An active compensation circuit

Abstract

An active compensation circuit includes a passive compensation network, an active amplifier circuit, a power processing module, and a coupling coefficient adjustment module. The passive compensation network includes three groups of LCR compensation circuits connected in series. The passive compensation network adjusts the coupling coefficient from a first coupling coefficient to a second coupling coefficient. The output end of the passive compensation network is connected to the active amplifier circuit, and the active amplifier circuit amplifies the second coupling coefficient. The power processing module is connected to the active amplifier circuit, and the power processing module converts an external direct current power supply into an electrical signal to provide a power supply voltage and a bias voltage for the active amplifier circuit. The input end of the coupling coefficient adjustment module is connected to the output end of the active amplifier circuit, and the coupling coefficient adjustment module stabilizes the second coupling coefficient at a first flatness. The present invention adjusts the coupling coefficient outputted by the coupling structure of a directional coupler with a cavity structure to ‑63~‑50dB, and the absolute value of the flatness is less than or equal to 1dB.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and more specifically, to an active compensation circuit. Background Art

[0002] A directional coupler is a commonly used RF component that can couple a portion of the power from the main transmission path and output it to a specific port, thereby achieving the purpose of online monitoring of forward transmission power and reflected power.

[0003] In medium and high power RF measurement systems, in order to reduce the insertion loss on the main transmission path, the coupling coefficient of the directional coupler is usually small, generally between -60dB and -40dB. The directional coupler with cavity structure has the characteristics of large power capacity, good directivity, and small main line insertion loss, and has been widely used. Since the front-end coupling coefficient of the directional coupler increases by 6dB per octave, the passive compensation network can usually only compensate for the change of 30 to 40dB coupling. The bandwidth of high-power directional couplers on the market is generally less than 50 octaves, which means that if you want to cover 1MHz~1.2GHz, you usually need a combination of more than two broadband couplers (for example, split into two modules of 1MHz~30MHz and 25MHz~1.2GHz), which brings a lot of inconvenience and more measurement uncertainty to users.

[0004] Medium and high power measurement systems usually require the coupling coefficient of the coupler to be a relatively fixed value with as little fluctuation as possible; however, the original value of the coupling coefficient of the high power 1MHz~1.2GHz bandwidth coupler has a large span, exceeding -60dB, and cannot be applied in existing systems. Only by adjusting the original coupling coefficient with a large span to a commonly used value can it be connected to the existing system.

[0005] Therefore, the problems existing in the prior art need to be further improved and developed. Summary of the invention

[0006] (I) Purpose of the invention: To solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide an active compensation circuit, which adjusts the coupling coefficient of the coupling structure output in the range of -85dB~-22dB to -63~-50dB, with a flatness of ±1dB.

[0007] (II) Technical solution: In order to solve the above technical problems, the present technical solution provides an active compensation circuit, including a passive compensation network, an active amplification circuit, a power processing module, and a coupling coefficient adjustment module; the passive compensation network includes three groups of LCR compensation circuits connected in series, the LCR compensation circuits are composed of capacitors, inductors, and resistors connected in parallel with each other, and a grounded inductor and resistor branch is arranged behind each group of LCR compensation circuits; the passive compensation network adjusts the coupling coefficient from a first coupling coefficient to a second coupling coefficient;

[0008] The output end of the passive compensation network is connected to the active amplifier circuit, which is composed of a low-noise broadband amplifier module and an impedance matching circuit. The second coupling coefficient is amplified by the active amplifier circuit and is complementary to the coupling coefficient output externally.

[0009] The power processing module is connected to the active amplifier circuit, and the power processing module includes magnetic beads, capacitors, inductors, and low-noise low-voltage dropout linear regulators; the power processing module converts an external DC power supply into an electrical signal to provide a power supply voltage and a bias voltage for the active amplifier circuit;

[0010] The input end of the coupling coefficient adjustment module is connected to the output end of the active amplifier circuit; the coupling coefficient adjustment module is composed of a resistance attenuation network, and the coupling coefficient adjustment module stabilizes the second coupling coefficient at the first flatness.

[0011] Preferably, a fixed attenuator is added between the external coupling structure and the passive compensation network, the output end of the fixed attenuator is connected to the passive compensation network, and the input end is connected to the external coupling structure, and the power value of the external coupling structure is buffered by the fixed attenuator.

