Compensation circuit and active filter

Abstract

The invention discloses a compensating circuit and an active filter. The active filter comprises a sampling circuit, a feedback circuit and an amplifying circuit, the input end of the sampling circuit and the output end of the feedback circuit are connected with one end of the power supply end and one end of the power utilization end, the grounding end of the sampling circuit and the grounding end of the feedback circuit are connected with the other end of the power supply end and the other end of the power utilization end, the output end of the sampling circuit is connected with the input end of the amplification circuit, and the output end of the amplification circuit is connected with the input end of the feedback circuit; the amplifying circuit comprises an operational amplifier; the compensating circuit is used for compensating the amplitude margin of the active filter to stabilize the amplitude margin; the compensation circuit comprises resistors R1, R2 and R3 and a capacitor C1; one end of the resistor R1 is connected with the input end of the amplifying circuit, the other end of the resistor R1 is connected with one end of the resistor R2 and the inverted input end of the operational amplifier, the other end of the resistor R2 is connected with one end of the resistor R3 and one end of the capacitor C1, and the other ends of the resistor R3 and the capacitor are connected with the output end of the operational amplifier. Compared with an existing active filter, the low-frequency stability is better, and the filtering effect is better.

Description

Technical Field

[0001] The present invention relates to the field of filtering technology, and in particular to a compensation circuit and an active filter. Background Art

[0002] In recent years, as switching power supplies and other power equipment are moving towards miniaturization, in order to ensure the reliability of these technologies and products, higher requirements will inevitably be placed on EMI filters. Passive filter circuits are limited by size and weight and are not suitable for the current development trend. Hybrid filter circuits have attracted widespread attention due to the use of active elimination technology, small size, easy integration, and good dynamic characteristics.

[0003] Traditional active filters are limited by circuit stability, the amplifier gain is small, and the noise filtering effect is poor. Among them, a compensation circuit is disclosed in a Chinese patent with publication number CN108696117A and the name "Compensated Active Electromagnetic Interference Filter". The schematic diagram of the compensation circuit is as follows Figure 1 As shown, the working principle of the compensation circuit is to increase the phase margin of the filter at low frequency through the capacitor 304 so that the filter can be stabilized, but the existence of the capacitor 304 will reduce the amplification factor of the amplifier circuit, which will cause the filtering effect of the filter to deteriorate.

[0004] The Chinese patent with publication number CN116886068A and titled "A Compensation Circuit" discloses a compensation circuit. The schematic diagram of the compensation circuit is shown in FIG. Figure 2 As shown, the working principle of the compensation circuit is that resistors R2, R4, R3 and capacitor C3 form a feedback compensation network of the amplifier circuit, and the maximum leading phase angle is used as the cutoff frequency of the filter after compensation, which can improve the amplitude margin of the filter. However, since this scheme increases the open-loop gain while reducing the cutoff frequency, the compensation capability is limited. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a compensation circuit and an active filter, which can improve the stability of the active compensation circuit without sacrificing its filtering effect.

[0006] As a first aspect of the present invention, an embodiment of the compensation circuit provided is as follows: A compensation circuit is applied to an active filter, the active filter comprising a sampling circuit, a feedback circuit and an amplifier circuit; the input end of the sampling circuit and the output end of the feedback circuit are used to connect one end of a power supply end and one end of a power consumption end at the same time, the ground end of the sampling circuit and the ground end of the feedback circuit are used to connect the other end of the power supply end and the other end of the power consumption end at the same time, the output end of the sampling circuit is connected to the input end of the amplifier circuit, and the output end of the amplifier circuit is connected to the input end of the feedback circuit; the sampling circuit is used to sample the noise current flowing into the power consumption end and convert it into a first voltage, the amplifier circuit is used to convert the first voltage into a second voltage after amplification, and the feedback circuit The circuit is used to convert the second voltage into a feedback current, the feedback current is equal to the noise current in magnitude and opposite in direction, so as to prevent the noise current from flowing into the power supply end; the amplification circuit includes an operational amplifier; wherein: the compensation circuit is used to compensate for the amplitude margin of the active filter to make it stable, and the compensation circuit includes a resistor R1, a resistor R2, a resistor R3 and a capacitor C1; one end of the resistor R1 is connected to the input end of the amplification circuit, and the other end is simultaneously connected to one end of the resistor R2 and the inverting input end of the operational amplifier, the other end of the resistor R2 is simultaneously connected to one end of the resistor R3 and one end of the capacitor C1, and the other ends of the resistor R3 and the capacitor are simultaneously connected to the output end of the operational amplifier.

