CN104883150A - Broadband common mode filter device - Google Patents

Abstract

The broadband common-mode filtering device of one embodiment of the invention comprises a first common-mode filter, a second common-mode filter and a third common-mode filter, wherein the first common-mode filter is provided with a first filtering frequency band; a second common mode filter having a second filtering band, wherein the first filtering band is different from the second filtering band; and a switching element configured to electrically connect the output of the first common mode filter to the input or the output of the second common mode filter. The wideband common mode filter device according to another embodiment of the present invention includes a first common mode filter having a first filter band; a second common mode filter having a second filtering band, wherein the first filtering band is different from the second filtering band; a third common mode filter having a third filtering band, wherein the third filtering band is different from the first filtering band and the second filtering band; and a switching element configured to electrically connect the output of the first common mode filter to the input of the second common mode filter or the input of the third common mode filter.

Description

Broadband common mode filter device

technical field

The invention discloses a broadband common-mode filter device, in particular to a broadband common-mode filter device that uses switching elements to connect multiple common-mode filters in series.

Background technique

In the development of network communication and digital data transmission, with the continuous improvement of signal transmission rate, differential signal transmission (Differential Transmission) method has been applied to transmission specifications in many industries; for example, Universal Serial Bus (Universal Serial Bus, USB ), IEEE-1394 interface standard, low-voltage differential signaling (LVDS), digital video interface (Digital Visual Interface, DVI), high-resolution multimedia interface (High-DefinitionMultimedia Interface, HDMI), mobile industry processor Interface (Mobile Industry Processor Interface, MIPI).

Common mode noise is noise that is conducted in the same direction on all wires. To suppress common mode noise, a common mode filter (or choke) can be installed on the line that conducts the noise. In response to the needs of portable electronic products, chip-type common-mode filters have been developed. A known chip-type common mode filter includes two coil conductor layers, two lead-out electrode layers, multiple insulation layers and two magnetic layers. Each coil wire layer includes a coil, and the two lead electrode layers are used to respectively extend the ends located in the two coils to the edge of the chip-type common mode filter to facilitate external electrical connection. The insulating layer is used to electrically isolate the coil wire layer and the lead electrode layer. The coil wire layer, lead electrode layer and insulating layer are arranged between the two magnetic layers. However, after the known common mode filter is manufactured, its filtering frequency band has been determined and cannot be expanded; if there is a demand for a new filtering frequency band, it must be redesigned and manufactured to meet the new demand.

In addition, since 4G communication (LTE) uses different frequency bands in different countries, common-mode filters must provide wide-band signal processing capabilities, otherwise mobile phones may not be able to be used across borders; another solution is to use multiple sets of common-mode filters for mobile phones, but its The disadvantage is that the internal space occupied by multiple sets of common mode filters increases.

The above "background technology" description only provides background technology, and does not admit that the above "background technology" description discloses the subject of the present invention, and does not constitute the prior art of the present invention, and any description of the above "background technology" Neither should be considered as any part of the present invention.

Contents of the invention

The invention provides a broadband common-mode filtering device which uses a switching element to connect multiple common-mode filters in series.

A broadband common-mode filtering device according to an embodiment of the present invention includes a first common-mode filter with a first filtering frequency band; a second common-mode filter with a second filtering frequency band, wherein the first filtering frequency band is different from the second filtering frequency band; and a switching element configured to electrically connect the output terminal of the first common-mode filter to the input terminal or output terminal of the second common-mode filter.

A broadband common-mode filter device according to another embodiment of the present invention includes a first common-mode filter with a first filter frequency band; a second common-mode filter with a second filter frequency band, wherein the first filter frequency band is different from In the second filtering frequency band; a third common mode filter having a third filtering frequency band, wherein the third filtering frequency band is different from the first filtering frequency band and the second filtering frequency band; and a switching element configured to electrically Connect the output end of the first common mode filter to the input end of the second common mode filter or the input end of the third common mode filter.

After the known common-mode filter is manufactured, its filtering frequency band has been determined (the filtering bandwidth of the known common-mode filter is not greater than 2 GHz), and cannot be expanded; in contrast, the broadband common-mode filtering device disclosed in the embodiment of the present invention A plurality of common-mode filters with different frequency responses are connected in series, and the filtering frequency band of the broadband common-mode filtering device is larger than that of individual common-mode filters through the superposition effect of the frequency response characteristics of these common-mode filters.

