A dual-resonant MEMS sensor and method of operation thereof

Abstract

The application discloses a kind of double-resonance MEMS sensor and its working method, double-resonance MEMS sensor includes: first oscillator, second oscillator, frequency discriminator and phase detector and delay control circuit;Oscillator includes resonator and resonance circuit, resonance circuit includes delayer;Resonator detects the capacitive signal generated by signal to be measured, resonance circuit is used to output analog feedback signal under the control of delayer according to capacitive signal, analog feedback signal is input into resonator to form closed loop circuit;Frequency discriminator and phase detector detect the frequency and phase of the digital signal input into two delayers, output control signal of delay control circuit when frequency difference is less than preset first threshold and phase difference is less than preset second threshold, and delay control circuit controls two delayers to carry out delay adjustment according to control signal, so that the phase of two analog feedback signals is out of step.The application can avoid the problem of resonance measurement blind area when the frequency of two resonators of double-resonance MEMS sensor is close.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of double-resonant MEMS sensor and its working method, belong to electronic circuit technical field. BACKGROUND

[0002] Resonant MEMS sensor utilizes the change of inherent frequency of micro mechanical structure vibration to realize the accurate perception of to-be-measured quantity. Since temperature change will cause the inherent frequency of micro mechanical structure to change, and then produce measurement error, therefore, resonant MEMS sensor usually adopts double-resonator design scheme, that is, two resonators are designed in sensor, wherein the inherent frequency of one resonator changes positively with measured quantity, and the inherent frequency of another resonator changes negatively with measured quantity. By measuring the frequency difference of the two resonators, the sensitivity is increased (differential mode useful signal), and the error signals such as temperature are suppressed (common mode error signal).

[0003] After actual processing, due to manufacturing error, the frequency values of the two resonators are not exactly the same. When the resonators sense the to-be-measured signal, the frequency of one resonator increases, and the frequency of another resonator decreases. If the input to-be-measured signal just makes the resonator with smaller resonant frequency increase, and the resonator with larger resonant frequency decrease, then at a certain input to-be-measured signal, the frequencies of the two resonators change to the same frequency. When the frequency difference of the two resonators is very small, the micro mechanical structures of the two resonators resonate, and then the vibration frequencies of the two resonators are locked to the same frequency, and no longer change with input signal. Only when the input to-be-measured signal deviates from the value, the two resonators are unlocked, the micro mechanical structures of the two resonators no longer resonate, and the resonant frequencies of the two resonators change with input signal again, to realize the measurement of input signal. The region in which the input signal makes the micro mechanical structure of resonator resonate is the measurement blind area.

[0004] The essence of this phenomenon is that the motion of resonator always tends to consume the least energy. The vibration frequencies and phases of the two resonator structures are the same in synchronous resonance state, so that the energy loss of vibration is minimized.

[0005] Taking a capacitive MEMS double-resonant sensor as an example, a simplified model of a micro mechanical structure of double-resonant MEMS sensor is shown in FIG. 1. The left side is resonator 1, and the right side is resonator 2. When the frequency difference of the two resonators is very small, the two resonators resonate, and work at the same resonant frequency, to form in-phase resonance, as shown in FIG. 2. Then, the vibration frequencies of the two resonators are locked to the same frequency, and no longer change with input signal. At this time, the double-resonant sensor cannot detect input signal, and forms measurement blind area, as shown in FIG. 3. Figure 1 Figure 2 Figure 3 ​​​

[0006] In summary, the existing double-resonance sensor has a resonance measurement blind area when the frequencies of the two resonators are close. SUMMARY

[0007] The present application aims to overcome the deficiencies in the prior art, and provides a double-resonance MEMS sensor and a working method thereof, which can avoid the problem of resonance measurement blind area when the frequencies of the two resonators of the double-resonance MEMS sensor are close. To achieve the above-mentioned purpose, the present application is realized by using the following technical solutions:

[0008] In a first aspect, the present application provides a double-resonance MEMS sensor, comprising: a first oscillator, a second oscillator, a frequency and phase discriminator, and a delay control circuit; the first oscillator comprises a first resonator and a first resonance circuit, the first resonance circuit comprises a first delay, the second oscillator comprises a second resonator and a second resonance circuit, and the second resonance circuit comprises a second delay;

[0009] The first resonator is used to detect a to-be-measured signal to generate a first capacitance signal, the first resonance circuit is used to output a first analog feedback signal under the control of the first delay according to the first capacitance signal, and the first analog feedback signal is input into the first resonator to form a closed-loop circuit;