[0007] Preferably, the resistor R1 has a value of 1KΩ-10KΩ, the resistor R2 is 5-20 times the resistance of the resistor R1, the resistor R3 is 5-20 times the resistance of the resistor R2, and the turning frequency formed by the capacitor C1 and the resistor R3 is less than 100KHz.

[0008] As a second aspect of the present invention, an embodiment of the active filter provided is as follows: An active wave circuit, the active filter comprises a sampling circuit, a feedback circuit and an amplifier circuit; the input end of the sampling circuit and the output end of the feedback circuit are used to connect one end of the power supply end and one end of the power consumption end at the same time, the ground end of the sampling circuit and the ground end of the feedback circuit are used to connect the other end of the power supply end and the other end of the power consumption end at the same time, the output end of the sampling circuit is connected to the input end of the amplifier circuit, and the output end of the amplifier circuit is connected to the input end of the feedback circuit; the sampling circuit is used to sample the noise current flowing into the power consumption end and convert it into a first voltage, the amplifier circuit is used to convert the first voltage into a second voltage after amplification, and the feedback circuit is used to convert the second voltage into a feedback current, the feedback current is equal to the noise current in magnitude and opposite in direction, so as to avoid the noise current flowing into the power supply end; the amplifier circuit comprises an operational amplifier; wherein: the active wave circuit also comprises the compensation circuit described in any one of the first aspects above, and the compensation circuit is used to compensate the amplitude margin of the active filter to make it stable.

[0009] Preferably, the sampling circuit includes a transformer TX1, a resistor R6 and a capacitor C2, the same-name end of the primary winding of the transformer TX1 is used to connect one end of the power consumption end, and the opposite-name end is used to connect one end of the power supply end, the same-name end of the secondary winding of the transformer TX1 is connected to one end of the capacitor C2, and the opposite-name end and one end of the resistor R6 are connected together to connect the other end of the power supply end and the other end of the power consumption end, and the other end of the capacitor and the other end of the resistor R6 are connected together as the output end of the sampling circuit.

[0010] Preferably, the sampling circuit includes a resistor R8 and a capacitor C4, one end of the capacitor C4 serves as the input end of the sampling circuit, and the other end is connected with one end of the resistor R8 as the output end of the sampling circuit, and the other end of the resistor R8 serves as the ground end of the sampling circuit.

[0011] Preferably, the amplifier circuit also includes a resistor R5 and a resistor R4, one end of the resistor R4 is used to connect to the input power supply terminal of the operational amplifier, and the other end is simultaneously connected to one end of the resistor R5 and the in-phase input terminal of the operational amplifier, the other end of the resistor R5 is connected to the ground terminal of the operational amplifier, and the output terminal of the operational amplifier is the output terminal of the amplifier circuit.

[0012] Preferably, the feedback circuit comprises a resistor R7 and a capacitor C3, one end of the resistor R7 is the input end of the feedback circuit, and the other end is connected to one end of the capacitor C3, and the other end of the capacitor C3 is the output end of the feedback circuit.

[0013] The working principle of the present invention is analyzed in detail in the specific implementation mode in combination with the amplitude-frequency logarithmic characteristic curve diagram. The beneficial effects of the present invention are as follows: 1. The compensation circuit of the embodiment of the present invention can improve the amplitude margin of the active filter. Compared with the solution of the traditional active filter without the compensation circuit, the present invention is conducive to improving the stability of the active filter; 2. The compensation circuit of the embodiment of the present invention does not change the high-frequency amplification factor of the active filter circuit. Compared with the compensation circuit solution of the traditional active filter, the present invention does not sacrifice the high-frequency filtering effect on noise; 3. The compensation circuit of the embodiment of the present invention can effectively lower the phase of the active filter. Compared with the existing active filter compensation circuit solution, the present invention has a better compensation effect on the instability of the active filter caused by the resonance of the passive device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The circuit schematic diagram of the active filter compensation scheme with publication number CN108696117A; Figure 2 The circuit schematic diagram of the active filter compensation scheme with publication number CN116886068A; Figure 3 for Figure 1 Active filter amplitude-frequency logarithmic characteristic curve; Figure 4 for Figure 2 Active filter amplitude-frequency logarithmic characteristic curve; Figure 5 is a schematic diagram of an active filter including a compensation circuit of the present invention; Figure 6 for Figure 5 Active filter amplitude-frequency logarithmic characteristic curve; Figure 7 for Figure 5 The first type of circuit diagram is more specific in schematic diagram; Figure 8 for Figure 5 The second type of circuit diagram is more specific in its schematic. DETAILED DESCRIPTION

[0015] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0016] In addition, the embodiments and features of the embodiments in this application may be combined with each other if there is no conflict.

