A MEMS mutual synchronous oscillator based on phase control

Abstract

The present invention discloses a MEMS mutually synchronous oscillator based on phase control, which belongs to the field of micromechanical systems and nonlinear dynamics technology. The MEMS mutually synchronous oscillator includes a PID controller and a pair of oscillator modules, and the oscillator module is composed of a resonator, an oscillation circuit and a phase control circuit; the oscillation circuit in each oscillator module is used to enable the resonator in the oscillator module to achieve self-excited oscillation, and the signal of the oscillation circuit is injected into the oscillation circuit in another oscillator module after adjusting the amplitude and phase through the phase control circuit; the PID controller is connected to one of the oscillation circuits to obtain the oscillation frequency, and outputs a phase control amount to change the phase of the injected signal according to the error between the current oscillation frequency obtained and the set oscillation frequency. The present invention realizes flexible regulation of the oscillation frequency of the mutually synchronous oscillator without introducing additional thermal noise and increasing power, thereby improving the frequency stability of the MEMS oscillator.

Description

Technical Field

[0001] The invention belongs to the technical field of micromechanical systems and nonlinear dynamics, and in particular relates to a MEMS mutual synchronous oscillator based on phase control. Background Art

[0002] MEMS oscillators are mechanical structures manufactured based on micro-electromechanical technology. They have been widely used as core components in telecommunications, transportation, consumer electronics and other fields, and continue to influence the development of emerging technology industries such as the Internet of Things, big data, and intelligent manufacturing. They have many advantages such as small size, high integration, high signal-to-noise ratio, low power consumption, low cost and high reliability, and have very broad application prospects or potential utilization value.

[0003] Due to the scale effect caused by the extremely small size of MEMS oscillators, it is easy to cause nonlinear problems, and at the same time bring about poor frequency stability and phase noise problems, which have become a constraint on the production of high-performance micromechanical oscillators. At present, there are some methods in the world that use nonlinear effects to improve frequency stability. Synchronization is a special phenomenon in nonlinear effects. From the current results, the improvement effect of synchronization on MEMS oscillators is very competitive, which provides a new idea for further improving the performance of micromechanical oscillators.

[0004] For micromechanical oscillators, frequency stability directly determines whether they can provide accurate and stable frequency references for electronic components and equipment. Generally, the frequency output by a MEMS synchronous oscillator based on self-excited oscillation will be reduced due to changes in the working environment temperature, coupling noise in the oscillation circuit, electromagnetic radiation in the system, and power supply voltage. Existing research on the frequency stability of synchronous oscillators mainly focuses on improving device structure, temperature compensation, circuit optimization, etc., and the adjustment process inevitably introduces additional thermal noise and increases system power. Therefore, it is urgent to explore new means of frequency regulation and improving frequency stability. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned prior art, the present invention provides a MEMS mutually synchronous oscillator based on phase control, which can achieve flexible regulation of the oscillation frequency of the mutually synchronous oscillator without introducing additional thermal noise or increasing power, thereby improving the frequency stability of the MEMS oscillator.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A phase-controlled MEMS mutual synchronous oscillator comprises a PID controller and a pair of oscillator modules, wherein the oscillator modules are composed of a resonator, an oscillation loop and a phase control circuit;

[0008] The oscillation circuit in each oscillator module is used to enable the resonator in the oscillator module to achieve self-oscillation;

[0009] The signal of the oscillation loop in each oscillator module is injected into the oscillation loop in another oscillator module through the phase control circuit in the oscillator module;

[0010] The PID controller is connected to the oscillation circuit in one of the oscillator modules and the phase control circuit in the other oscillator module to obtain the oscillation frequency in the connected oscillation circuit. The PID controller outputs a phase control amount according to the error between the obtained oscillation frequency and the set oscillation frequency. The phase control amount acts on the phase control circuit in the other oscillator module to change the phase of the injected signal.

