Signal amplification device and system for photoacoustic spectroscopy

Abstract

The invention relates to a signal amplification device and system for photoacoustic spectrometry, and relates to the technical field of photoacoustic spectrometry, and the device comprises a buffer which is connected with a crystal resonator and is used for receiving a photoacoustic spectrometry signal emitted by the crystal resonator, and outputting a first amplification signal according to the photoacoustic spectrometry signal; the instrument amplifier is connected with the buffer and is used for receiving the first amplified signal, providing a common-mode rejection ratio and outputting a second amplified signal based on the first amplified signal and the common-mode rejection ratio; and the digital control gain amplifier is connected with the instrument amplifier and the remote control end, and is used for performing gain adjustment in response to a remote control instruction sent by the remote control end, and outputting a third amplification signal as an amplified photoacoustic spectrum signal based on the adjusted gain and the second amplification signal. By adopting the device, the noise interference in the photoacoustic spectrum signal amplification process can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of photoacoustic spectroscopy, and in particular to a signal amplification device and system for photoacoustic spectroscopy. Background Art

[0002] In the photoacoustic spectroscopy gas detection technology, since the content of the gas to be measured is usually low, the generated photoacoustic signal is very weak. The signal amplification module is the core component of the entire photoacoustic spectroscopy technology, and its performance directly affects the detection sensitivity and signal-to-noise ratio. In order to improve the detection sensitivity, these weak photoacoustic signals need to be effectively amplified and detected. In the related art, the signal amplifier usually adopts a transimpedance amplifier. The gain of the transimpedance amplifier is determined by the value of the feedback resistor. In theory, the gain can be increased by increasing the value of the feedback resistor. In practical applications, this method has limitations because high-value resistors will cause the input impedance of the circuit to decrease, thereby affecting the resonant characteristics. Under high gain settings, the noise of the circuit will also increase, which limits the sensitivity improvement of the system. In addition, the transimpedance amplifier has limited suppression ability for common-mode signals, which may cause signal distortion in complex electromagnetic environments. Therefore, the signal amplification method of photoacoustic spectroscopy in the related art has the problem of strong noise interference. Summary of the invention

[0003] Based on this, it is necessary to provide a signal amplification device and system for photoacoustic spectroscopy that can reduce noise interference in order to solve the above technical problems.

[0004] In a first aspect, the present application provides a signal amplification device for photoacoustic spectroscopy, comprising:

[0005] A buffer connected to the crystal resonator, configured to receive a photoacoustic spectroscopy signal emitted by the crystal resonator, and output a first amplified signal according to the photoacoustic spectroscopy signal;

[0006] an instrument amplifier connected to the buffer, configured to receive the first amplified signal, provide a common mode rejection ratio, and output a second amplified signal based on the first amplified signal and the common mode rejection ratio;

[0007] A digitally controlled gain amplifier is connected to the instrument amplifier and the remote control terminal, and is used to perform gain adjustment in response to a remote control instruction issued by the remote control terminal, and output a third amplified signal based on the adjusted gain and the second amplified signal as an amplified photoacoustic spectroscopy signal.

[0008] In one of the embodiments, the buffer includes a first buffer amplifier and a second buffer amplifier;

[0009] Among them, the non-phase input terminal of the first buffer amplifier is connected to one end of the crystal resonator, and the inverting input terminal and the output terminal of the first buffer amplifier are both connected to the inverting input terminal of the instrument amplifier; the non-phase input terminal of the second buffer amplifier is connected to the other end of the crystal resonator, and the inverting input terminal and the output terminal of the second buffer amplifier are both connected to the non-phase input terminal of the instrument amplifier.

[0010] In one embodiment, the first buffer amplifier and the second buffer amplifier are amplifiers of the same specification, which are used to provide an input resistance of 9 TΩ to 11 TΩ and an input bias current of 0.4 pA to 0.6 pA.

[0011] In one embodiment, the first buffer amplifier and the second buffer amplifier are configured for unity gain.

