Two-wire charge amplifier circuit for high-frequency large signals and its implementation method

Abstract

The present invention discloses an anti-high-frequency large-signal two-wire charge amplification circuit and its implementation method, which includes a charge-to-voltage conversion circuit, a low-pass filter circuit, an AC amplification circuit, and a power supply processing circuit; the low-pass filter circuit is a sixth-order low-pass filter circuit, the output end of the charge-to-voltage conversion circuit is connected to the low-pass filter circuit, the low-pass filter circuit is connected to the AC amplification circuit, and the AC amplification circuit is connected to the power supply processing circuit. By adopting a constant current source two-wire power supply to reduce the wiring harness, the front-stage charge-to-voltage conversion circuit uses a circuit with a field-effect transistor as the core to convert and attenuate the signal, so as to reduce the requirements for the electrical performance indicators of the operational amplifier in the subsequent signal processing circuit, and adopts a signal link based on signal attenuation, low-pass filtering, signal amplification, and power supply processing to achieve the suppression of high-frequency large signals under the condition of ensuring the amplitude-frequency characteristics of the required working frequency band, and ensure that the signal is not clipped and distorted and deeply saturated.

Description

Technical Field

[0001] The present invention relates to the technology of circuit control, and in particular to an anti-high-frequency large-signal two-wire charge amplifier circuit and its implementation method. Background Art

[0002] In aeroengines or other internal combustion power machinery, vibration measurement is required. Currently, in a high-temperature environment, piezoelectric effect type acceleration sensors with excellent characteristics and an output of charge are mostly used for vibration measurement sensors. Since the charge signal cannot be directly detected, a charge amplifier is also required to convert the charge signal into a voltage signal, so as to amplify, filter, perform calculus operations, etc. on the output voltage signal, and further transmit it to the backend acquisition system.

[0003] Existing charge-voltage signal conversion technologies generally consist of an integrated operational amplifier plus a feedback capacitor to form the main circuit and then a secondary signal gain adjustment to reach the signal voltage range required by the user. The main defects of existing charge-voltage signal conversion technologies are as follows:

[0004] 1. The traditional circuit structure requires single-ended or double-ended power supply, and the power supply line, signal line, and ground line need to be routed separately, which has relatively high requirements for the number, wiring, and cost of signal lines.

[0005] 2. Due to the limitations of the electrical performance indicators of the output voltage and current of the operational amplifier, when the amplitude of the output voltage signal is large, nonlinear distortion will occur due to saturation.

[0006] 3. When the sensor inevitably generates an equivalent output charge amount far greater than the set measurement range of the charge amplifier due to reasons such as drastic temperature changes, electromagnetic interference, resonance, etc., it will cause clipping distortion of the charge amplifier and even reach deep saturation.

[0007] Therefore, it is necessary to study a solution to solve the above problems. Summary of the Invention

[0008] In view of this, in view of the deficiencies existing in the prior art, the main purpose of the present invention is to provide an anti-high-frequency large-signal two-wire charge amplifier circuit and its implementation method, which can reduce the wire harness and ensure that the signal does not have clipping distortion and deep saturation.

[0009] To achieve the above purpose, the present invention adopts the following technical solutions:

[0010] A two-wire charge amplification circuit resistant to high-frequency large signals, comprising a charge-to-voltage circuit, a low-pass filter circuit, an AC amplification circuit, and a power supply processing circuit; the low-pass filter circuit is a sixth-order low-pass filter circuit, the output end of the charge-to-voltage circuit is connected to the low-pass filter circuit, the low-pass filter circuit is connected to the AC amplification circuit, the AC amplification circuit is connected to the power supply processing circuit, the current excitation input end of the power supply processing circuit is also the signal output end, the power supply processing circuit is respectively connected to the charge-to-voltage circuit, the low-pass filter circuit, and the AC amplification circuit, and the power supply processing circuit supplies power to the charge-to-voltage circuit, the low-pass filter circuit, and the AC amplification circuit.

[0011] Preferably, the charge-to-voltage circuit includes a field effect transistor Q3, a feedback capacitor CF1, a capacitor C3, a resistor R2, a resistor R3, a resistor R5, a resistor R7, a resistor R11, a resistor R12, a capacitor CF1, a capacitor C4, and an operational amplifier U1A; among them, the field effect transistor Q3, the feedback capacitor CF1, the resistor R2, the resistor R3, the resistor R7, the capacitor C3, and the resistor R11 form the core circuit of charge-to-voltage; the operational amplifier U1A, the capacitor C4, and R12 constitute a voltage follower circuit.

