A slot-line resonator based bidirectional absorptive common mode filter

Abstract

The application discloses a bidirectional absorption type common mode filter based on slot line resonators, which comprises a dielectric substrate, a metal ground plate, a physical structure, a first slot line resonator, a second slot line resonator and a third slot line resonator with the same size, and a coupling microstrip line; the first slot line resonator, the second slot line resonator and the third slot line resonator are etched on the metal ground plate from left to right along a symmetry plane AA1; the three slot line resonators each comprise a first slot line and a second slot line; the first slot line and the second slot line are both in a "C" type structure, the second slot line is arranged inside the first slot line and the opening direction of the second slot line is opposite to that of the first slot line; the coupling microstrip line comprises a first microstrip line and a second microstrip line which are symmetrically arranged along the symmetry plane AA1, and the symmetry plane AA1 is arranged at a middle position between the openings of the first slot line and the second slot line; the application has the advantages of simple structure, bidirectional common mode absorption performance, large common mode absorption bandwidth and effective protection of signal integrity of a differential mode signal.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic compatibility, specifically relating to a bidirectional absorption common-mode filter based on a slotted wire resonator. Background Technology

[0002] Common-mode filters, as an important microwave device, are mainly used to eliminate destructive common-mode noise in high-speed digital electronic circuits and protect the signal integrity of high-speed transmitted differential-mode signals, thereby improving the overall electromagnetic compatibility of the circuit system.

[0003] Based on their design principles, common-mode filters can be broadly classified into two categories: absorptive and reflective. Extensive research has shown that absorptive common-mode filters can convert the electromagnetic energy of common-mode noise into the heat energy of the resistor, thus more thoroughly resolving the electromagnetic compatibility issues caused by common-mode noise. Therefore, absorptive common-mode filters have significant advantages over reflective designs.

[0004] Currently, most absorptive common-mode filters are designed by adding resistors to the resonant circuit of a resonator. Commonly used resonators for absorptive common-mode filters include mushroom-shaped multimode resonators, lumped-element resonant circuits, and slot-wire resonators. Among these, mushroom-shaped resonators are more complex to design and more expensive to manufacture due to their multi-layered circuit structure, and they also have a narrower common-mode absorption bandwidth. Furthermore, lumped-element resonant circuits, while achieving excellent common-mode absorption performance, require semiconductor passive integration technology, resulting in higher costs. Due to the high impedance characteristics of slot wires, slot-wire resonators are widely used in common-mode filter design. Typically, common-mode filters based on slot-wire resonators require only two metal layers, resulting in lower costs; however, this design also faces performance challenges posed by practical application requirements, namely, a large common-mode absorption bandwidth and bidirectional common-mode absorption characteristics. Currently, existing research on common-mode filters based on slot-wire resonators struggles to simultaneously meet these performance requirements; therefore, the design of superior absorptive common-mode filters has significant scientific research and industrial application value. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a bidirectional absorptive common-mode filter based on a slotted wire resonator. The slotted wire filter features a simple design structure, low manufacturing cost, and the ability to achieve bidirectional common-mode absorption performance. It also boasts a large common-mode absorption bandwidth, effectively protecting the signal integrity of differential-mode signals.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0007] This invention provides a bidirectional absorptive common-mode filter based on slot line resonators, comprising: a dielectric substrate, a metal ground plane located at the bottom layer of the dielectric substrate, a first slot line resonator, a second slot line resonator, and a third slot line resonator with the same physical structure and size, and a coupled microstrip line located at the top layer of the dielectric substrate.

[0008] The first slot resonator, the second slot resonator, and the third slot resonator are respectively etched on the metal ground plane from left to right along the symmetry plane AA1; the first slot resonator, the second slot resonator, and the third slot resonator each include a first slot and a second slot; the first slot and the second slot are both "C" shaped structures, and the second slot is placed inside the first slot and its opening direction is opposite to that of the first slot.

[0009] The coupled microstrip line includes a first microstrip line and a second microstrip line symmetrically arranged along a symmetry plane AA1, with the symmetry plane AA1 located at the midpoint between the openings of the first and second slot lines.

[0010] Optionally, the bidirectional absorption common-mode filter is symmetrical about the symmetry plane AA1.

[0011] Optionally, the first slot resonator is oriented in the same direction as the second slot resonator, and in the opposite direction to the third slot resonator.

