Noise canceller

Abstract

The utility model discloses a noise canceller which comprises a sampling unit, a first frequency band channel, a second frequency band channel, an injection unit and a power supply unit. The sampling unit is used for sampling the interference signal to obtain a sampling signal; the first frequency band path is used for acquiring a first frequency band signal and processing the first frequency band signal to obtain a first elimination signal; the second frequency band channel is used for obtaining a second frequency band signal and processing the second frequency band signal to obtain a second elimination signal; and the injection unit is used for injecting the first elimination signal and the second elimination signal into the line to be subjected to noise elimination. According to the noise canceller provided by the utility model, the first frequency band signal and the second frequency band signal are subjected to reverse-phase amplification processing to obtain the first cancelling signal and the second cancelling signal, and the first cancelling signal and the second cancelling signal are subjected to superposition coupling and are injected into a line to be subjected to noise elimination so as to suppress noise interference. The noise interference suppression effect can be greatly improved, and the power density of the whole terminal equipment is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of integrated circuits, and in particular relates to a noise canceller. Background Art

[0002] In industrial / automotive power supply equipment, the switching process of power devices will produce rapid voltage change rate (or current change rate) jumps, causing increasingly serious electromagnetic interference, such as common mode noise interference. In order to pass relevant safety standards, a large noise interference filter is generally added to the circuit loop.

[0003] At present, the filters that are widely used all use common-mode filter inductors and Y capacitors to form LC (or π-shaped) filters to filter out common-mode interference. In order to optimize the filtering effect, the industry has proposed the idea of ​​a noise eliminator, which samples the interference signal through a voltage-current conversion circuit, and then undergoes a voltage-current (VI) conversion. The processed signal is then injected into the original loop in the form of a current, thereby offsetting the common-mode interference to achieve a filtering effect.

[0004] However, since the input differential circuit of the voltage-current conversion circuit is difficult to be completely symmetrical, there is an offset voltage. In addition, in general noise cancellers, the circuit injection circuit is a DC isolation circuit. When the AC input in the loop changes greatly or contains a small amount of transient DC components, the signal output by the amplifier will be distorted, which will seriously affect the performance of the noise canceller and affect its normal operation.

[0005] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to a person skilled in the art. Utility Model Content

[0006] The purpose of the utility model is to provide a noise eliminator, which can effectively reduce the distortion produced by traditional filters, and at the same time can reduce the demand for passive common-mode filter inductors, and even save the common-mode filter inductors, thereby improving the performance and cost-effectiveness of the entire filter.

[0007] In order to achieve the above objective, a specific embodiment of the present invention provides a noise eliminator, including: a sampling unit, a first frequency band path, a second frequency band path and an injection unit.

[0008] The sampling unit is used to sample the interference signal on the noise elimination line to obtain a sampling signal; the first frequency band path is connected to the sampling unit, and is used to obtain a first frequency band signal with a frequency in the first frequency band in the sampling signal, and condition the first frequency band signal to obtain a first elimination signal; the second frequency band path is connected to the sampling unit, and is used to obtain a second frequency band signal with a frequency in the second frequency band in the sampling signal, and condition the second frequency band signal to obtain a second elimination signal; the injection unit is connected to the first frequency band path, the second frequency band path and the noise elimination line, and is used to superimpose and couple the first elimination signal and the second elimination signal and then inject them into the noise elimination line; wherein, the first frequency band and the second frequency band have non-overlapping frequency components.

[0009] In one or more embodiments of the present invention, the sampling unit includes a first capacitor and a first resistor, the first end of the first capacitor is connected to the circuit to be eliminated, the second end of the first capacitor is connected to the first frequency band path, the second frequency band path and the first end of the first resistor, and the second end of the first resistor is connected to the first reference voltage.

[0010] In one or more embodiments of the present invention, the first frequency band path includes a first frequency selection unit and a first inverting amplifier unit, the first frequency selection unit is connected to the sampling unit, the first frequency selection unit is used to obtain a first frequency band signal with a frequency in the first frequency band from the sampling signal, the first inverting amplifier unit is connected to the first frequency selection unit, and the first inverting amplifier unit is used to invert and amplify the first frequency band signal to generate a first elimination signal.

[0011] In one or more embodiments of the present invention, the first frequency selection unit is used to amplify a first frequency band signal having a frequency in the first frequency band, and the first inverting amplifier unit is used to invert the amplified first frequency band signal to generate a first elimination signal.

[0012] In one or more embodiments of the present invention, the second frequency band path includes a second frequency selection unit and a second inverting amplifier unit, the second frequency selection unit is connected to the sampling unit, the second frequency selection unit is used to obtain a second frequency band signal with a frequency in the second frequency band from the sampling signal, and the second inverting amplifier unit is connected to the second frequency selection unit, and the second inverting amplifier unit is used to invert and amplify the second frequency band signal to generate a second elimination signal.

[0013] In one or more embodiments of the present invention, the second frequency selection unit is used to amplify the second frequency band signal with a frequency in the second frequency band, and the second inverting amplifier unit is used to invert the amplified second frequency band signal to generate a second elimination signal.

[0014] In one or more embodiments of the present invention, the first frequency band path also includes a first deviation correction unit, which is connected to the first inverting amplifier unit, and the first deviation correction unit is used to generate a first correction signal to eliminate the influence of DC deviation and / or offset error on the first elimination signal.

[0015] In one or more embodiments of the present invention, the second frequency band path also includes a second deviation correction unit, which is connected to the second inverting amplifier unit, and the second deviation correction unit is used to generate a second correction signal to eliminate the influence of DC deviation and / or offset error on the second elimination signal.

[0016] In one or more embodiments of the present utility model, the first frequency selection unit includes a first amplifier, a third resistor, a fifth resistor and a second capacitor;

[0017] The first input terminal of the first amplifier is connected to the sampling unit, the first end of the third resistor is connected to the second input terminal of the first amplifier, the second end of the third resistor is connected to the first end of the second capacitor, the second end of the second capacitor is connected to the first reference voltage, the first end of the fifth resistor is connected to the second input terminal of the first amplifier, and the second end of the fifth resistor is connected to the output terminal of the first amplifier.