[0012] Preferably, the zener diode D1 of the power supply processing circuit supplies power to the charge-to-voltage circuit through a coupling resistor R5. The gain of the charge-to-voltage circuit is jointly determined by the capacitor C3 and the feedback capacitor CF1. When the capacitance value of the capacitor C3 is more than 10 times that of the feedback capacitor CF1, the output voltage Vq≈Q / CF1, where Q is the output charge of the piezoelectric acceleration sensor; the output DC voltage of the charge-to-voltage circuit is determined by the gate-source voltage Vgs of the field effect transistor Q3, the resistor R3, and the resistor R7, that is, Vq (DC) =Vgs (Q3) *(1 + R3 / R7); the low-frequency lower cut-off frequency f L =R7 / (2*pi*R2*(R3 + R7)*CF1).

[0013] Preferably, the low-pass filter circuit includes operational amplifiers U1B, U2A, U2B, U3A, resistors R13, R14, R15, R16, R17, R18, capacitors C6, C7, C8, C9, C10, and C11, where U3A is a voltage follower.

[0014] Preferably, the AC amplification circuit includes an operational amplifier U3B, resistors R6, R9, and a capacitor C1, where the non-inverting input terminal PIN5 of the operational amplifier U3B is provided by the zener diode D1 of the power supply processing circuit after voltage division by the resistors R8 and R11.

[0015] Preferably, the power supply processing circuit is composed of a zener diode D1, a Darlington transistor Q1, a Darlington transistor Q2, a resistor R1, a resistor R4, a resistor R8, a resistor R11, and a protection diode CR1.

[0016] Preferably, both the Darlington transistor Q1 and the Darlington transistor Q2 are of NPN type, and the zener diode D1 is a low voltage regulation current type diode.

[0017] Preferably, the output voltage Vz of the zener diode D1 supplies power to the charge-to-voltage part of the circuit through a coupling resistor R5. At the same time, the output voltage Vz of the zener diode D1 is connected to the non-inverting input terminal PIN3 of the operational amplifier U1A to provide a DC bias voltage for the low-pass filter part of the circuit. The output voltage Vo is also the power supply VCC for each operational amplifier.

[0018] Preferably, the final output DC voltage Vo of the power supply processing circuit is V R1 +V1’ = VR1 + Vz + Vbe’ = Vz*R11*R1 / ((R8 + R11)*R4) + Vz + Vbe’, where V R1 is the voltage drop across the resistor R1, V1’ is the base voltage of the Darlington transistor Q1, and Vbe’ is the voltage between the base and emitter of the Darlington transistor Q. When R8 = R11, Vo = Vz*R1 / (2*R4) + Vz + Vbe’. Generally, Vbe’ ≈ 1.4V; in this power supply processing circuit, the resistor R1, the resistor R4, and the Darlington transistor Q1 form a signal amplification circuit with an amplification factor of R1 / R4. Therefore, the total signal gain of the AC amplification circuit and the power supply processing circuit is R6*R1 / (R9*R4).

[0019] A method for implementing a two-wire charge amplifier circuit for high-frequency large signals includes the following steps:

[0020] (1) The charge signal output by the piezoelectric sensor is sent to the charge-to-voltage circuit;

[0021] (2) The charge-to-voltage circuit converts the charge signal output by the piezoelectric sensor into a voltage signal;

[0022] (3) The voltage signal is filtered by a low-pass filter circuit to reduce high-frequency interference;

[0023] (4) The amplitude of the filtered signal is amplified to an appropriate size by an AC amplification circuit;

[0024] (5) The amplified signal is output from the signal output port via the power supply processing circuit, and the signal output port is also the excitation current input port.

