Signal amplification circuit for gas sensor array and detection device based on signal amplification circuit

Abstract

The invention belongs to the technical field of gas sensor signal processing, and particularly discloses a signal amplification circuit for a gas sensor array and a detection device based on the signal amplification circuit. The circuit is composed of a first amplification circuit, a voltage following circuit, a second amplification circuit and a third amplification circuit which are sequentially connected in series. The first amplification circuit obtains a sensor initial signal; the voltage follower circuit performs impedance matching of the two-stage amplification circuit, so that the problem of signal attenuation caused by relatively high output impedance of the gas sensor can be effectively adapted, and uA-stage current is accurately amplified; the second amplification circuit is provided with a precise proportion adjustable resistance network so as to realize high-precision adjustment of standard reference voltage and eliminate a direct-current bias signal when the gas concentration is 0, so that interference caused by sensor baseline drift and environment temperature is eliminated; and the third amplification circuit amplifies the second-stage output signal, so that the second-stage output signal is easy to measure, and the gain is adjustable.

Description

Technical Field

[0001] This application belongs to the technical field of gas sensor signal processing, and more specifically, relates to a signal amplification circuit for a gas sensor array and a detection device based on the same. Background Art

[0002] As an important detection device, gas sensors are widely used in the fields of environmental monitoring, industrial safety, medical health, etc. At present, the acquisition and processing of gas sensor signals mainly rely on two types of solutions: the dedicated amplification circuit of a single sensor and the general-purpose commercial amplifier. Among them, the main working principle of the dedicated amplification circuit is to design a customized circuit according to the performance parameters of a specific sensor, including pre-amplification, signal conditioning, output processing, etc.; this solution can specifically solve the signal processing requirements of a specific sensor, but lacks universality and is only applicable to this sensor model or sensors with similar parameter ranges. When changing the sensor type, such as from resistive to capacitive, etc., the original circuit cannot be directly adapted and needs to be redesigned, and the cost is relatively high. The main working principle of the general-purpose commercial amplifier is to use a standard operational amplifier to construct a basic amplification circuit and realize signal amplification through a simple resistor-capacitor network; this solution has the advantages of low cost and simple operation, but there are problems such as signal distortion, poor anti-interference ability, and inability to effectively eliminate baseline drift, and is only applicable to low-precision application scenarios.

[0003] Both of the above two solutions have limitations such as limited applicable ranges, difficulty in simultaneously processing signals of multiple types of sensors, inability to effectively eliminate baseline drift and environmental interference, and small gain adjustment ranges, and cannot meet the diverse requirements of the signal processing circuit for the sensor array in practical applications. Especially in the occasion where it is necessary to simultaneously collect and process signals of multiple different types of gas sensors, the existing solutions often require designing multiple sets of independent signal processing circuits, which not only increases the complexity and cost of the system, but also easily introduces additional noise interference. In addition, the problems of zero drift and baseline drift that generally exist in the actual use process of sensors are also difficult to be effectively solved by the existing solutions. Summary of the Invention

[0004] Aiming at the defects of the prior art, the purpose of this application is to provide a signal amplification circuit for a gas sensor array and a detection device based on the same, aiming to solve the problems of poor universality and poor anti-interference ability of the prior art.

[0005] The first aspect of the present application relates to a signal amplification circuit for a gas sensor array, including: a first amplification circuit for in-phase amplifying the weak voltage signal collected by the gas sensor; a voltage follower circuit for achieving impedance matching between the first amplification circuit and the second amplification circuit; a second amplification circuit for subtracting the output voltage signal of the voltage follower circuit from the reference voltage and then performing inverting amplification to obtain a pure response signal; a third amplification circuit for in-phase amplifying the pure response signal output by the second amplification circuit to ensure that the amplified signal can be read by the analog-to-digital converter in the MCU.

[0006] In some embodiments, the amplification factor of the first amplification circuit ranges from [10, 100], the amplification factor of the second amplification circuit ranges from [1, 10], the amplification factor of the third amplification circuit ranges from [10, 100], and the amplification factor of the entire signal amplification circuit ranges from [1000, 10000].

