CN113271074A - High-frequency-resistant large-signal two-wire system charge amplification circuit and implementation method thereof - Google Patents

High-frequency-resistant large-signal two-wire system charge amplification circuit and implementation method thereof Download PDF

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Publication number
CN113271074A
CN113271074A CN202110749624.3A CN202110749624A CN113271074A CN 113271074 A CN113271074 A CN 113271074A CN 202110749624 A CN202110749624 A CN 202110749624A CN 113271074 A CN113271074 A CN 113271074A
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circuit
resistor
voltage
charge
signal
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陈昌鹏
李坚
周富强
陈俊龙
翁新全
许静玲
柯银鸿
刘瑞林
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Xiamen Niell Electronics Co ltd
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Xiamen Niell Electronics Co ltd
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/70—Charge amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32—Modifications of amplifiers to reduce non-linear distortion

Abstract

The invention discloses a high-frequency-resistant large-signal two-wire charge amplification circuit and an implementation method thereof, wherein the high-frequency-resistant large-signal two-wire charge amplification circuit comprises a charge-to-voltage circuit, a low-pass filter circuit, an alternating current amplification circuit and a power supply processing circuit; the low-pass filter circuit is a six-order low-pass filter circuit, the output end of the charge voltage conversion circuit is connected with the low-pass filter circuit, the low-pass filter circuit is connected with the alternating current amplification circuit, and the alternating current amplification circuit is connected with the power supply processing circuit. The two-wire power supply of the constant current source is adopted to reduce wiring harnesses, the front-stage charge-to-voltage circuit adopts a circuit based on a field effect tube as a core to convert and attenuate signals so as to reduce the requirement of the subsequent signal processing circuit on the electrical performance index of an operational amplifier, and a signal link based on signal attenuation, low-pass filtering, signal amplification and power supply processing is adopted to realize the inhibition of high-frequency large signals under the condition of ensuring the amplitude-frequency characteristic of the required working frequency band and ensure that the signals are not clipped, distorted and deeply saturated.

Description

High-frequency-resistant large-signal two-wire system charge amplification circuit and implementation method thereof
Technical Field
The invention relates to the technical field of circuit control, in particular to a high-frequency-resistant large-signal two-wire charge amplification circuit and an implementation method thereof.
Background
In aircraft engines or other internal combustion power machines, vibration measurements are required. At present, in a high-temperature environment, a piezoelectric effect type acceleration sensor with excellent characteristics and an output of electric charge is mostly adopted as a sensor for measuring vibration. Because the charge signal can not be directly detected, a charge amplifier is also needed to be used for converting the charge signal into a voltage signal so as to amplify, filter, perform calculus operation and the like on the output voltage signal, and further transmit the voltage signal to a rear-end acquisition system.
In the existing charge-voltage signal conversion technology, a main circuit is generally formed by an integrated operational amplifier and a feedback capacitor, and then a secondary signal gain is adjusted to reach a signal voltage range required by a user. The main defects of the existing charge-voltage signal conversion technology are as follows:
1. the traditional circuit structure needs single-end or double-end power supply of a power supply, a power supply line, a signal line and a ground wire need to be wired independently, and the requirements on the number, the wiring and the cost of the signal line are high.
2. Due to the limitations of the electrical performance indexes of the output voltage and the current of the operational amplifier, when the amplitude of the output voltage signal is large, nonlinear distortion is caused by a saturation phenomenon.
3. When the sensor is subjected to reasons such as temperature drastic change, electromagnetic interference, resonance and the like, the sensor inevitably generates equivalent output charge quantity which is far larger than the set measuring range of the charge amplifier, so that clipping distortion of the charge amplifier is caused, and even deep saturation is achieved.
Therefore, there is a need to develop a solution to the above problems.
Disclosure of Invention
In view of the above, the present invention is directed to a two-wire charge amplification circuit for high frequency resistant large signals and a method for implementing the same, which can reduce the wire harness and ensure no clipping distortion and deep saturation of the signal.
