A resonator frequency shift detection device based on phase-locked loop

Abstract

The present invention discloses a resonator frequency shift detection device based on a phase-locked loop, including a crystal oscillator, a phase-locked loop, a low-pass filter, an inverting amplifier, a single-chip microcomputer and a host computer. The crystal oscillator excites the resonator to be detected to resonate and outputs a resonant signal to the phase-locked loop. The phase-locked loop completes phase locking and outputs a stable voltage signal to the low-pass filter. The low-pass filter denoises the received signal and outputs a more stable and smooth voltage signal to the inverting amplifier. The inverting amplifier inverts and proportionally amplifies the received voltage signal, and inputs the inverted amplified voltage signal to the single-chip microcomputer. The single-chip microcomputer parses the received voltage signal into a digital signal and transmits the digital signal to the host computer. The host computer obtains the frequency shift size of the resonator to be detected based on the digital signal. The present invention can reduce the difficulty and complexity of the frequency response analysis of the sensor, and provide a hardware foundation for the large-scale market development of component detection sensors based on resonators.

Description

Technical Field

[0001] The invention belongs to the field of resonator frequency detection, and in particular relates to a resonator frequency shift detection device based on a phase-locked loop. Background Art

[0002] Resonators based on the piezoelectric effect, such as quartz crystal microbalance resonators (QCM) and film bulk acoustic resonators (FBAR), have been used as component detection sensors in more and more applications. According to the piezoelectric effect, this type of resonator changes its resonant frequency by attaching trace substances (substances to be tested) on its surface, thereby realizing the detection of trace substances. It is worth noting that, according to the principle, the response of the resonator to the substance to be tested is reflected in the change of its resonant frequency. In traditional testing environments, the detection of high-frequency resonant frequencies of megahertz and gigahertz often requires equipment such as vector network analyzers and high-frequency impedance analyzers that can analyze high-frequency signals. Although this type of analysis equipment has strong performance, it is not convenient for the integration and application of portable and miniaturized detection systems because of its large size, bulkiness and high price. Therefore, the design and development of a detection device for the change of the resonant frequency of the resonator is of great value and application significance.

[0003] The resonators commonly used for component detection have two characteristics. One is that their resonant frequency is relatively high, often around 10 7 ~10 10 Hz level, the higher the basic resonant frequency means the higher the detection sensitivity of the tiny mass; secondly, the frequency shift change is limited. For example, the frequency of a 10MHz QCM in component detection often does not change more than 1000Hz, while the resonant frequency of an FBAR with a resonant frequency of 1GHz as a component detection sensor often varies between 1kHz and 100kHz. Therefore, it is necessary to design a frequency shift detection sensor according to the characteristics of this type of resonator in the sensing detection application, so as to meet the characteristics of the detection device in high-frequency detection and also meet the characteristics of a certain linear bandwidth at high frequency.

[0004] Currently, few existing frequency-to-voltage converters can work at such high frequencies, and their linear range is large, almost covering their maximum operating frequency, which also means that their sensitivity and resolution are poor, making it difficult to meet the needs of high-precision frequency detection. In addition, there is no device that can detect the magnitude of frequency changes. Summary of the invention

[0005] In order to solve the problems in the prior art, the present invention proposes a resonator frequency shift detection device based on a phase-locked loop.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The invention discloses a resonator frequency shift detection device based on a phase-locked loop, comprising a crystal oscillator, a phase-locked loop, a low-pass filter, an inverting amplifier, a single-chip microcomputer and a host computer. The crystal oscillator excites a resonator to be detected to resonate and outputs a resonance signal to the phase-locked loop. The phase-locked loop completes phase locking and outputs a stable voltage signal to the low-pass filter. The low-pass filter denoises the received signal and outputs a more stable and smooth voltage signal to the inverting amplifier. The inverting amplifier inverts and proportionally amplifies the received voltage signal and inputs the inverted amplified voltage signal into the single-chip microcomputer. The single-chip microcomputer parses the received voltage signal into a digital signal and transmits the digital signal to the host computer. The host computer obtains the frequency shift size of the resonator to be detected based on the digital signal.