[0025] The present invention has obvious advantages and beneficial effects compared with the prior art. Specifically, as can be seen from the above technical solutions:

[0026] By adopting a two-wire power supply with a constant current source to reduce the wire harness, the front-stage charge-to-voltage circuit uses a circuit based on a field-effect transistor as the core to convert and attenuate the signal, so as to reduce the requirements for the electrical performance indicators of the operational amplifier in the subsequent signal processing circuit, and adopts a signal link based on signal attenuation, low-pass filtering, signal amplification, and power supply processing to achieve the suppression of high-frequency large signals under the condition of ensuring the amplitude-frequency characteristics of the required working frequency band, and ensure that the signal is not clipped and distorted and does not reach deep saturation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic block diagram of a preferred embodiment of the present invention;

[0028] Figure 2 is a specific circuit schematic diagram of a preferred embodiment of the present invention;

[0029] Figure 3 is an enlarged schematic diagram of the charge-to-voltage circuit in a preferred embodiment of the present invention;

[0030] Figure 4 is an enlarged schematic diagram of the low-pass filter circuit in a preferred embodiment of the present invention;

[0031] Figure 5 is an enlarged schematic diagram of the AC amplifier circuit in a preferred embodiment of the present invention;

[0032] Figure 6 is an enlarged schematic diagram of the power supply processing circuit in a preferred embodiment of the present invention;

[0033] Figure 7 is the amplitude-frequency curve graph of the low-pass filter circuit in a preferred embodiment of the present invention.

[0034] DESCRIPTION OF THE REFERENCE NUMERALS:

[0035] 10. Charge-to-voltage circuit 20. Low-pass filter circuit

[0036] 30. AC amplifier circuit 40. Power supply processing circuit

[0037] 50. Constant current source DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] Please refer to Figures 1 to 6 as shown, which shows the specific structure of a two-wire charge amplifier circuit for resisting high-frequency large signals in a preferred embodiment of the present invention, including a charge-to-voltage circuit 10, a low-pass filter circuit 20, an AC amplifier circuit 30, and a power supply processing circuit 40.

[0039] The charge-to-voltage circuit 10 employs a charge-to-voltage circuit composed of discrete FET-based devices, with the gain adjusted to attenuation so that when a large high-frequency signal (charge) is input, the output does not saturate and distort. Specifically, as Figure 3 shown, the charge-to-voltage circuit 10 includes a field-effect transistor Q3 (N-MOSFET), a feedback capacitor CF1, a capacitor C3, a resistor R2, a resistor R3, a resistor R5, a resistor R7, a resistor R11, a resistor R12, a capacitor CF1, a capacitor C4, and an operational amplifier U1A. Among them, the field-effect transistor Q3, the feedback capacitor CF1, the resistor R2, the resistor R3, the resistor R7, the capacitor C3, and the resistor R11 form the core charge-to-voltage circuit; the operational amplifier U1A, the capacitor C4, and the R12 constitute a voltage follower circuit. The zener diode D1 of the power supply processing circuit 40 supplies power to the charge-to-voltage circuit through a coupling resistor R5. The gain of the charge-to-voltage circuit 10 is jointly determined by the capacitor C3 and the feedback capacitor CF1. When the capacitance value of the capacitor C3 is more than 10 times that of the feedback capacitor CF1, the output voltage Vq≈Q / CF1, where Q is the output charge of the piezoelectric acceleration sensor. The output DC voltage of this charge-to-voltage circuit is determined by the gate-source voltage Vgs of the field-effect transistor Q3, the resistor R3, and the resistor R7, that is, Vq (DC) = Vgs (Q3) *(1 + R3 / R7); the low-frequency lower cut-off frequency f L = R7 / (2*pi*R2*(R3 + R7)*CF1).

[0040] The low-pass filter circuit 20 is a sixth-order low-pass filter circuit. The output end of the charge-to-voltage circuit 10 is connected to the low-pass filter circuit 20, and the low-pass filter circuit 20 is connected to the AC amplification circuit 30. The low-pass filter circuit 20 causes a sharp attenuation at high frequencies while the operating frequency band is not affected, so as to attenuate the high-frequency large signal to an acceptable range as much as possible. Specifically, as Figure 4 shown, the low-pass filter circuit 20 includes operational amplifiers U1B, U2A, U2B, U3A, resistors R13, R14, R15, R16, R17, R18, capacitors C6, C7, C8, C9, C10, and C11, where U3A is a voltage follower.