[0018] In one or more embodiments of the present utility model, the second frequency selection unit includes a fourth amplifier, a thirteenth resistor and a fourteenth resistor, the first input end of the fourth amplifier is connected to the sampling unit, the first end of the thirteenth resistor and the first end of the fourteenth resistor are connected to the second input end of the fourth amplifier, the second end of the thirteenth resistor is connected to the first reference voltage, and the second end of the fourteenth resistor is connected to the output end of the fourth amplifier and the second inverting amplification unit.

[0019] In one or more embodiments of the present utility model, the first frequency selection unit also includes a second resistor and / or a fourth resistor and / or a third capacitor, the first end of the second resistor is connected to the first input end of the first amplifier, the second end of the second resistor is connected to the sampling unit, the first end of the fourth resistor is connected to the output end of the first amplifier, the second end of the fourth resistor is connected to the second input end of the first amplifier, the first end of the third capacitor is connected to the second end of the fifth resistor, and the second end of the third capacitor is connected to the output end of the first amplifier and the first inverting amplifier unit.

[0020] In one or more embodiments of the present invention, the second frequency selection unit further includes a twelfth resistor, a first end of the twelfth resistor is connected to the first input end of the fourth amplifier, and a second end of the twelfth resistor is connected to the sampling unit.

[0021] In one or more embodiments of the present invention, the first inverting amplifying unit includes a second amplifier and a seventh resistor, the first end of the seventh resistor is connected to the second input end of the second amplifier and is simultaneously connected to the first frequency selection unit, the first input end of the second amplifier is connected to the first reference voltage, and the second end of the seventh resistor is connected to the output end of the second amplifier to output a first elimination signal.

[0022] In one or more embodiments of the present utility model, the second inverting amplifying unit includes a fifth amplifier, a sixteenth resistor and an eighth capacitor, the first end of the sixteenth resistor and the first end of the eighth capacitor are connected to the first input end of the second amplifier and to the second frequency selection unit, the first input end of the fifth amplifier is connected to the first reference voltage, and the second end of the sixteenth resistor is connected to the output end of the fifth amplifier to output a second elimination signal.

[0023] In one or more embodiments of the present utility model, the first inverting amplification unit also includes a fourth capacitor and / or a sixth resistor; the first end of the fourth capacitor is connected to the second input end of the second amplifier, the second end of the fourth capacitor is connected to the output end of the second amplifier, the first end of the sixth resistor is connected to the first frequency selection unit, and the second end of the sixth resistor is connected to the second input end of the second amplifier.

[0024] In one or more embodiments of the present utility model, the second inverting amplifying unit also includes a seventh capacitor and / or a fifteenth resistor, the first end of the seventh capacitor is connected to the second end of the sixteenth resistor, the second end of the seventh capacitor is connected to the output end of the fifth amplifier, the first end of the fifteenth resistor is connected to the second frequency selection unit, and the second end of the fifteenth resistor is connected to the second input end of the fifth amplifier.

[0025] In one or more embodiments of the present invention, the first deviation correction unit includes a third amplifier, a tenth resistor and a fifth capacitor, the first input terminal of the third amplifier is connected to a reference voltage, the first end of the tenth resistor is connected to the output terminal of the first inverting amplifier unit to receive a first elimination signal, the second end of the tenth resistor and the first end of the fifth capacitor are connected to the second input terminal of the third amplifier, and the second end of the fifth capacitor is connected to the output terminal of the third amplifier and the first input terminal of the first inverting amplifier unit to output a first correction signal.

[0026] In one or more embodiments of the present utility model, the second deviation correction unit includes a sixth amplifier, a nineteenth resistor and a ninth capacitor, the first input terminal of the sixth amplifier is connected to the reference voltage, the first end of the nineteenth resistor is connected to the output terminal of the second inverting amplifier unit to receive the second elimination signal, the second end of the nineteenth resistor and the first end of the ninth capacitor are connected to the second input terminal of the sixth amplifier, and the second end of the ninth capacitor is connected to the output terminal of the sixth amplifier and the first input terminal of the second inverting amplifier unit to output the second correction signal.

[0027] In one or more embodiments of the present invention, the first deviation correction unit also includes an eighth resistor and / or a ninth resistor, the first end of the eighth resistor is connected to the first input end of the first inverting amplifier unit, the second end of the eighth resistor is connected to the output end of the third amplifier, the first end of the ninth resistor is connected to the reference voltage, and the second end of the ninth resistor is connected to the first input end of the third amplifier.

[0028] In one or more embodiments of the present invention, the second deviation correction unit also includes a seventeenth resistor and / or an eighteenth resistor, the first end of the seventeenth resistor is connected to the first input end of the second inverting amplifier unit, the second end of the seventeenth resistor is connected to the output end of the sixth amplifier, the first end of the eighteenth resistor is connected to the reference voltage, and the second end of the eighteenth resistor is connected to the first input end of the sixth amplifier.

[0029] In one or more embodiments of the present utility model, the injection unit includes a first isolation compensation unit, a second isolation compensation unit and a coupling unit, the first isolation compensation unit is connected to the first frequency band path, the first isolation compensation unit is used to isolate and phase compensate the first elimination signal, the second isolation compensation unit is connected to the second frequency band path, the second isolation compensation unit is used to isolate and phase compensate the second elimination signal, the coupling unit is connected to the first isolation compensation unit, the second isolation compensation unit and the line to be eliminated, and the coupling unit is used to superimpose and couple the first elimination signal and the second elimination signal after isolation compensation and inject them into the line to be eliminated.

[0030] In one or more embodiments of the present invention, the first isolation compensation unit includes a sixth capacitor, a first end of the sixth capacitor is connected to the first frequency band path to receive the first cancellation signal, and a second end of the sixth capacitor is connected to the coupling unit.

[0031] In one or more embodiments of the present invention, the first isolation compensation unit further includes an eleventh resistor, a first end of the eleventh resistor is connected to the second end of the sixth capacitor, and a second end of the eleventh resistor is connected to the coupling unit.

[0032] In one or more embodiments of the present invention, the second isolation compensation unit includes a twentieth resistor, a first end of the twentieth resistor is connected to the second frequency band path to receive the second cancellation signal, and a second end of the twentieth resistor is connected to the coupling unit.

[0033] In one or more embodiments of the present invention, the coupling unit includes a tenth capacitor, a first end of the tenth capacitor is connected to the first isolation compensation unit and the second isolation compensation unit, and a second end of the tenth capacitor is connected to the circuit to be eliminated.