[0007] In some embodiments, the first amplification circuit includes a first operational amplifier U1, resistors R2 - R4, and a decoupling capacitor C1; the inverting input terminal of the first operational amplifier U1 is grounded through the resistor R2, the non-inverting input terminal is connected to the common terminal between the voltage-dividing resistor and the gas sensor, the VCC terminal is grounded through the decoupling capacitor C1, the output terminal is grounded through the resistor R4 and the resistor R2 in sequence, the output terminal is also connected to the non-inverting input terminal of the second operational amplifier U2, and the E / D pin is connected to the operating voltage through the resistor R3; the resistance value of the resistor R3 is 100 kΩ, the resistors R2 and R4 are both in the kΩ level, and , is the amplification factor of the first amplification circuit, and the decoupling capacitor is a capacitor in the uf level.

[0008] In some embodiments, the second amplification circuit includes a third operational amplifier U3 and resistors R5, R7, and R8; the non-inverting input terminal of the third operational amplifier U3 is connected to the reference voltage, the inverting input terminal is connected to the output terminal through the resistor R7 and is also connected to the output terminal of the voltage follower circuit through the resistor R5, the output terminal is connected to the non-inverting input terminal of the third amplification circuit, and the E / D pin is connected to the operating voltage through the resistor R8; the resistance value of the resistor R8 is 100 kΩ, the resistors R5 and R7 are both in the kΩ level, and , is the amplification factor of the second amplification circuit.

[0009] In some embodiments, the third amplification circuit includes a fourth operational amplifier U4 and resistors R9 - R11; the inverting input terminal of the fourth operational amplifier U4 is grounded through the resistor R9, the output terminal is connected to the inverting input terminal through the resistor R10, the output terminal is used to connect to the MCU, and the E / D pin is connected to the operating voltage through the resistor R11; the resistance value of the resistor R11 is 100 kΩ, the resistors R9 and R10 are both in the kΩ level, and , is the amplification factor of the third amplifier circuit.

[0010] In some embodiments, it further includes a calibration circuit for providing reference voltage of different magnitudes, which includes a fifth operational amplifier U5, a resistor R12, a sliding rheostat R13, and a resistor R14; the non-inverting input terminal of the fifth operational amplifier U5 is connected to the common terminal between the resistor R12 and the sliding rheostat R13, the inverting input terminal is connected to the output terminal via the resistor R14, and the output terminal is used to provide the reference voltage; the resistor R14 is a resistor in the kΩ level, and the maximum resistance value of the sliding rheostat R13 is 5 times the resistance value of the resistor R12.

[0011] The second aspect of the present application relates to a detection device based on the signal amplification circuit as described in the first aspect, including: an MCU and multiple signal amplification circuits; the multiple signal amplification circuits correspond to the gas sensors in the gas sensor array one by one; the MCU is configured to perform real-time high-precision sampling on the output signals of each signal amplification circuit, convert the analog signals into digital signals, and then convert the digital signals into function curves for display.

[0012] In some embodiments, it further includes a power supply module composed of a multi-value voltage generation circuit and a voltage stabilization phase-shifting circuit; the multi-value voltage generation circuit is used to generate an adjustable voltage of 1.24V - 60V and the corresponding negative voltage according to the change of the resistance value; the voltage stabilization phase-shifting circuit is used to filter the output signal of the multi-value voltage generation circuit to form various stable working voltages required for each amplifier circuit.