[0008] Further, the phase-locked loop includes a phase frequency detector, a loop filter and a voltage-controlled oscillator;

[0009] The crystal oscillator outputs a resonant signal to a frequency detector and a phase detector. At the same time, the voltage-controlled oscillator outputs an initial frequency signal to the frequency detector. The frequency detector makes a difference between the frequencies corresponding to the two received signals and outputs a pulse signal to the loop filter. The loop filter integrates the input pulse signal and outputs a smooth voltage signal to the voltage-controlled oscillator. The voltage-controlled oscillator is controlled and adjusted by the voltage signal output by the loop filter, and outputs a signal with the same frequency as the resonant signal to the frequency detector, and the phase-locked loop completes phase locking. The loop filter outputs a stable voltage signal to a low-pass filter.

[0010] Furthermore, the stable voltage signal output by the loop filter to the low-pass filter is a DC voltage signal, and the smooth voltage signal output by the loop filter to the voltage-controlled oscillator is also a DC voltage signal; and the voltage of the voltage signal output by the loop filter to the low-pass filter is equal to the voltage of the voltage signal output by the loop filter to the voltage-controlled oscillator, and the voltage signals both reflect the magnitude of the frequency shift occurring in the current resonator.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The present invention is specially used for detecting the frequency change of a high-frequency resonator. Compared with the traditional frequency-voltage converter, the present invention aims to solve the problem of measuring the change of the resonant frequency with high sensitivity, and can simplify the method of detecting the change of the resonant frequency of various resonators.

[0013] The core components of the phase-locked loop used in the present invention: the frequency detector and the voltage-controlled oscillator can be selected and matched according to the level of the basic resonant frequency of the resonator to meet different use conditions and measurement requirements;

[0014] The product of the sensitivity and the frequency modulation range in the present invention is a certain number. The amplification gain of the inverting amplifier can be changed by adjusting the variable resistance of the inverting amplifier, thereby changing the frequency modulation range and the sensitivity, and finding the highest sensitivity that can meet the minimum frequency modulation range under the detection conditions; the frequency modulation range is the linear interval in which the detection device of the present invention can measure the frequency shift change. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the circuit module design of the resonator frequency shift detection device based on the phase-locked loop in the present invention;

[0016] Figure 2 It is a schematic diagram of the circuit design principle of the resonator frequency shift detection device based on the phase-locked loop in the present invention;

[0017] Figure 3 It is a schematic diagram of the PCB three-dimensional structure of the resonator frequency shift detection device based on the phase-locked loop in the present invention;

[0018] Figure 4 This is a PCB physical picture of the resonator frequency shift detection device based on the phase-locked loop in the present invention;

[0019] Figure 5 It is a schematic diagram of the use of the detection device in the present invention;

[0020] Figure 6 is the frequency-voltage characteristic curve of the voltage-controlled oscillator used in the present invention;

[0021] Figure 7 It is a schematic diagram of a voltage-frequency shift characteristic curve of a frequency shift detection device in the present invention;

[0022] Figure 8 This is a frequency-voltage conversion test data diagram implemented by the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0024] Example 1

[0025] like Figure 1 The circuit module design schematic diagram of the resonator frequency shift detection device based on a phase-locked loop is shown, which embodies several functional modules involved in the present invention, including: a power supply module, a crystal oscillator, a frequency detector, a loop filter, a voltage-controlled oscillator, a low-pass filter, an inverting amplifier, a single-chip microcomputer and a host computer, wherein the frequency detector, the loop filter and the voltage-controlled oscillator constitute a phase-locked loop.

[0026] Among them, the crystal oscillator, phase frequency detector, and voltage-controlled oscillator are electronic components sold on the market. The loop filter is a second-order proportional-integral filter designed independently using chip capacitors and resistors. The low-pass filter and inverting amplifier are designed independently using operational amplifiers and chip capacitors and resistors.

[0027] The single-chip microcomputer is an Arduino Uno single-chip microcomputer, and a power module is integrated in the single-chip microcomputer. The Arduino Uno single-chip microcomputer supplies power to the remaining electrical components in the frequency shift detection device (i.e., supplies power to a crystal oscillator, a frequency detector, a loop filter, a voltage-controlled oscillator, a low-pass filter and an inverting amplifier) ​​through the power module, and provides standard power supply voltages of +5V, +3.3V and a zero potential point (GND); at the same time, the single-chip microcomputer also provides a bias reference voltage signal for the inverting amplifier; the voltage signal output by the inverting amplifier is transmitted to the single-chip microcomputer by a wire, and the analog-to-digital converter of the single-chip microcomputer is used to resolve the analog voltage signal into a digital signal, and the digital signal is transmitted to a host computer by a transmission line, and the host computer uses python and an Arduino compiler to control the single-chip microcomputer, thereby realizing data reading, display and storage, and the frequency shift size of the resonator to be detected can be obtained.

