A dual-band filter based on SISL

Abstract

The application relates to a double-passband filter based on SISL, which comprises a five-layer dielectric substrate covered with metal layers on the top layer and the bottom layer, the five-layer dielectric substrate is sub1-sub5 from top to bottom, the metal layers on the top layer and the bottom layer of the five-layer dielectric substrate are G1-G10 from top to bottom, square metallized via arrays 1 are arranged in the middle regions of the five-layer dielectric substrate, the square metallized via arrays 1 on the five-layer dielectric substrate correspond to each other, an integrated DGS1 is arranged on the dielectric substrate sub1, a microwave circuit is arranged on the dielectric substrate sub3, an integrated DGS2 is arranged on the dielectric substrate sub5, air cavities are arranged on the dielectric substrate sub2 and the dielectric substrate sub4, the air cavity on the dielectric substrate sub2 and the air cavity on the dielectric substrate sub4 correspond to each other, the application realizes a double-passband filtering effect and improves the selectivity of the double-passband.

Description

Technical Field

[0001] This invention belongs to the field of filter technology, and in particular relates to a dual-passband filter based on SISL. Background Technology

[0002] With the massive increase in information volume and the growing demand for portability in modern society, communication technology is rapidly developing towards broadband, high capacity, and miniaturization. In this context, traditional single-passband filters can no longer meet the needs of the rapidly evolving information transmission landscape. Dual-band filters have attracted significant attention due to their ability to simultaneously select two different frequency bands. This technology allows communication systems to operate on two frequency bands simultaneously while saving system size and cost, thus making better use of spectrum resources. This is crucial for modern communication systems, especially given the increasing scarcity of spectrum resources. Dual-band filters, with their advantages of high Q value (quality factor), miniaturization, integration, high selectivity, low loss, and self-packaging, represent one of the trends in the development of modern microwave and millimeter-wave front-end circuits.

[0003] The journal article "A Self-Packaged Low-Loss and Compact SISL DBBPF With Multiple TZs" (Journal: IEEE Microwave and Wireless Components Letters, 2019, Volume: 29, Issue: 3) reports a dual-passband filter based on SISL. The circuit consists of a resonator with a short-circuited stub in the middle and a slotted feeder. This dual-band filter utilizes the mode response of the resonator with the short-circuited stub in the middle to form the first passband. The proposed slotted feeder can be considered as two U-shaped resonators, which form the second passband. Overall, it achieves dual-passband filtering performance. However, while the overall size is reduced by using double-layer wiring, the miniaturization of the components is still insufficient. Furthermore, the lower stopband of the first passband does not introduce a transmission zero, limiting the selectivity of the first passband and requiring further improvement in filtering performance. Summary of the Invention

[0004] To address the problems existing in the background technology, this invention proposes a dual-passband filter based on SISL, comprising: a five-layer dielectric substrate with a top and bottom layer respectively covered by a metal layer, the five dielectric substrates being sub1-sub5 from top to bottom; the metal layers of the top and bottom layers of the five dielectric substrates being G1-G10 from top to bottom; a square metallized via array 1 is provided in the middle region of each of the five dielectric substrates; the square metallized via array 1 on the five dielectric substrates are vertically aligned; an integrated DGS1 is provided on dielectric substrate sub1; a microwave circuit is provided on dielectric substrate sub3; an integrated DGS2 is provided on dielectric substrate sub5; and air cavities are provided on dielectric substrate sub2 and dielectric substrate sub4, the air cavities of dielectric substrate sub2 and dielectric substrate sub4 being vertically aligned.

[0005] Preferably, the integrated DGS1 includes: a metallized via array 2 disposed on the metal layer G2 along the inner edge of the square metallized via array 1, and two G-shaped DGS1 structures disposed in the area enclosed by the metallized via array 2, wherein the two G-shaped DGS1 structures and the metallized via array 2 constitute the integrated DGS1.

[0006] Preferably, the two G-shaped DGS1 structures are symmetrical from left to right.

[0007] Preferably, the microwave circuit includes: two GCPWs disposed on the metal layer G5, two T-shaped feeds disposed on the metal layer G5, and two square feeds disposed on the metal layer G6; the two T-shaped feeds and the two square feeds are disposed within the area enclosed by the square metallized via array 1;

[0008] The two GCPWs are respectively connected to the two T-type feeders to form the T-type feeders for the transition of the two GCPWs to the SSL; the two square feeders are respectively connected to the two T-type feeders through metallized vias.