[0013] In some embodiments, the multi-value voltage generation circuit includes a linear voltage regulator u1, a linear voltage regulator u2, capacitors c1 - c4, resistors r1 - r2, a first sliding rheostat r3, and a second sliding rheostat r4; the input pin of the linear voltage regulator u1 is grounded via the capacitor c3, the output pin is grounded via the capacitor c2, the adjustable pin is grounded via the first sliding rheostat r3, and the output pin is also connected to the common terminal between the adjustable pin and the first sliding rheostat r3 via the resistor r2, and the output pin is used to connect to the gas sensor and the operational amplifier in each amplifier circuit to provide the working voltage VDD; the input pin of the linear voltage regulator u2 is connected to the output pin of the linear voltage regulator u1, the input pin is also grounded via the capacitor c1, the output pin is grounded via the capacitor c4, the adjustable pin is grounded via the second sliding rheostat r4, and the output pin is also connected to the common terminal between the adjustable pin and the second sliding rheostat r4 via the resistor r1, and the output pin is connected to the input terminal of the voltage stabilization phase-shifting circuit and is used to connect to the operational amplifier in each amplifier circuit to provide the positive power supply voltage VCC; the capacitances of the capacitors c1 and c3 are both 1uf, the capacitances of the capacitors c2 and c4 are both 3.3uf, and the resistors r1 - r2 are all resistors in the kΩ level, and at the same time, it satisfies that the output voltage of the linear voltage regulator u1 , the output voltage of the linear voltage regulator U2 .

[0014] In some embodiments, the voltage stabilizing phase-shifting circuit includes an operational amplifier U3 and resistors R5 - R7; the non-inverting input terminal of the operational amplifier U3 is grounded through the resistor R7, the inverting input terminal is connected to the input terminal of the multi-valued voltage generating circuit through the resistor R5, the output terminal is connected to the inverting input terminal through the resistor R6, and the output terminal is used to be connected to the operational amplifiers in each amplifier circuit to provide a negative power supply voltage VEE; the resistors R5 - R7 are all kΩ-level resistors and have equal resistance values.

[0015] Generally speaking, compared with the prior art through the above technical solutions conceived by the present application, the following beneficial effects are obtained: (1) The present application provides a signal amplification circuit for a gas sensor array, which is composed of a first amplifier circuit, a voltage follower circuit, a second amplifier circuit, and a third amplifier circuit connected in series in sequence. The first amplifier circuit acquires the initial signal of the sensor; the voltage follower circuit performs impedance matching of the two-stage amplifier circuit, can effectively adapt to the signal attenuation problem caused by the relatively high output impedance of the gas sensor, and accurately amplifies the uA-level current; the second amplifier circuit sets a precise proportional adjustable resistor network to achieve high-precision adjustment of the reference voltage, eliminate the DC bias signal when the gas concentration is 0, thereby eliminating the baseline drift of the sensor and the interference caused by the ambient temperature; the third amplifier circuit amplifies the output signal of the second stage to make it easy to measure, and its gain is adjustable.

[0016] (2) The present application provides a detection device based on the signal amplification circuit, including: an MCU and a plurality of signal amplification circuits. The sliding rheostats of the plurality of signal amplification circuits have different adjusted resistance values to achieve different amplification multiples, so as to be applicable to different sensors, thereby meeting the acquisition requirements of high-precision, high-sensitivity, and high-reliability signals of the array-type sensor. In addition, a sensitive material with a lower cost is used as the sensor, and a signal calibration and amplification circuit is designed with a low-cost operational amplifier, ultimately reducing the cost. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of a signal amplification circuit for a gas sensor array provided by an embodiment of the present application.

[0018] Figure 2 is a schematic structural diagram of a calibration circuit provided by an embodiment of the present application.

[0019] Figure 3 is a schematic structural diagram of a power supply module provided by an embodiment of the present application. Detailed Embodiments

[0020] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0022] As Figure 1 shown, the present application provides a signal amplification circuit for a gas sensor array, including: a first amplification circuit for in-phase amplifying the weak voltage signal collected by the gas sensor; a voltage follower circuit for achieving impedance matching between the first amplification circuit and the second amplification circuit; a second amplification circuit for subtracting the voltage signal output by the voltage follower circuit from the reference reference voltage and then performing inverting amplification to obtain a pure response signal; a third amplification circuit for in-phase amplifying the pure response signal output by the second amplification circuit to ensure that the amplified signal can be read by the analog-to-digital converter in the MCU.

[0023] For multiple gas sensors in the gas sensor array, the present application is provided with multiple calibration circuits and multiple signal amplification circuits, which correspond to each other one by one. The reference reference voltages of the multiple calibration circuits are different, and the resistance values of the sliding rheostats R13 of the multiple signal amplification circuits are adjusted differently, so as to be applicable to different sensors.