In order to achieve the purpose, the invention adopts the following technical scheme:
a high-frequency-resistant large-signal two-wire charge amplification circuit comprises a charge-to-voltage conversion circuit, a low-pass filter circuit, an alternating current amplification circuit and a power supply processing circuit; the low-pass filter circuit is a six-order low-pass filter circuit, the output end of the charge-to-voltage conversion circuit is connected with the low-pass filter circuit, the low-pass filter circuit is connected with the alternating current amplification circuit, the alternating current amplification circuit is connected with the power supply processing circuit, the current excitation input end of the power supply processing circuit is also a signal output end, the power supply processing circuit is respectively connected with the charge-to-voltage conversion circuit, the low-pass filter circuit and the alternating current amplification circuit, and the power supply processing circuit supplies power to the charge-to-voltage conversion circuit, the low-pass filter circuit and the alternating current amplification circuit.
Preferably, the charge-to-voltage conversion circuit comprises 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; 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 a charge-to-voltage core circuit; the operational amplifier U1A, the capacitor C4, and the capacitor R12 constitute a voltage follower circuit.
Preferably, a zener diode D1 of the power supply processing circuit supplies power to the charge-to-voltage conversion circuit through a coupling resistor R5, the gain of the charge-to-voltage conversion circuit is determined by a capacitor C3 and a feedback capacitor CF1, and when the capacitance value of the capacitor C3 is more than 10 times larger than 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 conversion circuit is determined by the gate-source voltage Vgs of the field effect transistor Q3, the resistor R3 and the resistor R7, namely Vq(DC)＝Vgs(Q3)(1+ R3/R7); the low-frequency lower-limit cut-off frequency f of the charge-to-voltage circuitL＝R7/(2*pi*R2*(R3+R7)*CF1)。
Preferably, the low-pass filter circuit comprises an operational amplifier U1B, an operational amplifier U2A, an operational amplifier U2B, an operational amplifier U3A, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10 and a capacitor C11, wherein U3A is a voltage follower.
Preferably, the alternating current amplifying circuit comprises an operational amplifier U3B, a resistor R6, a resistor R9 and a capacitor C1, wherein the non-inverting input terminal PIN5 of the operational amplifier U3B is provided by a voltage-stabilizing diode D1 of the power supply processing circuit after being divided by the resistor R8 and the resistor R11.
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 CR 1.
Preferably, the darlington transistor Q1 and the darlington transistor Q2 both adopt NPN types, and the voltage regulator diode D1 adopts a low-voltage-stabilizing current type diode.
Preferably, the output voltage Vz of the zener diode D1 supplies power to the charge-to-voltage conversion circuit via the coupling resistor R5, and the output voltage Vz of the zener diode D1 is connected to the non-inverting input PIN3 of the operational amplifier U1A to provide a dc bias voltage for the low-pass filter circuit, and the output voltage Vo is also the power supply VCC for supplying power to each operational amplifier.
Preferably, the final output dc voltage Vo of the power supply processing circuit is VR1+V1’＝VR1+ Vz + Vbe '═ Vz R11R 1/((R8+ R11) R4) + Vz + Vbe', where V isR1For the voltage drop across resistor R1, V1 'is the base voltage of darlington Q1, and Vbe' is the voltage between the base and emitter of darlington Q. When R8 ═ R11, Vo ═ Vz × R1/(2 × R4) + Vz + Vbe'. Typically, Vbe' is approximately 1.4V; the resistor R1, the resistor R4 and the Darlington transistor Q1 in the power supply processing circuit form a signal amplifying circuit, and the amplification factor is R1/R4, so the total signal gain of the alternating current amplifying circuit and the power supply processing circuit is R6R 1(R9*R4)。
A method for realizing a two-wire charge amplification circuit resisting high-frequency large signals comprises the following steps:
(1) the charge signal output by the piezoelectric sensor is sent to a charge-to-voltage circuit;
(2) the charge-to-voltage circuit converts a charge signal output by the piezoelectric sensor into a voltage signal;
(3) the voltage signal is subjected to high-frequency filtering through a low-pass filtering circuit, so that high-frequency interference is reduced;
(4) amplifying the amplitude of the filtered signal to a proper amplitude through an alternating current amplifying circuit;
(5) and outputting the amplified signal from a signal output port through the power supply processing circuit, wherein the signal output port is also an excitation current input port.
