Signal enhancement circuit, signal enhancement method and device of sensor system

Abstract

The invention relates to a signal enhancement circuit, a signal enhancement method and equipment of a sensor system. The signal enhancement circuit comprises a differential input module, a differential amplification module and a conversion module, the first end of the differential input module is connected with the output end of a signal source, the second end of the differential input module is connected with the first end of a transmission cable of the signal source, the input end of the differential amplification module is connected with the second end of the transmission cable, and the output end of the differential amplification module is connected with the input end of the conversion module; the differential amplification module is used for acquiring an original signal of a signal source and carrying out noise reduction and signal enhancement on the original signal to obtain a differential signal; the conversion module is used for converting the differential signal into a single-ended signal and outputting the single-ended signal. According to the invention, the problems of signal attenuation and interference caused by long cable connection can be effectively solved.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a signal enhancement circuit, a signal enhancement method and a device for a sensor system. Background Art

[0002] In many remote sensor applications, the sensor and the electronic device need to be connected via long cables. However, long cables introduce parasitic capacitance, external interference (such as common mode interference, CMI), and triboelectric effects, leading to signal loading, reduced sensitivity, and deterioration of signal-to-noise ratio (SNR) performance. Although traditional charge amplifiers can effectively reduce these effects, for piezoelectric polymer sensors whose sensitivity is mainly reflected in voltage response, the use of charge amplifiers will lead to further reduction in sensitivity, especially in the case of long cable connections, where signal attenuation is more obvious. Summary of the invention

[0003] Based on this, it is necessary to provide a signal enhancement circuit, a signal enhancement method and a device for a sensor system that can improve sensitivity and suppress external interference in a long cable connection.

[0004] A signal enhancement circuit for a sensor system, comprising: the circuit comprises a differential input module, a differential amplification module and a conversion module;

[0005] The first end of the differential input module is connected to the output end of the signal source, the second end of the differential input module is connected to the first end of the transmission cable of the signal source, the input end of the differential amplifier module is connected to the second end of the transmission cable, and the output end of the differential amplifier module is connected to the input end of the conversion module;

[0006] The differential amplification module is used to obtain the original signal of the signal source, and perform noise reduction and signal enhancement on the original signal to obtain a differential signal;

[0007] The conversion module is used for converting the differential signal into a single-ended signal and outputting the single-ended signal.

[0008] In one of the embodiments, the differential input module includes a first input resistor and a second input resistor;

[0009] A first end of the first input resistor is connected to a first output end of the signal source, and a second end of the first input resistor is connected to a first wire input end of the transmission cable;

[0010] A first end of the second input resistor is connected to a second output end of the signal source, and a second end of the second input resistor is connected to a second wire input end of the transmission cable.

[0011] In one embodiment, the differential amplification module includes a first amplification unit, an inverting input terminal of the first amplification unit is connected to a first conductor output terminal of a transmission cable, a non-inverting input terminal of the first amplification unit is grounded, and an output terminal of the first amplification unit is connected to a first input terminal of the conversion module.

[0012] In one embodiment, the differential amplifier module further includes a first feedback resistor, a first end of the first feedback resistor is connected to the inverting input end of the first amplifier unit, and a second end of the first feedback resistor is connected to the output end of the first amplifier unit.

[0013] In one embodiment, the differential amplification module also includes a second amplification unit, the inverting input terminal of the second amplification unit is connected to the second wire output terminal of the transmission cable, the non-phase input terminal of the second amplification unit is connected to the shielding layer of the transmission cable and grounded, and the output terminal of the second amplification unit is connected to the second input terminal of the conversion module.

[0014] In one embodiment, the differential amplifier module further includes a second feedback resistor, a first end of the second feedback resistor is connected to the inverting input end of the second amplifier unit, and a second end of the second feedback resistor is connected to the output end of the second amplifier unit.