[0024] When the gas to be measured passes through, the gas sensor will generate corresponding current and voltage signals, which enter the signal amplification circuit in the present application through the data acquisition module. The first amplification circuit obtains the initial signal of the sensor; the voltage follower circuit performs impedance matching of the two-stage amplification circuit, can effectively adapt to the signal attenuation problem caused by the high output impedance of the gas sensor, and accurately amplifies the uA-level current; the second amplification circuit sets a precision ratio adjustable resistor network to achieve high-precision adjustment of the reference reference voltage, eliminate the DC bias signal when the gas concentration is 0, and thus eliminate the baseline drift of the sensor and the interference caused by the ambient temperature; the third amplification circuit amplifies the output signal of the second stage to make it easy to measure, and its gain is adjustable. Specifically, different amplification multiples are obtained by adjusting the resistance to realize the processing of signals of different types of gas sensors. In the present invention, both the light response signal and the gas response signal can be collected and processed by this circuit.

[0025] The MCU performs real-time high-precision sampling on the output signal of the third-stage amplification circuit. The analog signal is converted into a digital signal, and the digital signal is converted into a function curve, and the change trend of the signal is intuitively displayed on the display screen or other interfaces. And the original data obtained by sampling and the function curve data after conversion are saved to the built-in flash memory or external storage device to form a historical data record for subsequent data analysis, signal processing or fault backtracking.

[0026] In some embodiments, the amplification factor of the first amplifier circuit ranges from [10, 100], the amplification factor of the second amplifier circuit ranges from [1, 10], the amplification factor of the third amplifier circuit ranges from [10, 100], and the amplification factor of the entire signal amplification circuit ranges from [1000, 10000].

[0027] In some embodiments, such as Figure 1 shown, the first amplifier circuit includes a first operational amplifier U1, resistors R2 - R4, and a decoupling capacitor C1; the inverting input terminal of the first operational amplifier U1 is grounded through resistor R2, the non-inverting input terminal is connected to the common terminal between the voltage-dividing resistor and the gas sensor, the VCC terminal is grounded through the decoupling capacitor C1, the output terminal is grounded through resistor R4 and resistor R2 in sequence, the output terminal is also connected to the non-inverting input terminal of the second operational amplifier U2, and the E / D pin is connected to the operating voltage through resistor R3; the resistance value of resistor R3 is 100 kΩ, the resistors R2 and R4 are both in the kΩ range, and , is the amplification factor of the first amplifier circuit, and the decoupling capacitor is in the uf range.

[0028] In some embodiments, such as Figure 1 shown, the second amplifier circuit includes a third operational amplifier U3 and resistors R5, R7, and R8; the non-inverting input terminal of the third operational amplifier U3 is connected to the reference voltage, the inverting input terminal is connected to the output terminal through resistor R7, and is also connected to the output terminal of the voltage follower circuit through resistor R5, the output terminal is connected to the non-inverting input terminal of the third amplifier circuit, and the E / D pin is connected to the operating voltage through resistor R8; the resistance value of resistor R8 is 100 kΩ, the resistors R5 and R7 are both in the kΩ range, and , is the amplification factor of the second amplifier circuit.

[0029] In some embodiments, such as Figure 1 shown, the third amplifier circuit includes a fourth operational amplifier U4 and resistors R9 - R11; the inverting input terminal of the fourth operational amplifier U4 is grounded through resistor R9, the output terminal is connected to the inverting input terminal through resistor R10, the output terminal is used to be connected to the MCU, and the E / D pin is connected to the operating voltage through resistor R11; the resistance value of resistor R11 is 100 kΩ, the resistors R9 and R10 are both in the kΩ range, and , is the amplification factor of the third amplifier circuit.