[0010] The second resonator is used to detect a to-be-measured signal to generate a second capacitance signal, the second resonance circuit is used to output a second analog feedback signal under the control of the second delay according to the second capacitance signal, and the second analog feedback signal is input into the second resonator to form a closed-loop circuit;

[0011] The frequency and phase discriminator is connected in parallel with the first delay and the second delay, and is used to detect the frequency and phase of a first digital signal input into the first delay and a second digital signal input into the second delay, and output a control signal of the delay control circuit when the frequency difference between the first digital signal and the second digital signal is less than a preset first threshold value and the phase difference is less than a preset second threshold value, the delay control circuit controls the first delay and the second delay to adjust the delay according to the control signal, so that the phases of the first analog feedback signal and the second analog feedback signal are out of synchronization.

[0012] In combination with the first aspect, optionally, the first resonator and the second resonator are the same resonator assembly;

[0013] The resonator assembly comprises a micro-mechanical structure, a detection capacitance, and a driving capacitance;

[0014] The micro-mechanical structure is used to generate a vibration signal by changing the micro-mechanical structure vibration with the to-be-measured signal;

[0015] The input end of the detection capacitor is connected to the micro mechanical structure, and the output end is connected to a resonance circuit, which is used for detecting the displacement of the vibration signal, generating a capacitor signal according to the detected displacement of the vibration signal, and outputting to the resonance circuit;

[0016] The input end of the drive capacitor is connected to the resonance circuit, and the output end is connected to the micro mechanical structure. The drive capacitor of the first resonator is used for driving the first resonator to vibrate according to the first analog feedback signal output by the first resonance circuit. The drive capacitor of the second resonator is used for driving the second resonator to vibrate according to the second analog feedback signal output by the second resonance circuit.

[0017] When the phases of the first analog feedback signal and the second analog feedback signal are out of synchronization, the vibration signals generated by the micro mechanical structure of the first resonator and the micro mechanical structure of the second resonator are out of synchronization.

[0018] In combination with the first aspect, optionally, the working mode resonance frequency of the first resonator increases with the increase of the to-be-measured signal, and the working mode resonance frequency of the second resonator decreases or remains unchanged with the increase of the to-be-measured signal.

[0019] In combination with the first aspect, optionally, the first resonator stably vibrates at a first working mode resonance frequency, and the first working mode resonance frequency increases with the increase of the to-be-measured signal.

[0020] The second resonator stably vibrates at a second working mode resonance frequency, and the second working mode resonance frequency decreases or remains unchanged with the increase of the to-be-measured signal.

[0021] In combination with the first aspect, optionally, the first resonance circuit comprises a first C / V conversion circuit, a first A / D conversion circuit, a first AGC gain circuit, a first delay unit and a first D / A conversion circuit.

[0022] The input end of the first C / V conversion circuit is connected to the output end of the first resonator, and is used for converting the first capacitor signal into a first voltage signal, so as to convert the motion signal of the first resonator into a first analog electric signal.

[0023] The input end of the first A / D conversion circuit is connected to the output end of the first C / V conversion circuit, and is used for converting the first voltage signal into a first digital signal.

[0024] The input end of the first AGC gain circuit is connected to the output end of the first A / D conversion circuit, and is used for performing amplitude stabilization control on the first digital signal, so as to make the vibration amplitude of the first resonator constant.

[0025] The input end of the first delay timer is connected with the output end of the first AGC gain circuit and the output end of the delay control circuit, for outputting a first digital feedback signal under the control of the delay control circuit;

[0026] The input end of the first D / A conversion circuit is connected with the output end of the first delay timer, and the output end is connected with the first resonator, for converting the first digital feedback signal into a first analog feedback signal to input the first resonator to form a closed loop circuit.

[0027] In combination with the first aspect, optionally, the second resonant circuit comprises a second C / V conversion circuit, a second A / D conversion circuit, a second AGC gain circuit, a second delay timer and a second D / A conversion circuit;

[0028] The input end of the second C / V conversion circuit is connected with the output end of the second resonator, for converting the second capacitive signal into a second voltage signal to realize the conversion of the motion signal of the second resonator into a second analog electric signal;

[0029] The input end of the second A / D conversion circuit is connected with the output end of the second C / V conversion circuit, for converting the second voltage signal into a second digital signal;

[0030] The input end of the second AGC gain circuit is connected with the output end of the second A / D conversion circuit, for performing amplitude stabilization control on the second digital signal to make the vibration amplitude of the second resonator constant;

[0031] The input end of the second delay timer is connected with the output end of the second AGC gain circuit and the output end of the delay control circuit, for outputting a second digital feedback signal under the control of the delay control circuit;

[0032] The input end of the second D / A conversion circuit is connected with the output end of the second delay timer, and the output end is connected with the second resonator, for converting the second digital feedback signal into a second analog feedback signal to input the second resonator to form a closed loop circuit.