[0034] In one or more embodiments of the present invention, the noise canceller further comprises a power supply unit, the power supply unit is connected to the circuit to be noise canceled or to an external power source, and the power supply unit is used to generate a positive voltage and / or a negative voltage to supply power to the first frequency band path and / or the second frequency band path.

[0035] Compared with the prior art, the noise eliminator of the present invention obtains the first elimination signal and the second elimination signal by performing inverse amplification processing on the first frequency band signal and the second frequency band signal through the first frequency band path and the second frequency band path respectively, and injects the first elimination signal and the second elimination signal into the circuit to be eliminated by superposition coupling through the injection unit to suppress noise interference. This method can greatly improve the effect of suppressing noise interference, and can reduce (or even eliminate) the common-mode filter inductance, reduce the volume and cost of the common-mode filter, and improve the power density of the terminal device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 FIG. 4 is a circuit diagram of a noise canceller in one embodiment of the present invention.

[0038] Figure 2 1 is an equivalent circuit diagram of the sixth capacitor and the twentieth resistor under the input of a low-frequency signal in one embodiment of the present invention.

[0039] Figure 3 1 is an equivalent circuit diagram of the sixth capacitor and the twentieth resistor under high-frequency signal input in one embodiment of the utility model. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0041] The words "coupled" or "connected" or "connected" in the specification include both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connection may also include connection through other active or passive devices on the basis of achieving the same or similar functional purpose, such as connection through circuits or components such as switches and follower circuits. In addition, in the utility model, words such as "first" and "second" are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship, quantity or order between these technical features.

[0042] In the detailed description of the specification, reference is made to the accompanying drawings forming a part thereof, wherein like reference numerals refer to like parts throughout, and wherein are shown by way of exemplary embodiments that may be implemented. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description should not be considered in a limiting sense.

[0043] The various operations in the specification may be described in turn as multiple discrete actions or operations in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be interpreted as implying that these operations must be order-dependent. Specifically, these operations may not be performed in the order presented. The described operations may be performed in an order different from the described embodiments. Various additional operations may be performed and / or the described operations may be omitted in additional embodiments.

[0044] For purposes of this disclosure, the phrase "A and / or B" means (A), (B), or (A and B). For purposes of this disclosure, the phrase "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0045] Various components and devices may be referred to or shown in the singular form in this document (for example, "MOS tube", "transistor", "switch", etc.), but this is only for convenience of discussion, and any element mentioned in the singular form may include multiple such elements according to the teachings of this document.

[0046] The specification describes the use of the phrases "in one embodiment" or "in other embodiments" or "in some embodiments", which may each refer to one or more of the same or different embodiments. In addition, the terms "including", "comprising", "having", etc. used in relation to the embodiments of the present disclosure are synonymous.

[0047] like Figure 1 As shown, a noise eliminator in an embodiment of the present invention includes: a power supply unit, a sampling unit 10 , a first frequency band path 20 , a second frequency band path 30 and an injection unit 40 .

[0048] Among them, the power supply unit is connected to the circuit L to be eliminated by noise or to an external power supply, and the power supply unit is used to generate a positive voltage and / or a negative voltage to power the first frequency band path and / or the second frequency band path, that is, the power supply unit can be directly taken from the sampled circuit L to be eliminated by noise, and the first frequency band path 20 and the second frequency band path 30 are powered after the voltage conversion of the power supply unit itself; it can also be obtained by an externally supplied DC power supply, and then through the conversion of the power supply unit itself to obtain a positive voltage and / or a negative voltage, so the power supply unit is suitable for circuit scenarios that require positive and negative dual power supplies or a single positive power supply or negative power supply.

[0049] The sampling unit 10 is connected to the line L to be eliminated from noise, and is used to sample the interference signal on the line L to be eliminated from noise to obtain a sampling signal.

[0050] Those skilled in the art should understand that Figure 1 In the embodiment shown, only one line to be noise-eliminated is shown by way of example. In other embodiments, noise elimination can be performed on two or more lines according to the application scenario, for example, in a two-phase power supply or a three-phase power supply, noise elimination can be performed on part or all of the power supply lines as required.

[0051] The first frequency band path 20 is connected to the sampling unit 10, and is used to obtain a first frequency band signal in the sampling signal whose frequency is in the first frequency band, and to condition the first frequency band signal to obtain a first elimination signal; the second frequency band path 30 is connected to the sampling unit 10, and is used to obtain a second frequency band signal in the sampling signal whose frequency is in the second frequency band, and to condition the second frequency band signal to obtain a second elimination signal. The first frequency band and the second frequency band have non-overlapping frequency components.

[0052] In one embodiment, the conditioning includes one or more of inverting, amplifying, and filtering the signal.

[0053] Exemplarily, the frequency range of the common-mode interference signal on the line L to be eliminated from noise may cover from 100kHz to 100MHz. In one embodiment, the frequency band greater than or equal to 100kHz to less than or equal to 1MHz may be considered as the second frequency band, and the frequency band greater than 1MHz to less than or equal to 100MHz may be the first frequency band. In other embodiments, the first frequency band may be a frequency range between 1MHz and 100MHz, and / or the second frequency band may be a frequency range between 100kHz and 1MHz, and the two frequency bands do not overlap. In another embodiment, the frequencies of the first frequency band and the second frequency band may partially overlap. In one embodiment, by using the first frequency band path 20 and the second frequency band path 30 to process the common-mode interference of the first frequency band and the second frequency band respectively, the suppression effect of the common-mode interference signal with a wide frequency range can be maximized.

[0054] The injection unit 40 is connected to the first frequency band path 20 , the second frequency band path 30 and the line L to be eliminated. The injection unit 40 is used to inject the first elimination signal and the second elimination signal into the line L to be eliminated after superposition coupling.

[0055] like Figure 1 As shown, the sampling unit 10 in one embodiment includes a first capacitor C1 and a first resistor R1, the first end of the first capacitor C1 is connected to the noise elimination line L, the second end of the first capacitor C1 is connected to the first frequency band path 20, the second frequency band path 30 and the first end of the first resistor R1, and the second end of the first resistor R1 is connected to the first reference voltage. In one embodiment, the first reference voltage can be a ground voltage.

[0056] The common-mode interference signal is sampled through the first capacitor C1 to obtain the common-mode current I, I = C1*du / dt, C1*du / dt represents the relationship between the current flowing through the first capacitor C1 per unit time and the voltage change, and is converted into the common-mode voltage U after passing through the first resistor R1 to realize the conversion of current and voltage, U = R1*C1*du / dt.