[0009] Preferably, when viewed from above, the projections of the two T-shaped feeds and the two square feeds onto the dielectric substrate sub2 or the dielectric substrate sub4 are located within the projection of the air cavity of the dielectric substrate sub2 or the air cavity of the dielectric substrate sub4.

[0010] Preferably, symmetrical square substrates are cut off from both the left and right ends of the dielectric substrates sub1 and sub2, with the cut-off portions located directly above the two GCPWs, so that the two GCPWs are partially exposed.

[0011] Preferably, the two GCPWs extend inward from the left and right sides of the dielectric substrate sub3, respectively; the two GCPWs transition to the T-shaped feed of SSL are symmetrical from left to right, and the two square feeds are symmetrical from left to right.

[0012] Preferably, the integrated DGS2 includes: a metallized via array 3 disposed on the metal layer G9 along the inner edge of the square metallized via array 1, and two G-shaped DGS2 structures disposed in the area enclosed by the metallized via array 3, wherein the two G-shaped DGS2 structures and the metallized via array 3 constitute the integrated DGS2.

[0013] Preferably, the two G-shaped DGS2 structures are symmetrical.

[0014] Preferably, when viewed from above, the projections of the integrated DGS1 and integrated DGS2 onto the dielectric substrate sub2 or dielectric substrate sub4 are located within the projection of the air cavity of the dielectric substrate sub2 or the air cavity of the dielectric substrate sub4.

[0015] The present invention has at least the following beneficial effects

[0016] This invention uses SISL technology and has the following advantages: (1) Multilayer wiring: The circuit distribution of the upper and lower layers of Sub3 introduces great flexibility to the circuit design. On the other hand, the circuit area is reduced by using the G2 / G9 metal layers for circuit design. (2) Low loss: Air cavities are set on the dielectric substrates sub2 and sub4 by the "dielectric removal" method. The field distribution of SISL is mainly in the air cavities. The multilayer circuits are connected by the square metallized via array, which greatly reduces the insertion loss of the structure. (3) Self-encapsulation: The dual passband filter is composed of five dielectric substrates. The upper and lower air cavities are formed by hollowing out the middle two dielectric substrates and then pressing the five dielectric substrates together. No additional shielding box is needed for electromagnetic shielding, which reduces the design cost and weight. (4) Better selectivity: Five transmission zeros are introduced on both sides of the passband and between the passbands by source-load coupling, which improves the out-of-band selectivity. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 A schematic diagram of the structure of the bottom metal layer G2 of the dielectric substrate sub1 of the invention;

[0019] Figure 3 This is a schematic diagram of the structure of the dielectric substrate sub2 of the invention;

[0020] Figure 4 A schematic diagram of the structure of the top metal layer G5 of the dielectric substrate sub3 of the invention;

[0021] Figure 5 A schematic diagram of the structure of the bottom metal layer G6 of the dielectric substrate sub3 of the invention;

[0022] Figure 6 This is a schematic diagram of the structure of the dielectric substrate sub4 of the invention;

[0023] Figure 7 A schematic diagram of the structure of the top metal layer G9 of the dielectric substrate sub5 of the invention;

[0024] Figure 8 The simulation diagram of the S-parameters of the invention;

[0025] Figure 9 This is a schematic diagram of the topology of a dual-passband filter. Detailed Implementation

[0026] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0027] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures, and should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0028] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying 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, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0029] Please see Figures 1 to 8This invention proposes a dual-passband filter based on SISL, comprising: a five-layer dielectric substrate with a top and bottom layer respectively coated with a metal layer, the five dielectric substrates being sub1-sub5 from top to bottom; the metal layers of the top and bottom layers of the five dielectric substrates being G1-G10 from top to bottom; a square metallized via array 1 is provided in the middle region of each of the five dielectric substrates; the square metallized via array 1 on the five dielectric substrates are vertically aligned; an integrated DGS1 is provided on dielectric substrate sub1; a microwave circuit is provided on dielectric substrate sub3; an integrated DGS2 is provided on dielectric substrate sub5; and air cavities are provided on dielectric substrate sub2 and dielectric substrate sub4, the air cavities of dielectric substrate sub2 and dielectric substrate sub4 being vertically aligned.