[0028] The power supply module provides working voltage to the remaining electrical components in the frequency shift detection device, and realizes common grounding of the components through copper plating on the top layer of the double-layer printed circuit board of the detection device.

[0029] The crystal oscillator is a Pierce oscillator constructed using a crystal drive element, thereby exciting the quartz crystal resonator with a standard resonant frequency of 10MHz to resonate.

[0030] The low-pass filter is used to filter and remove noise from the output voltage signal of the loop filter to achieve stable output of the signal;

[0031] The inverting amplifier is composed of an active operational amplifier, a chip capacitor, a chip resistor and a variable resistor, wherein the inverting amplifier sets a reference voltage, subtracts the reference voltage from the low-pass filter output signal at the current moment and multiplies it by the amplification gain to obtain an inverted amplified voltage signal, and the amplification gain of the inverting amplifier can be changed by adjusting the variable resistor, thereby adjusting the sensitivity of the detection device of the present invention to frequency shift detection; due to the limitation of the reference voltage, the linear range of the frequency shift change that the detection device can detect is the reference voltage divided by the sensitivity, so when the reference voltage is a certain value, the linear range is negatively correlated with the sensitivity.

[0032] The resonator frequency shift detection device based on the phase-locked loop of the present invention needs to be used in conjunction with a single-chip microcomputer. It is necessary to send instructions to the single-chip microcomputer through the host computer, and connect the power supply port, GND port, and inverting amplifier reference voltage input port of the device to the single-chip microcomputer for control; the output signal of the inverting amplifier is connected to the single-chip microcomputer, and its analog-to-digital converter is used to convert the analog signal into a digital signal, which is then transmitted to the host computer for reading, display, and storage.

[0033] like Figure 2 As shown in the figure, it is a schematic diagram of the circuit design principle of the resonator frequency shift detection device based on the phase-locked loop. The core electronic component models of each module used in this case are: the driver of the crystal resonator is SN74LVC1GX04, the frequency detector and phase detector are TLC2933, the voltage-controlled oscillator is SiT3808AC-C2-33NX-10.000000, the low-pass filter is LM358, and the inverting amplifier is INA333.

[0034] like Figure 2 As shown in the schematic diagram, the detection device is designed with a total of 4 power ports and 8 input and output ports, of which the 4 power ports are: +5V, +3.3V power supply ports and two GND ports; the input ports are: two ports of the crystal resonator (ports 4 and 5) and the inverting amplifier bias reference voltage signal input port (port 8); the output ports are: crystal resonant signal output port (port 3), voltage-controlled oscillator output port (port 12), loop filter output port (port 11), low-pass filter output port (port 10) and inverting amplifier output port (port 9).

[0035] like Figure 3 As shown in the figure, it is a schematic diagram of the PCB structure of the resonator frequency shift detection device based on the phase-locked loop. The size of the entire detection device PCB is a square circuit board of 40mm×40mm, with a total of 12 ports on the left and right sides. The left port provides the working voltage and inputs the crystal oscillator signal, and the right port is responsible for inputting the control signal of the single-chip microcomputer and outputting various voltage signals. And the actual PCB picture of the resonator frequency shift detection device based on the phase-locked loop is as follows Figure 4 As shown, Figure 4 The location of each port is described in the Figure 5The figure shows a schematic diagram of the detection device, which points out the main equipment required in use: the first resonator frequency shift detection device, the quartz crystal resonator, the single-chip microcomputer (Arduino Uno) and the host computer. The first resonator frequency shift detection device includes a phase-locked loop, a crystal oscillator, a low-pass filter and an inverting amplifier. In this example, a quartz crystal resonator with a base frequency of 10MHz is selected as the test element. The quartz crystal is clamped on the crystal bracket, and the two ends are connected to ports 4 and 5 respectively; the device is provided with working voltages of +5V and +3.3V through the single-chip microcomputer, which are connected to ports 1 and 2 of the detection device respectively, and the GND port of the single-chip microcomputer is connected to ports 6 and 7 of the detection device. After the device is powered on, the crystal oscillator excites the quartz crystal in a resonant state, and an oscilloscope can be connected through port 3 for monitoring. The crystal oscillator outputs a resonant signal to the frequency detector, and at the same time the voltage-controlled oscillator starts working, and its initial frequency signal is input into the frequency detector; the frequency detector compares the frequencies of the two and makes a difference, and outputs the frequency difference as a pulse signal, which is input into the loop filter. After the pulse signal is integrated by the loop filter, it is converted into a smooth voltage signal (i.e. Figure 1 The loop filter control signal in the phase-locked loop is output to the voltage-controlled oscillator; the voltage-controlled oscillator is controlled by the signal output by the loop filter and adjusts its own output frequency until the frequency of the signal output by the voltage-controlled oscillator is consistent with the frequency of the resonant signal output by the crystal resonator. The phase-locked loop enters a "locked" state, and the control signal of the loop filter to the voltage-controlled oscillator is a DC voltage signal, which is stable and unchanged.