[0012] Preferably, the fixed attenuator is composed of one or more fixed resistors, and the resistance values ​​of the fixed resistors are predetermined.

[0013] Preferably, the current output through the coupling structure first flows through the fourth resistor, then flows through the first LCR compensation circuit formed by the first inductor, the first resistor and the first capacitor in parallel, then flows through the second LCR compensation circuit formed by the second inductor, the second resistor and the second capacitor in parallel, and finally flows out of the passive compensation network after passing through the third LCR compensation circuit formed by the third inductor, the third resistor and the third capacitor in parallel;

[0014] A fourth capacitor and a fifth resistor are connected between the first LCR compensation circuit and the second LCR compensation circuit and then grounded; a fifth capacitor and a sixth resistor are connected between the second LCR compensation circuit and the third LCR compensation circuit and then grounded; a sixth capacitor and a seventh resistor are connected between the third LCR compensation circuit and the output end and then grounded.

[0015] Preferably, the resistance value in the LCR compensation circuit is 10Ω~2kΩ; the capacitance value is 1pF~1nF; and the inductance value is 10nH~3.3μH.

[0016] Preferably, the current passing through the passive compensation network first flows through the first amplifying capacitor, and then enters the input end of the low-noise broadband amplifying module, the low-noise broadband amplifying module has two grounding branches, the output end of the low-noise broadband amplifying module is connected to the second amplifying capacitor, and the current finally flows out of the active amplifying circuit after passing through the second amplifying capacitor;

[0017] The low-noise broadband amplification module is connected to a power supply device, which includes a first amplification resistor and a third amplification capacitor connected in parallel with a power supply voltage, and the other end of the third amplification capacitor is grounded; the other end of the first amplification resistor is connected to a radio frequency choke and a fourth amplification capacitor in parallel, the other end of the radio frequency choke is connected to the low-noise broadband amplification module, and the other end of the fourth amplification capacitor is grounded.

[0018] Preferably, the active amplifier circuit has a high gain at low frequencies and a low gain at high frequencies, the coupling coefficient of the coupling structure increases with increasing frequency, and the active amplifier circuit is complementary to the coupling structure.

[0019] Preferably, the input voltage first passes through the magnetic bead to suppress high-frequency noise and electromagnetic interference, and at the same time, the magnetic bead is connected in parallel with a first power processing capacitor, and the other end of the first power processing capacitor is grounded; the other end of the magnetic bead is connected to a filter inductor, and the filter inductor is connected in parallel with a second power processing capacitor, and the other end of the second power processing capacitor is grounded; the other end of the filter inductor is connected to the input end and the signal control end of the low-noise low-voltage difference linear regulator, and the low-noise low-voltage difference linear regulator is connected in parallel with a third power processing capacitor, and the other end of the third power processing capacitor is grounded; the ground end of the low-noise low-voltage difference linear regulator is grounded, and the output end of the low-noise low-voltage difference linear regulator is connected to the active amplifier circuit to provide a power supply voltage and a bias voltage for the low-noise broadband amplifier module; the pressure transmitter end of the low-noise low-voltage difference linear regulator is connected to a fourth power processing capacitor, and the other end of the fourth power processing capacitor is grounded; the output end of the low-noise low-voltage difference linear regulator is also connected to a fifth power processing capacitor, and the other end of the fifth power processing capacitor is grounded.

[0020] Preferably, the coupling coefficient adjustment module is a three-resistance attenuation network, including a T-type attenuation network or a Pi-type attenuation network;

[0021] By selecting three resistors with different resistance values ​​for combination, a three-resistance attenuation network is obtained. By selecting resistors with different resistance values, the coupling coefficient output by the active amplifier circuit is adjusted.

[0022] Preferably, the first coupling coefficient is greater than the second coupling coefficient, the first coupling coefficient is -85dB~-22dB, the second coupling coefficient is -63~-50dB, and the absolute value of the first flatness is less than or equal to 1dB.