[0030] In this embodiment, the five-layer dielectric substrate can be designed using substrates of the same size. Each dielectric substrate includes two metal surfaces. Dielectric substrates sub2 and sub4 are partially cut away to create an air cavity. Dielectric substrate sub3 is used to design microwave circuits. The uppermost and lowermost dielectric substrates, together with the square metallized via array 1 connected vertically around the perimeter, form a metal shielding structure, reducing radiation loss. Finally, the multiple dielectric substrates are assembled to form a dielectric integrated suspension line. Multiple positioning vias are also provided on each dielectric substrate to facilitate the positioning and assembly of the dielectric substrates. Positioning vias are distributed around the outer edge of the square metallized via array 1. Those skilled in the art can design accordingly based on the actual device conditions. Furthermore, the air cavities of the dielectric substrate sub2 and the dielectric substrate sub4 are both set within the area enclosed by the square metallized via array 1 of the corresponding dielectric substrates. An integrated DGS1 is provided on the dielectric substrate sub1 to achieve a specific filtering function, which affects the electromagnetic characteristics of the circuit by changing the structure of the ground plane. An integrated DGS2 is provided on the dielectric substrate sub5, which works together with DGS1 to achieve a dual-passband filtering effect.

[0031] Please see Figure 2 Preferably, the integrated DGS1 includes: a metallized via array 2 disposed along the inner edge of the square metallized via array 1 on the metal layer G2, and two G-shaped DGS1 structures disposed within the area enclosed by the metallized via array 2. The two G-shaped DGS1 structures and the metallized via array 2 constitute the integrated DGS1. The integrated DGS1, shielded by the surrounding square metallized via array 1, metallized via array 2, and metal layer G1, can limit most of the EM field between the integrated DGS1 and the G1 metal layer, and can further reduce the radiation loss of the integrated DGS1 resonator.

[0032] In this embodiment Figure 2Only the structure of metal layer G2 is shown. Metal layer G1, which only contains through-holes corresponding to the square metallized via array 1, metallized via array 2, and positioning vias in metal layer G2, and has no other design features, is omitted from the view. This should be understandable to those skilled in the art. Please refer to [link to relevant documentation]. Figure 3 and Figure 6 , Figure 3 This diagram illustrates the structure of dielectric substrate sub2. The top and bottom layers of dielectric substrate sub2 have the same structure, therefore... Figure 3 This schematic diagram can simultaneously represent the top metal layer G3 and the bottom metal layer G4 of the dielectric substrate sub2, which should be understandable to those skilled in the art. Figure 6 A schematic diagram of the structure of dielectric substrate sub4. The top and bottom layers of dielectric substrate sub4 have the same structure, therefore... Figure 3 This schematic diagram can simultaneously represent the top metal layer G7 and the bottom metal layer G8 of the dielectric substrate sub4, which should be understandable to those skilled in the art.

[0033] Preferably, the two G-shaped DGS1 structures are symmetrical. By bending to form the G-shaped DGS, the device can be miniaturized. The position of the pole in the first passband can be adjusted by adjusting the symmetrical distance between the two DGS1 structures, and the coupling of the resonator can also be adjusted.

[0034] Please see Figure 4 and Figure 5 Preferably, the microwave circuit includes: two GCPWs disposed on the metal layer G5, two T-type feeds disposed on the metal layer G5, and two square feeds disposed on the metal layer G6; the two T-type feeds and the two square feeds are disposed within the area enclosed by the square metallized via array 1;

[0035] The two GCPWs are connected to two T-shaped feeds respectively to form T-shaped feeds for the transition from the two GCPWs to the SSL; the two square feeds are connected to the two T-shaped feeds respectively through metallized vias. Using the T-shaped feed structure can widen the stopband range of the upper stopband and provide coupling feed for the resonator in layer G2, while the square feed at G6 feeds the resonator at G9. Furthermore, source-load coupling can generate zeros, improving the selectivity of the filter.

[0036] In this embodiment, metal layer G5 is the top metal layer of dielectric substrate sub3, and metal layer G6 is the bottom metal layer of dielectric substrate sub3.

[0037] Preferably, when viewed from above, the projections of the two T-shaped feeds and the two square feeds onto dielectric substrate sub2 or dielectric substrate sub4 are located within the projection of the air cavity of dielectric substrate sub2 or dielectric substrate sub4. In this embodiment, by removing the dielectric to form an air cavity, the G5 / 6 layer becomes a suspended line structure, and the feed structure distributed on it is located within the air cavity, thus the field distribution is located in the air, which helps to reduce losses.