[0057] It can be seen that the sampling unit 10 adopts a capacitive coupling method for sampling. Compared with the conventional inductive coupling method, the obvious advantage is that the inductive coupling has very high consistency requirements on the magnetic components, and it is very easy to convert the common mode signal into a differential mode signal, resulting in inaccurate sampling. The consistency of the capacitive coupling method is easier to control, and for the end customer, there is more room for autonomy and choice, and the end user has a higher degree of freedom in design.

[0058] like Figure 1As shown, the first frequency band path 20 includes a first frequency selection unit 21, a first inverting amplifier unit 22 and a first deviation correction unit 23. The first frequency selection unit 21 is connected to the sampling unit 10, and is used to obtain a first frequency band signal with a frequency in the first frequency band from the sampling signal, and is also used to amplify the first frequency band signal with a frequency in the first frequency band. The first inverting amplifier unit 22 is connected to the first frequency selection unit 21, and the first deviation correction unit 23 is connected to the first inverting amplifier unit 22. The first inverting amplifier unit 22 is used to invert and amplify the amplified first frequency band signal to generate a first elimination signal, and the first deviation correction unit 23 is used to generate a first correction signal to eliminate the influence of DC deviation and / or offset error on the first elimination signal.

[0059] The first frequency selection unit 21 includes a first amplifier A1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a second capacitor C2 and a third capacitor C3.

[0060] Specifically, the first end of the second resistor R2 is connected to the first end of the first resistor R1 of the sampling unit 10, the second end of the second resistor R2 is connected to the first input end of the first amplifier A1, the first end of the third resistor R3, the first end of the fourth resistor R4, and the first end of the fifth resistor R5 are connected to the second input end of the first amplifier A1, the second end of the third resistor R3 is connected to the first end of the second capacitor C2, and the second end of the second capacitor C2 is connected to the first reference voltage. The second end of the fifth resistor R5 is connected to the first end of the third capacitor C3, the second end of the fourth resistor R4, and the second end of the third capacitor C3 are connected to the output end of the first amplifier A1 and the first inverting amplifier unit 22. In one embodiment, the first input end of the first amplifier A1 is a positive input end, and the second input end of the first amplifier A1 is a negative input end.

[0061] From the above, it can be seen that the gain of the first frequency band signal brought by the first frequency selection unit 21 is Among them, R3 represents the resistance value of the third resistor R3, R4 represents the resistance value of the fourth resistor R4, R5 represents the resistance value of the fifth resistor R5, C2 represents the capacitance value of the second capacitor C2, and C3 represents the capacitance value of the third capacitor C3. By adjusting the values ​​of the third resistor R3, the fourth resistor R4, the fifth resistor R5, the second capacitor C2 and the third capacitor C3, the signal gain of the first frequency band can be increased, while the signal gain of the low frequency band can be suppressed.

[0062] In other embodiments, one, two or three of the second resistor R2, the fourth resistor R4 and the third capacitor C3 may not be provided. If the second resistor R2 is not provided, the first input terminal of the first amplifier A1 is directly connected to the first terminal of the first resistor R1. If the fourth resistor R4 is not provided, the fourth resistor R4 is directly removed. If the third capacitor C3 is not provided, the second terminal of the fifth resistor R5 is directly connected to the output terminal of the first amplifier A1.

[0063] like Figure 1 As shown, the first inverting amplifying unit 22 includes a second amplifier A2, a sixth resistor R6, a seventh resistor R7 and a fourth capacitor C4.

[0064] Specifically, the first end of the sixth resistor R6 is connected to the output end of the first amplifier A1 of the first frequency selection unit 21, the second end of the sixth resistor R6, the first end of the seventh resistor R7, the first end of the fourth capacitor C4 are connected to the second input end of the second amplifier A2, the second end of the seventh resistor R7, the second end of the fourth capacitor C4 are connected to the output end of the second amplifier A2 to output the first elimination signal, and the first input end of the second amplifier A2 is connected to the first deviation correction unit 23. In one embodiment, the first input end of the second amplifier A2 is a positive input end, and the second input end of the second amplifier A2 is a negative input end.

[0065] As can be seen from the above, the gain of the first frequency band signal amplified by the first frequency selection unit 21 brought by the first inverting amplifier unit 22 is Among them, R6 represents the resistance value of the sixth resistor R6, R7 represents the resistance value of the seventh resistor R7, and C4 represents the capacitance value of the fourth capacitor C4. Through the inverting amplification of the first inverting amplifier unit 22, the first elimination signal and the first frequency band signal amplified by the first frequency selection unit 21 have opposite phases.

[0066] In other embodiments, the first deviation correction unit 23 may not be provided. In the case where the first deviation correction unit 23 is not provided, the first input terminal of the second amplifier A2 is directly connected to the first reference voltage, or the first input terminal of the second amplifier A2 is connected to the first reference voltage through a resistor. In other embodiments, the fourth capacitor C4 and / or the sixth resistor R6 may not be provided. If the fourth capacitor C4 is not provided, the fourth capacitor C4 is directly removed. If the sixth resistor R6 is not provided, the second input terminal of the second amplifier A2 is directly connected to the output terminal of the first amplifier A1.

[0067] like Figure 1 As shown, the first deviation correction unit 23 includes a third amplifier A3, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and a fifth capacitor C5.

[0068] Specifically, the first end of the ninth resistor R9 is connected to the reference voltage Vref, the second end of the ninth resistor R9 is connected to the first input end of the third amplifier A3, the first end of the tenth resistor R10 is connected to the output end of the second amplifier A2 of the first inverting amplifier unit 22 to receive the first elimination signal, the second end of the tenth resistor R10 and the first end of the fifth capacitor C5 are connected to the second input end of the third amplifier A3, the second end of the fifth capacitor C5 is connected to the output end of the third amplifier A3 and the second end of the eighth resistor R8, and the first end of the eighth resistor R8 is connected to the first input end of the second amplifier A2 of the first inverting amplifier unit 22 to output the first correction signal. In other embodiments, the eighth resistor R8 and / or the ninth resistor R9 may not be provided, if the eighth resistor R8 is not provided, the output end of the third amplifier A3 is directly connected to the first input end of the second amplifier A2, and if the ninth resistor R9 is not provided, the first input end of the third amplifier A3 is directly connected to the reference voltage Vref.