[0017] For the amplifier circuit of the traditional active filter without compensation circuit, the voltage transfer function from its output end to its input end is K1, where K1 represents the voltage amplification factor from the output end to the input end of the amplifier circuit, that is, within the frequency range of (0, ∞), its voltage amplification factor remains unchanged, which will lead to insufficient phase margin and poor stability of the active filter.

[0018] The inventors of the present application have conducted in-depth research on existing active filters with compensation functions and found the following problems: for Figure 1 For an active filter with compensation function, the voltage transfer function from the output to the input is: ;

[0019] Wherein, K2 represents the DC voltage amplification factor of the output end of the amplifier circuit 204 to the input end, T1 represents the product of the feedback resistor 504 and the compensation capacitor 304 of the amplifier circuit, ω represents the angular frequency of the input end signal, j Represents an imaginary unit.

[0020] The inventor of this application obtained through theoretical calculation and simulation Figure 3 , Figure 3 for Figure 1 The active filter amplitude-frequency logarithmic characteristic curve is given by Figure 3 From the amplitude-frequency logarithmic characteristic curve, it can be seen that: in the first frequency range, its voltage amplification factor remains unchanged at 20lgK2; in the second frequency range, its voltage amplification factor changes at a rate of -20dB / dec, which makes the filter cutoff frequency earlier than before correction, thereby improving the phase margin of the filter. However, since the voltage amplification factor of the amplifier circuit is reduced in the second frequency range, this will cause the filtering effect of the filter circuit to deteriorate; Among them, the first frequency range is: ; The second frequency range is: .

[0021] for Figure 2 For an active filter with compensation function, the voltage transfer function from the output to the input is: ; in: ; ; ; ; In the above formulas, the reference numerals of resistors represent the resistance values ​​of the corresponding resistors, the reference numerals of capacitors represent the capacitance values ​​of the corresponding capacitors, ω represents the angular frequency of the input signal,j Represents an imaginary unit.

[0022] The inventor of this application obtained through theoretical calculation and simulation Figure 4 , Figure 4 for Figure 2 The active filter amplitude-frequency logarithmic characteristic curve is given by Figure 4 The amplitude-frequency logarithmic characteristic curve shows that: within the third frequency range, the voltage amplification factor remains unchanged, i.e., 20lgK; within the fourth frequency range, the voltage at the output of the amplification compensation circuit 103 changes at a rate of 20dB / dec relative to the voltage at the input; within the fifth frequency range, the voltage at the output of the amplification compensation circuit 103 changes at a rate of 20dB / dec relative to the voltage at the input, thereby keeping the voltage amplification factor unchanged. The maximum leading angular frequency of the amplification compensation circuit 103 is: ; The leading phase angle corresponding to the above maximum leading angle frequency is: ; Taking the maximum leading phase angle as the cutoff frequency of the compensated active filter can improve the amplitude margin of the active filter, but since this scheme increases the open-loop gain while reducing the cutoff frequency, the compensation capability is limited; Among them, the third frequency range is: ; The fourth frequency range is: ; The fifth frequency range is: .

[0023] Based on the shortcomings of the above active filtering compensation scheme, the embodiment of the present invention provides a compensation circuit, which connects a resistor in series and a capacitor in parallel to the feedback resistor. Compared with the traditional active filtering compensation technology, the filtering effect is better. Compared with the existing active filtering compensation technology, the compensation effect is better. Figure 5 1 is a schematic diagram of an active filter including the compensation circuit of the present invention. The active filter 101 includes a sampling circuit 102 , an amplifying compensation circuit 103 and a feedback circuit 104 .