[0033] In combination with the first aspect, optionally, the first AGC gain circuit and the second AGC gain circuit are arranged in the same digital circuit and work independently.

[0034] In combination with the first aspect, optionally, the input end of the delay control circuit is further connected with a system clock module, for taking the system clock signal as a reference time to make the delay control circuit output different delay signals to the first delay timer and the second delay timer.

[0035] Secondly, the application provides a working method of the double-resonant MEMS sensor based on the first aspect, comprising:

[0036] In response to detecting the to-be-tested signal, the first resonator generates a first capacitance signal, and the second resonator generates a second capacitance signal;

[0037] The frequency discriminator detects a frequency difference and a phase difference between the first digital signal input to the first delay unit and the second digital signal input to the second delay unit;

[0038] In response to the frequency difference between the first digital signal and the second digital signal being less than a preset first threshold value and the phase difference being less than a preset second threshold value, the frequency discriminator outputs a control signal of the delay control circuit; the delay control circuit controls the first delay unit and the second delay unit to perform delay adjustment according to the control signal, the first resonant circuit outputs a first analog feedback signal under the control of the first delay unit according to the first capacitance signal, and the second resonant circuit outputs a second analog feedback signal under the control of the second delay unit according to the second capacitance signal; wherein the phases of the first analog feedback signal and the second analog feedback signal are not synchronized.

[0039] The first analog feedback signal is input to the first resonator to form a closed-loop circuit, and the second analog feedback signal is input to the second resonator to form a closed-loop circuit.

[0040] In combination with the second aspect, optionally, the delay control circuit controls the first delay unit and the second delay unit to perform delay adjustment according to the control signal, including:

[0041] The delay control circuit outputs a first delay signal of the first delay unit and a second delay signal of the second delay unit according to the control signal output by the frequency discriminator;

[0042] The first delay unit performs delay adjustment on the first digital signal according to the first delay signal to output a first digital feedback signal; and the second delay unit performs delay adjustment on the second digital signal according to the second delay signal to output a second digital feedback signal.

[0043] In combination with the second aspect, optionally, the control of the first delay unit and the second delay unit to perform delay adjustment includes single delay adjustment and synchronous delay adjustment.

[0044] The single delay adjustment: outputs the first delay signal or the second delay signal, controls either of the first delay unit and the second delay unit to work, and the digital feedback signal output by the delay unit performing delay adjustment is different in phase from the input digital signal, the digital feedback signal output by the delay unit not performing delay adjustment is the same in phase as the input digital signal, so that the phases of the digital feedback signals output by the first delay unit and the second delay unit are not synchronized.

[0045] The synchronous delay adjustment outputs a first delay signal and a second delay signal, simultaneously performs delay adjustment on the first delay device and the second delay device, the delay time of the first delay signal and the second delay signal is different, and the phases of the analog feedback signals output by the first delay device and the second delay device are different.

[0046] Compared with the prior art, the double-resonance MEMS sensor and the working method thereof provided by the embodiment of the application have the following beneficial effects:

[0047] The double-resonance MEMS sensor provided by the application comprises a frequency and phase discriminator, when the frequency difference and the phase difference of the first digital signal and the second digital signal are detected to be less than the preset first threshold value and the preset second threshold value, respectively, a control signal of a delay control circuit is output, and the delay control circuit controls the first delay device and the second delay device to output the first digital feedback signal and the second digital feedback signal with different phases according to the control signal; the delay control circuit provided by the application enables the increased phase control not to affect the vibration amplitude and the frequency of the resonator under the 360º phase constraint condition of the resonator closed loop, and not to affect the sensitivity of the double-resonance MEMS sensor.