[0011] Preferably, the oscillation circuit includes a transimpedance amplifier, a phase detector, a loop PI controller, a digitally controlled oscillator and an adder; the signal input end of the transimpedance amplifier is connected to the detection plate of the resonator, and the signal output end of the transimpedance amplifier is fed back to the excitation plate of the resonator after passing through the phase detector, the loop PI controller, the digitally controlled oscillator and the adder.

[0012] Preferably, the phase detector, loop PI controller and digitally controlled oscillator also constitute a sub-loop; the transimpedance amplifier converts the high internal resistance dynamic current signal obtained by the resonator detection plate into a low internal resistance voltage signal, the phase detector detects the phase difference between the output signal of the transimpedance amplifier and the feedback signal of the digitally controlled oscillator, and converts the detected phase difference signal into a voltage signal and outputs it to the loop PI controller, the loop PI controller adjusts the received signal, outputs a stable voltage signal to control the digitally controlled oscillator, and the voltage signal output by the digitally controlled oscillator is fed back to the phase detector; after repeated phase detection, adjustment and feedback, the voltage signal output by the digitally controlled oscillator is finally returned to the excitation plate of the resonator through the adder.

[0013] Preferably, the phase control circuit includes an amplitude controller and a phase shifter, the signal input end of the amplitude controller is connected to the signal output end of the transimpedance amplifier in the oscillation circuit, the signal output end of the amplitude controller is connected to the signal input end of the phase shifter, and the signal output end of the phase shifter is connected to the adder in the oscillation circuit.

[0014] Preferably, the signal input end of the PID controller is connected to the signal output end of the digitally controlled oscillator in the oscillation loop, and the signal output end of the PID controller is connected to the control end of the phase shifter in the phase control circuit.

[0015] Preferably, the phase control method of the MEMS mutually synchronous oscillator comprises:

[0016] (1) Establish mutually synchronized oscillators:

[0017] Apply an excitation signal to the resonator in each oscillator module to achieve closed-loop oscillation; adjust the phase control circuit in the oscillator module to change the phase of the injection signal, so that the phase of the injection signal received by each oscillator module only affects the oscillation frequency of the oscillator module until a pair of oscillation loops are synchronized to establish a mutually synchronized oscillator;

[0018] (2) Stabilize the oscillation frequency of mutually synchronized oscillators:

[0019] The oscillation frequency of the mutually synchronous oscillator is preset, and the PID controller obtains the oscillation frequency of the connected oscillation loop as the current oscillation frequency of the mutually synchronous oscillator, and calculates the error between the current oscillation frequency and the set oscillation frequency, and outputs a phase control amount according to the error value. The phase control amount acts on the connected phase control circuit, and adjusts the current oscillation frequency of the mutually synchronous oscillator by changing the phase of the injected signal, so that the current oscillation frequency of the mutually synchronous oscillator is stabilized at the set oscillation frequency.

[0020] Preferably, the phase control amount output by the PID controller acts on a phase shifter in the phase control circuit.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] In summary, the present invention is based on the mutual coupling synchronization mechanism, and controls the oscillation frequency of the entire mutually synchronous oscillator by adjusting the first phase shifter or the second phase shifter. The PID controller calculates the output phase control amount according to the error between the current oscillation frequency and the set oscillation frequency to change the phase of the signal injected into the second oscillation loop by the first oscillation loop, thereby realizing the regulation of the oscillation frequency of the mutually synchronous oscillator, and then realizing the improvement of the frequency stability of the mutually synchronous oscillator. The two oscillation loops of the present invention are constructed based on the form of phase feedback. Without introducing additional thermal noise and increasing power, they have the advantages of excellent real-time performance and high control accuracy, and greatly improve the long-term frequency stability of the MEMS oscillator. In addition, in an environment with temperature changes, the present invention can well suppress the drift of the oscillation frequency of the oscillator caused by temperature changes.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural diagram of the MEMS mutual synchronous oscillator proposed by the present invention;

[0025] Figure 2 This is the relationship diagram between the injection phase and the frequency of the mutually synchronized oscillator obtained in the experiment;

[0026] Figure 3is a flow chart of the phase control method of the present invention;

[0027] Figure 4 The figure is a comparison diagram of frequency stability characterized by Allan variance before and after the application of the present invention.