[0012] In one of the embodiments, the digitally controlled gain amplifier includes a first digital potentiometer, a second digital potentiometer, and an operational amplifier;

[0013] The non-inverting input terminal of the operational amplifier is connected to the output terminal of the instrument amplifier, the inverting input terminal of the operational amplifier is respectively connected to one end of the first digital potentiometer and one end of the second digital potentiometer, the other end of the first digital potentiometer is grounded, and the other end of the second digital potentiometer is connected to the output terminal of the operational amplifier.

[0014] In one embodiment, the first digital potentiometer and the second digital potentiometer are digital potentiometers of the same specification, and are used to provide a variable voltage gain with 8-bit precision.

[0015] In one embodiment, the instrument amplifier is configured to provide a common mode rejection ratio greater than or equal to 120 dB.

[0016] In one embodiment, the device further comprises:

[0017] A power supply module is respectively connected to the positive power supply terminal of the buffer, the positive power supply terminal of the instrument amplifier and the positive power supply terminal of the digital control gain amplifier.

[0018] In one embodiment, the power module includes a single lithium-ion battery, and the supply voltage ranges from 3.3V to 4.2V.

[0019] In a second aspect, the present application provides a signal amplification system for photoacoustic spectroscopy, including a signal amplification device for photoacoustic spectroscopy as described in any one of the above embodiments;

[0020] It also includes a remote control terminal, which is connected to the digital control gain amplifier in the signal amplifying device.

[0021] The above-mentioned photoacoustic spectroscopy signal amplification device and system, the device includes: a buffer, an instrument amplifier and a digital control gain amplifier. Among them, the buffer is connected to the crystal resonator, used to receive the photoacoustic spectroscopy signal emitted by the crystal resonator, and outputs a first amplified signal according to the photoacoustic spectroscopy signal, thereby performing the first stage amplification on the photoacoustic spectroscopy signal, and isolating the crystal resonator from the subsequent circuit to avoid the influence of the subsequent circuit on the crystal resonator; the instrument amplifier is connected to the buffer, used to receive the first amplified signal, and provide a common mode rejection ratio, and output a second amplified signal based on the first amplified signal and the common mode rejection ratio; the digital control gain amplifier is connected to the instrument amplifier and the remote control end, used to respond to the remote control instruction issued by the remote control end, perform gain adjustment, realize remote gain adjustment, increase convenience, and output a third amplified signal based on the adjusted gain and the second amplified signal as the amplified photoacoustic spectroscopy signal, which not only realizes the effective amplification of the photoacoustic spectroscopy signal, but also improves the sensitivity by adjusting the gain to adapt to different measurement requirements, and effectively reduces the noise in the photoacoustic spectroscopy signal amplification process through the setting of the buffer and the instrument amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A schematic diagram of the structure of a signal amplification device for photoacoustic spectroscopy in one embodiment;

[0024] Figure 2 A schematic diagram of the structure of a signal amplification device for photoacoustic spectroscopy in another embodiment;

[0025] Figure 3 A schematic diagram of the structure of a signal amplification device for photoacoustic spectroscopy in another embodiment;

[0026] Figure 4 FIG. 4 is a schematic diagram of the structure of a signal amplification system for photoacoustic spectroscopy in one embodiment. DETAILED DESCRIPTION

[0027] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0029] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0030] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0031] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.