[0048] The application forces the phases of the two analog feedback signals to be different, forces the vibrations of the two resonators to be different, prevents the vibrations of the two resonators from interfering with each other to form resonance, and avoids the problem of the resonance measurement blind area when the frequencies of the two resonators are close; at the same time, the phase information can distinguish the vibration signals of the two resonators, and higher-resolution sensing detection can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a simplified model diagram of the micro-mechanical structure of the double-resonance MEMS sensor provided by the background art of the application;

[0050] Figure 2 is a frequency change curve diagram of the double-resonance MEMS sensor provided by the background art of the application when resonance occurs;

[0051] Figure 3 is a schematic diagram of the in-phase vibration of the resonant structure of the double-resonance MEMS sensor provided by the background art of the application when resonance occurs;

[0052] Figure 4 is a structure diagram of the double-resonance MEMS sensor provided by embodiment 1 of the application;

[0053] Figure 5 is a frequency change curve of the resonator of the double-resonance MEMS sensor provided by embodiment 1 of the application;

[0054] Figure 6is another variation curve of the frequency of a resonator of a dual-resonant MEMS sensor provided by Embodiment 1 of the present application with respect to an input quantity;

[0055] Figure 7 is a schematic diagram of different out-of-sync mechanical structure vibrations of a resonator of a dual-resonant MEMS sensor provided by Embodiment 1 of the present application under adjustment of a time delay control circuit. DETAILED DESCRIPTION

[0056] The present application will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0057] Embodiment 1

[0058] As shown in Figure 4 , the present application provides a dual-resonant MEMS sensor, comprising: a first oscillator, a second oscillator, a frequency discriminator and a time delay control circuit.

[0059] The first oscillator and the second oscillator are the same closed loop circuit. The first oscillator comprises a first resonator and a first resonant circuit, and the first resonant circuit comprises a first time delay device. The second oscillator comprises a second resonator and a second resonant circuit, and the second resonant circuit comprises a second time delay device.

[0060] The first resonator is used to detect a to-be-measured signal to generate a first capacitance signal. The first resonant circuit is used to output a first analog feedback signal under control of the first time delay device according to the first capacitance signal. The first analog feedback signal is input into the first resonator to form a closed loop circuit.

[0061] The second resonator is used to detect a to-be-measured signal to generate a second capacitance signal. The second resonant circuit is used to output a second analog feedback signal under control of the second time delay device according to the second capacitance signal. The second analog feedback signal is input into the second resonator to form a closed loop circuit.

[0062] The first resonator and the second resonator are the same resonator assembly.

[0063] Specifically, the resonator assembly comprises a micro mechanical structure, a detection capacitance and a driving capacitance.

[0064] The micro mechanical structure is used to generate a micro mechanical structure vibration with the to-be-measured signal changing, to generate a vibration signal.

[0065] The input end of the detection capacitance is connected to the micro mechanical structure, and the output end is connected to the resonant circuit. The detection capacitance is used to detect the displacement of the vibration signal, to generate a capacitance signal according to the detected displacement of the vibration signal, and to output the capacitance signal to the resonant circuit.

[0066] The input end of the driving capacitor is connected with the resonant circuit, and the output end is connected with the micro mechanical structure. The driving capacitor of the first resonator is used to drive the first resonator to vibrate according to the first analog feedback signal output by the first resonant circuit. The driving capacitor of the second resonator is used to drive the second resonator to vibrate according to the second analog feedback signal output by the second resonant circuit. When the phases of the first analog feedback signal and the second analog feedback signal are out of synchronization, the vibration signals generated by the micro mechanical structure of the first resonator and the micro mechanical structure of the second resonator are out of synchronization.

[0067] As shown in Figure 5 and Figure 6 , the first resonator stably vibrates at the first working mode resonant frequency, and the first working mode resonant frequency increases with the increase of the to-be-measured signal.

[0068] The second oscillator stably vibrates at the second working mode resonant frequency, and the second working mode resonant frequency decreases (as shown in Figure 5 ) / remains unchanged (as shown in Figure 6 ) with the increase of the to-be-measured signal.

[0069] As shown in Figure 4 , the first resonant circuit includes a first C / V conversion circuit, a first A / D conversion circuit, a first AGC gain circuit, a first delay timer and a first D / A conversion circuit.

[0070] The input end of the first C / V conversion circuit is connected with the output end of the first resonator, and is used to convert the motion signal of the first resonator into the first analog electric signal by converting the first capacitance signal into the first voltage signal.

[0071] The input end of the first A / D conversion circuit is connected with the output end of the first C / V conversion circuit, and is used to convert the first voltage signal into the first digital signal.

[0072] The input end of the first AGC gain module is connected with the output end of the first A / D conversion circuit, and is used to perform amplitude stabilization control on the first digital signal to make the vibration amplitude of the first resonator constant.

[0073] The input end of the first delay timer is connected with the output end of the first AGC gain module and the output end of the delay control circuit, and is used to output the first digital feedback signal under the control of the delay control circuit.