[0023] (III) Beneficial effects: An active compensation circuit of the present invention adjusts the coupling coefficient of the coupling structure output of a directional coupler with a cavity structure from -85dB~-22dB to -63~-50dB, and the absolute value of the flatness is less than or equal to 1dB; by coupling part of the power in the directional coupler through the active compensation circuit, the purpose of online monitoring of the forward transmission power and the reflected power is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a principle structure diagram of a first embodiment of an active compensation circuit of the present invention;

[0025] Figure 2 It is a schematic diagram of the coupling coefficient of a directional coupler with a cavity structure that has not been adjusted by an active compensation circuit of the present invention;

[0026] Figure 3 It is a principle structure diagram of a second embodiment of an active compensation circuit of the present invention;

[0027] Figure 4 It is a schematic diagram of the coupling coefficient of a directional coupler with a cavity structure after being adjusted by an active compensation circuit of the present invention;

[0028] Figure 5 It is a schematic diagram of the connection relationship of the passive compensation network;

[0029] Figure 6 This is a schematic diagram of the connection relationship of the active compensation circuit;

[0030] Figure 7 It is a schematic diagram of the connection relationship of the power processing module;

[0031] Figure 8 It is a schematic diagram of the connection relationship of the T-type attenuation network;

[0032] Fig. 9 This is a schematic diagram of the connection relationship of the Pi-type attenuation network. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with preferred embodiments. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0034] The accompanying drawings are schematic diagrams of embodiments of the present invention. It should be noted that the drawings are only examples and are not drawn to scale, and should not be used to limit the actual protection scope of the present invention.

[0035] An active compensation circuit, such as Figure 1 As shown, it includes a passive compensation network, an active amplification circuit, a power processing module, and a coupling coefficient adjustment module. The passive compensation network is composed of an LCR compensation circuit, and the LCR compensation circuit is composed of capacitors, inductors, and resistors connected in parallel; the values ​​of the capacitors, inductors, and resistors are adjusted according to the input coupling coefficient, so that the impedance, energy distribution, phase, and other characteristics in the passive compensation network affect the coupling coefficient. The passive compensation network includes three groups of LCR compensation circuits connected in series, and a grounded inductor and resistor branch is set after each group of LCR compensation circuits.

[0036] More specifically, Figure 5As shown, the current I output by the coupling structure first flows through the fourth resistor R4, which plays the role of current limiting, voltage dividing, etc., further adjusts the characteristics of the input signal, and provides suitable input conditions for the subsequent coupling coefficient adjustment module. The resistance value of the additional resistor R1 can be adjusted; then it passes through the first LCR compensation circuit formed by the first inductor L1, the first resistor R1 and the first capacitor C1 in parallel, and then passes through the second LCR compensation circuit formed by the second inductor L2, the second resistor R2 and the second capacitor C2 in parallel, and finally flows out of the passive compensation network after passing through the third LCR compensation circuit formed by the third inductor L3, the third resistor R3 and the third capacitor C3 in parallel. The fourth capacitor C4 and the fifth resistor R5 are connected between the first LCR compensation circuit and the second LCR compensation circuit and then grounded; the fifth capacitor C5 and the sixth resistor R6 are connected between the second LCR compensation circuit and the third LCR compensation circuit and then grounded; the sixth capacitor C6 and the seventh resistor R7 are connected between the third LCR compensation circuit and the output end and then grounded. By adjusting different resistance, inductance and capacitance values, the input signal current and voltage values ​​can be distributed in sequence to achieve precise control of the coupling coefficient adjustment. The coupling coefficient through the coupling structure is adjusted from the first coupling coefficient to the second coupling coefficient through the passive compensation network; and the first coupling coefficient is greater than the second coupling coefficient; that is, the passive compensation network adjusts the larger coupling coefficient through the coupling structure to a relatively flat coupling coefficient.

[0037] The resistance value range of the LCR compensation circuit is 10Ω~2kΩ; the capacitance value range is 1pF~1nF; the inductance value range is 10nH~3.3uH. That is, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7 all have a value range of 10Ω~2kΩ; the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5, and the sixth capacitor C6 all have a value range of 1pF~1nF; the first inductor L1, the second inductor L2, and the third inductor L3 all have a value range of 10nH~3.3uH.

[0038] The output end of the passive compensation network is connected to the active amplifier circuit, and the coupling coefficient is stabilized by the active amplifier circuit. The active amplifier circuit is composed of a low-noise broadband amplifier module and an impedance matching circuit, and the smaller signal output by the passive compensation network is amplified to a suitable power by the active amplifier circuit. In addition, the active amplifier circuit has a high gain at low frequencies and a low gain at high frequencies, while the original coupling coefficient of the external coupling structure increases with the increase of frequency; the active amplifier circuit can complement the original coupling coefficient well, and together reduce the complexity of the passive compensation network.