[0032] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0033] As described in the background technology, the signal amplification means of the photoacoustic spectroscopy of the related art has the problem of strong noise interference. The inventors have found that the reason for this problem is that in the photoacoustic spectroscopy gas detection technology, the photoacoustic signal generated is very weak because the content of the gas to be measured is usually low. The signal amplification module is the core component of the entire photoacoustic spectroscopy technology, and its performance directly affects the sensitivity and signal-to-noise ratio of the detection. In order to improve the detection sensitivity, these weak photoacoustic signals need to be effectively amplified and detected. Signal amplification usually uses a transimpedance amplifier (TIA, TransimpedanceAmplifier). The gain of the transimpedance amplifier is determined by the value of the feedback resistor. In theory, the gain can be increased by increasing the value of the feedback resistor. In practical applications, this method has limitations. High-value resistors will cause the input impedance of the circuit to decrease, thereby affecting the resonance characteristics. Under high gain settings, the noise of the circuit will also increase, which limits the sensitivity improvement of the system. In addition, the transimpedance amplifier has limited suppression ability for common-mode signals, which may cause signal distortion in complex electromagnetic environments. In order to overcome these limitations, the related art includes a variety of signal amplification technologies. One way to improve signal amplification performance is to use a charge amplifier. Charge amplifiers are suitable for situations where the signal source has capacitive characteristics, and their gain is proportional to the amount of charge in the signal source and is independent of frequency. However, it is very difficult to achieve a gain level comparable to that of a transimpedance amplifier because a feedback capacitor with a specific value is required, and the influence of parasitic capacitance is often difficult to control in practical applications. In addition, with the development of digital signal processing technology, the concept of digitally controlled gain stages has also been introduced into the signal amplification module of photoacoustic spectroscopy. The digitally controlled gain stage allows the gain of the amplifier to be dynamically adjusted through a digital interface, providing greater flexibility and precision. This design can be implemented using a digital potentiometer, which can adjust the resistance value through a digital signal to change the gain of the amplifier. The advantage of this design is that the gain can be adjusted remotely without physically contacting the circuit. However, the application of these advanced amplification technologies also brings new challenges. For example, the design and debugging of instrument amplifiers and charge amplifiers requires precise circuit knowledge and experience. Although the digitally controlled gain stage provides flexibility, it also increases the complexity of the system and requires additional digital control circuits and software support. In addition, the performance of these advanced amplifiers is often affected by power supply stability, temperature changes, and circuit noise, which requires that these factors must be taken into account during design. Therefore, in order to achieve high-performance signal amplification, circuit designers must find a balance between gain, noise, bandwidth, linearity, and stability. This usually requires accurate circuit simulation and experimental verification. For example, to reduce noise, it may be necessary to select a low-noise operational amplifier or add a filter to the circuit to suppress high-frequency noise. To increase bandwidth, it may be necessary to optimize the layout of the circuit and reduce the effects of parasitic capacitance and inductance.In order to ensure linearity, it may be necessary to consider the influence of nonlinear distortion in the design of the amplifier. To this end, the inventors of the present application proposed a signal amplification device for photoacoustic spectroscopy.

[0034] In an exemplary embodiment, see Figure 1 , provides a signal amplification device for photoacoustic spectroscopy, comprising:

[0035] Buffer 101 , instrumentation amplifier 102 , and digitally controlled gain amplifier 103 .

[0036] Among them, the buffer 101 is connected to the crystal resonator, and is used to receive the photoacoustic spectroscopy signal emitted by the crystal resonator, and outputs a first amplified signal according to the photoacoustic spectroscopy signal, thereby performing a first-stage amplification on the photoacoustic spectroscopy signal, and isolating the crystal resonator from the subsequent circuit to avoid the influence of the subsequent circuit on the crystal resonator; the instrument amplifier 102 is connected to the buffer 101, and is used to receive the first amplified signal and provide a common mode rejection ratio, and output a second amplified signal based on the first amplified signal and the common mode rejection ratio; the digital control gain amplifier 103 is connected to the instrument amplifier 102 and the remote control end, and is used to respond to the remote control instruction issued by the remote control end to adjust the gain, realize remote gain adjustment, increase convenience, and output a third amplified signal based on the adjusted gain and the second amplified signal as the amplified photoacoustic spectroscopy signal, which not only realizes the effective amplification of the photoacoustic spectroscopy signal, but also improves the sensitivity by adjusting the gain to adapt to different measurement requirements, and through the settings of the buffer 101 and the instrument amplifier 102, effectively reduces the noise in the amplification process of the photoacoustic spectroscopy signal.