[0015] In one embodiment, the conversion module includes a third amplifying unit, a non-phase input terminal of the third amplifying unit is connected to the output terminal of the first amplifying unit, an inverting input terminal of the third amplifying unit is connected to the output terminal of the second amplifying unit, and the output terminal of the third amplifying unit is connected to a back-end device.

[0016] A signal enhancement method, applied to the signal enhancement circuit as described in any of the above embodiments, the method comprising:

[0017] Acquire an original signal, and perform noise reduction and signal enhancement on the original signal to obtain a differential signal;

[0018] The differential signal is converted into a single-ended signal, and the single-ended signal is output.

[0019] In one embodiment, the original signal includes a first original signal and a second original signal, the differential signal includes a first differential signal and a second differential signal, and the acquiring the original signal and performing noise reduction and signal enhancement on the original signal to obtain the differential signal includes:

[0020] Performing noise reduction and signal enhancement on the first original signal to obtain the first differential signal;

[0021] Performing noise reduction and signal enhancement on the second original signal to obtain the second differential signal;

[0022] The step of converting the differential signal into a single-ended signal comprises:

[0023] The single-ended signal is calculated based on the first differential signal and the second differential signal.

[0024] A signal enhancement device comprises the signal enhancement circuit as described in any one of the above embodiments.

[0025] The above-mentioned signal enhancement circuit utilizes a differential amplifier module to eliminate the influence of cable parasitic capacitance. In addition, the differential amplifier module can effectively amplify the difference between the two original signals and has good common-mode interference suppression capability. Finally, a single-ended output signal is generated through a conversion module, which has the advantages of improving the sensitivity and signal-to-noise ratio of the system and being able to effectively deal with the signal attenuation and interference problems caused by long cable connections. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 A module structure diagram of the signal enhancement circuit provided in this application;

[0028] Figure 2 An electrical schematic diagram of the signal enhancement circuit provided in this application;

[0029] Figure 3 It is an electrical schematic diagram of the prior art;

[0030] Figure 4 A flow chart of the signal enhancement method provided in this application;

[0031] Figure 5 One of the experimental data for a specific implementation method;

[0032] Figure 6 A schematic diagram of a PCB layout of a specific implementation method;

[0033] Figure 7 This is the second experimental data of a specific implementation method;

[0034] Figure 8 This is the third experimental data of a specific implementation method. DETAILED DESCRIPTION

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least part of an element” means part or all of an element.

[0040] 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.

[0041] Piezoelectric sensors play an important role in various industries and application fields, and are widely used in multiple scenarios such as automobiles, industrial automation, medical, aerospace, environmental monitoring, structural health monitoring, etc. This type of sensor can effectively measure physical quantities such as pressure, acceleration, temperature, displacement and strain. With its high reliability, good linearity, wide operating temperature range and anti-electromagnetic interference, it has become the first choice in many applications. Among piezoelectric materials, piezoelectric ceramics and piezoelectric polymers are the two main categories. Piezoelectric polymer materials, such as polyvinylidene fluoride (PVDF), are widely used in underwater acoustic transducers, medical ultrasound imaging, biosensors, energy harvesters and other fields due to their excellent voltage sensitivity, flexibility, chemical tolerance, low acoustic impedance and low dielectric loss. Compared with piezoelectric ceramic materials, piezoelectric polymer materials such as PVDF have higher voltage sensitivity, but at the same time their charge sensitivity is lower. Based on these characteristics, voltage amplifiers are usually used to improve sensitivity.

[0042] In many remote sensor applications, the sensor and electronic equipment need to be connected via long cables. However, long cables introduce parasitic capacitance, external interference (such as common-mode interference, CMI), and triboelectric effects, leading to signal loading, reduced sensitivity, and deterioration of signal-to-noise ratio (SNR) performance. Although traditional charge amplifiers can effectively reduce these effects, for piezoelectric polymer sensors whose sensitivity is mainly reflected in voltage response, the use of charge amplifiers will lead to further reduction in sensitivity, especially in the case of long cable connections, where signal attenuation is more obvious. Therefore, there is an urgent need for a voltage amplifier solution that can improve sensitivity and suppress external interference in long cable connections.