[0039] More specifically, Figure 6 As shown, the active amplifier circuit includes a low-noise broadband amplifier module LNA, and an impedance matching circuit is integrated in the low-noise broadband amplifier module LNA to match according to different impedances. The current I passing through the passive compensation network first flows through the first amplifier capacitor CM1, and then enters the input end of the low-noise broadband amplifier module LNA. The low-noise broadband amplifier module LNA has two grounding branches G1 and G2. The output end of the low-noise broadband amplifier module LNA is connected to the second amplifier capacitor CM2, and the current I finally flows out of the active amplifier circuit after passing through the second amplifier capacitor CM2. The low-noise broadband amplifier module LNA mainly amplifies the input weak RF signal, while reducing the noise introduced by itself as much as possible. The low-noise broadband amplifier module LNA is also connected to a power supply device, which is connected to a resistor, an inductor, and a capacitor. More specifically, the power supply device includes a power supply voltage VCC connected to a first amplifier resistor RM1 and a third amplifier capacitor CM3 connected in parallel, and the other end of the third amplifier capacitor CM3 is grounded; the other end of the first amplifier resistor RM1 is connected to a radio frequency choke RFC and a fourth amplifier capacitor CM4 connected in parallel, and the other end of the radio frequency choke RFC is connected to the low-noise broadband amplifier module LNA to provide a stable DC voltage for the low-noise broadband amplifier module LNA; the other end of the fourth amplifier capacitor CM4 is grounded.

[0040] The power processing module is connected to the active amplifier circuit. The power processing module converts the external DC power supply into a low-noise, amplitude-stable electrical signal, provides the active amplifier circuit with a low-noise, low-ripple, high-stability power supply voltage and bias voltage, and ensures the normal operation of the active amplifier circuit.

[0041] More specifically, Figure 7As shown, the power processing module includes a magnetic bead FB, filter devices such as capacitors and inductors, and a low-noise low-voltage dropout linear regulator LDO. The input voltage first passes through the magnetic bead FB to suppress high-frequency noise and electromagnetic interference. At the same time, the magnetic bead FB is connected in parallel with a first power processing capacitor CP1, and the other end of the first power processing capacitor CP1 is grounded; the other end of the magnetic bead FB is connected to a filter inductor LP1, and the filter inductor LP1 is connected in parallel with a second power processing capacitor CP2, and the other end of the second power processing capacitor CP2 is grounded; the other end of the filter inductor LP1 is connected to the input terminal IN and the signal control terminal SHDN of the low-noise low-voltage dropout linear regulator LDO, and the low-noise low-voltage dropout linear regulator LDO is connected in parallel with a third power processing capacitor CP3, and the third inductor LP1 is connected in parallel with the input terminal IN and the signal control terminal SHDN of the low-noise low-voltage dropout linear regulator LDO. The other end of the source processing capacitor CP3 is grounded; the ground end GND of the low-noise low-voltage difference linear regulator LDO is grounded, and the output end OUT of the low-noise low-voltage difference linear regulator LDO is connected to the active amplifier circuit to provide a power supply voltage and a bias voltage for the low-noise broadband amplifier module LNA; the pressure transmitter end BP of the low-noise low-voltage difference linear regulator LDO is connected to the fourth power processing capacitor CP4, and the other end of the fourth power processing capacitor CP4 is grounded; the output end OUT of the low-noise low-voltage difference linear regulator LDO is also connected to the fifth power processing capacitor CP5, and the other end of the fifth power processing capacitor CP5 is grounded. Connecting the power processing capacitors forms a low-resistance loop to ensure the stable operation of the power processing module.

[0042] The low-noise low-dropout linear regulator LDO has extremely low self-noise and high power supply rejection ratio, and has functions such as overcurrent protection, overtemperature protection, and precision reference source. The low-noise low-dropout linear regulator LDO stabilizes a large input voltage to a small constant output voltage.

[0043] The magnetic bead FB is an electronic component made of ferrite material, which presents high impedance to high-frequency current and low impedance to low-frequency current. When high-frequency noise current passes through the magnetic bead, the magnetic bead FB will generate a magnetic field, which will hinder the passage of high-frequency noise current, thereby converting high-frequency noise into heat energy for consumption. Therefore, the magnetic bead can effectively suppress high-frequency noise on the power line and improve the power quality of the low-noise broadband amplifier module LNA.