Compared with the prior art, the invention has obvious advantages and beneficial effects, and specifically, the technical scheme includes that:
the two-wire power supply of the constant current source is adopted to reduce wiring harnesses, the front-stage charge-to-voltage circuit adopts a circuit based on a field effect tube as a core to convert and attenuate signals so as to reduce the requirement of the subsequent signal processing circuit on the electrical performance index of an operational amplifier, and a signal link based on signal attenuation, low-pass filtering, signal amplification and power supply processing is adopted to realize the inhibition of high-frequency large signals under the condition of ensuring the amplitude-frequency characteristic of the required working frequency band and ensure that the signals are not clipped, distorted and deeply saturated.
Drawings
FIG. 1 is a block diagram schematically illustrating the structure of a preferred embodiment of the present invention;
FIG. 2 is a specific circuit diagram of the preferred embodiment of the present invention;
FIG. 3 is an enlarged schematic diagram of a charge-to-voltage circuit according to a preferred embodiment of the present invention;
FIG. 4 is an enlarged schematic diagram of a low pass filter circuit according to a preferred embodiment of the present invention;
FIG. 5 is an enlarged schematic diagram of an AC amplifying circuit according to a preferred embodiment of the present invention;
FIG. 6 is an enlarged schematic diagram of a power supply processing circuit in accordance with a preferred embodiment of the present invention;
FIG. 7 is a graph of the amplitude and frequency of the low pass filter circuit in the preferred embodiment of the present invention.
The attached drawings indicate the following:
10. charge-to-voltage circuit 20 and low-pass filter circuit
30. AC amplifying circuit 40 and power supply processing circuit
50. Constant current source
Detailed Description
Referring to fig. 1 to fig. 6, a specific structure of a two-wire charge amplifying circuit for resisting high frequency large signals according to a preferred embodiment of the invention is shown, which includes a charge-to-voltage converting circuit 10, a low pass filter circuit 20, an ac amplifying circuit 30 and a power supply processing circuit 40.
The charge-to-voltage conversion circuit 10 adopts a charge-to-voltage conversion circuit composed of discrete devices based on FETs, and the gain is adjusted to be attenuated, so that a large signal (charge) is input and unsaturated distortion is output when the frequency is high, specifically, as shown in fig. 3, the charge-to-voltage conversion 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; 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 a charge-to-voltage core circuit; the operational amplifier U1A, the capacitor C4 and the capacitor R12 form a voltage follower circuit; the voltage stabilizing diode D1 of the power supply processing circuit 40 supplies power to the charge-to-voltage conversion circuit through the coupling resistor R5, the gain of the charge-to-voltage conversion 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 larger than that of the feedback capacitor CF1, the output voltage Vq is approximately equal to Q/CF1, and Q is the output charge of the piezoelectric acceleration sensor; the output DC voltage of the charge-to-voltage conversion circuit is determined by the gate-source voltage Vgs of the field effect transistor Q3, the resistor R3 and the resistor R7, namely Vq(DC)＝Vgs(Q3)(1+ R3/R7); the low-frequency lower-limit cut-off frequency f of the charge-to-voltage circuitL＝R7/(2*pi*R2*(R3+R7)*CF1)。
The low-pass filter circuit 20 is a six-order low-pass filter circuit, the output end of the charge-to-voltage conversion circuit 10 is connected with the low-pass filter circuit 20, the low-pass filter circuit 20 is connected with the alternating current amplification circuit 30, the low-pass filter circuit 20 enables the high frequency to be rapidly attenuated, the working frequency band is not affected, and the high frequency large signal is attenuated to an acceptable range as far as possible; specifically, as shown in fig. 4, the low pass filter circuit 20 includes an operational amplifier U1B, an operational amplifier U2A, an operational amplifier U2B, an operational amplifier U3A, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, and a capacitor C11, where U3A is a voltage follower.