[0043] Currently, signal conditioning for piezoelectric sensors mainly uses two amplifier configurations: charge mode amplifiers and voltage mode amplifiers. Charge amplifiers are usually used for piezoelectric materials with high charge sensitivity to improve signal quality by reducing the loading of sensor capacitance and avoiding signal loss caused by cable parasitic capacitance. However, for piezoelectric polymer sensors with high voltage sensitivity, the use of charge amplifiers will lead to a decrease in sensitivity due to their low charge sensitivity, especially in the case of long cable connections, the signal attenuation is more obvious. In voltage mode amplifiers, signal loading caused by cable parasitic capacitance is one of the main problems. The cable capacitance will form a voltage divider effect with the sensor capacitance, thereby weakening the amplitude of the sensor output signal and resulting in reduced sensitivity. In addition, the triboelectric effect of the cable and external electromagnetic interference (such as common-mode interference) will further deteriorate the signal quality, thereby reducing the signal-to-noise ratio of the system.

[0044] See also Figure 3 , Figure 3 FIG. 1 shows a single-ended amplifier in the prior art. OA1 represents a single-ended amplifier, C cRepresents the interface cable capacitance, R i Represents the input resistance, R f The input resistance and feedback resistance determine the gain of the amplifier. i Represents the voltage from the signal source, C f Represents the amplifier’s filter capacitor, V i represents the output of the amplifier, Q p represents the equivalent inductance of the sensor, C p represents the equivalent capacitance of the sensor, R p Indicates the equivalent resistance of the sensor.

[0045] The existing single-ended voltage amplifier configuration has obvious deficiencies in suppressing cable parasitic capacitance and common-mode interference. Although differential amplifiers can mitigate the impact of common-mode interference to a certain extent, there is no effective solution in the existing technology to completely eliminate the impact of cable parasitic capacitance, especially in application scenarios that require long-distance transmission, the system sensitivity and signal-to-noise ratio are difficult to be effectively guaranteed.

[0046] Therefore, the existing technology mainly has the following problems: First, the parasitic capacitance introduced by the long cable will cause signal loading, significantly reducing the sensitivity of the sensor. Secondly, the triboelectric effect of the cable and external electromagnetic interference (especially common-mode interference) will have an adverse effect on the signal and reduce the signal-to-noise ratio of the system. Finally, the common-mode interference suppression effect of the single-ended voltage amplifier when dealing with long cable connections is limited, and it is difficult to meet the requirements of high sensitivity and high signal-to-noise ratio. In summary, the existing technology has many defects in the remote piezoelectric polymer sensor system, and an improved differential voltage amplifier solution is urgently needed to improve the sensitivity and signal-to-noise ratio of the system, and effectively deal with the signal attenuation and interference problems caused by long cable connections.

[0047] like Figure 1 As shown, this embodiment provides a signal enhancement circuit of a sensor system, the circuit includes a differential input module 100, a differential amplification module 200 and a conversion module 300;

[0048] The first end of the differential input module 100 is connected to the output end of the signal source 400, the second end of the differential input module 100 is connected to the first end of the transmission cable 500 of the signal source 400, the input end of the differential amplifier module 200 is connected to the second end of the transmission cable 500, and the output end of the differential amplifier module 200 is connected to the input end of the conversion module 300; the differential amplifier module 200 is used to obtain the original signal of the signal source 400, and perform noise reduction and signal enhancement on the original signal to obtain a differential signal; the conversion module 300 is used to convert the differential signal into a single-ended signal and output the single-ended signal.