[0069] The third amplifier A3 is a single-ended amplifier. Compared with a double-ended amplifier, the application of this amplifier can save costs in actual production and has better cost advantages.

[0070] The third amplifier A3 cooperates with the tenth resistor R10 and the fifth capacitor C5 to integrate the received first elimination signal, and inputs the first correction signal obtained by the integration operation to the first input terminal of the second amplifier A2 to perform a difference operation with the signal at the second input terminal of the second amplifier A2. The first correction signal is a voltage signal to realize voltage feedback, thereby realizing the elimination of DC deviation, and at the same time, the offset error between the two input terminals of the second amplifier A2 can also be eliminated.

[0071] A reference voltage Vref is connected to the first input terminal of the third amplifier A3. It should be noted that the reference voltage Vref can be a ground voltage or a voltage related to the power supply VCC and can be adjusted as needed. The power supply VCC is the power supply of the amplifier, and the reference voltage Vref can be obtained through the power supply VCC.

[0072] By adjusting the reference voltage Vref, the DC reference of the first correction signal can be adjusted, thereby changing the output range of the third amplifier A3 to ensure that the DC deviation can be eliminated under different working conditions. For example, when the third amplifier A3 is powered by dual power supplies (one positive and one negative), the reference voltage Vref can be a ground voltage of 0V, so that the third amplifier A3 can output a sine wave with a DC reference of 0. When the working conditions or customer requirements limit the power supply of the third amplifier A3 to a single power supply (positive or negative), if the third amplifier A3 needs to output a sine wave to prevent distortion, the DC reference needs to be adjusted, and the purpose of adjustment can be achieved by adjusting the reference voltage Vref.

[0073] like Figure 1 As shown, the second frequency band path 30 includes a second frequency selection unit 31, a second inverting amplifier unit 32, and a second deviation correction unit 33. The second frequency selection unit 31 is connected to the sampling unit 10, and is used to obtain and amplify a second frequency band signal having a frequency in the second frequency band from the sampling signal, the second inverting amplifier unit 32 is connected to the second frequency selection unit 31, and the second deviation correction unit 33 is connected to the second inverting amplifier unit 32, and the second inverting amplifier unit 32 is used to invert and amplify the amplified second frequency band signal to generate a second elimination signal, and the second deviation correction unit 33 is used to generate a second correction signal to eliminate the influence of DC deviation and / or offset error on the second elimination signal.

[0074] The second frequency selection unit 31 includes a fourth amplifier A4, a twelfth resistor R12, a thirteenth resistor R13 and a fourteenth resistor R14.

[0075] Specifically, the first end of the twelfth resistor R12 is connected to the first end of the first resistor R1 of the sampling unit 10, the second end of the twelfth resistor R12 is connected to the first input end of the fourth amplifier A4, the first end of the thirteenth resistor R13 and the first end of the fourteenth resistor R14 are connected to the second input end of the fourth amplifier A4, the second end of the thirteenth resistor R13 is connected to the first reference voltage, and the second end of the fourteenth resistor R14 is connected to the output end of the fourth amplifier A4 and the second inverting amplifier unit 32. In one embodiment, the first input end of the fourth amplifier A4 is a positive input end, and the second input end of the fourth amplifier A4 is a negative input end.

[0076] It can be seen from the above that the gain of the second frequency band signal brought by the second frequency selection unit 31 is (R13+R14) / R13, wherein R13 represents the resistance value of the thirteenth resistor R13, and R14 represents the resistance value of the fourteenth resistor R14.

[0077] In other embodiments, the twelfth resistor R12 may not be provided, and the first input terminal of the fourth amplifier A4 is directly connected to the first terminal of the first resistor R1 of the sampling unit 10 .

[0078] like Figure 1 As shown, the second inverting amplifying unit 32 includes a fifth amplifier A5, a fifteenth resistor R15, a sixteenth resistor R16, a seventh capacitor C7 and an eighth capacitor C8.

[0079] Specifically, the first end of the fifteenth resistor R15 is connected to the output end of the fourth amplifier A4 of the second frequency selection unit 31, the second end of the fifteenth resistor R15, the first end of the sixteenth resistor R16, and the first end of the eighth capacitor C8 are connected to the first input end of the second amplifier A2, the second end of the sixteenth resistor R16 is connected to the first end of the seventh capacitor C7, the second end of the seventh capacitor C7, and the second end of the eighth capacitor C8 are connected to the output end of the fifth amplifier A5 to output the second elimination signal, and the first input end of the fifth amplifier A5 is connected to the second deviation correction unit 33. In one embodiment, the first input end of the fifth amplifier A5 is a positive input end, and the second input end of the fifth amplifier A5 is a negative input end. In other embodiments, the positions of the sixteenth resistor R16 and the seventh capacitor C7 can be exchanged.

[0080] As can be seen from the above, the gain of the second frequency band signal amplified by the second frequency selection unit 31 brought by the second inverting amplifier unit 32 is Among them, R15 represents the resistance of the fifteenth resistor R15, R16 represents the resistance of the sixteenth resistor R16, C7 represents the capacitance of the seventh capacitor C7, and C8 represents the capacitance of the eighth capacitor C8. Through the inverting amplification of the second inverting amplifier unit 32, the second elimination signal is opposite in phase to the second frequency band signal amplified by the second frequency selection unit 31.

[0081] In other embodiments, the second deviation correction unit 33 may not be provided. In the case where the second deviation correction unit 33 is not provided, the first input terminal of the fifth amplifier A5 is directly connected to the first reference voltage or the first input terminal of the fifth amplifier A5 is connected to the first reference voltage through a resistor. In other embodiments, the seventh capacitor C7 and / or the fifteenth resistor R15 may not be provided. If the seventh capacitor C7 is not provided, the second end of the sixteenth resistor R16 is directly connected to the output terminal of the fifth amplifier A5. If the fifteenth resistor R15 is not provided, the second input terminal of the fifth amplifier A5 is directly connected to the output terminal of the fourth amplifier A4.

[0082] like Figure 1 As shown, the second deviation correction unit 33 includes a sixth amplifier A6, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19 and a ninth capacitor C9.