The ac amplifying circuit 30 is connected to a power supply processing circuit 40, a current excitation input end of the power supply processing circuit 40 is also a signal output end, the power supply processing circuit 40 is respectively connected to the charge-to-voltage converting circuit 10, the low pass filter circuit 20 and the ac amplifying circuit 30, and the power supply processing circuit 40 supplies power to the charge-to-voltage converting circuit 10, the low pass filter circuit 20 and the ac amplifying circuit 30.
Specifically, as shown in fig. 5, the ac amplifying circuit 30 includes an operational amplifier U3B, a resistor R6, a resistor R9, and a capacitor C1, wherein a non-inverting input PIN5 of the operational amplifier U3B is provided by a zener diode D1 of the power supply processing circuit after being divided by the resistor R8 and the resistor R11.
The power supply processing circuit 40 receives power supplied by the constant current source 50, provides power and voltage reference to other partial circuits, the constant current source 50 can output 5-10mA of current, and simultaneously realizes that the final output voltage signal and the current excitation signal are collinear, specifically, as shown in fig. 6, the power supply processing circuit 40 is composed of a zener diode D1, a darlington tube Q1, a darlington tube Q2, a resistor R1, a resistor R4, a resistor R8, a resistor R11 and a protection diode CR 1. The darlington tube Q1 and the darlington tube Q2 both adopt NPN type, and the voltage stabilizing diode D1 adopts a low voltage stabilizing current type diode so as to reduce the lower limit of the exciting current of the constant current source 50. What is needed isThe output voltage Vz of the zener diode D1 is supplied to the charge-to-voltage conversion circuit through the coupling resistor R5, and the output voltage Vz of the zener diode D1 is connected to the non-inverting input PIN3 of the operational amplifier U1A to provide a dc bias voltage for the low-pass filter circuit, and the output voltage Vo is also the power source VCC for supplying power to the operational amplifiers. The final output direct current voltage Vo of the power supply processing circuit is VR1+V1’＝VR1+ Vz + Vbe '═ Vz R11R 1/((R8+ R11) R4) + Vz + Vbe', where V isR1For the voltage drop across resistor R1, V1 'is the base voltage of darlington Q1, and Vbe' is the voltage between the base and emitter of darlington Q. When R8 ═ R11, Vo ═ Vz × R1/(2 × R4) + Vz + Vbe'. Typically, Vbe' is approximately 1.4V; the resistor R1, the resistor R4 and the Darlington transistor Q1 in the power supply processing circuit form a signal amplifying circuit, and the amplification factor is R1/R4, so the total signal gain of the alternating current amplifying circuit and the power supply processing circuit is R6R 1/(R9R 4).
The invention also discloses a method for realizing the high-frequency-resistant large-signal two-wire system charge amplification circuit, which comprises the following steps of:
(1) the charge signal output by the piezoelectric sensor is sent to a charge-to-voltage circuit 10.
(2) The charge-to-voltage circuit 10 converts a charge signal output from the piezoelectric sensor into a voltage signal.
(3) The voltage signal is high-frequency filtered by the low-pass filter circuit 20, thereby reducing high-frequency interference.
(4) The amplitude of the filtered signal is amplified to an appropriate magnitude by the ac amplification circuit 30.
(5) The amplified signal is output from a signal output port, which is also an excitation current input port, via the power supply processing circuit 40.