[0012] Optionally, a resistor R is connected across the first slot line of both the first and third slot line resonators, and a resistor R is connected across the first and second slot lines of the second slot line resonator; the resistor R is located on the plane of symmetry AA1.

[0013] Optionally, the first and second slot lines are further provided with a corrugated short-circuit slot line support array on the edges parallel to the symmetry plane AA1.

[0014] Optionally, the first microstrip line includes a first port microstrip line, a first coupling microstrip line, and a second port microstrip line connected in sequence; the second microstrip line includes a third port microstrip line, a second coupling microstrip line, and a fourth port microstrip line connected in sequence.

[0015] Optionally, the first port microstrip line and the third port microstrip line constitute a first differential port pair, and the second port microstrip line and the fourth port microstrip line constitute a second differential port pair. Both the first differential port pair and the second differential port pair can be used as inputs or outputs of the circuit.

[0016] Optionally, the differential-mode impedance between the first coupled microstrip line and the second coupled microstrip line is 100Ω.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The invention proposes a bidirectional absorptive common-mode filter based on a slotted wire resonator, which consists of only two metal layers: a coupled microstrip line and a metal ground plane. The structure is simple, easy to implement, and has low processing cost. The design of the C-type slotted wire resonator in this common-mode filter can protect the signal integrity of differential-mode signals over a wide frequency range and supports bidirectional common-mode absorption performance. It has a large common-mode absorption bandwidth and is more applicable than a unidirectional absorptive common-mode filter. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0020] Figure 1 The image shown is a top view of the structure of a bidirectional absorptive common-mode filter in one embodiment of the present invention;

[0021] Figure 2 The diagram shown is a schematic diagram of the structural parameters of a bidirectional absorptive common-mode filter in one embodiment of the present invention;

[0022] Figure 3 The image shown is a side view of the structure of a bidirectional absorption common-mode filter according to one embodiment of the present invention;

[0023] Figure 4 The diagram shown is a schematic diagram of the structural parameters of the first slot wire resonator, the second slot wire resonator, and the third slot wire resonator in one embodiment of the present invention.

[0024] Figure 5 The figure shows the simulation results of the mixed-mode S-parameters of the bidirectional absorptive common-mode filter of the present invention;

[0025] In the figure: S1, first slot line resonator; S2, second slot line resonator; S3, third slot line resonator; 1, first slot line; 2, second slot line; 3, first microstrip line; 3-1, first port microstrip line; 3-2, first coupled microstrip line; 3-3, second port microstrip line; 4, second microstrip line; 4-1, third port microstrip line; 4-2, second coupled microstrip line; 4-3, fourth port microstrip line; 5, dielectric substrate. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0028] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0029] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0030] The application principle of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] This invention provides a bidirectional absorptive common-mode filter based on slot line resonators, comprising: a dielectric substrate 5, a metal ground plane located at the bottom layer of the dielectric substrate 5, a first slot line resonator S1, a second slot line resonator S2 and a third slot line resonator S3 with the same physical structure and size, and a coupled microstrip line located at the top layer of the dielectric substrate 5.

[0032] The first slot resonator S1, the second slot resonator S2, and the third slot resonator S3 are respectively etched from left to right along the symmetry plane AA1 on the metal ground plane; the first slot resonator S1, the second slot resonator S2, and the third slot resonator S3 each include a first slot 1 and a second slot 2; the first slot 1 and the second slot 2 are both "C" shaped structures, and the second slot 2 is placed inside the first slot 1 and its opening direction is opposite to that of the first slot 1.

[0033] The coupled microstrip line includes a first microstrip line 3 and a second microstrip line 4 symmetrically arranged along a symmetry plane AA1, with the symmetry plane AA1 located at the midpoint between the openings of the first slot line 1 and the second slot line 2.

[0034] In one specific embodiment of the present invention, such as Figure 1 As shown, the first slot resonator S1 and the second slot resonator S2 have the same orientation, while the third slot resonator S3 has the opposite orientation. Specifically, the first slot resonator S1 can face left or right, and the orientations of the second slot resonator S2 and the third slot resonator S3 vary depending on the orientation of the first slot resonator S1. In this embodiment, the first slot line 1 in the first slot resonator S1 faces right (the C-shaped opening faces right), and the second slot line 2 faces left (the C-shaped opening faces left). The second slot resonator S2 has the same structural orientation as the first slot resonator S1 and is positioned to the right of the first slot resonator S1 along the symmetry plane AA1. The third slot resonator S3 has the opposite structural orientation to the first slot resonator S1 and is positioned to the right of the second slot resonator S2 along the symmetry plane AA1. In the third slot resonator S3, the first slot line 1 faces left (the C-shaped opening faces left), and the second slot line 2 faces right (the C-shaped opening faces right).