[0049] Exemplarily, the signal source 400 may be a piezoelectric sensor. Piezoelectric sensors utilize the piezoelectric effect, which is the phenomenon that certain materials generate an electric charge or voltage when subjected to mechanical stress (such as pressure, vibration). These materials are called piezoelectric materials, and they are widely used in many industrial and scientific applications to measure physical quantities such as pressure, acceleration, vibration, etc. Piezoelectric materials can be roughly divided into two categories: one is piezoelectric ceramic materials, such as barium titanate and lead zirconate titanate, which have high charge sensitivity and are commonly used for high-precision measurements. The second is piezoelectric polymer materials, such as polyvinylidene fluoride (PVDF), which have high voltage sensitivity and are widely used in many applications due to their flexibility and bendability.

[0050] The basic principle of the piezoelectric effect is that when a piezoelectric material is subjected to a force, the internal electric dipoles are rearranged, resulting in a potential difference (voltage) or charge across the material. The output signal of a piezoelectric sensor can be characterized in two ways. One is charge sensitivity, which indicates the amount of charge generated by the sensor when a unit force is applied, and the unit is pico-coulomb / newton (pC / N); the other is voltage sensitivity, which indicates the voltage generated by the sensor when a unit force is applied, and the unit is volt-meter / newton (V·m / N). In general, piezoelectric polymer materials (such as PVDF) have higher voltage sensitivity and are therefore more suitable for using voltage amplifiers to process signals. However, when a long cable is used to connect the sensor and the signal processing circuit, the parasitic capacitance of the cable will have a serious impact on the output signal of the sensor, resulting in a decrease in sensitivity.

[0051] In addition, in remote sensing applications, the sensor and its back-end electronic devices usually need to be connected through long cables. In this case, the cable will introduce a certain amount of parasitic capacitance, which will have an adverse effect on the output signal of the sensor. The parasitic capacitance is mainly composed of the following two parts: one is the cable capacitance C c , which is caused by the capacitance effect between the conductor and the shielding layer in the cable; the second is the shielding capacitance C s , caused by the capacitive effect between the conductors of the cable.

[0052] In a typical voltage amplifier configuration, these parasitic capacitances will react with the internal equivalent capacitance of the sensor, C p Together they form a voltage divider network, causing the sensor output signal to attenuate. Worse still, the movement of the cable may cause dynamic changes in the parasitic capacitance, which in turn affects the stability of the output signal.

[0053] Based on this, the present embodiment introduces a differential amplifier module 200, which can effectively suppress common-mode interference and eliminate the influence of cable parasitic capacitance through special wiring, thereby improving the sensitivity and signal-to-noise ratio (SNR) of the sensor. Since the differential amplifier module 200 actually obtains two differential signals, a conversion module 300 is also provided to convert the two differential signals into single-ended signals and then output them to the back-end device.

[0054] This embodiment uses the differential amplifier module 200 to solve the problems of signal attenuation and reduced signal-to-noise ratio (SNR) due to cable parasitic capacitance and common mode interference (CMI) in a sensor system connected by a long cable, while achieving signal enhancement.

[0055] In one embodiment, Figure 2 As shown, the differential input module 100 includes a first input resistor R1 and a second input resistor R2; the first end of the first input resistor R1 is connected to the first output end of the signal source 400, and the second end of the first input resistor R1 is connected to the first wire input end of the transmission cable 500; the first end of the second input resistor R2 is connected to the second output end of the signal source 400, and the second end of the second input resistor R2 is connected to the second wire input end of the transmission cable 500.

[0056] By using the differential input module 100 , the first input resistor R1 and the second input resistor R2 are moved to the end of the signal source 400 , which can further reduce the load effect of the cable parasitic capacitance on the signal and ensure the integrity of the sensor signal.

[0057] In one embodiment, the differential amplifier module 200 includes a first amplifier unit OA1, an inverting input terminal of the first amplifier unit OA1 is connected to the first wire output terminal of the transmission cable 500, a non-inverting input terminal of the first amplifier unit OA1 is grounded, and an output terminal of the first amplifier unit OA1 is connected to the first input terminal of the conversion module 300.

[0058] The first amplifying unit OA1 is an operational amplifier, and an inverting input terminal of the first amplifying unit OA1 is connected to one of the two wires of the transmission cable 500 . For the convenience of description, the first wire is used here to refer to it.