For example, the frequency response characteristics of the known common-mode filter only have a filtering effect on a single frequency range, and cannot simultaneously have the effect of multi-band filtering; in contrast, the broadband common-mode filter device disclosed in the embodiment of the present invention is connected in series with multiple different The common mode filter expands the filtering frequency band and can simultaneously have the effect of multi-band filtering, thus supporting the filtering requirements of multi-band.

In addition, if there is a demand for a new filtering frequency band, the known technology must redesign and manufacture the common-mode filter to meet the new demand; in contrast, the technology of the present invention utilizes the frequency response characteristics of these common-mode filters Superposition effect, the total frequency response characteristics of the broadband common-mode filtering device is different from the individual frequency response characteristics of these common-mode filters, that is, the technology of the present invention does not need to redesign and manufacture common-mode filters, only needs to be based on the new To meet the new requirements, select a common-mode filter with specific frequency response characteristics and connect them in series.

Furthermore, by switching the switching element between the first switching state and the second switching state, the broadband common-mode filter device has two kinds of frequency responses, corresponding to two kinds of filtering frequency bands, and can be applied to different filtering requirements, for example Noise filtering applied to different frequency bands of 4G communication (LTE) in various countries. In other words, a single filter element has at least two types of frequency responses, corresponding to at least two types of filter frequency bands. Users can selectively connect different common-mode filters in series by switching the switching state of the switching element to use the required filter frequency bands. .

The technical features and advantages of the present invention have been summarized quite broadly above, so that the following detailed description of the present invention can be better understood. Additional technical features and advantages forming the subject of the claims of the invention will be described hereinafter. Those skilled in the art of the present invention should understand that the concepts and specific embodiments disclosed below can be used to modify or design other structures or processes to achieve the same purpose as the present invention. Those of ordinary skill in the technical field to which the present invention belongs should also understand that such equivalent constructions cannot deviate from the spirit and scope of the present invention defined by the appended claims.

Description of drawings

By referring to the foregoing description and the following drawings, the technical features and advantages of the present invention can be fully understood.

FIG. 1 illustrates a broadband common-mode filter device according to an embodiment of the present invention;

Fig. 2 illustrates the frequency response of the first common mode filter of Fig. 1;

Fig. 3 illustrates the frequency response of the second common mode filter of Fig. 1;

Fig. 4 illustrates the frequency response of the broadband common mode filter device of Fig. 1;

FIG. 5 illustrates a broadband common-mode filter device according to another embodiment of the present invention;

Fig. 6 illustrates the frequency response of the first common mode filter of Fig. 5;

Fig. 7 illustrates the frequency response of the second common mode filter of Fig. 5;

Fig. 8 illustrates the frequency response of the third common mode filter of Fig. 5;

Fig. 9 illustrates the first frequency response of the broadband common mode filter device of Fig. 5; And

FIG. 10 illustrates a second frequency response of the broadband common-mode filter device of FIG. 5 .

Wherein, the reference signs are explained as follows:

10 Broadband common mode filter device

20 First common mode filter

21 Inputs

23 Output

30 switching elements

31 First switching state

33 Second switching state

40 Second common mode filter

41 input

43 Output

50 Third common mode filter

51 input

53 output

60 Broadband common mode filter device

Detailed ways

In order to enable those skilled in the art to fully understand the present invention, detailed steps and structures will be presented in the following description. Obviously, the implementation of the invention is not limited to specific details familiar to those of ordinary skill in the relevant art. In other instances, well-known structures or steps are not described in detail in order to avoid unnecessarily limiting the invention. The preferred embodiments of the present invention will be described in detail as follows, but in addition to these detailed descriptions, the present invention can also be widely implemented in other embodiments, and the scope of the present invention is not limited, it is based on the appended claims .

Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. The "embodiment", "this embodiment", "other embodiment" and so on mentioned in the description mean that the specific characteristics, configurations, or characteristics included in the embodiment of the present invention are described. The appearances of the phrase "in this embodiment" in various places in the specification do not necessarily all refer to the same embodiment.

The invention relates to a broadband common-mode filter device connected in series with a plurality of common-mode filters. The following records describe in detail the implementation steps and structure of the present invention so that the present invention can be fully understood. Implementation of the present invention is not limited to those of ordinary skill in the art with specific knowledge. In addition, known structures and steps are not described below in order not to limit the present invention unnecessarily. Preferred embodiments of the present invention will be described below, but the present invention can also be widely implemented in other embodiments besides the following. The scope of the present invention should not be limited by the description below but defined by the claims.