[0036] When the phase-locked loop is "locked", the loop filter outputs a stable voltage signal (i.e. Figure 1 The loop filter output signal in the low-pass filter is transmitted to the low-pass filter according to the frequency-voltage characteristic curve of the voltage-controlled oscillator (such as Figure 6 As shown in the figure, the value of the signal is proportional to the output frequency of the voltage-controlled oscillator, and the output signal frequency of the voltage-controlled oscillator has been locked with the frequency of the resonant signal, and the two are constantly equal. Therefore, the output signal of the loop filter is also proportional to the frequency of the crystal resonant signal.

[0037] According to the input-output characteristics of the voltage-controlled oscillator, that is, the frequency-voltage characteristic curve, it can be obtained that the voltage value of the input control signal of the voltage-controlled oscillator is proportional to the frequency of the output signal. Therefore, the voltage value of the input control signal of the voltage-controlled oscillator can reflect the frequency of the resonant signal. And the stable voltage signal output from the loop filter to the low-pass filter is a DC voltage signal, which is equal to the control signal voltage output from the loop filter to the voltage-controlled oscillator.

[0038] Afterwards, the stable voltage signal output by the loop filter is further de-noised by a low-pass filter, and a more stable and smooth signal can be obtained. According to the principle of the resonator in component detection, the resonant frequency of the resonator often decreases due to the increase of the mass attached to it, which is reflected in the fact that the voltage value of the output signal of the loop filter will also decrease. In order to directly and intuitively link the output signal of the device with the mass attached to the crystal, the mass attached to the crystal increases, so that the voltage value of the output signal of the detection device (i.e., the digital signal output by the single-chip microcomputer) also increases. Therefore, it is considered to connect an inverting amplifier after the low-pass filter to achieve a proportional relationship between the increase of the mass attached to the crystal and the voltage rise of the output signal of the detection device. Therefore, the output voltage value of the loop filter corresponding to the basic resonant frequency of the resonator is recorded as a reference voltage value, and the single-chip microcomputer inputs the voltage value as a bias reference signal into the detection device port 8 (i.e., the single-chip microcomputer also outputs a bias reference voltage signal to the inverting amplifier, and the voltage value of the bias reference voltage signal is equal to the output voltage signal of the loop filter when the resonator to be tested does not have a frequency offset; the inverting amplifier uses the bias reference voltage signal output by the single-chip microcomputer as a reference signal). The voltage value of the output signal of the inverting amplifier is the voltage value corresponding to the reference signal subtracted from the voltage value of the voltage signal output by the low-pass filter and then multiplied by the amplification gain, that is:

[0039] V amp =(V ref -V lpf )×A amp

[0040] Among them, V ref V is the voltage value of the bias reference voltage signal output by the microcontroller; lpf A is the voltage value of the output signal of the loop filter after filtering by the low-pass filter. amp is the gain of the inverting amplifier, V amp is the voltage value of the output signal of the inverting amplifier.

[0041] The inverting amplifier inverts and proportionally amplifies the received voltage signal, and inputs the inverted and amplified voltage signal into the single-chip microcomputer. The single-chip microcomputer parses the received voltage signal into a digital signal and transmits the digital signal to the host computer. The host computer obtains the frequency shift size of the resonator to be detected based on the digital signal.