[0041] The AC amplification circuit 30 is connected to the power supply processing circuit 40. The current excitation input end of the power supply processing circuit 40 is also the signal output end. The power supply processing circuit 40 is respectively connected to the charge-to-voltage circuit 10, the low-pass filter circuit 20, and the AC amplification circuit 30, and the power supply processing circuit 40 supplies power to the charge-to-voltage circuit 10, the low-pass filter circuit 20, and the AC amplification circuit 30.

[0042] The AC amplifier circuit 30 adjusts its gain through a basic inverting amplifier circuit to meet the final gain requirement on the signal chain. Specifically, as Figure 5 shown, the AC amplifier circuit 30 includes an operational amplifier U3B, a resistor R6, a resistor R9, and a capacitor C1. The non-inverting input terminal PIN5 of the operational amplifier U3B is provided by the voltage regulator diode D1 of the power supply processing circuit after voltage division by the resistors R8 and R11.

[0043] The power supply processing circuit 40 is powered by a constant current source 50 and provides power supply and voltage reference to other parts of the circuit. The constant current source 50 can output a current of 5 - 10 mA, and at the same time, the final output voltage signal and current excitation signal are collinear. Specifically, as Figure 6 shown, the power supply processing circuit 40 is composed of a voltage regulator diode D1, a Darlington transistor Q1, a Darlington transistor Q2, a resistor R1, a resistor R4, a resistor R8, a resistor R11, and a protection diode CR1. Both the Darlington transistor Q1 and the Darlington transistor Q2 are of NPN type. The voltage regulator diode D1 is a low-voltage-regulating-current type diode to reduce the lower limit of the excitation current of the constant current source 50. The output voltage Vz of the voltage regulator diode D1 supplies power to the charge-to-voltage part of the circuit through the coupling resistor R5. At the same time, the output voltage Vz of the voltage regulator diode D1 is connected to the non-inverting input terminal PIN3 of the operational amplifier U1A to provide a DC bias voltage for the low-pass filter part of the circuit. The output voltage Vo is also the power supply VCC for each operational amplifier. The final output DC voltage Vo of the power supply processing circuit = V R1 +V1’ = VR1 + Vz + Vbe’ = Vz * R11 * R1 / ((R8 + R11) * R4) + Vz + Vbe’, where V R1 is the voltage drop across the resistor R1, V1’ is the base voltage of the Darlington transistor Q1, and Vbe’ is the voltage between the base and emitter of the Darlington transistor Q. When R8 = R11, Vo = Vz * R1 / (2 * R4) + Vz + Vbe’. Generally, Vbe’ ≈ 1.4 V; in this power supply processing circuit, the resistor R1, the resistor R4, and the Darlington transistor Q1 form a signal amplification circuit with an amplification factor of R1 / R4. Therefore, the total signal gain of the AC amplifier circuit and the power supply processing circuit is R6 * R1 / (R9 * R4).

[0044] The present invention also discloses a method for implementing the aforementioned two-wire charge amplifier circuit for anti-high-frequency large signals, including the following steps:

[0045] (1) The charge signal output by the piezoelectric sensor is sent to the charge-to-voltage circuit 10.

[0046] (2) The charge-to-voltage circuit 10 converts the charge signal output by the piezoelectric sensor into a voltage signal.

[0047] (3) The voltage signal is subjected to high-frequency filtering through the low-pass filter circuit 20 to reduce high-frequency interference.

[0048] (4) The amplitude of the filtered signal is amplified to an appropriate size through the AC amplification circuit 30.

[0049] (5) The amplified signal is output from the signal output port via the power supply processing circuit 40, and the signal output port is also the excitation current input port.

[0050] The working principle of this embodiment is described in detail as follows:

[0051] During operation, the signal is output as a corresponding voltage signal by attenuating the charge signal according to a set value through the first-stage charge-to-voltage circuit. Then, the high-frequency signal is filtered out through the second-stage low-pass filter circuit while ensuring that the required working frequency band is not attenuated. Finally, the third-stage AC signal amplification circuit and the power supply processing circuit are used to achieve the final signal output with a specified gain, which can not only suppress the high-frequency large-signal components but also ensure the requirements of the signal within the required working frequency. Specifically:

[0052] First, for the charge-to-voltage circuit 10 part, the signal sensitivity of this part is jointly determined by the capacitor C3 and the feedback capacitor CF1. When the capacitance value of the capacitor C3 is greater than 10 times the capacitance value of CF1, it is basically determined by CF1, and Vq (AC) ≈Q / CF1, where Vq (AC) is the charge-to-voltage output value, and Q is the charge change amount. By reasonably setting the feedback capacitor CF1, the gain of this part is attenuated. The purpose of reasonably setting the gain is to ensure that the output of this part is not saturated and distorted under the condition of large-signal input. The DC output voltage of this part is related to the turn-on voltage Vgs of the FET and the resistance values of R3 and R7, and Vq (DC) =Vgs*(1 + R3 / R7). Reasonably select the resistance values of the resistor R3 and the resistor R7 so that the output DC voltage is at a reasonable level. The power supply for this part is provided by the regulated voltage value Vz of the zener diode D1 of the power supply processing circuit 40 through the coupling resistor R5, and the current provided to this part is I = (Vz - Vq) / R5. The low-frequency lower cut-off frequency of this part: f L1 =R7 / (2*pi*R2*(R3 + R7)*CF1).

[0053] After the charge-to-voltage Vq, it needs to pass through a voltage follower and then enter the subsequent low-pass filter part. Here, U1A is the voltage follower. After Vq passes through the C4 and R12 high-pass filter circuit, only the AC part Vq (AC) enters the subsequent circuit, and Vz provides a DC voltage bias for U1A. That is, the final output Vfi of U1A is Vz superimposed on the AC part of Vq, and Vfi = Vz + Vq (AC)The cut-off frequency of this high-frequency part is determined by capacitor C4 and resistor R12. Assuming capacitor C4 = 0.1uF and resistor R12 = 20MΩ, then f L = 1 / (2π*C4*R12) = 0.08Hz.

[0054] Secondly, for the low-pass filter circuit 20 part, as Figure 7 shown, the amplitude-frequency characteristic of this part of the circuit is exemplified as follows: the 15kHz frequency point is -1dB, the 25kHz frequency point is -20dB, and it is 0dB within the 10kHz operating frequency band.

[0055] Furthermore, for the AC amplifier circuit 30 part, this is a typical inverting amplifier circuit. If the capacitance value of capacitor C1 is large enough, the AC gain within the operating frequency band is V7 (AC) / Vfo (AC) = R6 / R9. The voltage Vref at the non-inverting input terminal PIN5 is the voltage after dividing the voltage Vz by resistors R8 and R11, that is, Vref = Vz*R11 / (R8 + R11). Assuming resistor R8 = resistor R11, so Vref = Vz / 2. The output V7 of this part is the DC bias voltage Vref superimposed on the AC amplified signal, that is, V7 = Vref + V7 (AC) = Vref + Vfo (AC) *R6 / R9.

[0056] In addition, for the power supply processing circuit 40 part, since the power supply is a two-wire system of a constant current source 50 and the excitation current and the output voltage signal are on the same wire, it is different from the voltage power supply circuit and the power supply part needs to be processed. After the excitation current enters from the Out terminal, it passes through the CE terminal of the Darlington transistor Q1 to provide a regulated current for the zener diode D1, so that a regulated voltage Vz is generated at the D1 terminal. Vz is divided by R8 and R11 to generate a voltage reference Vref for the non-inverting input terminal PIN5 of the operational amplifier U3B. As described above, assuming R8 = R11, then Vref = Vz / 2. The U3B part is an AC amplifier circuit and does not amplify DC, so the DC output is V7 (DC) = Vref. Therefore, under DC conditions, the voltage at the B pole of Q2 is V2' = Vref + Vbe, where Vbe is the voltage between the BE poles of the Darlington transistor Q2, approximately 1.4V. And the voltage at the B pole of Q1 is V1' = Vz + Vbe', where Vbe' is the voltage between the BE poles of the Darlington transistor Q1, approximately 1.4V. Therefore, the voltage drop across the R4 resistor is V R4 = V1' - V2' = Vz + Vbe' - (Vref + Vbe) = Vz - Vref = Vz / 2. And the current flowing through R1 and R4 is almost equal, so the voltage drop across the R1 resistor is V R1 = V R4*R1 / R4=Vz*R1 / (2*R4). So the final output DC voltage Vo=V R1 +V1'=V R1 +Vz+Vbe'=Vz*R1 / (2*R4)+Vz+1.4V. Assuming Vz=7.5V, R1=62K, R4=36K, substituting into the calculation, we get Vo=15.36V.