[0028] Among them: 1-1. First transimpedance amplifier; 1-2. First phase detector; 1-3. First loop PI controller; 1-4. First digitally controlled oscillator; 1-5. First adder; 1-6. First resonator; 2-1. Second transimpedance amplifier; 2-2. Second phase detector; 2-3. Second loop PI controller; 2-4. Second digitally controlled oscillator; 2-5. Second adder; 2-6. Second resonator; 3-1. First amplitude controller; 3-2. First phase shifter; 4-1. Second amplitude controller; 4-2. Second phase shifter; 5. PID controller. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the description of the present invention, it is to be understood that the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in combination with specific circumstances.

[0032] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0033] The present invention provides a MEMS mutually synchronous oscillator based on phase control, comprising two oscillation loops, two phase control circuits and a PID controller, wherein the signal of the first oscillation loop is injected into the second oscillation loop through the first phase control circuit, and the signal of the second oscillation loop is injected into the first oscillation loop through the second phase control circuit. The oscillation frequencies of the two oscillation loops can be adjusted by the two phase control circuits, and when the oscillation frequencies of the two oscillation loops are close, synchronization can occur to establish a mutually synchronous oscillator, and then the current oscillation frequency of the entire mutually synchronous oscillator can be controlled by adjusting any one of the two phase control circuits. The PID controller outputs a phase control amount according to the error between the current oscillation frequency and the set oscillation frequency to change the phase of the signal injected into the second oscillation loop by the first oscillation loop, or changes the phase of the signal injected into the first oscillation loop by the second oscillation loop, so as to achieve regulation of the oscillation frequency of the mutually synchronous oscillator to stabilize the oscillation frequency.

[0034] See also Figure 1 The present invention provides a phase-controlled MEMS mutual synchronous oscillator, which includes a first oscillation circuit, a second oscillation circuit, a first phase control circuit, a second phase control circuit and a PID controller.

[0035] In a specific implementation of the present invention, the first oscillation circuit includes a first transimpedance amplifier 1-1, a first phase detector 1-2, a first loop PI controller 1-3, a first digitally controlled oscillator 1-4 and a first adder 1-5; the first oscillation circuit enables the first resonator 1-6 to achieve self-excited oscillation, wherein the input end of the first transimpedance amplifier 1-1 is connected to the detection plate of the first resonator 1-6, and the output end of the first transimpedance amplifier 1-1 is input into the first resonator 1-6 after passing through the first phase detector 1-2, the first loop PI controller 1-3, the first digitally controlled oscillator 1-4 and the first adder 1-5 to achieve closed-loop oscillation. Specifically, the first transimpedance amplifier 1-1 converts the high internal resistance dynamic current signal obtained by the detection plate of the first resonator 1-6 into a low internal resistance voltage signal output by the amplifier, the first phase detector 1-2 detects the phase difference between the output signal of the first transimpedance amplifier 1-1 and the feedback signal of the first digital controlled oscillator 1-4, and converts the detected phase difference signal into a voltage signal for output, the first loop PI controller 1-3 adjusts the signal output by the first phase detector 1-2 by proportion and integration, outputs a stable voltage signal to control the first digital controlled oscillator 1-4, and the output signal of the first digital controlled oscillator 1-4 is fed back to the input end of the first phase detector 1-2. After repeated phase detection, adjustment and feedback, the voltage signal output by the first digital controlled oscillator 1-4 finally has the same frequency and phase as the input signal obtained by the first phase detector 1-2, and the voltage signal is returned to the excitation plate of the first resonator 1-6 through the first adder 1-5 to form a loop.