[0038] Preferably, symmetrical square substrates are cut off from both the left and right ends of the dielectric substrates sub1 and sub2, with the cut-off portions located directly above the two GCPWs, so that the two GCPWs are partially exposed.

[0039] In this embodiment, symmetrical square substrates are cut off at both ends of dielectric substrates sub1 and sub2 to facilitate the installation of SMA connectors on the dual passband filter. Exposing the two GCPW portions facilitates the connection between the two GCPW portions and the SMA connectors. The two GCPWs are the input and output ports of the dual passband filter.

[0040] Preferably, the two GCPWs extend inward from the left and right sides of the dielectric substrate sub3, respectively; the two GCPWs transition to the T-shaped feed of the SSL are symmetrical left and right, and the two square feeds are also symmetrical left and right. These feed the resonators that are symmetrical about the G2 / 9 metal layers.

[0041] Please see Figure 7 Preferably, the integrated DGS2 includes: a metallized via array 3 disposed along the inner edge of the square metallized via array 1 on the metal layer G9, and two G-shaped DGS2 structures disposed within the area enclosed by the metallized via array 3. The two G-shaped DGS2 structures and the metallized via array 3 constitute the integrated DGS2. By bending to form the G-shaped DGS, the device can be miniaturized. The position of the second passband pole can be adjusted by adjusting the symmetrical distance between the two DGS2 structures, and the coupling magnitude of the resonator can also be adjusted.

[0042] In this embodiment Figure 7 The top metal layer G9 of the dielectric substrate sub5 is shown. The bottom metal layer G10 of the dielectric substrate sub5 has no other design features except for the square metallized via array 1, metallized via array 3 and positioning vias that are provided corresponding to the top metal layer G9. Therefore, this view is omitted in this invention, which should be understood by those skilled in the art.

[0043] Preferably, the two G-shaped DGS2 structures are symmetrical. By bending to form the G-shaped DGS, the device can be miniaturized. The position of the second passband pole can be adjusted by adjusting the symmetrical distance between the two DGS2 structures, and the coupling of the resonator can also be adjusted.

[0044] Preferably, when viewed from above, the projections of the integrated DGS1 and integrated DGS2 onto the dielectric substrate sub2 or dielectric substrate sub4 lie within the projection of the air cavity of the dielectric substrate sub2 or dielectric substrate sub4. Within the air cavity, the dielectric constant of air is low, which helps reduce signal loss during transmission.

[0045] The working principle of the dual-passband filter of this invention is as follows: The input signal is transitioned to the T-shaped feed of the SSL through the first GCPW, and then transmitted to the first T-shaped feed structure located on the G5 layer. Energy is then coupled and transmitted to the first G-shaped DGS1 located on the metal layer G2 through the air cavity of the dielectric substrate sub2. Energy is transmitted between the two G-shaped DGS1s through electromagnetic hybrid coupling. The second G-shaped DGS1 couples energy to the second T-shaped feed at the output end through the air cavity of the dielectric substrate sub2, and then transitions to the T-shaped feed of the SSL through the second GCPW to obtain the output signal. The entire transmission forms the first passband. The first T-shaped feed passes through a metallized via. Energy is transferred to the first square feed in the G6 layer via coupling. This first square feed couples energy to the first G-shaped DGS2 through the air cavity in the dielectric substrate sub4. Energy is transferred between the two G-shaped DGS2 via electromagnetic hybrid coupling. The second G-shaped DGS2 couples energy to the second square feed through the air cavity in the dielectric substrate sub4. Finally, the second square feed couples energy to the T-shaped feed at the output end through coupling and metallized vias. This entire transmission forms the second passband. Source-load coupling is introduced using the two T-shaped feed structures. Transmission zeros are introduced between the first and second passbands and on both sides of the passband to achieve higher selectivity. The center frequency of the first passband can be adjusted by the overall length of the G-shaped DGS1, while the center frequency of the second passband can be adjusted by the overall length of the G-shaped DGS2. The topology of the dual-passband filter is as follows: Figure 9 As shown.