Detailed description the working principle of the present embodiment is as follows:
during working, the signal attenuates the charge signal to be a corresponding voltage signal output according to the setting through the first-stage charge-to-voltage conversion circuit, then the high-frequency signal is filtered through the second-stage low-pass filter circuit, meanwhile, the required working frequency band is ensured not to be attenuated, and finally, the final signal output according to the specified gain is realized through the third-stage alternating current signal amplification circuit and the power supply processing circuit, so that the high-frequency large signal component can be restrained, and meanwhile, the requirement of the signal in the required working frequency is ensured. Specifically, the method comprises the following steps:
first, for the charge-to-voltage conversion circuit 10, the signal sensitivity of the circuit is determined by the capacitor C3 and the feedback capacitor CF1, and when the capacitance of the capacitor C3 is larger than 10 times the capacitance of the capacitor CF1, it is basically determined by CF1, Vq(AC)Q/CF1, where Vq(AC)The charge-to-voltage output value, Q is the charge variation. The gain of the part is attenuated by reasonably setting the feedback capacitor CF 1. The purpose of setting the gain appropriately is to ensure that in the case of a large signal input, the part outputs unsaturated distortion. The DC output voltage of the part is related by the turn-on voltage Vgs of the FET and the resistance values of R3 and R7, Vq(DC)Vgs (1+ R3/R7). The resistance values of the resistor R3 and the resistor R7 are reasonably selected so that the output direct-current voltage is at a reasonable level. The partial supply is provided by the zener diode D1 of the supply processing circuit 40 at a zener value Vz via a coupling resistor R5, and the current provided to the partial supply is I ═ Vq)/R5. Low-frequency lower-limit cutoff frequency of this section: f. ofL1＝R7/(2*pi*R2*(R3+R7)*CF1)。
After the charge is converted into the voltage Vq, the voltage Vq needs to pass through a voltage follower and then enters a back-end low-pass filtering part. U1A is voltage follower, Vq passes through C4 and R12 high-pass filter circuit, and only AC part Vq(AC)Enters a back-end circuit, and Vz provides a direct current voltage bias for U1A, namely, the output Vfi of the final U1A is Vz and Vq alternating current part, and Vfi is Vz + Vq(AC). The cut-off frequency of the partial high frequency is determined by a capacitor C4 and a resistor R12, and if the capacitor C4 is 0.1uF and the resistor R12 is 20M Ω, f isL＝1/(2pi*C4*R12)＝0.08Hz。
Next, as shown in fig. 7, for the low-pass filter circuit 20, the amplitude-frequency characteristics of the circuit are shown as follows, where the 15kHz frequency point is-1 dB, the 25kHz frequency point is-20 dB, and the operating band is 0dB within 10 kHz.
Furthermore, for the ac amplifying circuit 30, which is a typical inverting amplifying circuit, if the capacitance of the capacitor C1 is large enough, the operating frequency band is ac-connectedFlow gain of V7(AC)/Vfo(AC)R6/R9. The voltage Vref of the non-inverting input PIN5 is a voltage obtained by dividing Vz by the resistor R8 and the resistor R11, that is, Vref Vz R11/(R8+ R11). Assuming that the resistor R8 is the resistor R11, Vref is Vz/2. The partial output V7 is a DC bias voltage Vref superposed AC amplified signal, i.e. V7 is Vref + V7(AC)＝Vref+Vfo(AC)*R6/R9。
In addition, for the power supply processing circuit 40, since the power supply is a two-wire system of the constant current source 50 and the excitation current and the output voltage signal are the same line, the processing of the power supply portion is required unlike the voltage supply circuit. After the excitation current enters from the Out end, the CE end of the Darlington tube Q1 provides the stabilized current for the voltage stabilizing diode D1, so that the D1 end generates the stabilized voltage Vz. Vz is divided by R8 and R11 to generate a voltage reference Vref to the non-inverting input PIN5 of the operational amplifier U3B. As described above, assuming that R8 is R11, Vref is Vz/2. The U3B part is an AC amplifying circuit, which does not amplify DC, so the DC output is V7(DC)Vref. Therefore, under the dc condition, the B voltage of Q2 is V2 ═ Vref + Vbe, where Vbe is the BE voltage of darlington Q2, about 1.4V. And the B-voltage of Q1, V1 ', Vz + Vbe ', where Vbe ' is the BE-voltage of darlington Q1, about 1.4V. Thus, the voltage drop across the R4 resistor is VR4V1 '-V2 ═ Vz + Vbe' - (Vref + Vbe) ═ Vz-Vref ═ Vz/2. The current flowing through R1 is almost equal to that of R4, so the voltage drop V of R1 resistorR1＝VR4R1/R4 ═ Vz R1/(2 ═ R4). So that the final output dc voltage Vo is VR1+V1’＝VR1+ Vz + Vbe ═ Vz R1/(2 × R4) + Vz + 1.4V. Let Vz be 7.5V, R1 be 62K, R4 be 36K, and substitute the calculated Vo be 15.36V.