[0059] In one implementation, the differential amplifier module 200 further includes a first feedback resistor, a first end of the first feedback resistor is connected to the inverting input end of the first amplifier unit OA1 , and a second end of the first feedback resistor is connected to the output end of the first amplifier unit OA1 .

[0060] The gain of the first amplifying unit OA1 can be determined by the ratio of the first feedback resistor to the first input resistor R1. Specifically, the gain of the first amplifying unit OA1 is the inverse of the ratio of the first feedback resistor to the first input resistor R1.

[0061] In one embodiment, the differential amplifier module 200 also includes a second amplifier unit OA2, the inverting input terminal of the second amplifier unit OA2 is connected to the second wire output terminal of the transmission cable 500, the non-phase input terminal of the second amplifier unit OA2 is connected to the shielding layer of the transmission cable 500 and grounded, and the output terminal of the second amplifier unit OA2 is connected to the second input terminal of the conversion module 300.

[0062] The second amplifying unit OA2 is also an operational amplifier, and the inverting input terminal of the second amplifying unit OA2 is connected to the other of the two wires of the transmission cable 500, which is referred to as the second wire for ease of description. The non-inverting input terminals of the first amplifying unit OA1 and the second amplifying unit OA2 are grounded and connected to the shielding layer of the transmission cable 500.

[0063] At the inverting input of the operational amplifier, the voltage will be maintained at 0V due to the existence of negative feedback. This phenomenon is called the virtual ground effect. By connecting the signal end of the cable to the inverting input of the operational amplifier, the virtual ground effect can short-circuit the parasitic capacitance of the cable, thereby preventing the parasitic capacitance of the cable from loading the sensor output signal. Through the virtual ground effect of the operational amplifier, the parasitic capacitance C c and C s It is equivalent to a short circuit, ensuring that the signal will not be shunted due to the existence of parasitic capacitance, thereby avoiding the problem of signal attenuation.

[0064] The differential amplifier module 200 can not only effectively amplify the difference between the two input signals, but also has good common-mode interference suppression capability. When the cable is exposed to an electromagnetic interference environment, the external interference signal often acts on the two signal lines of the cable at the same time. These interference signals are called common-mode signals. The first amplifier unit OA1 and the second amplifier unit OA2 only amplify the difference between the two input signals, so they can effectively suppress the influence of the common-mode signal and improve the signal-to-noise ratio of the signal.

[0065] For example, Figure 2 There are also filter capacitors C1 and C2 connected between the inverting input and output of the operational amplifier, as well as resistors R5, R6, R7, and R8 in the circuit, which play the role of current limiting, filtering, and protection.

[0066] In one implementation, the differential amplifier module 200 further includes a second feedback resistor, a first end of the second feedback resistor is connected to the inverting input end of the second amplifier unit OA2, and a second end of the second feedback resistor is connected to the output end of the second amplifier unit OA2.

[0067] The gain of the second amplifying unit OA2 can be determined by the ratio of the second feedback resistor to the second input resistor R2. Specifically, the gain of the second amplifying unit OA2 is the inverse of the ratio of the second feedback resistor to the second input resistor R2.

[0068] In one embodiment, the conversion module 300 includes a third amplifying unit OA3, a non-inverting input terminal of the third amplifying unit OA3 is connected to the output terminal of the first amplifying unit OA1, an inverting input terminal of the third amplifying unit OA3 is connected to the output terminal of the second amplifying unit OA2, and an output terminal of the third amplifying unit OA3 is connected to a back-end device. The third amplifying unit OA3 can be configured as a unity gain amplifier without changing the signal amplitude.

[0069] In summary, in the design of the differential amplifier module 200, the two output ends of the signal source 400 are respectively connected to the inverting input ends of the two operational amplifiers, which constitute the input stage of the differential amplifier module 200. The shielding layer of the cable is grounded to reduce external interference. Through the virtual ground effect, the parasitic capacitance of the cable is effectively short-circuited, thereby avoiding signal attenuation. Finally, the output of the differential amplifier is converted to a single-ended conversion module 300 to generate a single-ended output signal, and the single-ended signal is output to the back-end device.