[0083] Specifically, the first end of the eighteenth resistor R18 is connected to the reference voltage Vref, the second end of the eighteenth resistor R18 is connected to the first input end of the sixth amplifier A6, the first end of the nineteenth resistor R19 is connected to the output end of the fifth amplifier A5 of the second inverting amplifier unit 32 to receive the second elimination signal, the second end of the nineteenth resistor R19 and the first end of the ninth capacitor C9 are connected to the second input end of the sixth amplifier A6, the second end of the ninth capacitor C9 is connected to the output end of the sixth amplifier A6 and the second end of the seventeenth resistor R17, and the first end of the seventeenth resistor R17 is connected to the first input end of the fifth amplifier A5 of the second inverting amplifier unit 32 to output the second correction signal. In other embodiments, the eighteenth resistor R18 and / or the seventeenth resistor R17 may not be provided, if the eighteenth resistor R18 is not provided, the first input end of the sixth amplifier A6 is directly connected to the reference voltage Vref, and if the seventeenth resistor R17 is not provided, the output end of the sixth amplifier A6 is directly connected to the second input end of the fifth amplifier A5.

[0084] The sixth amplifier A6 is a single-ended amplifier. Compared with a double-ended amplifier, the use of this amplifier can save costs in actual production and has better cost advantages.

[0085] The sixth amplifier A6 cooperates with the nineteenth resistor R19 and the ninth capacitor C9 to perform an integration operation on the received second elimination signal, and inputs the second correction signal obtained by the integration operation to the first input terminal of the fifth amplifier A5 to perform a difference operation with the signal at the second input terminal of the fifth amplifier A5. The second correction signal is a voltage signal to realize voltage feedback, thereby realizing the elimination of DC deviation, and at the same time, the offset error between the two input terminals of the fifth amplifier A5 can also be eliminated.

[0086] A reference voltage Vref is connected to the first input terminal of the sixth amplifier A6. It should be noted that the reference voltage Vref can be a ground voltage or a voltage related to the power supply VCC and can be adjusted as needed. The power supply VCC is the power supply of the amplifier, and the reference voltage Vref can be obtained through the power supply VCC.

[0087] By adjusting the reference voltage Vref, the DC reference of the second correction signal can be adjusted, thereby changing the output range of the sixth amplifier A6 to ensure that the DC deviation can be eliminated under different working conditions. When the sixth amplifier A6 is powered by dual power supplies (one positive and one negative), the reference voltage Vref can be a ground voltage of 0V, so that the sixth amplifier A6 can output a sine wave with a DC reference of 0. When the working conditions or customer requirements limit the power supply to the sixth amplifier A6, only a single power supply (positive or negative) can be provided to power the sixth amplifier A6. At this time, if the sixth amplifier A6 needs to output a sine wave to prevent distortion, the DC reference needs to be adjusted. At this time, the purpose of adjustment can be achieved by adjusting the reference voltage Vref.

[0088] In summary, the common-mode interference signal on the line L to be eliminated is mainly an AC signal. In the process of sampling and modulating it, an inevitable DC bias will be generated due to the deviation of the sampling element, the bias current and the bias voltage of the amplifier. And because the gain brought by the entire first band path 20 and the second band path 30 is relatively large, the DC deviation introduced by the bias current and the bias voltage of the amplifier (especially the second amplifier A2 and the fifth amplifier A5) itself will easily cause the output of the amplifier (the second amplifier A2 and the fifth amplifier A5) to be saturated during the conditioning process of the common-mode interference signal, affecting the overall effect of the first band path 20 and the second band path 30 in the full frequency band. The DC deviation of the first band path 20 is suppressed by the first deviation correction unit 23, and the DC deviation of the second band path 30 is suppressed by the second deviation correction unit 33, so as to minimize the influence of the DC deviation on the signal conditioning effect and ensure the conditioning effect of the full frequency band.

[0089] In one embodiment, the power supply unit is used to provide dual power supply or single power supply to the first amplifier A1, the second amplifier A2, the third amplifier A3, the fourth amplifier A4, the fifth amplifier A5 and the seventh amplifier A6 in the first frequency band path 20 and the second frequency band path 30.

[0090] like Figure 1 As shown, the injection unit 40 includes a first isolation compensation unit 41, a second isolation compensation unit 42 and a coupling unit 43. The first isolation compensation unit 41 is connected to the first frequency band path 20, and the first isolation compensation unit 41 is used to isolate and phase compensate the first elimination signal. The second isolation compensation unit 42 is connected to the second frequency band path 30, and the second isolation compensation unit 42 is used to isolate and phase compensate the second elimination signal. The coupling unit 43 is connected to the first isolation compensation unit 41, the second isolation compensation unit 42 and the line L to be eliminated. The coupling unit 43 is used to superimpose and couple the first elimination signal and the second elimination signal after isolation compensation and inject them into the line L to be eliminated.

[0091] The first isolation compensation unit 41 includes an eleventh resistor R11 and a sixth capacitor C6. A first end of the sixth capacitor C6 is connected to an output end of the second amplifier A2 of the first frequency band path 20 to receive a first cancellation signal, a second end of the sixth capacitor C6 is connected to a first end of the eleventh resistor R11, and a second end of the eleventh resistor R11 is connected to the coupling unit 40. In other embodiments, the positions of the eleventh resistor R11 and the sixth capacitor C6 may be exchanged. In other embodiments, the eleventh resistor R11 may not be provided.

[0092] The second isolation compensation unit 42 includes a twentieth resistor R20 , a first end of the twentieth resistor R20 is connected to the output end of the fifth amplifier of the second frequency band path 30 to receive the second cancellation signal, and a second end of the twentieth resistor R20 is connected to the coupling unit 43 .

[0093] In one embodiment, the first frequency band path 20 is a high frequency path, and the second frequency band path 30 is a low frequency path. To facilitate understanding of the role of the first isolation compensation unit 41 and the second isolation compensation unit 42 in the circuit, we can perform the following theoretical analysis.

[0094] When the high-frequency path has no signal output and only the low-frequency path in the circuit outputs a signal, the sixth capacitor C6 and the twentieth resistor R20 can be equivalent to the following: Figure 2 The circuit model shown, Figure 2 Where C is the equivalent capacitance of the sixth capacitor C6, R is the equivalent resistance of the twentieth resistor R20, and the second end of the sixth capacitor C6 is equivalent to grounding. The corresponding transfer function is: It enables the output signal to maintain a higher gain at low frequencies and suppresses the gain of high-frequency signals.

