is connected to the control system and is used to convert the heating voltage control signal into a voltage and transmit the Joule heat voltage to both ends of an integrated Joule heat heating beam connected to a suspended heat-averaging frame (7), thereby achieving temperature control of the MEMS resonator structure body (1), thereby achieving a constant temperature of the MEMS resonator structure body (1).

8. The frequency modulation system according to claim 7, characterized in that: The oscillation-maintaining system comprises: A first signal amplification module (8-1) and a second signal amplification module (9-1) connected to the first electrode plate (4-1) and the second electrode plate (4-2), respectively used to amplify motion signals of the first working mode and the second working mode; A first band-pass filtering module (8-2) and a second band-pass filtering module (9-2) connected to the first signal amplifying module (8-1) and the second signal amplifying module (9-1), respectively used to filter out stray signals in the first working mode and the second working mode motion signals; A first phase shifting module (8-3) and a second phase shifting module (9-3) connected to the first band-pass filtering module (8-2) and the second band-pass filtering module (9-2) are respectively used to adjust the phase difference values ​​in the first working mode and the second working mode closed-loop oscillation circuits, so that the two closed-loop oscillation circuits respectively meet the phase difference conditions for Barkhausen closed-loop oscillation, thereby achieving stable closed-loop oscillation; A first amplitude limiting module (8-4) and a second amplitude limiting module (9-4) connected to the first phase shifting module (8-3) and the second phase shifting module (9-3) are respectively used to stabilize the amplitude of the excitation signal in the first working mode and the second working mode closed-loop oscillation circuit; the first amplitude limiting module (8-4) and the second amplitude limiting module (9-4) are respectively provided with a signal output interface for outputting the vibration signal of the MEMS resonator; The number of closed-loop oscillation circuits in the sustaining oscillation system is adjusted according to the number of required output frequencies.

9. The frequency modulation system according to claim 7, characterized in that: The control system comprises: Analog / digital conversion module (10-1): the analog / digital conversion module (10-1) is connected to the integrated temperature measurement system and converts the temperature measurement current into a digital quantity; Error value calculation module (10-2): the error value calculation module (10-2) is connected to the output of 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; PID control module (10-3): The PID control module (10-3) is connected to the output of the error value calculation module (10-2), and is used to execute a temperature control program and output a corresponding Joule thermal voltage control signal according to the error current signal; A heating voltage control module (10-4): the heating voltage control module (10-4) is connected to the output of the PID control module (10-3), and the output of the heating voltage control module (10-4) is connected to the integrated Joule heat heating system, and is used to transmit the Joule heat voltage control signal generated by the PID control module (10-3) to the integrated Joule heat heating system, thereby controlling the heating power of the Joule heat heating beam and achieving constant temperature of the MEMS resonator.

10. The frequency modulation system according to claim 7, characterized in that: The integrated Joule heat heating system comprises: A first digital / analog conversion module (11-1) and a second digital / analog conversion module (11-2): connected to the heating voltage control module of the control system, used for Joule heat voltage control signal, and adjusting the heating power of the Joule heat heating beam in real time; Joule heat heating beams (flexible support beam A6-1, flexible support beam B6-2, flexible support beam E6-5, flexible support beam F6-6): used to execute heating instructions and transfer heat to the suspended heat-saturating frame (7) through four connecting rods connected to the suspended heat-saturating frame (7); A suspended heat-averaging frame (7) is connected to a Joule heat heating beam, and generates a uniform temperature change under the action of the heat generated by the Joule heat heating beam. The heat is transferred to the MEMS resonator structure body (1) through four transmission paths through four groups of evenly distributed series-connected phononic crystals, thereby ensuring 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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