[0044] When the signal control terminal SHDN is at a low level, the low-noise low-dropout linear regulator LDO is turned off and the output voltage is zero; when the signal control terminal SHDN is at a high level, the low-noise low-dropout linear regulator LDO is turned on and the output voltage is normal.

[0045] The input end of the coupling coefficient adjustment module is connected to the output end of the active amplifier circuit. The coupling coefficient adjustment module is composed of a resistor attenuation network. The coupling coefficient is adjusted by the coupling coefficient adjustment module to reduce the fluctuation introduced by the parameter difference of the filter device, so that the coupling coefficients of the couplers produced in the same batch are consistent, and the coupling coefficient of the active compensation circuit finally output is ensured to be stable within the first flatness; in this embodiment, the first flatness is preferably ±1dB, that is, the absolute value of the first flatness is less than or equal to 1dB.

[0046] The coupling coefficient output by the active compensation circuit finally meets the requirement of -63~-50dB, and the absolute value of the first flatness is less than or equal to 1dB. More preferably, the coupling output of the active compensation circuit finally has a preferred value of -60dB, and the absolute value of the first flatness is less than or equal to 1dB.

[0047] The couplers produced in the same batch in the present invention refer to couplers produced simultaneously using the same material and the same process.

[0048] More specifically, the important indicators of the coupler are coupling and insertion loss. Coupling is the ratio of the power of the coupling port to the input port. The larger the absolute value of the coupling, the smaller the loss of the coupler. Insertion loss is the ratio of the power of the output port to the input port. The larger the absolute value of the coupling, the smaller the absolute value of the insertion loss.

[0049] The insertion loss introduced by the directional coupler mainly includes three parts: mismatch loss, transmission loss and coupling loss. The mismatch loss is the loss caused by reflection due to mismatch, which is the difference between the power obtained by the load and the incident power. The smaller the absolute value of the mismatch loss, the better. The transmission loss is the ratio of output power to input power, which refers to the capacity loss caused by factors such as the transmission medium during the transmission process. The coupling loss refers to the energy loss that occurs when energy is transmitted from one circuit or a component therein to another circuit.

[0050] In medium and high power RF measurement systems, the power value on the main transmission path is mostly 1kW. For a directional coupler with a cavity structure, when the input frequency is within the range of 1.2GHz, the standing wave reaches within 1.05. At this time, the transmission loss of the directional coupler is less than 0.05dB, the mismatch loss is small, about 0.003dB, and the main transmission path loss of the cavity structure of the directional coupler is also very small. Here, the two are estimated together as transmission loss. If the insertion loss of the directional coupler is required to be less than or equal to 0.1dB, the coupling loss of the directional coupler must be less than or equal to 0.05dB.

[0051] There is no specific limitation on the power size of the medium and high power, and there will be great differences in different fields. In the present invention, the power ranging from tens of watts to several kilowatts is called medium and high power.

[0052] like Figure 2 As shown, the coupling coefficient of the first coupling coefficient is -85~-22dB, and the higher the input frequency, the greater the coupling coefficient and coupling loss. If the design power capacity of the directional coupler at the highest operating frequency is 1kW, the insertion loss at this time is 60dB. According to design experience, the coupling coefficient at the highest input frequency: 1.2GHz should be less than or equal to -22dB. That is, the maximum coupling coefficient of the directional coupler is -22dB, and the output power of the coupling structure is 5W at this time. Since there is also a 50Ω matching load inside the coupling structure, the internal resistance of the coupling structure also consumes 5W of power, and the total coupling loss is 10W.

[0053] More preferably, since the output power of the coupling structure is relatively large, and the capacitors, inductors, resistors and other components in the LCR compensation circuit in the passive compensation network cannot meet the rated power requirements due to the device packaging or size limitations of the directional coupler, a fixed attenuator is added between the external coupling structure and the passive compensation network, such as Figure 3 As shown, the output end of the fixed attenuator is connected to the passive compensation network, and the input end is connected to the external coupling structure. The fixed attenuator is used to buffer the input power value of the coupling structure, thereby increasing the flexibility of selecting components such as capacitors, inductors, resistors, etc. in the LCR compensation circuit in the passive compensation network, and ensuring that the rated power of the components in the passive compensation network matches the external coupling structure.

[0054] More specifically, the fixed attenuator is usually composed of one or more fixed resistors, the resistance of which is predetermined. By introducing the fixed attenuator into the circuit to consume a portion of the energy of the input signal, attenuation control of the input signal is achieved.