[0074] The input end of the first D / A conversion circuit is connected with the output end of the first delay timer, and the output end is connected with the first resonator, and is used to convert the first digital feedback signal into the first analog feedback signal and input the first resonator to form a closed loop circuit.

[0075] As shown in Figure 4The second resonant circuit comprises a second C / V conversion circuit, a second A / D conversion circuit, a second AGC gain circuit, a second delay timer and a second D / A conversion circuit.

[0076] The input end of the second C / V conversion circuit is connected with the output end of the second resonator, and is configured to convert the motion signal of the second resonator into a second analog electric signal by converting the second capacitance signal into a second voltage signal.

[0077] The input end of the second A / D conversion circuit is connected with the output end of the second C / V conversion circuit, and is configured to convert the second voltage signal into a second digital signal.

[0078] The input end of the second AGC gain circuit is connected with the output end of the second A / D conversion circuit, and is configured to perform amplitude stabilization control on the second digital signal, so as to make the vibration amplitude of the second resonator constant.

[0079] The input end of the second delay timer is connected with the output end of the second AGC gain circuit and the output end of the delay control circuit, and is configured to output a second digital feedback signal under the control of the delay control circuit.

[0080] The input end of the second D / A conversion circuit is connected with the output end of the second delay timer, and the output end is connected with the second resonator, and is configured to convert the second digital feedback signal into a second analog feedback signal and input the second analog feedback signal into the second resonator to form a closed loop circuit.

[0081] In the embodiment, the first AGC gain circuit and the second AGC gain circuit are arranged in the same digital circuit and work independently.

[0082] The design of the double-resonator assembly realizes the increase of the sensitivity of the measured quantity and the suppression of error signals such as temperature by measuring the frequency difference of the resonator assembly.

[0083] The frequency discriminator is connected with the first delay timer and the second delay timer in parallel, and is configured to detect the frequency and phase of the first digital signal input into the first delay timer and the second digital signal input into the second delay timer. When the frequency difference between the first digital signal and the second digital signal is less than a preset first threshold value and the phase difference is less than a preset second threshold value, a control signal of the delay control circuit is output, and the delay control circuit controls the first delay timer and the second delay timer to adjust the delay according to the control signal, so that the phases of the first analog feedback signal and the second analog feedback signal are out of synchronization.

[0084] Specifically, the delay control circuit outputs a first delay signal of the first delay timer and a second delay signal of the second delay timer according to the control signal output by the frequency discriminator. The input end of the delay control circuit is also connected with a system clock module, and is configured to take the system clock signal as a reference time, so that the first delay signal and the second delay signal output by the delay control circuit are different.

[0085] The embodiment adds a frequency discriminator and a delay control circuit in the control circuit of the dual-resonance MEMS sensor, uses a system clock signal as a time reference, and adjusts the delay of the first analog feedback signal and the second analog feedback signal, specifically, adds a single delay in a single period, realizes single delay of the feedback signals of the two closed-loop circuits in a single period, forces the phases of the two frequency close signals to be different, and makes the phases of the two resonators different at the same time as shown in the figure. Figure 7 The embodiment forces the phases of the two analog feedback signals to be different, realizes forced different vibration of the two resonator mechanical structures, makes the vibrations of the two resonators not interfere with each other to form resonance, and avoids the problem of the resonance measurement blind area when the frequencies of the two resonators are close. At the same time, through the phase information, the vibration signals of the two resonators can be distinguished, and higher resolution sensing detection can be realized. The embodiment forces the phases of the two analog feedback signals to be different, realizes forced different vibration of the two resonator mechanical structures, makes the vibrations of the two resonators not interfere with each other to form resonance, and avoids the problem of the resonance measurement blind area when the frequencies of the two resonators are close. At the same time, through the phase information, the vibration signals of the two resonators can be distinguished, and higher resolution sensing detection can be realized.

[0086] The delay control circuit provided in the embodiment makes the increased phase control not affect the vibration amplitude and frequency of the resonator under the 360º phase constraint condition of the resonator closed-loop circuit, and does not affect the sensitivity of the dual-resonance MEMS sensor.

[0087] The embodiment forces the phases of the two analog feedback signals to be different, realizes forced different vibration of the two resonator mechanical structures, makes the vibrations of the two resonators not interfere with each other to form resonance, and avoids the problem of the resonance measurement blind area when the frequencies of the two resonators are close. At the same time, through the phase information, the vibration signals of the two resonators can be distinguished, and higher resolution sensing detection can be realized.