[0057] In this circuit, R1 and R4 can amplify both DC and AC signals, and the amplification gain is R1 / R4. Therefore, combined with the AC amplifier circuit 30, the total AC gain of the two circuits is (R6 / R9)*(R1 / R4).

[0058] This part Vo is not only the final output voltage, but also the power supply VCC of each operational amplifier. Since the circuit of the present invention has the function of resisting high-frequency large signals, the high-frequency voltage on VCC will be suppressed in the end, and the voltage fluctuation on VCC will not affect the power supply of the operational amplifier, will not affect the basic performance of the operational amplifier, and will not cause distortion.

[0059] This part V Z At the same time, the first circuit is powered via the coupling resistor R5. Since Vz is a fixed voltage, the charge-to-voltage circuit 10 can operate stably.

[0060] The design focus of the present invention is: by adopting a constant current source two-wire power supply to reduce the wiring harness, the front-stage charge-to-voltage circuit adopts a circuit based on a field effect tube as the core to convert and attenuate the signal to reduce the electrical performance index requirements of the operational amplifier in the subsequent signal processing circuit, and adopts a signal chain based on signal attenuation, low-pass filtering, signal amplification, and power supply processing to achieve suppression of high-frequency large signals while ensuring the amplitude-frequency characteristics of the required working frequency band, ensuring that the signal is not clipped and distorted and deeply saturated.

[0061] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A two-wire charge amplifier circuit for high-frequency large signals, characterized in that: It includes a charge-to-voltage circuit, a low-pass filter circuit, an AC amplifier circuit, and a power supply processing circuit; the low-pass filter circuit is a sixth-order low-pass filter circuit. The output end of the charge-to-voltage circuit is connected to the low-pass filter circuit, the low-pass filter circuit is connected to the AC amplifier circuit, the AC amplifier circuit is connected to the power supply processing circuit. The current excitation input end of the power supply processing circuit is also the signal output end. The power supply processing circuit is respectively connected to the charge-to-voltage circuit, the low-pass filter circuit, and the AC amplifier circuit, and the power supply processing circuit supplies power to the charge-to-voltage circuit, the low-pass filter circuit, and the AC amplifier circuit; Among them, the charge-to-voltage circuit includes a field effect transistor Q3, a feedback capacitor CF1, a capacitor C3, a resistor R2, a resistor R3, a resistor R5, a resistor R7, a resistor R10, a resistor R12, a capacitor C4, and an operational amplifier U1A; among them, the field effect transistor Q3, the feedback capacitor CF1, the resistor R2, the resistor R3, the resistor R7, the capacitor C3, and the resistor R10 form a charge-to-voltage core circuit; the operational amplifier U1A, the capacitor C4, and R12 constitute a voltage follower circuit; Among them, one end of the capacitor C3 is connected to the positive output end of the piezoelectric sensor, the other end of the capacitor C3 is connected to one end of the resistor R10, the negative output end of the piezoelectric sensor is connected between the resistor R7 and the ground, the other end of the resistor R10 is connected to the input end of the field effect transistor Q3, one end of the resistor R2 is connected to the other end of the resistor R10, the other end of the resistor R2 is connected to the ground through the resistor R7, one end of the feedback capacitor CF1 is connected to the other end of the resistor R10, the other end of the feedback capacitor CF1 is connected to the output end of the field effect transistor Q3, one end of the resistor R3 is connected to the other end of the feedback capacitor CF1, the other end of the resistor R3 is connected to the other end of the resistor R2, the other end of the feedback capacitor CF1 is also connected to the other end of the resistor R5, the other end of the resistor R5 is connected to the positive input end of the operational amplifier U1A through the capacitor C4, one end of the resistor R12 is connected to the positive input end of the operational amplifier U1A, and the negative input end of the operational amplifier U1A is connected to the output end.