[0024] The sampling circuit 102 includes three ports, namely, the input terminal, the output terminal and the ground terminal of the sampling circuit 102; the feedback circuit 104 includes three ports, namely, the input terminal, the output terminal and the ground terminal of the feedback circuit 104; the amplification compensation circuit 103 includes an input terminal, an output terminal, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a capacitor C1 and an operational amplifier X1.

[0025] The input end of the sampling circuit 102 and the output end of the feedback circuit 104 are simultaneously connected to one end of the power supply end and one end of the power consumption end, the ground end of the sampling circuit 102 and the ground end of the feedback circuit 104 are simultaneously connected to the other end of the power supply end and the other end of the power consumption end, the output end of the sampling circuit 102 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to the inverting input end of the operational amplifier X1 and one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R3 and one end of the capacitor C1, the other end of the resistor R3 and the other end of the capacitor C1 are simultaneously connected to the output end of the operational amplifier X1 and the input end of the feedback circuit 104, one end of the resistor R4 is connected to the input power supply end VCC, the other end of the resistor R4 is connected to one end of the resistor R5 and the non-inverting input end of the operational amplifier X1, and the other end of the resistor R5 is connected to the ground end of the operational amplifier X1.

[0026] The sampling circuit 102 is used to sample the noise current flowing into the power end and convert it into a first voltage. The amplification and compensation circuit 103 is used to convert the first voltage into a second voltage after amplification and compensation. The feedback circuit 104 is used to convert the second voltage into a feedback current. The feedback current is equal to the noise current in magnitude and opposite in direction, thereby preventing the noise current from flowing into the power supply end.

[0027] The amplification and compensation circuit 103 includes an amplification circuit and a compensation circuit. Specifically, the amplification circuit includes an operational amplifier X1, a resistor R4 and a resistor R5; and the compensation circuit includes a resistor R1, a resistor R2, a resistor R3 and a capacitor C1.

[0028] In a specific implementation, the value of the resistor R1 is 1KΩ~10KΩ, the resistance of the resistor R2 is 5~20 times the resistance of the resistor R1, and the resistance of the resistor R3 is 5~20 times the resistance of the resistor R2. The turning frequency formed by the capacitor C1 and the resistor R3 is less than 100KHz.

[0029] Figure 5 The working principle of the amplification compensation circuit 103 in FIG. 1 is as follows: The amplification compensation circuit 103 is a hysteresis compensation circuit, and the voltage transfer function of its output terminal to its input terminal is: ; ; ; ; ; In the above formulas, the reference numerals of resistors represent the resistance values ​​of the corresponding resistors, the reference numerals of capacitors represent the capacitance values ​​of the corresponding capacitors, ω represents the angular frequency of the input signal, j Represents an imaginary unit.

[0030] The inventor of this application obtained through theoretical calculation and simulation Figure 6 , Figure 6 for Figure 5 The active filter amplitude-frequency logarithmic characteristic curve is given by Figure 6The amplitude-frequency logarithmic characteristic curve shows that: within the sixth frequency range, the voltage amplification factor remains unchanged, i.e., 20lgK; within the seventh frequency range, the voltage at the output of the amplifying and compensating circuit 103 changes at a speed of -20dB / dec to the voltage at the input; within the eighth frequency range, the voltage at the output of the amplifying and compensating circuit 103 changes at a speed of -20dB / dec to the voltage at the input, thereby keeping the voltage amplification factor unchanged. The maximum hysteresis angular frequency of the amplifying and compensating circuit 103 is: ; The lag phase angle corresponding to the above maximum lag angular frequency is: ; The maximum lagging phase angle frequency is used as the resonance frequency point caused by the passive filter device, which can significantly improve the amplitude margin of the active filter. Since the amplification factor of the amplifier circuit 103 is greater than that of the traditional compensation scheme at high frequencies, the filtering effect of this scheme is better. In addition, compared with the existing compensation scheme, this scheme does not increase the open-loop gain while reducing the phase of the open-loop active filter. Therefore, this scheme has a better compensation effect on the instability of the active filter caused by the resonance caused by the passive device; Among them, the sixth frequency range is: ; The seventh frequency range is: ; The eighth frequency range is: .

[0031] Through the above comparative analysis of the working principle of the amplification compensation circuit, it can be seen that Figure 5 The compensation circuit shown can improve the amplitude margin of the active filter while ensuring that the voltage amplification factor remains unchanged. Compared with the compensation scheme of the traditional active filter circuit, Figure 5 The compensation circuit shown makes the filtering effect of the active filter better. Figure 5 The compensation circuit shown in the figure reduces the cut-off frequency without increasing the open-loop gain. Compared with the existing compensation circuit scheme of the active filter, Figure 5 The stability of the compensation circuit shown is better.