[0088] Embodiment 2

[0089] The embodiment of the present application provides a working method of the dual-resonance MEMS sensor based on the embodiment 1, comprising:

[0090] In response to detecting the to-be-measured signal, the first resonator generates a first capacitance signal, and the second resonator generates a second capacitance signal;

[0091] The frequency discriminator detects the frequency difference and the phase difference between the first digital signal input into the first delay unit and the second digital signal input into the second delay unit;

[0092] In response to the frequency difference between the first digital signal and the second digital signal being less than a preset first threshold value and the phase difference being less than a preset second threshold value, the frequency discriminator outputs a control signal of the delay control circuit; the delay control circuit controls the first delay unit and the second delay unit to perform delay adjustment according to the control signal, the first resonant circuit outputs a first analog feedback signal under the control of the first delay unit according to the first capacitance signal, and the second resonant circuit outputs a second analog feedback signal under the control of the second delay unit according to the second capacitance signal; wherein the phases of the first analog feedback signal and the second analog feedback signal are different.

[0093] The first analog feedback signal is input into the first resonator to form a closed-loop circuit, and the second analog feedback signal is input into the second resonator to form a closed-loop circuit.

[0094] Specifically, it comprises:

[0095] Step 1: in response to detecting the to-be-tested signal, the micro-mechanical structure of the first resonator vibrates in response to the change of the to-be-tested signal, generating a first vibration signal; the micro-mechanical structure of the second resonator vibrates in response to the change of the to-be-tested signal, generating a second vibration signal.

[0096] Step 2: the detection capacitor of the first resonator detects the displacement of the first vibration signal, and generates a first capacitor signal according to the detected displacement of the first vibration signal. The detection capacitor of the second resonator detects the displacement of the second vibration signal, and generates a second capacitor signal according to the detected displacement of the second vibration signal.

[0097] Step 3: the first capacitor signal is input into the first C / V conversion circuit to be converted into a first voltage signal. The second capacitor signal is input into the second C / V conversion circuit to be converted into a second voltage signal.

[0098] Step 4: the first voltage signal is input into the first A / D conversion circuit to be converted into a first digital signal. The second voltage signal is input into the second A / D conversion circuit to be converted into a second digital signal.

[0099] Step 5: the first digital signal is input into the first AGC gain circuit for amplitude stabilization control, so as to ensure that a first analog feedback signal obtained based on the first digital signal can make the vibration amplitude of the micro-mechanical structure of the first resonator constant. The second digital signal is input into the second AGC gain circuit for amplitude stabilization control, so as to ensure that a second analog feedback signal obtained based on the second digital signal can make the vibration amplitude of the micro-mechanical structure of the second resonator constant.

[0100] Step 6: the adjusted first digital signal and second digital signal are output to the frequency discriminator.

[0101] Step 7: the frequency discriminator detects the frequency difference and phase difference between the first digital signal and the second digital signal.

[0102] If the frequency difference between the first digital signal and the second digital signal is greater than or equal to a preset first threshold, no delay adjustment is performed.

[0103] If the phase difference between the first digital signal and the second digital signal is greater than or equal to a preset second threshold, no delay adjustment is performed.

[0104] Step 8: in response to the frequency difference between the first digital signal and the second digital signal being less than the preset first threshold and the phase difference between the first digital signal and the second digital signal being less than the preset second threshold, the frequency discriminator outputs a control signal of a delay control circuit.

[0105] Step 9: the delay control circuit performs delay adjustment according to the control signal, and controls the first delay timer and the second delay timer to output the first digital feedback signal and the second digital feedback signal with different phases.

[0106] Step 9.1: The delay control circuit outputs a first delay signal of the first delay unit and a second delay signal of the second delay unit according to the control signal output by the phase detector.

[0107] Step 9.2: The first delay unit adjusts the first digital signal according to the first delay signal to output a first digital feedback signal. The second delay unit adjusts the second digital signal according to the second delay signal to output a second digital feedback signal.

[0108] Specifically, the delay adjustment includes single delay adjustment and synchronous delay adjustment.

[0109] Single delay adjustment: outputting the first delay signal or the second delay signal to control either the first delay unit or the second delay unit to work to perform delay adjustment, the digital feedback signal output by the delay unit not performing delay adjustment is in phase with the input digital signal, and the digital feedback signal output by the delay unit performing delay adjustment is out of phase with the input digital signal, so that the phases of the digital feedback signals output by the first delay unit and the second delay unit are different.