[0046] Experimental simulation:

[0047] Please see Figure 8 Simulation results show that the first filter passband is 2.35-2.57 GHz, and the second filter passband is 4.89-5.26 GHz. A transmission zero is introduced in the lower stopband of the first passband, and two transmission zeros are introduced between the first and second passbands and in the upper stopband of the second passband. The input return loss (S) is significant within both passbands. 11 Better than 20dB, two-passband insertion loss (S 21 The performance improvements are 0.33dB and 0.45dB respectively. The overall center circuit dimensions are 8.4mm*14mm (0.069λ). g *0.115λ gAs can be seen from the simulation results, the simulation examples of this invention exhibit excellent out-of-band rejection performance and a small circuit size. Compared with the simulation results of the dual-passband filter literature "ASelf-Packaged Low-Loss and Compact SISLDBBPF With Multiple TZs", which is also a dielectric integrated suspension line, the dual-passband structure proposed in this invention has more transmission zeros, better selectivity, and a smaller size.

[0048] In summary, the filter designed in this invention generates five zeros, improving the selectivity of the dual-passband filter. Through a multi-layer stacked circuit structure, miniaturization is achieved. Due to the superior performance of the SISL (Substrate Integrated Suspension Line) structure, the designed filter has low loss.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A SISL-based dual-band filter, characterized by, The application relates to a five-layer dielectric substrate covered with metal layers on the top layer and the bottom layer, wherein the five-layer dielectric substrate comprises sub1-sub5 from top to bottom; the metal layers on the top layer and the bottom layer of the five-layer dielectric substrate comprise G1-G10 from top to bottom; square metallized via arrays 1 are arranged in the middle regions of the five-layer dielectric substrate; the square metallized via arrays 1 on the five-layer dielectric substrate correspond to each other; an integrated DGS1 is arranged on the lower surface of the dielectric substrate sub1; a microwave circuit is arranged on the dielectric substrate sub3; an integrated DGS2 is arranged on the upper surface of the dielectric substrate sub5; air cavities are arranged on the dielectric substrate sub2 and the dielectric substrate sub4, and the air cavities on the dielectric substrate sub2 and the dielectric substrate sub4 correspond to each other. The microwave circuit comprises two GCPWs arranged on the metal layer G5, two T-shaped feeders arranged on the metal layer G5 and two square feeders arranged on the metal layer G6. The two T-shaped feeders and the two square feeders are arranged in the region surrounded by the square metallized via array 1. The two GCPWs are connected with the two T-shaped feeders to form two GCPW transition T-shaped feeders, and the two square feeders are connected with the two T-shaped feeders through metallized vias. The integrated DGS1 comprises a metallized via array 2 arranged on the metal layer G2 along the inner edge of the square metallized via array 1 and two G-shaped DGS1 structures arranged in the region surrounded by the metallized via array 2, and the two G-shaped DGS1 structures and the metallized via array 2 form the integrated DGS1. The two G-shaped DGS1 structures are left-right symmetrical.

2. The SISL-based dual-band filter of claim 1, wherein, When viewed from above, the projections of the two T-shaped feeders and the two square feeders on the dielectric substrate sub2 or the dielectric substrate sub4 are located in the projections of the air cavity of the dielectric substrate sub2 or the air cavity of the dielectric substrate sub4.

3. The SISL-based dual-band filter of claim 2, wherein, The left and right ends of the dielectric substrate sub1 and the dielectric substrate sub2 are cut to form symmetrical partial square substrates, and the cut parts are located directly above the two GCPWs to expose the two GCPWs.

4. The SISL-based dual-band filter of claim 1, wherein, The two GCPWs extend inward from the left and right sides of the dielectric substrate sub3, and the two GCPW transition T-shaped feeders and the two square feeders are left-right symmetrical.

5. The SISL-based dual-band filter of claim 1, wherein, The integrated DGS2 comprises a metallized via array 3 arranged on the metal layer G9 along the inner edge of the square metallized via array 1 and two G-shaped DGS2 structures arranged in the region surrounded by the metallized via array 3, and the two G-shaped DGS2 structures and the metallized via array 3 form the integrated DGS2.

6. The SISL-based dual-band filter of claim 1, wherein, The two G-shaped DGS2 structures are left-right symmetrical.

7. The SISL-based dual-band filter of claim 1, wherein, When viewed from above, the projections of the integrated DGS1 and the integrated DGS2 on the dielectric substrate sub2 or the dielectric substrate sub4 are located in the projections of the air cavity of the dielectric substrate sub2 or the air cavity of the dielectric substrate sub4.

8. The SISL-based dual-band filter of claim 7, wherein, ​ 9. The SISL-based dual-band filter of claim 1, wherein, ​

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