[0042] The host computer obtains the frequency shift of the resonator to be detected based on the digital signal; specifically:

[0043] The host computer stores the frequency shift-voltage conversion sensitivity of the frequency shift-voltage characteristic curve of the detection device. The host computer divides the digital signal by the frequency shift-voltage conversion sensitivity to obtain the frequency shift of the resonator to be detected. The frequency shift-voltage conversion sensitivity is the slope of the voltage-frequency shift characteristic curve.

[0044] In the present invention, the voltage-frequency shift characteristic curve is calibrated by the voltage value of the output signal of the inverting amplifier and the frequency shift size of the resonator to be detected, and the voltage-frequency shift characteristic curve is a linear function of the voltage value of the voltage signal output by the inverting amplifier relative to the frequency shift size of the resonator to be detected, and its slope is a certain value, which is equal to the amplification gain of the inverting amplifier divided by the voltage-controlled gain of the voltage-controlled oscillator. The slope of the voltage-frequency shift characteristic curve is the frequency shift-voltage conversion sensitivity; therefore, if the sensitivity and the voltage value of the output signal of the inverting amplifier are known, the frequency shift size of the resonator to be detected can be obtained.

[0045] In the circuit design, the starting frequency of the tuning range can be adjusted by adjusting the bias reference voltage of the microcontroller input to the inverting amplifier, so that the starting frequency can be adapted to the crystal resonator with different base frequencies, which can meet the frequency shift detection of crystal resonators with different base frequencies. In addition, since the upper limit voltage of the inverting amplifier is +3.3V, the amplification gain should not be too large, otherwise it will lead to a narrow tunable frequency shift range. Therefore, the amplification gain of the amplifier can be adjusted according to the required frequency shift detection range to achieve better detection sensitivity.

[0046] The detection sensitivity of the detection device of the present invention can be described as:

[0047]

[0048] Where Δf r is the frequency (negative) shift of the crystal resonator due to mass loading, V amp is the output signal of the inverting amplifier, A amp is the gain of the inverting amplifier, K VCO is the voltage-controlled gain of the voltage-controlled oscillator. By calibrating the input and output of the detection device, we can get Figure 7 The actual calibration sensitivity of the detection device of the present invention is the slope of the voltage-frequency shift characteristic curve, which is basically consistent with the theoretical sensitivity (ratio of the inverting amplifier to the voltage-controlled gain).

[0049] In this example, the gain of the inverting amplifier is set to 5 times, and the voltage-controlled gain of the voltage-controlled oscillator is measured to be 2.782Hz / mV. The theoretical value of the frequency-shift-to-voltage conversion sensitivity is 1.80mV / Hz, while the actual value of the frequency-shift-to-voltage conversion sensitivity obtained by actual calibration measurement is 1.86mV / Hz. The measured voltage-frequency shift characteristic curve has a high linearity, and the linear fitting R 2 =0.9995, such as Figure 7 It is shown that the frequency shift detection device based on the phase-locked ring resonator of the present invention has higher sensitivity and linearity.

[0050] The effect of the present invention can be further explained in combination with the application of the crystal resonator in component detection:

[0051] The detection device of the present invention is used for frequency shift detection when a quartz crystal resonator is used as a component detection sensor, such as Figure 8 The figure shows the comparison effect of the frequency change of the resonator resonance signal and the output signal of the device (i.e., the digital signal output by the single-chip microcomputer) when the detection device is used. During the entire use process, tiny substances are attached to the quartz crystal resonator four times, and the mass of the substances is increased in sequence (0.5 mg, 1 mg, 2 mg, and 3 mg, respectively). Among them, the frequency of the resonator resonance signal decreases as the crystal mass load increases, and the output signal of the inverting amplifier increases as the crystal mass load increases, realizing the proportional relationship between the resonator mass load and the output signal of the detection device (i.e., the digital signal output by the single-chip microcomputer) of the device. This example shows that the resonator frequency shift detection device based on the phase-locked loop of the present invention can effectively read the size of the resonator frequency shift, thereby providing a more convenient way for data reading and storage of the component detection sensor based on the resonator. In summary, the resonator frequency shift detection device based on the phase-locked loop designed by the present invention can accurately detect the frequency offset of the resonator, and its voltage-frequency shift specificity curve has good linearity and high sensitivity, and can realize frequency shift detection under different conditions through parameter adjustment. According to the above examples, its superiority in actual resonator frequency shift detection applications is fully reflected.