[0110] Synchronous delay adjustment: outputting the first delay signal and the second delay signal to simultaneously perform delay adjustment on the first delay unit and the second delay unit, the delay time lengths of the first delay signal and the second delay signal are different, so that the phases of the analog feedback signals output by the first delay unit and the second delay unit are different.

[0111] Step 10: The first analog feedback signal is input into the first resonant circuit to form a first closed loop circuit; and the second analog feedback signal is input into the second resonant circuit to form a second closed loop circuit.

[0112] A typical delay scheme is that when the frequency difference between the first digital signal and the second digital signal of the two resonant circuits is less than a preset first threshold and the phase difference is less than a preset second threshold, the delay control circuit outputs the first delay signal to make the first delay unit not delay at time t, and outputs the second delay signal to make the second delay unit output after a corresponding half cycle time of the delay signal at time t, so that the phases of the resonators of the first resonant circuit and the second resonant circuit are forced to be close to anti-phase by the delay control circuit.

[0113] Step 11: The first digital feedback signal is input into the first D / A conversion circuit to be converted into a first analog feedback signal. The second digital feedback signal is input into the second D / A conversion circuit to be converted into a second analog feedback signal.

[0114] Step 12: The first analog feedback signal is input into the first resonator to form a closed loop circuit. The second analog feedback signal is input into the second resonator to form a closed loop circuit.

[0115] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A dual-resonant MEMS sensor, characterized by, The application relates to a frequency and phase detector and a delay control circuit. The first oscillator comprises a first resonator and a first resonant circuit, the first resonant circuit comprises a first delay device, the second oscillator comprises a second resonator and a second resonant circuit, the second resonant circuit comprises a second delay device; The first resonator is used for detecting a to-be-tested signal to generate a first capacitance signal, the first resonant circuit is used for outputting a first analog feedback signal under the control of the first delay device according to the first capacitance signal, and the first analog feedback signal is input into the first resonator to form a closed loop circuit; The second resonator is used for detecting a to-be-tested signal to generate a second capacitance signal, the second resonant circuit is used for outputting a second analog feedback signal under the control of the second delay device according to the second capacitance signal, and the second analog feedback signal is input into the second resonator to form a closed loop circuit; The frequency and phase detector is connected with the first delay device and the second delay device in parallel, is used for detecting the frequency and phase of a first digital signal input into the first delay device and a second digital signal input into the second delay device, and outputs a control signal of the delay control circuit when the frequency difference between the first digital signal and the second digital signal is less than a preset first threshold value and the phase difference is less than a preset second threshold value; the delay control circuit controls the first delay device and the second delay device to adjust the delay according to the control signal, so that the phases of the first analog feedback signal and the second analog feedback signal are different.

2. The dual-resonance MEMS sensor of claim 1, wherein, The first resonator and the second resonator are the same resonator assembly; The resonator assembly comprises a micro mechanical structure, a detection capacitance and a driving capacitance; The micro mechanical structure is used for generating a vibration signal by changing the micro mechanical structure vibration along with the to-be-tested signal; The input end of the detection capacitance is connected with the micro mechanical structure, the output end is connected with the resonant circuit, the detection capacitance is used for detecting the displacement of the vibration signal, generating a capacitance signal according to the detected displacement of the vibration signal, and outputting the capacitance signal to the resonant circuit; The input end of the driving capacitance is connected with the resonant circuit, and the output end is connected with the micro mechanical structure; the driving capacitance of the first resonator is used for driving the first resonator to vibrate according to the first analog feedback signal output by the first resonant circuit; the driving capacitance of the second resonator is used for driving the second resonator to vibrate according to the second analog feedback signal output by the second resonant circuit; When the phases of the first analog feedback signal and the second analog feedback signal are different, the vibration signals generated by the micro mechanical structure of the first resonator and the micro mechanical structure of the second resonator are different.

3. The dual-resonance MEMS sensor of claim 2, wherein, The first resonator is stably vibrated at a first working mode resonant frequency, and the first working mode resonant frequency increases along with the increase of the to-be-tested signal; The second oscillator is stably vibrated at a second working mode resonant frequency, and the second working mode resonant frequency decreases or remains unchanged along with the increase of the to-be-tested signal.