In the partial circuit, R1 and R4 can amplify both direct current signals and alternating current signals, and the amplification gain is R1/R4, so that the ac amplification circuit 30 is combined to obtain the ac total gain of the two partial circuits of (R6/R9) (R1/R4).
The part Vo is not only the final output voltage but also the power supply VCC of each operational amplifier. Since the circuit has the function of resisting high-frequency large signals, the high-frequency voltage on VCC is finally inhibited, the voltage fluctuation on VCC does not influence the power supply of the operational amplifier, the basic performance of the operational amplifier is not influenced, and distortion is not caused.
The portion VZMeanwhile, the first partial circuit is powered through the coupling resistor R5, and the charge-to-voltage circuit 10 can stably operate because Vz is a fixed voltage.
The design key points of the invention are as follows: the two-wire power supply of the constant current source is adopted to reduce wiring harnesses, the front-stage charge-to-voltage circuit adopts a circuit based on a field effect tube as a core to convert and attenuate signals so as to reduce the requirement of the subsequent signal processing circuit on the electrical performance index of an operational amplifier, and a signal link based on signal attenuation, low-pass filtering, signal amplification and power supply processing is adopted to realize the inhibition of high-frequency large signals under the condition of ensuring the amplitude-frequency characteristic of the required working frequency band and ensure that the signals are not clipped, distorted and deeply saturated.
The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.

Claims (10)

1. A high-frequency-resistant large-signal two-wire charge amplification circuit is characterized in that: the device comprises a charge-to-voltage conversion circuit, a low-pass filter circuit, an alternating current amplification circuit and a power supply processing circuit; the low-pass filter circuit is a six-order low-pass filter circuit, the output end of the charge-to-voltage conversion circuit is connected with the low-pass filter circuit, the low-pass filter circuit is connected with the alternating current amplification circuit, the alternating current amplification circuit is connected with the power supply processing circuit, the current excitation input end of the power supply processing circuit is also a signal output end, the power supply processing circuit is respectively connected with the charge-to-voltage conversion circuit, the low-pass filter circuit and the alternating current amplification circuit, and the power supply processing circuit supplies power to the charge-to-voltage conversion circuit, the low-pass filter circuit and the alternating current amplification circuit.
2. The high-frequency-resistant large-signal two-wire charge amplification circuit according to claim 1, characterized in that: the charge-to-voltage circuit comprises 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; 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 a charge-to-voltage core circuit; the operational amplifier U1A, the capacitor C4, and the capacitor R12 constitute a voltage follower circuit.
3. The high-frequency-resistant large-signal two-wire charge amplification circuit according to claim 2, characterized in that: the voltage stabilizing diode D1 of the power supply processing circuit supplies power to the charge-to-voltage conversion circuit through the coupling resistor R5, the gain of the charge-to-voltage conversion 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 larger than that of the feedback capacitor CF1, the output voltage Vq is approximately equal to Q/CF1, and Q is the output charge of the piezoelectric acceleration sensor; the output DC voltage of the charge-to-voltage conversion circuit is determined by the gate-source voltage Vgs of the field effect transistor Q3, the resistor R3 and the resistor R7, namely Vq(DC)＝Vgs(Q3)(1+ R3/R7); the low-frequency lower-limit cut-off frequency f of the charge-to-voltage circuitL＝R7/(2*pi*R2*(R3+R7)*CF1)。
4. The high-frequency-resistant large-signal two-wire charge amplification circuit according to claim 1, characterized in that: the low-pass filter circuit comprises an operational amplifier U1B, an operational amplifier U2A, an operational amplifier U2B, an operational amplifier U3A, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10 and a capacitor C11, wherein U3A is a voltage follower.