2. The two-wire charge amplification circuit for resisting high-frequency large signals according to claim 1, wherein: The zener diode D1 of the power supply processing circuit supplies power to the charge-to-voltage circuit through the resistor R5. The gain of the charge-to-voltage circuit is jointly determined by the capacitor C3 and the feedback capacitor CF1. When the capacitance value of the capacitor C3 is more than 10 times the capacitance value of the feedback capacitor CF1, the output voltage Vq≈Q / CF1, where Q is the output charge of the piezoelectric acceleration sensor; the output DC voltage of the charge-to-voltage circuit is determined by the gate-source voltage Vgs of the field effect transistor Q3, the resistor R3, and the resistor R7, that is, Vq(DC) = Vgs(Q3)*(1 + R3 / R7); the low-frequency lower cut-off frequency fL of the charge-to-voltage circuit = R7 / (2*pi*R2*(R3 + R7)*CF1).

3. The two-wire charge amplifier circuit against high-frequency large signals according to claim 2, characterized in that: The low-pass filter circuit includes operational amplifier U1B, operational amplifier U2A, operational amplifier U2B, operational amplifier U3A, resistor R13, resistor R14, resistor R15, resistor R16, resistor R17, resistor R18, capacitor C6, capacitor C7, capacitor C8, capacitor C9, capacitor C10, and capacitor C11, where U3A is a voltage follower; Among them, one end of resistor R13 is connected to the output terminal of operational amplifier U1A, the other end of resistor R13 is connected to one end of resistor R14, the other end of resistor R14 is connected to the positive input terminal of operational amplifier U1B, one end of capacitor C6 is connected between resistor R13 and resistor R14, the other end of capacitor C6 is connected to the output terminal of operational amplifier U1B, one end of capacitor C9 is connected to the positive input terminal of operational amplifier U1B, the other end of capacitor C9 is grounded, and the negative input terminal of operational amplifier U1B is connected to the output terminal of operational amplifier U1B; One end of resistor R16 is connected to the output terminal of operational amplifier U1B, the other end of resistor R16 is connected to one end of resistor R15, the other end of resistor R15 is connected to the positive input terminal of operational amplifier U2A, one end of capacitor C7 is connected between resistor R16 and resistor R15, the other end of capacitor C7 is connected to the output terminal of operational amplifier U2A, one end of capacitor C10 is connected to the positive input terminal of operational amplifier U2A, the other end of capacitor C10 is grounded, and the negative input terminal of operational amplifier U2A is connected to the output terminal of operational amplifier U2A; One end of resistor R17 is connected to the output terminal of operational amplifier U2A, the other end of resistor R17 is connected to one end of resistor R18, the other end of resistor R18 is connected to the positive input terminal of operational amplifier U2B, one end of capacitor C8 is connected between resistor R17 and resistor R18, the other end of capacitor C8 is connected to the output terminal of operational amplifier U2B, one end of capacitor C11 is connected to the positive input terminal of operational amplifier U2B, the other end of capacitor C11 is grounded, and the negative input terminal of operational amplifier U2B is connected to the output terminal of operational amplifier U2B; The positive input terminal of operational amplifier U3A is connected to the output terminal of operational amplifier U2B, and the negative input terminal of operational amplifier U3A is connected to the output terminal of operational amplifier U3A.

4. The two-wire charge amplifier circuit against high-frequency large signals according to claim 3, characterized in that: The AC amplifier circuit includes operational amplifier U3B, resistor R6, resistor R9, and capacitor C1, where the non-inverting input terminal PIN5 of operational amplifier U3B is provided by the zener diode D1 of the power supply processing circuit after voltage division by resistor R8 and resistor R11; Among them, one end of capacitor C1 is connected to the output terminal of operational amplifier U3A, the other end of capacitor C1 is connected to one end of resistor R9, the other end of resistor R9 is connected to the negative input terminal of operational amplifier U3B, and the negative input terminal of operational amplifier U3B is also connected to the output terminal of operational amplifier U3B through resistor R6.

5. The two-wire charge amplifier circuit against high-frequency large signals according to claim 4, characterized in that: The power supply processing circuit is composed of zener diode D1, Darlington tube Q1, Darlington tube Q2, resistor R1, resistor R4, resistor R8, resistor R11, and protection diode CR1; Among them, the first end and the third end of the Darlington transistor Q2 are connected, the second end of the Darlington transistor Q2 is connected to the output end of the operational amplifier U3B, the third end of the Darlington transistor Q2 is connected to the first end of the Darlington transistor Q1 through the resistor R4, the first end of the Darlington transistor Q1 is also connected to VCC through the resistor R1, the second end of the Darlington transistor Q1 is connected to the ground through the zener diode D1, the second end of the Darlington transistor Q1 is also connected to the positive input end of the operational amplifier U1A through the resistor R12, the third end of the Darlington transistor Q1 is connected to VCC, the resistor R8 and the resistor R11 are connected in series and then connected in parallel with the zener diode D1, one end of the protection diode CR1 is connected to VCC to be used as the output end of the power supply processing circuit, and the other end of the protection diode CR1 is grounded.