[0037] Among them, gain refers to the proportional relationship between its input signal and output signal, usually refers to the open-loop voltage gain, that is, the amplification factor under ideal conditions, which is not affected by the feedback circuit. The gain of the operational amplifier in practical applications may be affected by many factors, such as changes in component parameters, power supply voltage fluctuations, etc. Under ideal conditions, the ideal operational amplifier gain can reach infinity (approximately infinite), but in actual design, a limited gain value is set to avoid saturation or nonlinear distortion. Op amps are often used in signal processing systems to provide the required amplification, filtering and other functions by configuring appropriate circuits.

[0038] It should be noted that the photoacoustic method is a spectral technology based on the photoacoustic effect. Gas molecules absorb modulated light radiation energy of a specific wavelength, transition from the vibrational ground state to the excited state, and then return to the ground state through a rapid radiative transition or a non-radiative transition process. When the gas molecules return to the ground state through the non-radiative transition process, heat energy will be generated, resulting in a change in the gas temperature, which in turn causes a change in the gas pressure, thereby generating an acoustic wave signal. The strength of the signal is proportional to the incident light intensity and the gas absorption amount. The gas concentration can be indirectly determined by detecting the sound signal. In the photoacoustic method, the gas is both the gas to be tested and the detector that absorbs light radiation. Using the same photoacoustic cell detection device, multiple gases can be detected by simply changing the wavelength of the light source. The photoacoustic spectroscopy signal is collected by QTF (Quartz Tuning Fork). The quartz tuning fork can be set in the cavity of the crystal resonator to form a signal source. In liquid or gas, when the laser is irradiated on the sample, the excited molecules will produce thermal expansion due to the absorption of light energy, and then generate sound waves. The quartz tuning fork responds to the sound waves, thereby generating a stable resonant frequency and causing the crystal resonator to generate a corresponding voltage signal, completing the conversion of the photoacoustic spectroscopy signal into a voltage signal for transmission, which is convenient for subsequent amplification and measurement.

[0039] It can be understood that the setting of the buffer 101 isolates the QTF signal source from the subsequent amplification circuit, avoids the subsequent amplification circuit from affecting the QTF signal source, can reduce the infection of external noise, and provide a stable signal for the subsequent signal amplification stage. The instrument amplifier 102 is a secondary amplification module in the signal amplification device of the photoacoustic spectroscopy, and adopts a differential amplifier. Since the differential amplifier has no amplification effect on the common-mode signal, the potential difference of the common-mode signal input through the differential amplifier output is 0, so the common-mode signal can be suppressed. The instrument amplifier 102 is responsible for providing a high common-mode rejection ratio to suppress the common-mode noise in the first amplified signal, thereby extracting a weak differential signal from the high common-mode voltage that may exist in the first amplified signal, and amplifying the differential signal to obtain a second amplified signal, which has the characteristics of high common-mode rejection ratio, low gain error, wide bandwidth and differential input. Optionally, the instrument amplifier 102 can use the AD8237 instrument amplifier, which can provide a common-mode rejection ratio of at least 120 dB, effectively suppress noise in a high common-mode voltage environment, and ensure signal accuracy. In addition, the gain error of the AD8237 is less than 0.005%, ensuring the accuracy of photoacoustic spectroscopy signal amplification. The AD8237 provides sufficient bandwidth to adapt to high-frequency response and ensure stable gain throughout the entire operating frequency range. The differential input design of the instrument amplifier 102 can effectively eliminate common-mode noise and further improve signal clarity and reliability.

[0040] In addition, the inventors have conducted experiments to find that the signal amplification device for photoacoustic spectroscopy in this embodiment has a signal-to-noise ratio of about 23 dB at the highest gain, which can provide a sensitivity improvement of about one order of magnitude, while reducing the demand for laser power and system cost. Through the combination of buffer 101 and instrument amplifier 102, the system can effectively amplify weak signals and improve the detection capability of low-concentration gas. The high common-mode rejection ratio and low gain error of instrument amplifier 102 significantly reduce the noise level of the system, improve the signal-to-noise ratio, and ensure the accuracy of the measurement.