[0055] After limiting the maximum coupling coefficient of the directional coupler, it is necessary to determine the minimum coupling coefficient of the directional coupler. When the input frequency is the lowest input frequency: 1MHz, the coupling coefficient of the directional coupler is only -85dB. If the coupling coefficient is too high, the loss on the main transmission path will increase. If the coupling coefficient is too low, it will not be applicable to the existing system. Therefore, in order to meet the application needs, the coupling coefficient is stabilized to -60dB, so an active amplifier circuit is added after the passive compensation network. In addition, since the gain of the active amplifier circuit is large at low frequencies, the gain will decrease as the frequency increases; and the coupling coefficient of the coupling structure increases with the frequency. Therefore, the coupling coefficient of the active amplifier circuit and the coupling structure complement each other, effectively reducing the complexity of the passive compensation network.

[0056] In order to ensure the stability of the coupling coefficient of the coupling structure, it is necessary to ensure the stability of the active amplifier circuit. Therefore, a power processing module is added as the input of the active amplifier circuit to provide a stable power supply voltage and bias voltage for the active amplifier circuit.

[0057] Considering the cavity structure of the directional coupler, due to the influence of the processing accuracy of the cavity structure and the discrete type of device parameters, the coupling coefficient adjusted by the passive compensation network and the active amplifier circuit will still have a certain deviation from the expected value. Therefore, a coupling coefficient adjustment module is added to the output end of the active amplifier circuit, and the coupling coefficient output by the active amplifier circuit is fine-tuned by the coupling coefficient adjustment module. The output coupling coefficient adjusted by the active compensation circuit is as follows: Figure 4 As shown, the coupling coefficient of the second coupling coefficient at the output port of the directional coupler is approximately -60 dB, and the absolute value of the first flatness is less than or equal to 1 dB.

[0058] The coupling coefficient adjustment module is a commonly used three-resistance attenuation network, including a T-type attenuation network or a Pi-type attenuation network; there is no specific limitation in the present invention. Figure 8 , Fig. 9 As shown, the T-type attenuation network is a series-parallel-series structure, and the Pi-type attenuation network is a parallel-series-parallel structure. By selecting three resistors with different resistance values ​​for combination, a three-resistance attenuation network is obtained. By selecting resistors with different resistance values, the coupling coefficient output by the active amplifier circuit can be fine-tuned, and the coupling coefficient output of the coupling coefficient adjustment module can be stabilized to the first flatness of the second coupling coefficient.

[0059] An active compensation circuit of the present invention adjusts the coupling coefficient of the coupling structure output of the directional coupler with a cavity structure from -85dB to -22dB to -63 to -50dB, and the absolute value of the flatness is less than or equal to 1dB. The active compensation circuit is used to couple part of the power in the directional coupler, thereby achieving the purpose of online monitoring of the forward transmission power and the reflected power.

[0060] The above content is an explanation of the preferred embodiments of the present invention, which can help those skilled in the art to more fully understand the technical solution of the present invention. However, these embodiments are merely illustrative, and it cannot be determined that the specific implementation methods of the present invention are limited to the description of these embodiments. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions and transformations can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. An active compensation circuit, characterized in that: It includes a passive compensation network, an active amplification circuit, a power processing module, and a coupling coefficient adjustment module; the passive compensation network includes three groups of LCR compensation circuits connected in series, the LCR compensation circuits are composed of capacitors, inductors, and resistors connected in parallel with each other, and a grounded inductor and resistor branch is arranged behind each group of LCR compensation circuits; The passive compensation network adjusts the coupling coefficient from the first coupling coefficient to the second coupling coefficient; The first coupling coefficient is greater than the second coupling coefficient, the first coupling coefficient is -85dB~-22dB, and the second coupling coefficient is -63~-50dB; The output end of the passive compensation network is connected to the active amplifier circuit, which is composed of a low-noise broadband amplifier module and an impedance matching circuit. The second coupling coefficient is amplified by the active amplifier circuit and is complementary to the coupling coefficient of the external output. The current passing through the passive compensation network first flows through the first amplifier capacitor and then enters the input end of the low-noise broadband amplifier module. The low-noise broadband amplifier module has two grounding branches. The output end of the low-noise broadband amplifier module is connected to the second amplifier capacitor. The current finally flows out of the active amplifier circuit after passing through the second amplifier capacitor. The low-noise broadband amplification module is connected to a power supply device, the power supply device includes a first amplification resistor and a third amplification capacitor connected in parallel to a power supply voltage, and the other end of the third amplification capacitor is grounded; the other end of the first amplification resistor is connected to a radio frequency choke and a fourth amplification capacitor connected in parallel, the other end of the radio frequency choke is connected to the low-noise broadband amplification module, and the other end of the fourth amplification capacitor is grounded; The power processing module is connected to the active amplifier circuit, and the power processing module includes magnetic beads, capacitors, inductors, and low-noise low-voltage dropout linear regulators; the power processing module converts an external DC power supply into an electrical signal to provide a power supply voltage and a bias voltage for the active amplifier circuit; The input end of the coupling coefficient adjustment module is connected to the output end of the active amplifier circuit; The coupling coefficient adjustment module is composed of a resistor attenuation network, and the coupling coefficient adjustment module stabilizes the second coupling coefficient at a first flatness; the absolute value of the first flatness is less than or equal to 1 dB.