[0035] In one specific embodiment of the present invention, both the first groove 1 and the second groove 2 are "C" shaped structures. The "C" shaped structure is not limited to a fixed C shape for the first groove 1 and the second groove 2, but is a semi-enclosed symmetrical structure with an opening.

[0036] In one specific embodiment of the present invention, the bidirectional absorptive common-mode filter is symmetrical about the symmetry plane AA1. Specifically, the first slot resonator S1, the second slot resonator S2, and the third slot resonator S3 are all symmetrical about the symmetry plane AA1, which is located in the middle of the openings of the first slot resonator S1, the second slot resonator S2, and the third slot resonator S3, that is, in the middle position of the openings of the first slot line and the second slot line. The coupling microstrip line located on the top layer of the dielectric substrate 5 is also symmetrical about the symmetry plane AA1, and the first microstrip line 3 and the second microstrip line 4 are symmetrical about the symmetry plane AA1.

[0037] In one specific embodiment of the present invention, such as Figure 1 and 4 As shown, resistors R are connected across the first slot line 1 of both the first slot line resonator S1 and the third slot line resonator S3, forming a resistive resonant circuit to achieve common-mode absorption. Resistors R are also connected across the first slot line 1 and the second slot line 2 of the second slot line resonator S2; the resistance value is R = 25Ω, and the resistors R are located on the symmetry plane AA1. A slot line is a basic transmission line in microwave science, consisting of two adjacent metal planes, with the gap between them forming the slot line. Connecting resistors R across the slot line involves connecting the two leads of a surface-mount resistor to the metal planes, i.e., bridging the two ends of the middle region of the slot line.

[0038] In one specific embodiment of the present invention, such as Figure 1 and 4 As shown, from left to right, there are three slot resonators: the first slot resonator S1, the second slot resonator S2, and the third slot resonator S3. Each slot resonator has the same physical structure and dimensions. Each slot resonator is composed of two "C"-shaped slots (the first slot 1 and the second slot 2) of different sizes placed facing each other. The edges of the first slot 1 and the second slot 2, which are parallel to the plane of symmetry AA1, are also provided with a corrugated array of short-circuit slot support segments. The corrugated short-circuit slot support segments are distributed at a periodic interval d1, and the three slot resonators are distributed at a periodic interval d2. Specifically, the linewidth of the first slot 1 and the second slot 2 is w1 = 0.4 mm, and the slot segments are l1 = 10 mm, l2 = 10 mm, l3 = 5.2 mm, l4 = 7.6 mm, l5 = 1.2 mm, and the periodic intervals are d1 = 1 mm and d2 = 11 mm.

[0039] In one specific embodiment of the present invention, such as Figure 1 and Figure 2As shown; the first microstrip line 3 includes a first port microstrip line 3-1, a first coupling microstrip line 3-2, and a second port microstrip line 3-3 connected in sequence; the second microstrip line 4 includes a third port microstrip line 4-1, a second coupling microstrip line 4-2, and a fourth port microstrip line 4-3 connected in sequence. The first port microstrip line 3-1 and the third port microstrip line 4-1 form a first differential port pair (Port1+, Port1-), and the second port microstrip line 3-3 and the fourth port microstrip line 4-3 form a second differential port pair (Port2+, Port2-). Both the first differential port pair (Port1+, Port1-) and the second differential port pair (Port2+, Port2-) can be used for the circuit's input or output. To ensure the complete transmission of the differential mode signal, the differential mode impedance between the first coupling microstrip line 3-2 and the second coupling microstrip line 4-2 is 100Ω. Specifically, to control the differential-mode impedance between the first coupled microstrip line 3-2 and the second coupled microstrip line 4-2, the structural parameters of the first coupled microstrip line 3-2 and the second coupled microstrip line 4-2 can be designed as follows: coupling spacing s = 1 mm, line width w m1 =1.47mm, line length l = 52.7mm. The linewidth w of the first-port microstrip line 3-1, the second-port microstrip line 3-3, the third-port microstrip line 4-1, and the fourth-port microstrip line 4-3 is... m2 =1.65mm.