FIG. 1 illustrates a broadband common-mode filter device 10 according to an embodiment of the present invention. In an embodiment of the present invention, the broadband common-mode filter device 10 includes a first common-mode filter 20 , a second common-mode filter 40 and a switching element 30 . In an embodiment of the present invention, the first common mode filter 20 includes an input end 21 and an output end 23, the second common mode filter 40 includes an input end 41 and an output end 43, the switching element 30 has a first switching state 31 (high level state) and a second switching state 33 (low level state).

In one embodiment of the present invention, when the common-mode current (common-mode signal) flows through the common-mode filter, the two coils will generate a magnetic field in the same direction, so that the common-mode filter exhibits high impedance (impedance), so as to suppress the common-mode Mode current (common mode signal) effect. At present, common-mode filters are required to be miniaturized and high-density in order to be applied to portable communication devices. Therefore, thin-film and multilayer common-mode filters are gradually replacing traditional wound-type common-mode filters. As the name suggests, the wound-type common mode filter is a shape in which a coil is wound on a cylindrical ferrite core (Ferrite Core). The thin-film and multi-layer types require more semiconductor manufacturing procedures. For example, thin-film common-mode filters are usually formed on a plate-like ferrite by using photolithography (Photo Lithography) technology to form a planar coil. . The common-mode filter used in the embodiment of the present invention can refer to the US patent application publications US20130015935, US20130076474, US20110025442, US20110316658, US20120119863 of the applicant of the present invention, which are incorporated by reference herein.

In an embodiment of the present invention, when the switching element 30 is in the first switching state 31, it is configured to electrically connect the output terminal 23 of the first common-mode filter 20 to the input of the second common-mode filter 40 Terminal 41 , that is, the first common-mode filter 20 is connected in series with the second common-mode filter 40 . In an embodiment of the present invention, when the switching element is in the second switching state 33, it is configured to electrically connect the output terminal 23 of the first common-mode filter 20 to the output terminal of the second common-mode filter 40 43 , that is, the second common-mode filter 40 is bypassed. The switching elements used in the embodiments of the present invention can refer to the radio frequency switch (radio frequency switch) disclosed in Chinese patent application publication CN101702627A, which is incorporated by reference here; in an embodiment of the present invention , the switching element 30 is realized by two radio frequency switches.

FIG. 2 illustrates the frequency response of the first common mode filter 20 of FIG. 1 . In one embodiment of the present invention, the first common mode filter 20 has a first filtering frequency band. If -15dB is used as the filtering criterion, the first filtering frequency band is about 1,500MHz to 3,200MHz, and the low cutoff frequency is about 1,500MHz, with a high cutoff frequency of approximately 3,200MHz.

FIG. 3 illustrates the frequency response of the second common mode filter 40 of FIG. 1 . In an embodiment of the present invention, the second common-mode filter 40 has a first filtering frequency band. If -15dB is used as the filtering criterion, the second filtering frequency band is about 300MHz to 1,700MHz, and the low cutoff frequency is about 300MHz. , with a high cutoff frequency of approximately 1,700MHz.

Referring to FIG. 2 and FIG. 3, it can be seen that the first filtering frequency band (approximately 1,500MHz to 3,200MHz) of the first common mode filter 20 is different from the second filtering frequency band (300MHz to 1,700MHz) of the second common mode filter 40 ).

FIG. 4 illustrates the frequency response of the broadband common-mode filter device 10 of FIG. 1 . In an embodiment of the present invention, when the switching element 30 is in the first switching state 31, it electrically connects the output terminal 23 of the first common-mode filter 20 to the input terminal 41 of the second common-mode filter 40; Thus, the frequency response of the broadband common-mode filter device 10 is the superposition of the frequency responses of the first common-mode filter 20 and the second common-mode filter 40 .

In an embodiment of the present invention, if -15dB is taken as the filtering criterion, the broadband common mode filter device 10 has a low total cut-off frequency (about 350 MHz) and a high total cut-off frequency (about 4,600 MHz). In an embodiment of the present invention, if -15dB is used as the filtering criterion, the broadband common-mode filter device 10 has a total filter frequency band, which is about 350MHz to 4,600MHz, which is larger than the first common-mode filter 20. The filtering frequency band and the second filtering frequency band of the second common mode filter 40 .

In an embodiment of the present invention, when the switching element 30 is in the second switching state 33, the output terminal 23 of the first common-mode filter 20 is directly electrically connected to the output terminal of the second common-mode filter 40 43, bypassing the second common-mode filter 40; thus, the frequency response of the broadband common-mode filter device 10 is the frequency response of the first common-mode filter 20 (that is, as shown in FIG. 2 ), and its filtering frequency band is about 1,500MHz to 3,200MHz.