[0095] When there is no signal output from the low-frequency path and only the high-frequency path in the circuit outputs a signal, the sixth capacitor C6 and the tenth resistor R20 can be equivalent to the following: Figure 3 The circuit model shown, Figure 3 R in the equation is the equivalent resistance of the twentieth resistor R20, C is the equivalent capacitance of the sixth capacitor C6, and the second end of the tenth resistor R20 is equivalent to grounding. The corresponding transfer function is: It enables the output signal to maintain a higher gain at high frequencies and suppresses the gain of low-frequency signals.

[0096] By setting the sixth capacitor C6 and the tenth resistor R20, a zero pole is equivalently formed in the circuit, so that the gains of the high-frequency path and the low-frequency path are staggered in the frequency band, further playing a role in isolating high and low frequency signals.

[0097] like Figure 1As shown, the coupling unit 43 includes a tenth capacitor C10, a first end of the tenth capacitor C10 is connected to the second end of the eleventh resistor R11 of the first isolation compensation unit 41 and the second end of the twentieth resistor R20 of the second isolation compensation unit 42, and a second end of the tenth capacitor C10 is connected to the noise elimination line L. In one embodiment, the tenth capacitor C10 of the coupling unit 43 is generally large. In the first frequency band path 20, if the second amplifier A2 is used to directly drive the tenth capacitor C10, it will bring stability risks. By setting the sixth capacitor C6, firstly, it can intercept the second frequency band signal and pass the high-frequency first elimination signal; at the same time, because the sixth capacitor C6 is added, the tenth capacitor C10 can reduce the overall capacitance after being connected to the sixth capacitor C6. In a high-frequency environment, the second amplifier A2 can be better driven, which compensates for the phase margin of the entire first frequency band path 20 and improves the overall stability.

[0098] After the first elimination signal is isolated and the phase margin is compensated by the sixth capacitor C6, and after the second elimination signal is isolated and the phase margin is compensated by the twentieth resistor R20, the first elimination signal and the second elimination signal after isolation and phase margin compensation are finally coupled through the tenth capacitor C10 in the form of current and injected into the circuit L to be eliminated, so as to compensate and offset the noise interference in the circuit L to be eliminated, thereby achieving the effect of suppressing noise interference.

[0099] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0100] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A noise canceller, characterized in that: include: A sampling unit, used for sampling the interference signal on the noise elimination line to obtain a sampling signal; A first frequency band path is connected to the sampling unit and is used to obtain a first frequency band signal with a frequency in the first frequency band in the sampling signal, and to condition the first frequency band signal to obtain a first elimination signal; A second frequency band path is connected to the sampling unit and is used to obtain a second frequency band signal with a frequency in the second frequency band in the sampling signal, and to condition the second frequency band signal to obtain a second cancellation signal; as well as An injection unit is connected to the first frequency band path, the second frequency band path and the line to be eliminated, and is used to inject the first elimination signal and the second elimination signal into the line to be eliminated after superposition coupling; The first frequency band and the second frequency band have non-overlapping frequency components.

2. The noise canceller according to claim 1, characterized in that The sampling unit includes a first capacitor and a first resistor, wherein the first end of the first capacitor is connected to the circuit to be noise eliminated, the second end of the first capacitor is connected to the first frequency band path, the second frequency band path and the first end of the first resistor, and the second end of the first resistor is connected to the first reference voltage.

3. The noise canceller according to claim 1, characterized in that The first frequency band path includes a first frequency selection unit and a first inverting amplifier unit. The first frequency selection unit is connected to the sampling unit, and is used to obtain a first frequency band signal with a frequency in the first frequency band from the sampling signal. The first inverting amplifier unit is connected to the first frequency selection unit, and is used to invert and amplify the first frequency band signal to generate a first elimination signal.

4. The noise canceller according to claim 3, characterized in that The first frequency selection unit is used to amplify a first frequency band signal having a frequency in a first frequency band, and the first inverting amplifier unit is used to invert and amplify the amplified first frequency band signal to generate a first cancellation signal.

5. The noise canceller according to claim 1, characterized in that The second frequency band path includes a second frequency selection unit and a second inverting amplifier unit, the second frequency selection unit is connected to the sampling unit, the second frequency selection unit is used to obtain a second frequency band signal with a frequency in the second frequency band from the sampling signal, and the second inverting amplifier unit is connected to the second frequency selection unit, the second inverting amplifier unit is used to invert and amplify the second frequency band signal to generate a second elimination signal.

6. The noise canceller according to claim 5, characterized in that The second frequency selection unit is used to amplify a second frequency band signal having a frequency in the second frequency band, and the second inverting amplifier unit is used to invert and amplify the amplified second frequency band signal to generate a second cancellation signal.

7. The noise canceller according to claim 3 or 4, characterized in that: The first frequency band path further comprises a first deviation correction unit, which is connected to the first inverting amplifier unit and is used to generate a first correction signal to eliminate the influence of DC deviation and / or offset error on the first elimination signal.

8. The noise canceller according to claim 5 or 6, characterized in that: The second frequency band path further comprises a second deviation correction unit, which is connected to the second inverting amplifier unit and is used to generate a second correction signal to eliminate the influence of DC deviation and / or offset error on the second elimination signal.

9. The noise canceller according to claim 3 or 4, characterized in that: The first frequency selection unit includes a first amplifier, a third resistor, a fifth resistor and a second capacitor; The first input terminal of the first amplifier is connected to the sampling unit, the first end of the third resistor is connected to the second input terminal of the first amplifier, the second end of the third resistor is connected to the first end of the second capacitor, the second end of the second capacitor is connected to the first reference voltage, the first end of the fifth resistor is connected to the second input terminal of the first amplifier, and the second end of the fifth resistor is connected to the output terminal of the first amplifier.

10. The noise canceller according to claim 5 or 6, characterized in that: The second frequency selection unit includes a fourth amplifier, a thirteenth resistor and a fourteenth resistor, the first input end of the fourth amplifier is connected to the sampling unit, the first end of the thirteenth resistor and the first end of the fourteenth resistor are connected to the second input end of the fourth amplifier, the second end of the thirteenth resistor is connected to the first reference voltage, and the second end of the fourteenth resistor is connected to the output end of the fourth amplifier and the second inverting amplification unit.