[0070] In one embodiment, the present application also provides a signal enhancement method, see Figure 4 , applied to a signal enhancement circuit as in any of the above embodiments, the method comprises:

[0071] Step 601, obtaining an original signal, and performing noise reduction and signal enhancement on the original signal to obtain a differential signal;

[0072] Step 602: Convert the differential signal into a single-ended signal and output the single-ended signal.

[0073] In one embodiment, the original signal includes a first original signal and a second original signal, the differential signal includes a first differential signal and a second differential signal, and the original signal is obtained, and noise reduction and signal enhancement are performed on the original signal to obtain the differential signal, including: based on the first amplification unit OA1, noise reduction and signal enhancement are performed on the first original signal to obtain the first differential signal; based on the second amplification unit OA2, noise reduction and signal enhancement are performed on the second original signal to obtain the second differential signal;

[0074] Converting the differential signal into a single-ended signal includes: calculating the single-ended signal based on the third amplification unit OA3, the first differential signal and the second differential signal. The single-ended signal finally obtained can be referred to the following formula:

[0075] Formula 1:

[0076] ;

[0077] in, represents the feedback resistor, represents the input resistance; in this embodiment, the ratio of the first feedback resistance to the first input resistance is the same as the ratio of the second feedback resistance to the second input resistance.

[0078] In one embodiment, the present application also provides a signal enhancement device, including the signal enhancement circuit as described in any of the above embodiments.

[0079] The signal enhancement circuit provided by the present application has significant advantages, especially in the piezoelectric sensor system connected by a long cable. First, the present application effectively eliminates the negative impact of the cable parasitic capacitance on the signal through the virtual ground effect, avoids the signal attenuation caused by the capacitor voltage divider effect, and thus maintains the high sensitivity of the sensor. Secondly, the differential amplifier structure can suppress common-mode interference in the external environment, greatly improve the signal-to-noise ratio, and enable the system to still work stably in a noisy environment. In addition, the experimental results show that when the present application is connected by a long cable (for example, 5 meters), the sensitivity is improved by 4.55 dB compared with the traditional differential amplifier, and the signal-to-noise ratio is improved by 18 dB, which verifies its superior performance in complex environments. Therefore, the present application is very suitable for scenarios where a long cable connection is required between the sensor and the electronic device, which not only improves the anti-interference ability of the system, but also greatly improves the signal quality and the overall performance of the system.

[0080] It can be understood that the above-mentioned signal enhancement circuit can also adopt other forms, and is not limited to the forms mentioned in the above embodiments, as long as it can achieve the function of completing signal enhancement.

[0081] In order to more clearly explain the signal enhancement circuit and signal enhancement method of this application, the performance of the signal enhancement circuit proposed in this application is verified as follows. The performance of the proposed signal enhancement circuit when the piezoelectric sensor is connected to a long cable is mainly verified, especially its effectiveness in dealing with cable parasitic capacitance and common mode interference (CMI). The experiment evaluates the actual effect of the scheme by building a hardware prototype and combining it with simulation, and compares it with the traditional single-ended voltage amplifier scheme.

[0082] First, see Figure 5 , Figure 5 (a) shows the prior art ( Figure 3) shows the single-ended configuration of the proposed voltage amplifier, and (b) shows the simulated FFT diagram of the output of the proposed signal enhancement circuit in the presence of common-mode interference. The ordinary differential voltage amplifier and the proposed signal enhancement circuit were simulated using LTspice, focusing on the analysis of the impact of cable parasitic capacitance and CMI on their performance. In the simulation, the piezoelectric sensor was modeled as a circuit with a series resistor (100Ω), a series capacitor (1000pF), and a leakage parallel resistor (10MΩ), and a two-core cable model was used, which included the cable's series resistor (2.5Ω), parasitic parallel capacitance (800pF) and shielding capacitance (1000pF). The simulation results show that the input signal of the conventional differential voltage amplifier is attenuated by 6 dB under the influence of cable parasitic capacitance, resulting in a decrease in sensitivity; while the proposed signal enhancement circuit is not affected by cable parasitic capacitance, and the simulation verifies that the sensitivity of the scheme is not affected by parasitic capacitance. In addition, the simulation also verifies the ability of the signal enhancement circuit to suppress common-mode interference. The results show that the scheme can effectively suppress common-mode interference and improve the signal-to-noise ratio (SNR).