In an embodiment of the present invention, by switching the switching element 30 between the first switching state 31 and the second switching state 33, the broadband common-mode filter device 10 has two types of frequency responses, corresponding to two types of filtering The frequency bands are 350MHz to 4,600MHz and 1,500MHz to 3,200MHz respectively, which can be applied to different filtering requirements, such as noise filtering applied to different frequency bands of 4G communication (LTE) in various countries.

FIG. 5 illustrates a broadband common-mode filter device 60 according to another embodiment of the present invention. In an embodiment of the present invention, the broadband common-mode filter device 60 includes a first common-mode filter 20 , a second common-mode filter 40 , a third common-mode filter 50 and a switching element 30 . In an embodiment of the present invention, the first common-mode filter 20 includes an input terminal 21 and an output terminal 23, the second common-mode filter 40 includes an input terminal 41 and an output terminal 43, and the third The common mode filter 50 includes an input terminal 51 and an output terminal 53 , and the switching element 30 has a first switching state 31 (high level state) and a second switching state 33 (low high level state).

In one embodiment of the present invention, when the common-mode current (common-mode signal) flows through the common-mode filter, the two coils will generate a magnetic field in the same direction, so that the common-mode filter exhibits high impedance (impedance), so as to suppress the common-mode Mode current (common mode signal) effect. At present, common-mode filters are required to be miniaturized and high-density in order to be applied to portable communication devices. Therefore, thin-film and multilayer common-mode filters are gradually replacing traditional wound-type common-mode filters. As the name suggests, the wound-type common mode filter is a shape in which a coil is wound on a cylindrical ferrite core (Ferrite Core). The thin-film and multi-layer types require more semiconductor manufacturing procedures. For example, thin-film common-mode filters are usually formed on a plate-like ferrite by using photolithography (Photo Lithography) technology to form a planar coil. . The common-mode filter used in the embodiments of the present invention can refer to the applicant's US patent application publications US20130015935, US20130076474, US20110025442, US20110316658, and US20120119863, which are incorporated by reference herein.

In an embodiment of the present invention, when the switching element 30 is in the first switching state 31, it is configured to electrically connect the output terminal 23 of the first common-mode filter 20 to the input of the second common-mode filter 40 Terminal 41 , that is, the first common-mode filter 20 is connected in series with the second common-mode filter 40 . In an embodiment of the present invention, when the switching element is in the second switching state 33, it is configured to electrically connect the output terminal 23 of the first common-mode filter 20 to the input terminal of the third common-mode filter 50 53 , that is, the first common-mode filter 20 is connected in series with the third common-mode filter 50 . The switching elements used in the embodiments of the present invention can refer to the radio frequency switch (radio frequency switch) disclosed in Chinese Patent Application Publication CN101702627A, which is incorporated by reference here; in an embodiment of the present invention , the switching element 30 is realized by two radio frequency switches.

FIG. 6 illustrates the frequency response of the first common mode filter 20 of FIG. 5 . In one embodiment of the present invention, the first common mode filter 20 has a first filtering frequency band. If -15dB is used as the filtering criterion, the first filtering frequency band is about 1,500MHz to 3,200MHz, and the low cutoff frequency is about 1,500MHz, with a high cutoff frequency of approximately 3,200MHz.

FIG. 7 illustrates the frequency response of the second common mode filter 40 of FIG. 5 . In an embodiment of the present invention, the second common-mode filter 40 has a first filtering frequency band. If -15dB is used as the filtering criterion, the second filtering frequency band is about 300MHz to 1,700MHz, and the low cutoff frequency is about 300MHz. , with a high cutoff frequency of approximately 1,700MHz.

FIG. 8 illustrates the frequency response of the third common mode filter 50 of FIG. 5 . In an embodiment of the present invention, the third common-mode filter 50 has a third filtering frequency band. If -15dB is used as the filtering criterion, the third filtering frequency band is about 800MHz to 1,800MHz, and the low cutoff frequency is about 800MHz. , with a high cutoff frequency of approximately 1,800MHz.

Referring to FIG. 6, FIG. 7 and FIG. 8, it can be seen that the first filtering frequency band (about 1,500MHz to 3,200MHz) of the first common mode filter 20, the second filtering frequency band (300MHz to 3,200MHz) of the second common mode filter 40 1,700 MHz) is different from the third filtering frequency band (800 MHz to 1,800 MHz) of the third common-mode filter 50 .