6. The two-wire charge amplification circuit for high-frequency large signals according to claim 5, characterized in that: Both the Darlington transistor Q1 and the Darlington transistor Q2 are of NPN type, and the zener diode D1 is a low zener current type diode.

7. The two-wire charge amplification circuit for high-frequency large signals according to claim 5, characterized in that: The output voltage Vz of the zener diode D1 supplies power to the charge-to-voltage partial circuit through the coupling resistor R5. At the same time, the output voltage Vz of the zener diode D1 is connected to the in-phase input end PIN3 of the operational amplifier U1A to provide a DC bias voltage for the low-pass filter partial circuit. The output voltage Vo is also the power supply VCC for supplying power to each operational amplifier.

8. The two-wire charge amplification circuit for high-frequency large signals according to claim 5, characterized in that: The final output DC voltage Vo of the power supply processing circuit = VR1 + V1’ = VR1 + Vz + Vbe’ = Vz * R11 * R1 / ((R8 + R11) * R4) + Vz + Vbe’, where VR1 is the voltage drop across the resistor R1, V1’ is the base voltage of the Darlington transistor Q1, and Vbe’ is the voltage between the base and the emitter of the Darlington transistor Q; when R8 = R11, Vo = Vz * R1 / (2 * R4) + Vz + Vbe’; generally, Vbe’ ≈ 1.4V; in this power supply processing circuit, the resistor R1, the resistor R4, and the Darlington transistor Q1 form a signal amplification circuit, and the amplification factor is R1 / R4. Therefore, the total signal gain of the AC amplification circuit and the power supply processing circuit is R6 * R1 / (R9 * R4).

9. A method for implementing a two-wire charge amplifier circuit for high-frequency large signals as described in any one of claims 1-8, characterized in that: It includes the following steps: (1) The charge signal output by the piezoelectric sensor is sent into the charge-to-voltage circuit; (2) The charge-to-voltage circuit converts the charge signal output by the piezoelectric sensor into a voltage signal; (3) The voltage signal is subjected to high-frequency filtering through the low-pass filter circuit to reduce high-frequency interference; (4) The amplitude of the filtered signal is amplified to an appropriate size through the AC amplification circuit; (5) The amplified signal is output from the signal output port via the power supply processing circuit, and the signal output port is also the excitation current input port; Among them, the charge-to-voltage circuit includes the field-effect transistor Q3, the feedback capacitor CF1, the capacitor C3, the resistors R2, R3, R5, R7, R10, R12, the capacitor C4, and the operational amplifier U1A; among them, the field-effect transistor Q3, the feedback capacitor CF1, the resistors R2, R3, R7, the capacitor C3, and the resistor R10 form the charge-to-voltage core circuit; the operational amplifier U1A, the capacitor C4, and R12 constitute a voltage follower circuit; Among them, one end of the capacitor C3 is connected to the positive output end of the piezoelectric sensor, the other end of the capacitor C3 is connected to one end of the resistor R10, the negative output end of the piezoelectric sensor is connected between the resistor R7 and the ground, the other end of the resistor R10 is connected to the input end of the field effect transistor Q3, one end of the resistor R2 is connected to the other end of the resistor R10, the other end of the resistor R2 is connected to the ground through the resistor R7, one end of the feedback capacitor CF1 is connected to the other end of the resistor R10, the other end of the feedback capacitor CF1 is connected to the output end of the field effect transistor Q3, one end of the resistor R3 is connected to the other end of the feedback capacitor CF1, the other end of the resistor R3 is connected to the other end of the resistor R2, the other end of the feedback capacitor CF1 is also connected to the other end of the resistor R5, the other end of the resistor R5 is connected to the positive input end of the operational amplifier U1A through the capacitor C4, one end of the resistor R12 is connected to the positive input end of the operational amplifier U1A, and the negative input end of the operational amplifier U1A is connected to the output end.

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