[0083] See also Figure 6 This application also passes Figure 6 The hardware layout shown further verifies the simulation results. The experimental setup includes an ultrasonic air sensor (AT200), a signal enhancement circuit assembled on a printed circuit board (PCB), a signal generation circuit, a digital storage oscilloscope (DSO), and a linear power supply. The low-noise, low-bias current, wide-bandwidth (60 MHz) LT6234 operational amplifier is used in the design of the differential amplifier module, and the amplifier gain is set to -10. The sensor and the differential amplifier are connected by a 5-meter-long two-core shielded cable. In the experiment, the direct digital synthesis (DDS) chip AD9833 is used to generate an 18 V peak-to-peak, 200 kHz continuous sine wave to excite the ultrasonic transmitting sensor. The transmitted sound wave is transmitted through the air to the receiving sensor, and the received signal is input into the differential amplifier for amplification. The entire system is powered by a ±5 V DC power supply, and the changes in the amplifier input and output signals are monitored by the DSO. It should be noted that Figure 6 This is only a schematic diagram of the PCB layout. The actual connection method depends on the specific situation.

[0084] See also Figure 7 , Figure 7 Screen shots of the digital storage oscilloscope waveforms at the input and output of the proposed signal enhancement circuit.

[0085] Specifically, the experiment first monitored the input and output signals of the differential voltage amplifier without connecting the cable. The input voltage was 261 mV peak-to-peak and the output voltage was 2.558 V peak-to-peak. When a 5-meter-long two-core shielded cable was connected, the input voltage dropped to 177 mV peak-to-peak and the output voltage dropped to 1.73 V peak-to-peak, and the signal was attenuated by about 3.4 dB. This attenuation is due to the load effect caused by the parasitic capacitance of the cable, which affects the sensitivity performance of the conventional differential voltage amplifier. However, when the input resistance of the differential amplifier is moved to the receiving sensor end and the signal is transmitted to the reverse input end of the amplifier through the cable, the input voltage only drops slightly to 254 mV peak-to-peak, while the output voltage increases to 2.92 V peak-to-peak, indicating that the scheme is insensitive to the parasitic capacitance of the cable and the sensitivity performance does not decrease significantly. However, due to the increase in output voltage, the parasitic capacitance of the cable needs to be handled carefully during design to avoid instability caused by gain peaking.

[0086] See also Figure 8 , Figure 8 (a) represents the signal enhancement circuit of the present application, and (b) represents the FFT (Fast Fourier Transform) diagram of the output voltage of the signal enhancement circuit of the present application in the presence of CMI. In order to test the impact of CMI on the signal-to-noise ratio, the cable was exposed to a strong electromagnetic interference environment in the laboratory, mainly from 50 Hz power line radiation. The output FFT diagrams of the single-ended amplifier and the enhanced differential voltage amplifier were compared by DSO. The results showed that in the single-ended amplifier, the 50 Hz power line interference signal was only 18 dB lower than the original signal, while in the signal enhancement circuit of the present application, the interference signal was further suppressed and reduced by 36 dB. This shows that compared with the single-ended solution, the signal enhancement circuit of the present application has improved by 18 dB in suppressing common-mode interference, significantly improving the SNR performance of the system.