[0032] This application Figure 5 The sampling circuit 102 and the feedback circuit 104 shown may be implemented in various ways.

[0033] Figure 7 for Figure 5 The first circuit diagram is more specific. Figure 7The sampling circuit 102 is composed of a transformer TX1, a capacitor C2 and a resistor R6, and the feedback circuit 104 is composed of a resistor R7 and a capacitor C3. One end of the primary winding of the transformer TX1 and one end of the secondary winding are the same end, and the other end of the primary winding of the transformer TX1 and the other end of the secondary winding are the same end. One end of the primary winding of the transformer TX1 is one end of the input end of the sampling circuit 102, and the other end of the primary winding of the transformer TX1 is the other end of the input end of the sampling circuit 102. One end of the secondary winding of the transformer TX1 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is connected to one end of the resistor R6 as the output end of the sampling circuit 102. The other end of the resistor R6 is connected to the other end of the secondary winding of the transformer TX1 as the ground end of the sampling circuit 102. One end of the resistor R7 is the input end of the feedback circuit 104, and the other end of the resistor R7 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is the output end of the feedback circuit 104.

[0034] Figure 7 The working principles of the sampling circuit 102 and the feedback circuit 104 are as follows: When the noise current I d1 Flows through transformer TX1, capacitor C2 and resistor R6. Resistor R6 converts the current I d1 Converted into voltage u i1 , voltage u i1 After amplification and compensation by the amplification and compensation circuit 103, the output voltage u o1 , the resistor R7 and the capacitor C3 will amplify the output voltage u of the compensation circuit 103 o1 Converted into feedback current I fb1 , feedback current I fb1 With the noise current I d1 Equal in magnitude and opposite in direction to avoid noise current I d1 Flow into the power supply end, thus avoiding affecting the normal operation of other devices at the power supply end.

[0035] Figure 8 for Figure 5 The second circuit diagram has a more specific schematic diagram. Figure 8 The sampling circuit 102 is composed of a capacitor C4 and a resistor R8. One end of the capacitor C4 is the input end of the sampling circuit 102. The other end of the capacitor C4 is connected to one end of the resistor R8 as the output end of the sampling circuit 102. The other end of the capacitor C4 is the ground end of the sampling circuit 102.

[0036] Figure 8 The working principles of the sampling circuit 102 and the feedback circuit 104 are as follows: Resistor R8 and capacitor C4 sample the noise current I d2 Converted into voltage u across resistor R8 i2 , voltage u i2After amplification and compensation by the amplification and compensation circuit 103, the voltage is converted into the output voltage u of the amplification and compensation circuit 103 o2 , the resistor R7 and the capacitor C3 will amplify the output voltage u of the compensation circuit 103 o2 Converted into feedback current I fb2 , feedback current I fb2 With the noise current I d2 The magnitudes are equal and the directions are opposite, thus preventing noise current from flowing into the power supply end.

[0037] It should be noted that the feedback current I fb1 With the noise current I d1 The opposite direction refers to the connection point (hereinafter referred to as the first node) between the sampling circuit input, the feedback circuit output, the power supply end, and the power consumption end. d1 Flowing into the first node, the feedback current I fb1 Flow out of the first node. This flow relationship is called opposite direction. According to Kirchhoff's current law, at any node in the circuit, at any time, the sum of the currents flowing into the node is equal to the sum of the currents flowing out of the node. Since the feedback current I fb1 With the noise current I d1 The magnitude is equal, that is, the current flowing into the first node (noise current I d1 ) and the current flowing out of the first node (the feedback current I fb1 ) are equal, then the current flowing into the power supply terminal of the first node must be zero, otherwise Kirchhoff’s current law is not satisfied.