5. The high-frequency-resistant large-signal two-wire charge amplification circuit according to claim 1, characterized in that: the alternating current amplifying circuit comprises an operational amplifier U3B, a resistor R6, a resistor R9 and a capacitor C1, wherein a non-inverting input end PIN5 of the operational amplifier U3B is provided by a voltage-stabilizing diode D1 of the power supply processing circuit after being divided by the resistor R8 and the resistor R11.
6. The high-frequency-resistant large-signal two-wire charge amplification circuit according to claim 1, characterized in that: the power supply processing circuit is composed of a voltage stabilizing diode D1, a Darlington tube Q1, a Darlington tube Q2, a resistor R1, a resistor R4, a resistor R8, a resistor R11 and a protection diode CR 1.
7. The high-frequency large-signal resistant two-wire charge amplification circuit according to claim 6, wherein: the Darlington tube Q1 and the Darlington tube Q2 both adopt NPN type, and the voltage stabilizing diode D1 adopts a low voltage stabilizing current type diode.
8. The high-frequency large-signal resistant two-wire charge amplification circuit according to claim 6, wherein: the output voltage Vz of the zener diode D1 supplies power to the charge-to-voltage conversion circuit via the coupling resistor R5, and the output voltage Vz of the zener diode D1 is connected to the non-inverting input PIN3 of the operational amplifier U1A to provide dc bias voltage for the low-pass filter circuit, and the output voltage Vo is also the power supply VCC for supplying power to the operational amplifiers.
9. The high-frequency large-signal resistant two-wire charge amplification circuit according to claim 6, wherein: the final output direct current voltage Vo of the power supply processing circuit is VR1+V1’＝VR1+ Vz + Vbe '═ Vz R11R 1/((R8+ R11) R4) + Vz + Vbe', where V isR1For the voltage drop across resistor R1, V1 'is the base voltage of darlington Q1, and Vbe' is the voltage between the base and emitter of darlington Q. When R8 ═ R11, Vo ═ Vz × R1/(2 × R4) + Vz + Vbe'. Typically, Vbe' is approximately 1.4V; the resistor R1, the resistor R4 and the Darlington transistor Q1 in the power supply processing circuit form a signal amplifying circuit, and the amplification factor is R1/R4, so the total signal gain of the alternating current amplifying circuit and the power supply processing circuit is R6R 1/(R9R 4).
10. A method for implementing the high-frequency-resistant large-signal two-wire charge amplification circuit according to any one of claims 1 to 9, wherein: the method comprises the following steps:
(1) the charge signal output by the piezoelectric sensor is sent to a charge-to-voltage circuit;
(2) the charge-to-voltage circuit converts a charge signal output by the piezoelectric sensor into a voltage signal;
(3) the voltage signal is subjected to high-frequency filtering through a low-pass filtering circuit, so that high-frequency interference is reduced;
(4) amplifying the amplitude of the filtered signal to a proper amplitude through an alternating current amplifying circuit;
(5) and outputting the amplified signal from a signal output port through the power supply processing circuit, wherein the signal output port is also an excitation current input port.
CN202110749624.3A 2021-07-01 2021-07-01 High-frequency-resistant large-signal two-wire system charge amplification circuit and implementation method thereof Pending CN113271074A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115021696A (en) * 2022-08-02 2022-09-06 宁波中车时代传感技术有限公司 Charge amplifier circuit and vibration sensor
CN115051662A (en) * 2022-08-11 2022-09-13 仪科模拟(成都)科技有限公司 High-frequency pre-charge amplifier constructed based on pure separation triode

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115021696A (en) * 2022-08-02 2022-09-06 宁波中车时代传感技术有限公司 Charge amplifier circuit and vibration sensor
CN115051662A (en) * 2022-08-11 2022-09-13 仪科模拟(成都)科技有限公司 High-frequency pre-charge amplifier constructed based on pure separation triode

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