[0041] In an exemplary embodiment, see Figure 2 , the buffer 101 includes a first buffer amplifier 1011 and a second buffer amplifier 1012 .

[0042] Among them, the non-phase input terminal of the first buffer amplifier 1011 is connected to one end of the crystal resonator, which can provide a suitable load for the crystal resonator to avoid signal attenuation or distortion. The reverse input terminal and the output terminal of the first buffer amplifier 1011 are both connected to the inverting input terminal of the instrument amplifier 102; the non-phase input terminal of the second buffer amplifier 1012 is connected to the other end of the crystal resonator, which also provides additional impedance matching and signal isolation for the crystal resonator. The reverse input terminal and the output terminal of the second buffer amplifier 1012 are both connected to the non-phase input terminal of the instrument amplifier 102.

[0043] The buffer circuit composed of the first buffer amplifier 1011 and the second buffer amplifier 1012 is also called an absorption circuit, which is an important protection circuit for power electronic devices. It is not only used for the protection of semi-controlled devices, but also plays a more important role in the application technology of fully controlled devices. The functions of the buffer circuit include suppression and absorption. It absorbs the overvoltage energy appearing on the device. The stray inductance in the lead of the buffer circuit must be limited to a minimum to prevent voltage spikes from appearing when the power electronic device is turned off and eliminate the oscillation generated by the crystal resonator.

[0044] It can be understood that the buffer 101 includes a first buffer amplifier 1011 and a second buffer amplifier 1012, and the first buffer amplifier 1011 and the second buffer amplifier 1012 are symmetrically connected. In addition, the first buffer amplifier 1011 and the second buffer amplifier 1012 use amplifiers of the same specifications to provide an input resistance of 9TΩ to 11TΩ and an input bias current of 0.4pA to 0.6pA, so that the device is more stable in terms of symmetry, ensuring that the photoacoustic spectroscopy signal is not affected by changes in impedance load during transmission, thereby maintaining signal integrity. Optionally, the first buffer amplifier 1011 and the second buffer amplifier 1012 can use AD8244 precision FET (Field-Effect Transistor) input quad buffers with an input resistance of 10TΩ and an input bias current of 0.5pA. Bias Current refers to a stable DC current applied in an electronic circuit to enable certain components (such as transistors, operational amplifiers, etc.) to work properly. This current helps ensure that these components work in a specific state, usually in their linear region, to achieve the required gain and performance.

[0045] It should be noted that the first buffer amplifier 1011 and the second buffer amplifier 1012 are configured as unit gain to avoid introducing additional gain errors, further ensuring the stable transmission of the photoacoustic spectroscopy signal and paving the way for subsequent signal amplification.

[0046] In an exemplary embodiment, continue to refer to Figure 2 The digitally controlled gain amplifier 103 includes a first digital potentiometer 1031 , a second digital potentiometer 1032 and an operational amplifier 1033 .

[0047] Among them, the non-inverting input terminal of the operational amplifier 1033 is connected to the output terminal of the instrument amplifier 102, the inverting input terminal of the operational amplifier 1033 is respectively connected to one end of the first digital potentiometer 1031 and one end of the second digital potentiometer 1032, the other end of the first digital potentiometer 1031 is grounded, and the other end of the second digital potentiometer 1032 is connected to the output terminal of the operational amplifier 1033.

[0048] Among them, the operational amplifier is a circuit unit with a very high amplification factor, which is provided with a positive input terminal Vin (+) (also known as the in-phase input terminal), an inverting input terminal Vin (-) and an output terminal Vout. Generally speaking, commonly used operational amplifiers include general-purpose operational amplifiers (such as μA741, LM358 and LM324, etc.), high-impedance operational amplifiers (such as LF355, CA3130 and CA3140, etc.), low-temperature drift operational amplifiers (such as OP07, OP27, AD508, etc.), high-speed operational amplifiers (such as LM318, μA715, etc.), low-power operational amplifiers (such as TL-022C, TL-060C, etc.), high-voltage and high-power operational amplifiers (such as D41) and programmable control types (such as PGA103A), etc. The operational amplifier used in this application can be any type of operational amplifier above, and is not specifically limited here. When the voltage of the positive input terminal Vin (+) is greater than the voltage of the inverting input terminal Vin (-), the output terminal Vout is forward amplified and output. When the voltage at the inverting input terminal Vin (-) is greater than the voltage at the non-inverting input terminal Vin (+), the output terminal Vout is negatively amplified.