2. An active compensation circuit according to claim 1, characterized in that: A fixed attenuator is added between the external coupling structure and the passive compensation network, the output end of the fixed attenuator is connected to the passive compensation network, and the input end is connected to the external coupling structure, and the power value of the external coupling structure is buffered by the fixed attenuator.

3. An active compensation circuit according to claim 2, characterized in that: The fixed attenuator is composed of one or more fixed resistors, and the resistance values ​​of the fixed resistors are predetermined.

4. The active compensation circuit according to claim 1, characterized in that: The current outputted by the coupling structure first flows through the fourth resistor, then flows through the first LCR compensation circuit formed by the first inductor, the first resistor and the first capacitor in parallel, then flows through the second LCR compensation circuit formed by the second inductor, the second resistor and the second capacitor in parallel, and finally flows out of the passive compensation network through the third LCR compensation circuit formed by the third inductor, the third resistor and the third capacitor in parallel; A fourth capacitor and a fifth resistor are connected between the first LCR compensation circuit and the second LCR compensation circuit and then grounded; a fifth capacitor and a sixth resistor are connected between the second LCR compensation circuit and the third LCR compensation circuit and then grounded; a sixth capacitor and a seventh resistor are connected between the third LCR compensation circuit and the output end and then grounded.

5. The active compensation circuit according to claim 1, characterized in that: The resistance value in the LCR compensation circuit is 10Ω~2kΩ; the capacitance value is 1pF~1nF; and the inductance value is 10nH~3.3μH.

6. The active compensation circuit according to claim 1, characterized in that: The active amplifier circuit has a high gain at low frequencies and a low gain at high frequencies. The coupling coefficient of the coupling structure increases with increasing frequency. The active amplifier circuit is complementary to the coupling structure.

7. The active compensation circuit according to claim 1, characterized in that: The input voltage first passes through the magnetic bead to suppress high-frequency noise and electromagnetic interference. At the same time, the magnetic bead is connected in parallel with a first power supply processing capacitor, and the other end of the first power supply processing capacitor is grounded; the other end of the magnetic bead is connected to a filter inductor, and the filter inductor is connected in parallel with a second power supply processing capacitor, and the other end of the second power supply processing capacitor is grounded; the other end of the filter inductor is connected to the input end and the signal control end of the low-noise low-voltage difference linear regulator, and the low-noise low-voltage difference linear regulator is connected in parallel with a third power supply processing capacitor, and the other end of the third power supply processing capacitor is grounded; the ground end of the low-noise low-voltage difference linear regulator is grounded, and the output end of the low-noise low-voltage difference linear regulator is connected to the active amplifier circuit to provide a power supply voltage and a bias voltage for the low-noise broadband amplifier module; the pressure transmitter end of the low-noise low-voltage difference linear regulator is connected to a fourth power supply processing capacitor, and the other end of the fourth power supply processing capacitor is grounded; the output end of the low-noise low-voltage difference linear regulator is also connected to a fifth power supply processing capacitor, and the other end of the fifth power supply processing capacitor is grounded.

8. The active compensation circuit according to claim 1, characterized in that: The coupling coefficient adjustment module is a three-resistance attenuation network, including a T-type attenuation network or a Pi-type attenuation network; By selecting three resistors with different resistance values ​​for combination, a three-resistance attenuation network is obtained. By selecting resistors with different resistance values, the coupling coefficient output by the active amplifier circuit is adjusted.

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