[0030] In some embodiments, a calibration circuit is further included for providing reference voltages of different magnitudes, such as Figure 2As shown, it includes a fifth operational amplifier U5, a resistor R12, a potentiometer R13, and a resistor R14; the non-inverting input terminal of the fifth operational amplifier U5 is connected to the common terminal between the resistor R12 and the potentiometer R13, the inverting input terminal is connected to the output terminal via the resistor R14, and the output terminal is used to provide a reference voltage; the resistor R14 is a kΩ-level resistor, and the maximum resistance value of the potentiometer R13 is 5 times the resistance value of the resistor R12.

[0031] This application also provides a detection device based on the above signal amplification circuit, including: an MCU and a plurality of signal amplification circuits; the plurality of signal amplification circuits correspond one-to-one to the gas sensors in the gas sensor array; the MCU is configured to perform real-time high-precision sampling on the output signals of each signal amplification circuit, convert the analog signals into digital signals, and then convert the digital signals into function curves for display.

[0032] In some embodiments, it further includes a power supply module composed of a multi-value voltage generation circuit and a voltage stabilization phase-shifting circuit; the multi-value voltage generation circuit is used to generate an adjustable voltage of 1.24V - 60V and the corresponding negative voltage according to the change of the resistance value; the voltage stabilization phase-shifting circuit is used to filter the output signal of the multi-value voltage generation circuit to form a variety of stable operating voltages required for each amplification circuit.

[0033] It should be noted that this application stabilizes the voltage through the power supply module to ensure the stability of the reference level; the calibration circuit adjusts the reference level through a variable resistor, so that the amplified voltage signal is 0 when the gas concentration is 0, thereby solving the problems of signal distortion and inability to effectively eliminate the baseline offset.

[0034] In some embodiments, such as Figure 3As shown, the multi-value voltage generation circuit includes a linear voltage regulator U1, a linear voltage regulator U2, capacitors C1 - C4, resistors R1 - R2, a first potentiometer R3, and a second potentiometer R4; the input pin of the linear voltage regulator U1 is grounded through the capacitor C3, the output pin is grounded through the capacitor C2, the adjustable pin is grounded through the first potentiometer R3, and the output pin is also connected to the common terminal between the adjustable pin and the first potentiometer R3 through the resistor R2. The output pin is used to connect to the gas sensor and the operational amplifiers in each amplifier circuit to provide the working voltage VDD; the input pin of the linear voltage regulator U2 is connected to the output pin of the linear voltage regulator U1, the input pin is also grounded through the capacitor C1, the output pin is grounded through the capacitor C4, the adjustable pin is grounded through the second potentiometer R4, and the output pin is also connected to the common terminal between the adjustable pin and the second potentiometer R4 through the resistor R1. The output pin is connected to the input end of the voltage stabilization and phase shift circuit, and the output pin is used to connect to the operational amplifiers in each amplifier circuit to provide the positive power supply voltage VCC; the capacitances of the capacitors C1 and C3 are both 1 μF, the capacitances of the capacitors C2 and C4 are both 3.3 μF, the resistors R1 - R2 are all kΩ-level resistors, and at the same time, it satisfies that the output voltage of the linear voltage regulator U1 , and the output voltage of the linear voltage regulator U2 .

[0035] It should be noted that the power supply module with the above design is preferably used. The output voltage value is adjusted through the potentiometer, and the voltage is stabilized through the 1 μF capacitors C1 and C3; a stable output voltage is provided through the LDO chip, and the multi-value voltage generation module generates various working voltages required by the system.

[0036] In some embodiments, as Figure 3 shown, the voltage stabilization and phase shift circuit includes an operational amplifier U3 and resistors R5 - R7; the non-inverting input terminal of the operational amplifier U3 is grounded through the resistor R7, the inverting input terminal is connected to the input end of the multi-value voltage generation circuit through the resistor R5, and the output terminal is connected to the inverting input terminal through the resistor R6. The output terminal is used to connect to the operational amplifiers in each amplifier circuit to provide the negative power supply voltage VEE; the resistors R5 - R7 are all kΩ-level resistors and have equal resistance values.