[0087] The experimental part verifies the effectiveness of the enhanced differential voltage amplifier scheme in dealing with cable parasitic capacitance and common-mode interference. The experimental results show that the scheme can significantly reduce the signal attenuation caused by cable parasitic capacitance and significantly suppress common-mode interference, thereby improving the sensitivity and signal-to-noise ratio of the system. Compared with the traditional single-ended voltage amplifier, the signal enhancement circuit of this application shows better stability and anti-interference ability under long cable connection conditions, and is suitable for use in noisy environments.

[0088] 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.

[0089] 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.

[0090] 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 enhancement circuit for a sensor system, characterized in that: The circuit includes a differential input module, a differential amplification module and a conversion module; The first end of the differential input module is connected to the output end of the signal source, the second end of the differential input module is connected to the first end of the transmission cable of the signal source, the input end of the differential amplifier module is connected to the second end of the transmission cable, and the output end of the differential amplifier module is connected to the input end of the conversion module; The differential amplification module is used to obtain the original signal of the signal source, and perform noise reduction and signal enhancement on the original signal to obtain a differential signal; The conversion module is used for converting the differential signal into a single-ended signal and outputting the single-ended signal.

2. The signal enhancement circuit according to claim 1, characterized in that: The differential input module includes a first input resistor and a second input resistor; A first end of the first input resistor is connected to a first output end of the signal source, and a second end of the first input resistor is connected to a first wire input end of the transmission cable; A first end of the second input resistor is connected to a second output end of the signal source, and a second end of the second input resistor is connected to a second wire input end of the transmission cable.

3. The signal enhancement circuit according to claim 1, characterized in that: The differential amplifier module includes a first amplifier unit, an inverting input terminal of the first amplifier unit is connected to a first wire output terminal of a transmission cable, a non-inverting input terminal of the first amplifier unit is grounded, and an output terminal of the first amplifier unit is connected to a first input terminal of the conversion module.

4. The signal enhancement circuit according to claim 3, characterized in that: The differential amplification module further includes a first feedback resistor, a first end of the first feedback resistor is connected to the inverting input end of the first amplification unit, and a second end of the first feedback resistor is connected to the output end of the first amplification unit.

5. The signal enhancement circuit according to claim 3, characterized in that: The differential amplification module also includes a second amplification unit, an inverting input end of the second amplification unit is connected to the second wire output end of the transmission cable, a non-phase input end of the second amplification unit is connected to the shielding layer of the transmission cable and grounded, and an output end of the second amplification unit is connected to the second input end of the conversion module.

6. The signal enhancement circuit according to claim 5, characterized in that: The differential amplification module further includes a second feedback resistor, a first end of the second feedback resistor is connected to the inverting input end of the second amplification unit, and a second end of the second feedback resistor is connected to the output end of the second amplification unit.

7. The signal enhancement circuit according to claim 5, characterized in that: The conversion module includes a third amplifying unit, a non-phase input terminal of the third amplifying unit is connected to the output terminal of the first amplifying unit, an inverting input terminal of the third amplifying unit is connected to the output terminal of the second amplifying unit, and the output terminal of the third amplifying unit is connected to a back-end device.

8. A signal enhancement method, characterized in that: Applied to the signal enhancement circuit according to any one of claims 1 to 7, the method comprises: Acquire an original signal, and perform noise reduction and signal enhancement on the original signal to obtain a differential signal; The differential signal is converted into a single-ended signal, and the single-ended signal is output.

9. The signal enhancement method according to claim 8, characterized in that: The original signal includes a first original signal and a second original signal, the differential signal includes a first differential signal and a second differential signal, and the acquiring the original signal and performing noise reduction and signal enhancement on the original signal to obtain the differential signal includes: Performing noise reduction and signal enhancement on the first original signal to obtain the first differential signal; Performing noise reduction and signal enhancement on the second original signal to obtain the second differential signal; The step of converting the differential signal into a single-ended signal comprises: The single-ended signal is calculated based on the first differential signal and the second differential signal.

10. A signal enhancement device, characterized in that: The method comprises a signal enhancement circuit according to any one of claims 1 to 7.

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