[0040] In one specific embodiment of the present invention, such as Figure 3 The diagram shows a side view of a bidirectional absorptive common-mode filter, including a coupled microstrip line on the top layer, an intermediate dielectric layer (dielectric substrate 5), and a metal ground plane on the bottom layer of dielectric substrate 5. Specifically, to design the differential-mode impedance of the coupled microstrip line to be 100Ω, Rogers 4003 dielectric material with a dielectric constant of ε is selected. r =3.55, loss tangent is tanδ=0.0027; medium thickness is h=0.813mm.

[0041] In one specific embodiment of the present invention, such as Figure 5 The figure shows the simulation results of the mixed-mode S-parameters of the bidirectional absorptive common-mode filter of this invention. The horizontal axis represents frequency in GHz, and the vertical axis represents the S-parameter values ​​in dB. It can be seen that within 6.2 GHz, the differential-mode transmission coefficient S... dd21 Maintaining above -3dB, while the differential mode reflection coefficient S dd11 Less than -10dB, therefore this filter can effectively protect the signal integrity of high-speed differential signals; the common-mode transmission coefficient S from the first differential port pair to the second differential port pair cc21 The common-mode transmission coefficient S from the second differential port pair to the first differential port pair cc12The two common-mode transmission coefficients S coincide; in the 2.6 GHz to 6.2 GHz frequency band, the two common-mode transmission coefficients S cc21 With S cc12 All are less than -10dB, and the common-mode reflection coefficient S at the first differential port pair is also less than -10dB. cc11 The common-mode reflection coefficient S at the second differential port pair cc22 All values ​​were less than -10dB, demonstrating the excellent bidirectional common-mode absorption performance of the filter, with a common-mode absorption bandwidth of 82%.

[0042] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A bidirectional absorptive common-mode filter based on a slotted wire resonator, characterized in that, include: The dielectric substrate, a metal ground plane located at the bottom of the dielectric substrate, a first slot line resonator, a second slot line resonator, and a third slot line resonator with the same physical structure and size, and a coupled microstrip line located at the top of the dielectric substrate. The first slot resonator, the second slot resonator, and the third slot resonator are respectively etched on the metal ground plane from left to right along the symmetry plane AA1; the first slot resonator, the second slot resonator, and the third slot resonator each include a first slot and a second slot; the first slot and the second slot are both "C" shaped structures, and the second slot is placed inside the first slot and its opening direction is opposite to that of the first slot. The coupled microstrip line includes a first microstrip line and a second microstrip line symmetrically arranged along a symmetry plane AA1, with the symmetry plane AA1 located at the midpoint between the openings of the first and second slot lines. The first slot line resonator and the second slot line resonator are oriented in the same direction, while the third slot line resonator is oriented in the opposite direction. A resistor R is connected across the first slot line of both the first and third slot line resonators, and a resistor R is connected across the first and second slot lines of the second slot line resonator; the resistor R is located on the plane of symmetry AA1. The first and second slot lines are further provided with a corrugated short-circuit slot line branch array on the edges parallel to the symmetry plane AA1.

2. The bidirectional absorption common-mode filter based on a slotted wire resonator according to claim 1, characterized in that: The bidirectional absorptive common-mode filter is symmetrical about the symmetry plane AA1.

3. The bidirectional absorption common-mode filter based on a slotted wire resonator according to claim 1, characterized in that: The first microstrip line includes a first port microstrip line, a first coupling microstrip line and a second port microstrip line connected in sequence; the second microstrip line includes a third port microstrip line, a second coupling microstrip line and a fourth port microstrip line connected in sequence.

4. The bidirectional absorption common-mode filter based on a slotted wire resonator according to claim 3, characterized in that: The first port microstrip line and the third port microstrip line form a first differential port pair, and the second port microstrip line and the fourth port microstrip line form a second differential port pair. Both the first differential port pair and the second differential port pair can be used as inputs or outputs of the circuit.

5. The bidirectional absorption common-mode filter based on a slotted wire resonator according to claim 3, characterized in that: The differential-mode impedance between the first coupled microstrip line and the second coupled microstrip line is 100Ω.

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