[0036] The second oscillation circuit includes a second transimpedance amplifier 2-1, a second phase detector 2-2, a second loop PI controller 2-3, a second digitally controlled oscillator 2-4 and a second adder 2-5; the second oscillation circuit enables the second resonator 2-6 to achieve self-excited oscillation, wherein the input end of the second transimpedance amplifier 2-1 is connected to the detection plate of the second resonator 2-6, and the output end of the second transimpedance amplifier 2-1 is input into the second resonator 2-6 after passing through the second phase detector 2-2, the second loop PI controller 2-3, the second digitally controlled oscillator 2-4 and the second adder 2-5 to achieve closed-loop oscillation. Specifically, the second transimpedance amplifier 2-1 converts the high internal resistance dynamic current signal obtained by the second resonator 2-6 detection plate into a low internal resistance voltage signal output by the amplifier, the second phase detector 2-2 detects the phase difference between the output signal of the second transimpedance amplifier 2-1 and the feedback signal of the second digital control oscillator 2-4, and converts the detected phase difference signal into a voltage signal for output, the second loop PI controller 2-3 adjusts the signal output by the second phase detector 2-2 by proportion and integration, outputs a stable voltage signal to control the second digital control oscillator 2-4, and the output signal of the second digital control oscillator 2-4 is fed back to the input end of the second phase detector 2-2. After repeated phase detection, adjustment and feedback, the voltage signal output by the second digital control oscillator 2-4 has the same frequency and phase as the input signal obtained by the second phase detector 2-2, and the voltage signal is returned to the excitation plate of the second resonator 2-6 through the second adder 2-5 to form a loop.

[0037] The first phase control circuit includes a first amplitude controller 3-1 and a first phase shifter 3-2. The signal output by the first transimpedance amplifier 1-1 in the first oscillation circuit is adjusted in amplitude by the first amplitude controller 3-1, and then the signal phase is adjusted by the first phase shifter 3-2 and then injected into the second oscillation circuit through the second adder 2-5. Before establishing mutual synchronization, the phase of the signal injected from the first oscillation circuit into the second oscillation circuit can be changed by adjusting the first phase shifter 3-2, thereby adjusting the oscillation frequency of the second oscillation circuit.

[0038] The second phase-shift feedback circuit includes a second amplitude controller 4-1 and a second phase shifter 4-2. The signal output by the second transimpedance amplifier 2-1 in the second oscillation circuit is adjusted in amplitude by the second amplitude controller 4-1, and then the signal phase is adjusted by the second phase shifter 4-2 before being injected into the first oscillation circuit through the first adder 1-5. Similarly, before establishing mutual synchronization, the phase of the signal injected into the first oscillation circuit by the second oscillation circuit can be changed by adjusting the second phase shifter 4-2, thereby achieving the adjustment of the oscillation frequency of the second oscillation circuit.

[0039] The PID controller 5 is connected to the first phase shifter 3-2 or the second phase shifter 4-2 to stabilize the oscillation frequency and suppress the drift of the oscillation frequency of the oscillator due to factors such as temperature changes. Figure 1 Taking the access to the first phase shifter 3-2 as an example, the input end of the PID controller 5 is connected to the output end of the second numerically controlled oscillator 2-4 in the second oscillation loop to obtain the oscillation frequency of the output signal of the second numerically controlled oscillator 2-4, that is, the current oscillation frequency; the output end of the PID controller 5 is connected to the first phase shifter 3-2. By setting the target oscillation frequency in the PID controller 5, the PID controller 5 calculates the output phase control amount according to the error between the current oscillation frequency and the set oscillation frequency, so as to control the first phase shifter 3-2 to change the phase of the signal injected into the second oscillation loop by the first oscillation loop.