4. The dual-resonance MEMS sensor of claim 1, wherein, The first resonant circuit comprises a first C / V conversion circuit, a first A / D conversion circuit, a first AGC gain circuit, a first delay device and a first D / A conversion circuit. The input end of the first C / V conversion circuit is connected with the output end of the first resonator, for converting the first capacitance signal into a first voltage signal, so as to convert the movement signal of the first resonator into a first analog electric signal; The input end of the first A / D conversion circuit is connected with the output end of the first C / V conversion circuit, for converting the first voltage signal into a first digital signal; The input end of the first AGC gain circuit is connected with the output end of the first A / D conversion circuit, for performing amplitude stable control on the first digital signal, so as to make the vibration amplitude of the first resonator constant; The input end of the first delay timer is connected with the output end of the first AGC gain circuit and the output end of the delay control circuit, for outputting a first digital feedback signal under the control of the delay control circuit; The input end of the first D / A conversion circuit is connected with the output end of the first delay timer, and the output end is connected with the first resonator, for converting the first digital feedback signal into a first analog feedback signal and inputting the first analog feedback signal into the first resonator to form a closed loop circuit.

5. The dual-resonance MEMS sensor of claim 4, wherein, The second resonator circuit comprises a second C / V conversion circuit, a second A / D conversion circuit, a second AGC gain circuit, a second delay timer and a second D / A conversion circuit; The input end of the second C / V conversion circuit is connected with the output end of the second resonator, for converting a second capacitance signal into a second voltage signal, so as to convert the movement signal of the second resonator into a second analog electric signal; The input end of the second A / D conversion circuit is connected with the output end of the second C / V conversion circuit, for converting the second voltage signal into a second digital signal; The input end of the second AGC gain circuit is connected with the output end of the second A / D conversion circuit, for performing amplitude stable control on the second digital signal, so as to make the vibration amplitude of the second resonator constant; The input end of the second delay timer is connected with the output end of the second AGC gain circuit and the output end of the delay control circuit, for outputting a second digital feedback signal under the control of the delay control circuit; The input end of the second D / A conversion circuit is connected with the output end of the second delay timer, and the output end is connected with the second resonator, for converting the second digital feedback signal into a second analog feedback signal and inputting the second analog feedback signal into the second resonator to form a closed loop circuit.

6. The dual-resonance MEMS sensor of claim 5, wherein, The first AGC gain circuit and the second AGC gain circuit are arranged in the same digital circuit and work independently.

7. The dual-resonance MEMS sensor of claim 1, wherein, The input end of the delay control circuit is also connected with a system clock module, for taking the system clock signal as a reference time, so that the delay control circuit outputs different delay signals to the first delay timer and the second delay timer.

8. A method of operating a dual-resonance MEMS sensor according to any one of claims 1-7, characterized by, Comprising: In response to detecting the to-be-tested signal, the first resonator generates a first capacitance signal, and the second resonator generates a second capacitance signal; The frequency difference and the phase difference of the first digital signal input into the first delay timer and the second digital signal input into the second delay timer are detected by the frequency and phase discriminator; In response to the frequency difference between the first digital signal and the second digital signal being less than a preset first threshold and the phase difference being less than a preset second threshold, the phase frequency detector outputs a control signal of the delay control circuit; the delay control circuit controls the first delay and the second delay to adjust the delay according to the control signal; the first resonant circuit outputs a first analog feedback signal under the control of the first delay according to the first capacitance signal, and the second resonant circuit outputs a second analog feedback signal under the control of the second delay according to the second capacitance signal; wherein the phases of the first analog feedback signal and the second analog feedback signal are different. The first analog feedback signal is input into the first resonator to form a closed loop circuit, and the second analog feedback signal is input into the second resonator to form a closed loop circuit.

9. The method of working according to claim 8, characterized in that, The delay control circuit controls the first delay and the second delay to adjust the delay according to the control signal, comprising: The delay control circuit outputs a first delay signal of the first delay and a second delay signal of the second delay according to the control signal output by the phase frequency detector; The first delay adjusts the delay of the first digital signal according to the first delay signal and outputs a first digital feedback signal; the second delay adjusts the delay of the second digital signal according to the second delay signal and outputs a second digital feedback signal.

10. The method of working according to claim 9, characterized in that, The control of the first delay and the second delay to adjust the delay comprises single delay adjustment and synchronous delay adjustment; The single delay adjustment: output the first delay signal or the second delay signal, control any one of the first delay and the second delay to work, the digital feedback signal output by the delay adjuster is different in phase from the input digital signal, the digital feedback signal output by the delay adjuster which does not adjust the delay is the same in phase as the input digital signal, so that the phases of the digital feedback signals output by the first delay and the second delay are different. The synchronous delay adjustment: output the first delay signal and the second delay signal, simultaneously adjust the delay of the first delay and the second delay, the delay time of the first delay signal and the second delay signal is different, so that the phases of the analog feedback signals output by the first delay and the second delay are different.

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