FIG. 9 illustrates a first frequency response of the broadband common-mode filter device 60 of FIG. 5 . In an embodiment of the present invention, when the switching element 30 is in the first switching state 31, it electrically connects the output terminal 23 of the first common-mode filter 20 to the input terminal 41 of the second common-mode filter 40; Thus, the frequency response of the broadband common-mode filter device 10 is the superposition of the frequency responses of the first common-mode filter 20 and the second common-mode filter 40 .

In an embodiment of the present invention, if -15dB is taken as the filtering criterion, the broadband common mode filter device 10 has a low total cut-off frequency (about 350 MHz) and a high total cut-off frequency (about 4,600 MHz). In an embodiment of the present invention, if -15dB is used as the filtering criterion, the broadband common-mode filter device 60 has a first combined filter frequency band, which is about 350 MHz to 4,600 MHz, which is greater than that of the first common-mode filter 20 The first filtering frequency band and the second filtering frequency band of the second common mode filter 40 .

FIG. 10 illustrates the second frequency response of the broadband common-mode filter device 60 of FIG. 5 . In an embodiment of the present invention, when the switching element 30 is in the second switching state 33, it electrically connects the output terminal 23 of the first common-mode filter 20 to the input terminal 51 of the third common-mode filter 50; Thus, the frequency response of the broadband common-mode filter device 60 is the superposition of the frequency responses of the first common-mode filter 20 and the third common-mode filter 50 . In addition, referring to FIG. 7 and FIG. 8 , it can be seen that the first frequency response of the broadband common mode filter device 60 is different from the second frequency response.

In an embodiment of the present invention, if -15dB is taken as the filtering criterion, the broadband common mode filter device 60 has a low total cut-off frequency (about 850 MHz) and a high total cut-off frequency (about 4,800 MHz). In an embodiment of the present invention, if -15dB is used as the filtering criterion, the broadband common-mode filter device 60 has a second total filter frequency band, which is about 850 MHz to 4,800 MHz, which is greater than that of the first common-mode filter 20 The first filtering frequency band and the third filtering frequency band of the third common mode filter 50 .

In an embodiment of the present invention, by switching the switching element 30 between the first switching state 31 and the second switching state 33, the broadband common-mode filter device 60 has two types of frequency responses, corresponding to two types of filtering The frequency bands are respectively the first total filter frequency band (about 350MHz to 4,600MHz) and the second total filter frequency band (about 850MHz to 4,800MHz), which can be applied to different filtering requirements, such as 4G communication (LTE ) for noise filtering in different frequency bands.

After the known common-mode filter is manufactured, its filtering frequency band (the filtering bandwidth of the known common-mode filter is not greater than 2 GHz) has been determined and cannot be expanded; The device is connected in series with a plurality of common-mode filters with different frequency responses, and the filtering frequency band of the broadband common-mode filtering device is greater than that of individual common-mode filters through the superposition of the frequency response characteristics of these common-mode filters.

For example, the frequency response characteristics of the known common-mode filter only have a filtering effect on a single frequency range, and cannot simultaneously have the effect of multi-band filtering; in contrast, the broadband common-mode filter device disclosed in the embodiment of the present invention is connected in series with multiple different The common mode filter expands the filtering frequency band and can simultaneously have the effect of multi-band filtering, thus supporting the filtering requirements of multi-band.

In addition, if there is a demand for a new filtering frequency band, the known technology must redesign and manufacture the common-mode filter to meet the new demand; in contrast, the technology of the present invention utilizes the frequency response characteristics of these common-mode filters Superposition effect, the total frequency response characteristics of the broadband common-mode filtering device is different from the individual frequency response characteristics of these common-mode filters, that is, the technology of the present invention does not need to redesign and manufacture common-mode filters, only needs to be based on the new To meet the new requirements, select a common-mode filter with specific frequency response characteristics and connect them in series.

Furthermore, by switching the switching element between the first switching state and the second switching state, the broadband common-mode filter device has two kinds of frequency responses, corresponding to two kinds of filtering frequency bands, and can be applied to different filtering requirements, for example Noise filtering applied to different frequency bands of 4G communication (LTE) in various countries. In other words, a single filter element has at least two types of frequency responses, corresponding to at least two types of filter frequency bands. Users can selectively connect different common-mode filters in series by switching the switching state of the switching element to use the required filter frequency bands. .