[0040] In this embodiment, the first resonator and the second resonator are both double-ended tuning fork beams with a length of 10 to 500 μm, and a width of a single tuning fork beam of 3 to 5 μm. Those skilled in the art may also use other types of resonators, such as cantilever beam resonators, disk resonators, etc. The resonators are each equipped with an excitation plate and a detection plate, wherein the excitation plate can be used to apply an AC signal and a DC signal to excite the resonator, and the detection plate can be used to detect and obtain the oscillation signal of the resonator.

[0041] The phase control process of the mutually synchronous oscillator proposed in the present invention is as follows:

[0042] (1) Establish mutual synchronization between the first oscillation circuit and the second oscillation circuit:

[0043] An excitation signal is applied to the excitation plates of the first resonator and the second resonator respectively, and the two resonators work. The signal of the first oscillation circuit is injected into the second oscillation circuit through the first amplitude controller and the first phase shifter, and the signal of the second oscillation circuit is injected into the first oscillation circuit through the second amplitude controller and the second phase shifter. The first phase shifter and the second phase shifter are adjusted simultaneously or separately. When the oscillation frequencies of the two oscillation circuits are close to each other, the two oscillation circuits can be synchronized to establish a mutually synchronized oscillator. After synchronization, the oscillation frequencies of the first oscillation circuit and the second oscillation circuit are the same. At this time, when the first phase shifter or the second phase shifter is adjusted again, the oscillation frequency of the entire mutually synchronized oscillator can be controlled. Figure 2 The figure shows the correspondence between the oscillation frequency of the mutually synchronous oscillator and the phase of the signal injected into the second oscillation circuit by the first oscillation circuit during the synchronization process. It can be seen that the oscillation frequency of the entire mutually synchronous oscillator can be controlled by adjusting the second phase shifter to change the phase of the signal injected into the second oscillation circuit by the first oscillation circuit.

[0044] The above-mentioned simultaneous or separate adjustment of the first phase shifter and the second phase shifter refers to adjusting the first phase shifter 3-2 to change the phase of the signal injected into the second oscillation loop by the first oscillation loop, and / or adjusting the second phase shifter 4-2 to change the phase of the signal injected into the first oscillation loop by the second oscillation loop.

[0045] (2) Stabilizing the oscillation frequency of mutually synchronized oscillators by phase control:

[0046] See also Figure 3 After mutual synchronization is established, the oscillation frequency of the mutual synchronization oscillator is preset PID controller obtains the current real-time oscillation frequency of the mutually synchronous oscillator After that, calculate the error between the current oscillation frequency and the set oscillation frequency , and outputs a phase control amount based on this error value. The phase control amount acts on the first phase shifter 3-2 to update the phase of the signal injected into the second oscillation loop by the first oscillation loop in real time, thereby realizing the regulation of the oscillation frequency of the mutually synchronous oscillator, so that the oscillation frequency of the mutually synchronous oscillator is always stable near the set oscillation frequency.

[0047] See also Figure 4 The mutually synchronous oscillator of the present invention is placed in an environment with changing temperature. As the temperature changes, the oscillation frequency of the oscillator will drift. By comparing the frequency stability of the oscillator with and without phase control, it can be seen that within 1000s, the frequency stability is characterized by Allan variance. The mutually synchronous oscillator with phase control can achieve a 3-order-of-magnitude improvement in frequency stability. The present invention can effectively suppress temperature drift and greatly improve frequency stability, providing a solution to the problem of frequency offset when the MEMS oscillator works in an environment with changing temperature.

[0048] The present invention can realize flexible regulation of the oscillation frequency of the MEMS oscillator without introducing additional thermal noise and increasing power, greatly improving the long-term frequency stability of the MEMS oscillator and solving the practical application problems caused by the poor frequency stability of the oscillator.