[0049] It is understandable that a digital potentiometer is a programmable variable resistor whose resistance value is controlled by a digital signal. In an electronic circuit, it is usually used to accurately adjust gain, bias or other parameters. In the present embodiment, the digital signal is a remote control instruction from a remote control terminal, which may be an instruction issued by a microcontroller or other digital signal source, and can be remotely adjusted, avoiding the need for physical contact with the circuit, reducing the loss of the circuit, extending the service life of the signal amplification device of the photoacoustic spectroscopy, and improving the convenience and efficiency of technicians using the signal amplification device of the photoacoustic spectroscopy. The first digital potentiometer 1031 and the second digital potentiometer 1032 are respectively used as the input resistor and feedback resistor of the operational amplifier 1033. Adjusting the resistance of the first digital potentiometer 1031 by a remote control instruction can adjust the influence of the input signal on the operational amplifier 1033, thereby directly affecting the gain of the operational amplifier 1033, and adjusting the resistance of the second digital potentiometer 1032 by a remote control instruction can change the impedance of the feedback network of the operational amplifier 1033, thereby affecting the gain of the operational amplifier 1033.

[0050] It should be noted that the first digital potentiometer 1031 and the second digital potentiometer 1032 use digital potentiometers of the same specifications to provide a variable voltage gain with 8-bit accuracy to adapt to different measurement ranges of photoacoustic spectroscopy signals. Optionally, the first digital potentiometer 1031 and the second digital potentiometer 1032 can use AD5206 digital potentiometers, and the channel matching accuracy of the AD5206 digital potentiometer is as high as 0.25%, ensuring the consistency and repeatability of the gain. In addition, the first digital potentiometer 1031 and the second digital potentiometer 1032 can also be connected to other circuit structures.

[0051] In an exemplary embodiment, see Figure 3 The signal amplification device for photoacoustic spectroscopy described in any one of the above embodiments further includes a power supply module 104.

[0052] The power module 104 is respectively connected to the positive power terminal of the buffer 101 , the positive power terminal of the instrument amplifier 102 , and the positive power terminal of the digital control gain amplifier 103 .

[0053] It can be understood that the power supply module 104 is respectively connected to the positive power supply terminal of the first buffer amplifier and the positive power supply terminal of the second buffer amplifier of the buffer 101, the positive power supply terminal of the instrument amplifier 102, and the positive power supply terminal of the operational amplifier of the digitally controlled gain amplifier 103, to provide a stable power supply for the signal amplification device of the photoacoustic spectroscopy, ensuring reliability under various working conditions.

[0054] Optionally, the power module 104 may be a single lithium-ion battery with a supply voltage of 3.3V to 4.2V. The design of the single-ion battery simplifies the power module 104, facilitates portable applications, and enhances the flexibility and convenience of the signal amplification device for photoacoustic spectroscopy. In addition, the signal amplification device for photoacoustic spectroscopy may also support the USB (Universal Serial Bus) standard, and may be directly powered or charged through a USB interface, and adopts a rail-to-rail operation circuit to fully utilize the supply voltage, improve the dynamic range of the signal, and ensure that stable signal amplification can be provided under low voltage conditions.

[0055] In an exemplary embodiment, see Figure 4 , provides a signal amplification system for photoacoustic spectroscopy, comprising the signal amplification device for photoacoustic spectroscopy described in any one of the above embodiments; and also comprising a remote control terminal.