[0052] The above-mentioned embodiments only express several implementation modes of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A resonator frequency shift detection device based on a phase-locked loop, characterized in that: It includes a crystal oscillator, a phase-locked loop, a low-pass filter, an inverting amplifier, a single-chip microcomputer and a host computer. The crystal oscillator excites the resonator to be detected to resonate and outputs a resonant signal to the phase-locked loop. The phase-locked loop completes phase locking and outputs a stable voltage signal to the low-pass filter. The low-pass filter denoises the received signal and outputs a more stable and smooth voltage signal to the inverting amplifier. The inverting amplifier inverts and proportionally amplifies the received voltage signal and inputs the inverted amplified voltage signal to the single-chip microcomputer. The single-chip microcomputer parses the received voltage signal into a digital signal and transmits the digital signal to the host computer. The host computer obtains the frequency shift of the resonator to be detected based on the digital signal. The phase-locked loop includes a phase frequency detector, a loop filter and a voltage-controlled oscillator; The crystal oscillator outputs a resonant signal to the frequency detector and phase detector. At the same time, the voltage-controlled oscillator outputs an initial frequency signal to the frequency detector. The frequency detector makes a difference between the frequencies corresponding to the two received signals and outputs a pulse signal to the loop filter. The loop filter integrates the input pulse signal and outputs a smooth voltage signal to the voltage-controlled oscillator. The voltage-controlled oscillator is controlled and adjusted by the voltage signal output by the loop filter, and outputs a signal with the same frequency as the resonant signal to the frequency detector. The phase-locked loop completes the phase locking. The loop filter outputs a stable voltage signal to the low-pass filter. The single chip microcomputer also outputs a bias reference voltage signal to the inverting amplifier, wherein the voltage value of the bias reference voltage signal is equal to the output voltage signal of the loop filter when the resonator to be measured has no frequency deviation; The inverting amplifier uses the bias reference voltage signal output by the single-chip microcomputer as the reference signal. The voltage value of the output signal of the inverting amplifier is the voltage value corresponding to the reference signal minus the voltage value of the voltage signal output by the low-pass filter and then multiplied by the amplification gain, that is: V amp =(V ref -V lpf )×A amp Among them, V ref V is the voltage value of the bias reference voltage signal output by the microcontroller; lpf A is the voltage value of the output signal of the loop filter after filtering by the low-pass filter. amp is the gain of the inverting amplifier, V amp is the voltage value of the output signal of the inverting amplifier; The host computer obtains the frequency shift size of the resonator to be detected based on the digital signal, specifically: The host computer stores the frequency shift-voltage conversion sensitivity of the voltage-frequency shift characteristic curve of the detection device, and the host computer divides the digital signal by the frequency shift-voltage conversion sensitivity to obtain the frequency shift of the resonator to be detected, and the frequency shift-voltage conversion sensitivity is the slope of the voltage-frequency shift characteristic curve; The voltage-frequency shift characteristic curve is calibrated by the voltage value of the output signal of the inverting amplifier and the frequency shift of the resonator to be detected, and the voltage-frequency shift characteristic curve is a linear function of the voltage value of the voltage signal output by the inverting amplifier relative to the frequency shift of the resonator to be detected, and its slope is a certain value, which is equal to the amplification gain of the inverting amplifier divided by the voltage-controlled gain of the voltage-controlled oscillator; therefore, by knowing the sensitivity and the voltage value of the output signal of the inverting amplifier, the frequency shift of the resonator to be detected can be obtained.

2. The resonator frequency shift detection device based on a phase-locked loop according to claim 1, characterized in that: The stable voltage signal output by the loop filter to the low-pass filter is a DC voltage signal, and the smooth voltage signal output by the loop filter to the voltage-controlled oscillator is also a DC voltage signal; and the voltage of the voltage signal output by the loop filter to the low-pass filter is equal to the voltage of the voltage signal output by the loop filter to the voltage-controlled oscillator.

3. The resonator frequency shift detection device based on a phase-locked loop according to claim 1, characterized in that: The single chip microcomputer is integrated with a power supply module, and the single chip microcomputer supplies power to a crystal oscillator, a frequency detector, a phase detector, a loop filter, a voltage controlled oscillator, a low pass filter and an inverting amplifier through the power supply module.

Images