[0037] It should be noted that the positive voltage is converted into a negative voltage through the voltage stabilization and phase shift circuit. The voltage stabilization and phase shift circuit provides stable positive and negative power supplies for each stage of the amplifier circuit, reducing the ripple signal of the power supply.

[0038] In this application, the three-stage amplifier circuit structure all adopts integrated amplifier chips with high common-mode rejection ratio, power supply rejection ratio, slew rate, and open-loop gain to improve the signal-to-noise ratio of the signal and ensure the stability of signal output. Specifically, operational amplifier U1 is a precision, high-speed, dual-power-supply, high-voltage, linear, non-inverting operational amplifier; operational amplifier U2 is a precision, low-noise, low-distortion, dual-power-supply, linear, voltage-follower operational amplifier; operational amplifier U3 is a precision, high-speed, dual-power-supply, high-voltage, linear, differential operational amplifier; operational amplifier U4 is a precision, high-speed, dual-power-supply, high-voltage, linear, non-inverting operational amplifier; operational amplifier U5 is a precision, low-noise, low-distortion, dual-power-supply, linear, voltage-follower operational amplifier. Linear voltage regulator u1 is a low-dropout linear voltage regulator, stable and low-noise; linear voltage regulator u2 is a low-dropout linear voltage regulator, stable and low-noise; operational amplifier u3 is a precision, low-noise, low-distortion, dual-power-supply, linear, inverting operational amplifier.

[0039] It should be understood that expressions such as "including" and "may include" that can be used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or a combination thereof, but cannot be interpreted as excluding the existence or possibility of addition of one or more other characteristics, numbers, operations, constituent elements, components, or a combination thereof.

[0040] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.

[0041] In the description of the embodiments of this application, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0042] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claimed rights.

Claims

1. A signal amplification circuit for a gas sensor array, characterized in that: include: The first amplifier circuit is used to amplify the weak voltage signal collected by the gas sensor in phase; A voltage follower circuit, used to achieve impedance matching between the first amplifying circuit and the second amplifying circuit; The second amplifier circuit is used to subtract the voltage signal output by the voltage follower circuit from the reference voltage, and then perform inverse amplification to obtain a pure response signal; The third amplifier circuit is used to amplify the pure response signal output by the second amplifier circuit in phase, ensuring that the amplified signal can be read by the analog-to-digital converter in the MCU.

2. The signal amplifying circuit according to claim 1, characterized in that: The value range of the amplification factor of the first amplifier circuit is [10, 100], the value range of the amplification factor of the second amplifier circuit is [1, 10], the value range of the amplification factor of the third amplifier circuit is [10, 100], and the value range of the amplification factor of the entire signal amplifier circuit is [1000, 10000].

3. The signal amplifying circuit according to claim 1, wherein: The first amplifying circuit includes a first operational amplifier U1, resistors R2-R4 and a decoupling capacitor C1; The inverting input terminal of the first operational amplifier U1 is grounded via a resistor R2, the non-inverting input terminal is connected to the common terminal between the voltage divider resistor and the gas sensor, the VCC terminal is grounded via a decoupling capacitor C1, the output terminal is grounded via resistors R4 and R2 in sequence, the output terminal is also connected to the non-inverting input terminal of the second operational amplifier U2, and the E / D pin is connected to the working voltage via a resistor R3; The resistance of resistor R3 is 100kΩ, and resistors R2 and R4 are both kΩ class resistors. , is the amplification factor of the first amplifier circuit, and the decoupling capacitor is a uf level capacitor.

4. The signal amplifying circuit according to claim 1, wherein: The second amplifying circuit includes a third operational amplifier U3 and resistors R5, R7 and R8; The non-inverting input terminal of the third operational amplifier U3 is connected to the reference voltage, the inverting input terminal is connected to the output terminal via the resistor R7, and is also connected to the output terminal of the voltage follower circuit via the resistor R5, the output terminal is connected to the non-inverting input terminal of the third amplifier circuit, and the E / D pin is connected to the working voltage via the resistor R8; The resistance of resistor R8 is 100kΩ, and resistors R5 and R7 are both kΩ class resistors. , is the amplification factor of the second amplifier circuit.