[0056] Optionally, the remote control terminal can be connected to the digital control gain amplifier 103 in the signal amplification device of the photoacoustic spectroscopy by wireless communication, and is used to issue control instructions according to the output of the signal amplification device of the photoacoustic spectroscopy to optimize the noise reduction effect and the signal amplification effect. Specifically, the setting of the control instructions can be determined according to the amplified photoacoustic spectroscopy signal output by the signal amplification device of the photoacoustic spectroscopy and the preset noise standard and the detection standard of the amplified signal. If it is detected that the amplified photoacoustic spectroscopy signal has met the actual measurement needs, there is no need to issue a control instruction to maintain the current operating state of the signal amplification device of the photoacoustic spectroscopy.

[0057] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0058] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A signal amplification device for photoacoustic spectroscopy, characterized in that: include: A buffer connected to the crystal resonator, configured to receive a photoacoustic spectroscopy signal emitted by the crystal resonator, and output a first amplified signal according to the photoacoustic spectroscopy signal; an instrument amplifier connected to the buffer, configured to receive the first amplified signal, provide a common mode rejection ratio, and output a second amplified signal based on the first amplified signal and the common mode rejection ratio; A digitally controlled gain amplifier is connected to the instrument amplifier and the remote control terminal, and is used to perform gain adjustment in response to a remote control instruction issued by the remote control terminal, and output a third amplified signal based on the adjusted gain and the second amplified signal as an amplified photoacoustic spectroscopy signal.

2. The signal amplification device for photoacoustic spectroscopy according to claim 1, characterized in that: The buffer includes a first buffer amplifier and a second buffer amplifier; Among them, the non-phase input terminal of the first buffer amplifier is connected to one end of the crystal resonator, and the inverting input terminal and the output terminal of the first buffer amplifier are both connected to the inverting input terminal of the instrument amplifier; the non-phase input terminal of the second buffer amplifier is connected to the other end of the crystal resonator, and the inverting input terminal and the output terminal of the second buffer amplifier are both connected to the non-phase input terminal of the instrument amplifier.

3. The signal amplification device for photoacoustic spectroscopy according to claim 2, characterized in that: The first buffer amplifier and the second buffer amplifier are amplifiers of the same specification, and are used to provide an input resistance of 9 TΩ to 11 TΩ and an input bias current of 0.4 pA to 0.6 pA.

4. The signal amplification device for photoacoustic spectroscopy according to claim 2, characterized in that: The first buffer amplifier and the second buffer amplifier are configured for unity gain.

5. The signal amplification device for photoacoustic spectroscopy according to claim 1, characterized in that: The digitally controlled gain amplifier comprises a first digital potentiometer, a second digital potentiometer and an operational amplifier; The non-inverting input terminal of the operational amplifier is connected to the output terminal of the instrument amplifier, the inverting input terminal of the operational amplifier is respectively connected to one end of the first digital potentiometer and one end of the second digital potentiometer, the other end of the first digital potentiometer is grounded, and the other end of the second digital potentiometer is connected to the output terminal of the operational amplifier.

6. The signal amplification device for photoacoustic spectroscopy according to claim 5, characterized in that: The first digital potentiometer and the second digital potentiometer are digital potentiometers of the same specification, and are used to provide a variable voltage gain with 8-bit accuracy.

7. The signal amplification device for photoacoustic spectroscopy according to any one of claims 1 to 6, characterized in that: The instrument amplifier is used to provide the common mode rejection ratio greater than or equal to 120 dB.

8. The signal amplification device for photoacoustic spectroscopy according to claim 1, characterized in that: The device also includes: A power supply module is respectively connected to the positive power supply terminal of the buffer, the positive power supply terminal of the instrument amplifier and the positive power supply terminal of the digital control gain amplifier.

9. The signal amplification device for photoacoustic spectroscopy according to claim 8, characterized in that: The power module includes a single lithium-ion battery, and the supply voltage ranges from 3.3V to 4.2V.

10. A signal amplification system for photoacoustic spectroscopy, characterized in that: A signal amplifying device for photoacoustic spectroscopy comprising any one of claims 1 to 9; It also includes a remote control terminal, which is connected to the digital control gain amplifier in the signal amplifying device.

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