[0038] The description of the above embodiments is only used to help understand the inventive concept of the present invention and is not intended to limit the present invention. For ordinary technicians in this technical field, any modifications, equivalent substitutions, improvements, etc. made without departing from the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A compensation circuit, applied to an active filter, the active filter comprising a sampling circuit, a feedback circuit and an amplifier circuit; the input end of the sampling circuit and the output end of the feedback circuit are used to connect one end of the power supply end and one end of the power consumption end at the same time, the ground end of the sampling circuit and the ground end of the feedback circuit are used to connect the other end of the power supply end and the other end of the power consumption end at the same time, the output end of the sampling circuit is connected to the input end of the amplifier circuit, and the output end of the amplifier circuit is connected to the input end of the feedback circuit; the sampling circuit is used to sample the noise current flowing into the power consumption end and convert it into a first voltage, the amplifier circuit is used to convert the first voltage into a second voltage after amplification, and the feedback circuit is used to convert the second voltage into a feedback current, the feedback current is equal to the noise current in magnitude and opposite in direction, so as to avoid the noise current flowing into the power supply end; the amplifier circuit comprises an operational amplifier; characterized in that: The compensation circuit is used to compensate the amplitude margin of the active filter to make it stable. The compensation circuit includes a resistor R1, a resistor R2, a resistor R3 and a capacitor C1; one end of the resistor R1 is connected to the input end of the amplifier circuit, and the other end is simultaneously connected to one end of the resistor R2 and the inverting input end of the operational amplifier; the other end of the resistor R2 is simultaneously connected to one end of the resistor R3 and one end of the capacitor C1; the other ends of the resistor R3 and the capacitor are simultaneously connected to the output end of the operational amplifier.

2. The compensation circuit according to claim 1, characterized in that: The resistor R1 has a value of 1KΩ~10KΩ, the resistor R2 is 5~20 times the resistance of the resistor R1, the resistor R3 is 5~20 times the resistance of the resistor R2, and the turning frequency formed by the capacitor C1 and the resistor R3 is less than 100KHz.

3. An active wave circuit, the active filter comprises a sampling circuit, a feedback circuit and an amplifier circuit; the input end of the sampling circuit and the output end of the feedback circuit are used to connect one end of the power supply end and one end of the power consumption end at the same time, the ground end of the sampling circuit and the ground end of the feedback circuit are used to connect the other end of the power supply end and the other end of the power consumption end at the same time, the output end of the sampling circuit is connected to the input end of the amplifier circuit, and the output end of the amplifier circuit is connected to the input end of the feedback circuit; the sampling circuit is used to sample the noise current flowing into the power consumption end and convert it into a first voltage, the amplifier circuit is used to convert the first voltage into a second voltage after amplification, and the feedback circuit is used to convert the second voltage into a feedback current, the feedback current is equal to the noise current in magnitude and opposite in direction, so as to avoid the noise current flowing into the power supply end; the amplifier circuit comprises an operational amplifier; characterized in that: The active wave circuit further comprises the compensation circuit as claimed in any one of claims 1 to 2, wherein the compensation circuit is used to compensate for the amplitude margin of the active filter to make it stable.

4. The active wave circuit according to claim 3, characterized in that: The sampling circuit includes a transformer TX1, a resistor R6 and a capacitor C2. The same-name end of the primary winding of the transformer TX1 is used to connect to one end of the power consumption end, and the opposite-name end is used to connect to one end of the power supply end. The same-name end of the secondary winding of the transformer TX1 is connected to one end of the capacitor C2, and the opposite-name end and one end of the resistor R6 are connected together to connect the other end of the power supply end and the other end of the power consumption end. The other end of the capacitor and the other end of the resistor R6 are connected together as the output end of the sampling circuit.

5. The active wave circuit according to claim 3, characterized in that: The sampling circuit includes a resistor R8 and a capacitor C4, one end of the capacitor C4 serves as the input end of the sampling circuit, and the other end is connected with one end of the resistor R8 as the output end of the sampling circuit, and the other end of the resistor R8 serves as the ground end of the sampling circuit.

6. The active wave circuit according to claim 3, characterized in that: The amplifier circuit also includes a resistor R5 and a resistor R4, one end of the resistor R4 is used to connect to the input power supply end of the operational amplifier, and the other end is simultaneously connected to one end of the resistor R5 and the in-phase input end of the operational amplifier, the other end of the resistor R5 is connected to the ground end of the operational amplifier, and the output end of the operational amplifier is the output end of the amplifier circuit.

7. The active wave circuit according to claim 3, characterized in that: The feedback circuit includes a resistor R7 and a capacitor C3. One end of the resistor R7 is the input end of the feedback circuit, and the other end is connected to one end of the capacitor C3. The other end of the capacitor C3 is the output end of the feedback circuit.

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