5. The signal amplifying circuit according to claim 1, wherein: The third amplifying circuit includes a fourth operational amplifier U4 and resistors R9-R11; The inverting input terminal of the fourth operational amplifier U4 is grounded via a resistor R9, the output terminal is connected to the inverting input terminal via a resistor R10, the output terminal is used to connect to the MCU, and the E / D pin is connected to the working voltage via a resistor R11; The resistance of resistor R11 is 100kΩ, and resistors R9 and R10 are both kΩ class resistors. , is the amplification factor of the third amplifier circuit.

6. The signal amplifying circuit according to any one of claims 1 to 5, characterized in that: Also included is a calibration circuit for providing reference voltages of different magnitudes, which includes a fifth operational amplifier U5, a resistor R12, a sliding rheostat R13 and a resistor R14; The non-inverting input terminal of the fifth operational amplifier U5 is connected to the common terminal between the resistor R12 and the sliding variable resistor R13, and the inverting input terminal is connected to the output terminal via the resistor R14, and the output terminal is used to provide a reference voltage; The resistor R14 is a kΩ class resistor, and the maximum resistance of the sliding rheostat R13 is 5 times the resistance of the resistor R12.

7. A detection device based on the signal amplification circuit according to any one of claims 1 to 6, characterized in that: include: MCU and multiple signal amplification circuits; The plurality of signal amplification circuits correspond one-to-one to the gas sensors in the gas sensor array; The MCU is configured to perform real-time high-precision sampling on the output signals of each signal amplification circuit, convert the analog signal into a digital signal, and then convert the digital signal into a function curve for display.

8. The detection device according to claim 7, characterized in that: Also included is a power supply module consisting of a multi-value voltage generating circuit and a voltage stabilizing phase shifting circuit; The multi-value voltage generating circuit is used to generate an adjustable voltage of 1.24V-60V and a corresponding negative voltage according to a change in resistance value; The voltage-stabilizing phase-shifting circuit is used to filter the output signal of the multi-value voltage generating circuit to form a variety of stable working voltages required by each amplifier circuit.

9. The detection device according to claim 8, characterized in that: The multi-value voltage generating circuit includes a linear voltage stabilizer u1, a linear voltage stabilizer u2, capacitors c1-c4, resistors r1-r2, a first sliding resistor r3 and a second sliding resistor r4; The input pin of the linear regulator u1 is grounded via capacitor c3, the output pin is grounded via capacitor c2, the adjustable pin is grounded via the first sliding rheostat r3, the output pin is also connected to the common end between the adjustable pin and the first sliding rheostat r3 via resistor r2, and the output pin is used to connect to the gas sensor and operational amplifiers in each amplification circuit to provide the working voltage VDD; The input pin of the linear regulator u2 is connected to the output pin of the linear regulator u1, the input pin is also grounded via the capacitor c1, the output pin is grounded via the capacitor c4, the adjustable pin is grounded via the second sliding rheostat r4, the output pin is also connected to the common end between the adjustable pin and the second sliding rheostat r4 via the resistor r1, the output pin is connected to the input end of the voltage stabilizing phase shifting circuit, and the output pin is used to connect to the operational amplifier in each amplifying circuit to provide a positive power supply voltage VCC; The capacitance of capacitors C1 and C3 is 1uf, the capacitance of capacitors C2 and C4 is 3.3uf, and the resistors R1-R2 are both kΩ resistors, which can meet the output voltage of linear regulator U1. , linear regulator u2 output voltage .

10. The detection device according to claim 8, characterized in that: The voltage-stabilizing phase-shifting circuit comprises an operational amplifier U3 and resistors R5-R7; The non-inverting input terminal of the operational amplifier u3 is grounded via a resistor r7, the inverting input terminal is connected to the input terminal of the multi-value voltage generating circuit via a resistor r5, the output terminal is connected to the inverting input terminal via a resistor r6, and the output terminal is used to connect to the operational amplifiers in each amplification circuit to provide a negative power supply voltage VEE; Resistors R5-R7 are all kΩ class resistors with equal resistance values.

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