In an embodiment of the present invention, a broadband common-mode filtering device includes a first common-mode filter with a first filtering band; a second common-mode filter with a second filtering band, wherein the first a filtering frequency band different from the second filtering frequency band; and a switching element configured to electrically connect the output terminal of the first common-mode filter to the input terminal or output terminal of the second common-mode filter.

In another embodiment of the present invention, a broadband common-mode filtering device includes a first common-mode filter with a first filtering band; a second common-mode filter with a second filtering band, wherein the first a filter frequency band different from the second filter frequency band; a third common mode filter having a third filter frequency band, wherein the third filter frequency band is different from the first filter frequency band and the second filter frequency band; and a switching element via configured to electrically connect the output terminal of the first common-mode filter to the input terminal of the second common-mode filter or the input terminal of the third common-mode filter.

The technical content and technical characteristics of the present invention have been disclosed above, but those of ordinary skill in the technical field of the present invention should understand that the teachings and disclosures of the present invention can be used without departing from the spirit and scope of the present invention defined by the appended claims. Various replacements and modifications. For example, many of the processes disclosed above could be implemented differently or replaced by other processes, or a combination of both.

In addition, the scope of rights in this case is not limited to the process, equipment, manufacturing, material components, devices, methods or steps of the specific embodiments disclosed above. Those of ordinary skill in the technical field to which the present invention belongs should understand that, based on the teachings and disclosures of the present invention, processes, machines, manufacturing, material components, devices, methods or steps, whether they exist now or will be developed in the future, they are related to the disclosure of the embodiment of this case. Those that perform substantially the same function in substantially the same manner and achieve substantially the same result can also be used in the present invention. Accordingly, the appended claims are intended to cover within their scope such processes, machines, manufacture, compositions of matter, means, methods or steps.

Claims (11)

1. A broadband common mode filtering device, comprising: a first common mode filter having a first filtering frequency band; a second common mode filter having a second filtering frequency band, wherein the first filtering frequency band is different from the second filtering frequency band; and A switching element configured to electrically connect the output terminal of the first common-mode filter to the input terminal or output terminal of the second common-mode filter. 2. The broadband common-mode filter device according to claim 1, wherein the switching element is configured to electrically connect the output end of the first common-mode filter to the second common-mode filter when in a first switching state input terminal. 3. The broadband common-mode filter device according to claim 2, wherein the switching element is configured to electrically connect the output end of the first common-mode filter to the second common-mode filter when in a second switching state output terminal. 4. The broadband common-mode filter device according to claim 1, wherein the frequency response of the broadband common-mode filter device is a superposition of the frequency responses of the first common-mode filter and the second common-mode filter. 5. The broadband common-mode filtering device according to claim 1, wherein when the switching element is in a first switching state, the broadband common-mode filtering device has a first frequency response, and when the switching element is in a second switching state , the broadband common-mode filtering device has a second frequency response, and the first frequency response is different from the second frequency response. 6. A broadband common-mode filtering device, comprising: a first common mode filter having a first filtering frequency band; a second common mode filter having a second filtering frequency band, wherein the first filtering frequency band is different from the second filtering frequency band; a third common mode filter having a third filtering frequency band, wherein the third filtering frequency band is different from the first filtering frequency band and the second filtering frequency band; and A switching element configured to electrically connect the output end of the first common-mode filter to the input end of the second common-mode filter or the input end of the third common-mode filter. 7. The broadband common-mode filtering device according to claim 6, wherein the switching element is configured to electrically connect the output end of the first common-mode filter to the second common-mode filter when in a first switching state input terminal. 8. The broadband common-mode filtering device according to claim 7, wherein the switching element is configured to electrically connect the output end of the first common-mode filter to the third common-mode filter when in a second switching state input terminal. 9. The broadband common-mode filter device according to claim 6, wherein when the switching element is in a first switching state, the frequency response of the broadband common-mode filter device is the first common-mode filter and the second common-mode The superposition of the frequency responses of the filters. 10. The broadband common-mode filter device according to claim 9, wherein when the switching element is in a second switching state, the frequency response of the broadband common-mode filter device is the first common-mode filter and the third common-mode filter The superposition of the frequency responses of the filters. 11. The broadband common-mode filtering device according to claim 6, wherein when the switching element is in a first switching state, the broadband common-mode filtering device has a first frequency response, and when the switching element is in a second switching state , the broadband common-mode filtering device has a second frequency response, and the first frequency response is different from the second frequency response.