11. The noise canceller according to claim 9, characterized in that The first frequency selection unit also includes a second resistor and / or a fourth resistor and / or a third capacitor, the first end of the second resistor is connected to the first input end of the first amplifier, the second end of the second resistor is connected to the sampling unit, the first end of the fourth resistor is connected to the output end of the first amplifier, the second end of the fourth resistor is connected to the second input end of the first amplifier, the first end of the third capacitor is connected to the second end of the fifth resistor, and the second end of the third capacitor is connected to the output end of the first amplifier and the first inverting amplifier unit.

12. The noise canceller according to claim 10, characterized in that The second frequency selection unit further includes a twelfth resistor, a first end of the twelfth resistor is connected to the first input end of the fourth amplifier, and a second end of the twelfth resistor is connected to the sampling unit.

13. The noise canceller according to claim 3 or 4, characterized in that: The first inverting amplifier unit includes a second amplifier and a seventh resistor, the first end of the seventh resistor is connected to the second input end of the second amplifier and is also connected to the first frequency selection unit, the first input end of the second amplifier is connected to the first reference voltage, and the second end of the seventh resistor is connected to the output end of the second amplifier to output a first elimination signal.

14. The noise canceller according to claim 5 or 6, characterized in that: The second inverting amplifying unit includes a fifth amplifier, a sixteenth resistor and an eighth capacitor, the first end of the sixteenth resistor and the first end of the eighth capacitor are connected to the first input end of the second amplifier and to the second frequency selecting unit, the first input end of the fifth amplifier is connected to the first reference voltage, and the second end of the sixteenth resistor is connected to the output end of the fifth amplifier to output a second elimination signal.

15. The noise canceller according to claim 13, characterized in that The first inverting amplification unit also includes a fourth capacitor and / or a sixth resistor; the first end of the fourth capacitor is connected to the second input end of the second amplifier, the second end of the fourth capacitor is connected to the output end of the second amplifier, the first end of the sixth resistor is connected to the first frequency selection unit, and the second end of the sixth resistor is connected to the second input end of the second amplifier.

16. The noise canceller according to claim 14, characterized in that The second inverting amplifying unit also includes a seventh capacitor and / or a fifteenth resistor, the first end of the seventh capacitor is connected to the second end of the sixteenth resistor, the second end of the seventh capacitor is connected to the output end of the fifth amplifier, the first end of the fifteenth resistor is connected to the second frequency selecting unit, and the second end of the fifteenth resistor is connected to the second input end of the fifth amplifier.

17. The noise canceller according to claim 7, characterized in that The first deviation correction unit includes a third amplifier, a tenth resistor and a fifth capacitor, the first input terminal of the third amplifier is connected to a reference voltage, the first end of the tenth resistor is connected to the output terminal of the first inverting amplifier unit to receive a first elimination signal, the second end of the tenth resistor and the first end of the fifth capacitor are connected to the second input terminal of the third amplifier, and the second end of the fifth capacitor is connected to the output terminal of the third amplifier and the first input terminal of the first inverting amplifier unit to output a first correction signal.

18. The noise canceller according to claim 8, characterized in that The second deviation correction unit includes a sixth amplifier, a nineteenth resistor and a ninth capacitor, the first input terminal of the sixth amplifier is connected to the reference voltage, the first end of the nineteenth resistor is connected to the output terminal of the second inverting amplifier unit to receive the second elimination signal, the second end of the nineteenth resistor and the first end of the ninth capacitor are connected to the second input terminal of the sixth amplifier, and the second end of the ninth capacitor is connected to the output terminal of the sixth amplifier and the first input terminal of the second inverting amplifier unit to output the second correction signal.

19. The noise canceller according to claim 17, characterized in that The first deviation correction unit also includes an eighth resistor and / or a ninth resistor, the first end of the eighth resistor is connected to the first input end of the first inverting amplifier unit, the second end of the eighth resistor is connected to the output end of the third amplifier, the first end of the ninth resistor is connected to the reference voltage, and the second end of the ninth resistor is connected to the first input end of the third amplifier.

20. The noise canceller according to claim 18, characterized in that The second deviation correction unit also includes a seventeenth resistor and / or an eighteenth resistor, the first end of the seventeenth resistor is connected to the first input end of the second inverting amplifier unit, the second end of the seventeenth resistor is connected to the output end of the sixth amplifier, the first end of the eighteenth resistor is connected to the reference voltage, and the second end of the eighteenth resistor is connected to the first input end of the sixth amplifier.

21. The noise canceller according to claim 1, characterized in that The injection unit includes a first isolation compensation unit, a second isolation compensation unit and a coupling unit, the first isolation compensation unit is connected to the first frequency band path, the first isolation compensation unit is used to isolate and phase compensate the first elimination signal, the second isolation compensation unit is connected to the second frequency band path, the second isolation compensation unit is used to isolate and phase compensate the second elimination signal, the coupling unit is connected to the first isolation compensation unit, the second isolation compensation unit and the line to be eliminated, and the coupling unit is used to superimpose and couple the first elimination signal and the second elimination signal after isolation compensation and inject them into the line to be eliminated.

22. The noise canceller according to claim 21, characterized in that The first isolation compensation unit includes a sixth capacitor, a first end of the sixth capacitor is connected to the first frequency band path to receive the first cancellation signal, and a second end of the sixth capacitor is connected to the coupling unit.

23. The noise canceller according to claim 22, characterized in that The first isolation compensation unit further includes an eleventh resistor, a first end of the eleventh resistor is connected to the second end of the sixth capacitor, and a second end of the eleventh resistor is connected to the coupling unit.

24. The noise canceller according to claim 21, characterized in that The second isolation compensation unit includes a twentieth resistor, a first end of the twentieth resistor is connected to the second frequency band path to receive the second cancellation signal, and a second end of the twentieth resistor is connected to the coupling unit.

25. The noise canceller according to claim 21, characterized in that The coupling unit includes a tenth capacitor, a first end of the tenth capacitor is connected to the first isolation compensation unit and the second isolation compensation unit, and a second end of the tenth capacitor is connected to the circuit to be eliminated.

26. The noise canceller according to claim 1, characterized in that The noise canceller further comprises a power supply unit connected to the circuit to be noise canceled or to an external power source, and configured to generate a positive voltage and / or a negative voltage to supply power to the first frequency band path and / or the second frequency band path.

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