[0049] 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 MEMS mutually synchronized oscillator based on phase control, characterized in that: It includes a PID controller and a pair of oscillator modules, wherein the oscillator modules are composed of a resonator, an oscillation loop and a phase control circuit; The oscillation circuit in each oscillator module is used to enable the resonator in the oscillator module to achieve self-oscillation; The signal of the oscillation loop in each oscillator module is injected into the oscillation loop in another oscillator module through the phase control circuit in the oscillator module; The PID controller is connected to the oscillation circuit in one of the oscillator modules and the phase control circuit in the other oscillator module to obtain the oscillation frequency in the connected oscillation circuit. The PID controller outputs a phase control amount according to the error between the obtained oscillation frequency and the set oscillation frequency. The phase control amount acts on the phase control circuit in the other oscillator module to change the phase of the injected signal.

2. The phase-controlled MEMS mutually synchronized oscillator according to claim 1, characterized in that: The oscillation circuit comprises a transimpedance amplifier, a phase detector, a loop PI controller, a digitally controlled oscillator and an adder; the signal input end of the transimpedance amplifier is connected to the detection plate of the resonator, and the signal output end of the transimpedance amplifier is returned to the excitation plate of the resonator after passing through the phase detector, the loop PI controller, the digitally controlled oscillator and the adder.

3. The phase-controlled MEMS mutually synchronized oscillator according to claim 2, characterized in that: The phase detector, loop PI controller and digitally controlled oscillator also constitute a sub-loop; the transimpedance amplifier converts the high internal resistance dynamic current signal obtained by the resonator detection plate into a low internal resistance voltage signal, the phase detector detects the phase difference between the output signal of the transimpedance amplifier and the feedback signal of the digitally controlled oscillator, and converts the detected phase difference signal into a voltage signal and outputs it to the loop PI controller, the loop PI controller adjusts the received signal, outputs a stable voltage signal to control the digitally controlled oscillator, and the voltage signal output by the digitally controlled oscillator is fed back to the phase detector; after repeated phase detection, adjustment and feedback, the voltage signal output by the digitally controlled oscillator is finally returned to the excitation plate of the resonator through the adder.

4. The phase-controlled MEMS mutually synchronized oscillator according to claim 2, characterized in that: The phase control circuit includes an amplitude controller and a phase shifter, wherein the signal input end of the amplitude controller is connected to the signal output end of the transimpedance amplifier in the oscillation circuit, the signal output end of the amplitude controller is connected to the signal input end of the phase shifter, and the signal output end of the phase shifter is connected to the adder in the oscillation circuit.

5. The phase-controlled MEMS mutually synchronized oscillator according to claim 4, characterized in that: The signal input end of the PID controller is connected to the signal output end of the digital controlled oscillator in the oscillation loop, and the signal output end of the PID controller is connected to the control end of the phase shifter in the phase control circuit.

6. The phase-controlled MEMS mutually synchronized oscillator according to claim 1, characterized in that: The phase control method of the MEMS mutually synchronous oscillator comprises: (1) Establish mutually synchronized oscillators: Apply an excitation signal to the resonator in each oscillator module to achieve closed-loop oscillation; adjust the phase control circuit in the oscillator module to change the phase of the injection signal, so that the phase of the injection signal received by each oscillator module only affects the oscillation frequency of the oscillator module until a pair of oscillation loops are synchronized to establish a mutually synchronized oscillator; (2) Stabilize the oscillation frequency of mutually synchronized oscillators: The oscillation frequency of the mutually synchronous oscillator is preset, and the PID controller obtains the oscillation frequency of the connected oscillation loop as the current oscillation frequency of the mutually synchronous oscillator, and calculates the error between the current oscillation frequency and the set oscillation frequency, and outputs a phase control amount according to the error value. The phase control amount acts on the connected phase control circuit, and adjusts the current oscillation frequency of the mutually synchronous oscillator by changing the phase of the injected signal, so that the current oscillation frequency of the mutually synchronous oscillator is stabilized at the set oscillation frequency.

7. The phase-controlled MEMS mutually synchronized oscillator according to claim 6, characterized in that: The phase control quantity output by the PID controller acts on the phase shifter in the phase control circuit.

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