Duplexer based on SISL and DGS

Abstract

The invention belongs to the technical field of filters, and particularly relates to a duplexer based on SISL and DGS. The duplexer comprises five layers of dielectric substrates which are sequentially arranged from top to bottom, wherein the five layers of dielectric substrates are sub1-sub5 respectively; the upper surface and the lower surface of each layer of dielectric substrate are covered with metal layers, and the ten metal layers G1-G10 are arranged from top to bottom. Three rectangular parts are cut off from the edges of the dielectric substrate sub1 and the dielectric substrate sub2, and the dielectric substrate sub1 and the dielectric substrate sub2 are overlapped; the five layers of dielectric substrates and the ten layers of metal layers are provided with through first metal through hole square arrays, and the metal through hole square arrays of the dielectric substrates and the metal through hole square arrays of the metal layers coincide. Two G-shaped DGS resonators are arranged in the metal layer G2; the duplexer designed by the invention is better in dual-passband out-of-band rejection effect, smaller in size and wider in stopband range.

Description

Technical Field

[0001] The invention belongs to the technical field of filters, and in particular relates to a duplexer based on SISL and DGS. Background Art

[0002] With the continuous development of society and technology, wireless communication technology has become an indispensable technology in people's lives and plays an important role in the development of the country. A duplexer is generally composed of two structures with filtering characteristics, which can be a bandpass filter, a low-pass filter, or a high-pass filter.

[0003] The development of duplexers is inseparable from the development of microwave filter design theory. A large number of filter design theories are used to design various types of duplexers. Duplexers based on bandpass filters have also developed rapidly. There are three main implementation methods for this type of duplexer. The first type is the T-type matching network solution: its design idea is to add an additional T-type matching network to achieve impedance matching and isolation of the duplexer after designing the bandpass filters working at different frequencies. The second type is distributed coupling technology: the duplexer is realized by coupling different channels on both sides of the input feeder. The third type is based on a shared resonator method: by sharing a common resonator, the common resonator not only plays the role of port matching, but also provides a resonant mode for the two channels.

[0004] Defective ground structure is a technology that changes the electromagnetic field distribution of the transmission line by etching different structures on the microstrip line. The introduction of this structure can change the distribution effect of the transmission line, thereby producing good stopband characteristics and slow-wave characteristics. Compared with other structures, the defective ground structure can achieve good band-stop characteristics without increasing the number of components, which is very beneficial for the design of circuits such as filters. This structure can also realize transmission lines with high impedance characteristics, thereby greatly reducing the area of ​​the circuit, which is especially important for the miniaturization design of circuits. By combining the defective ground structure technology, the designed duplexer has good filtering characteristics and integration, and also has advantages such as small size. Substrate Integrated Suspension Line (SISL) is a new type of microwave millimeter wave transmission line structure. The manufacturing process of SISL is relatively simple and uses common multi-layer printed circuit board technology, so the cost is relatively low. The dielectric integrated suspension line combines the advantages of microstrip line and waveguide, can be integrated with other planar structure circuits, and has the advantages of high quality factor and low loss of traditional suspension line structure.

[0005] However, the stopband of the duplexer designed in the prior art is not wide enough and the insertion loss is relatively large. In some environments, the filter is required to have a good wide stopband and a small insertion loss. In addition, the transmission zeros of the two passbands of the existing duplexer are not enough, which makes the out-of-band suppression effect of the duplexer limited, and the filtering performance needs to be further improved. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes a duplexer based on SISL and DGS, the duplexer comprising: five dielectric substrates arranged in sequence from top to bottom, namely sub1-sub5; the upper surface and the lower surface of each dielectric substrate are covered with a metal layer, and there are ten metal layers G1-G10 from top to bottom; three rectangular parts are cut off from the edges of the dielectric substrate sub1 and the dielectric substrate sub2, and the dielectric substrate sub1 and the dielectric substrate sub2 overlap; the five dielectric substrates and the ten metal layers are provided with a first square array of metal through holes, and the square array of metal through holes in each dielectric substrate and each metal layer overlap; two G-shaped DGS resonators are arranged in the metal layer G2.

[0007] Preferably, a second square array of metal through holes is arranged around the two G-shaped DGS resonators in the metal layer G2.

[0008] Preferably, three GCPW transition to T-shaped feeding structures are provided on the metal layer G5.

[0009] Furthermore, the GCPW transition to the T-shaped feeding structure includes a GCPW structure, a transition structure and a T-shaped feeding branch; the GCPW structure is arranged directly below the rectangular portion cut off from the edge of the dielectric substrate sub1; the T-shaped feeding branch is connected to the GCPW structure through the transition structure, and the T-shaped feeding branch is located inside the metal through-hole square array.

[0010] Preferably, an air cavity is disposed in the middle of both the dielectric substrate sub2 and the dielectric substrate sub4. The air cavity is inside the square array of metal through holes, and the air cavity of the dielectric substrate sub4 overlaps with the air cavity of the dielectric substrate sub2.

[0011] Preferably, a stepped impedance suspended line resonator with a center-loaded short-circuit branch is provided on the metal layer G6.

[0012] Preferably, fixed through holes are provided on the five-layer dielectric substrate and the ten-layer metal layer for fixing the duplexer.

[0013] The beneficial effects of the present invention are as follows: the duplexer designed by the present invention uses a G-shaped DGS resonator and a suspension line resonator to realize dual passbands. The transmission zero point is introduced by source-load coupling, so that the passband has high selectivity and better filtering performance. By adjusting the size of the G-shaped DGS resonator, the center frequency of the second passband can be adjusted. By adjusting the size of the suspension line resonator, the center frequency of the first passband can be adjusted; the duplexer designed by the present invention has better out-of-band suppression effect of the dual passband, smaller size and wider stopband range. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a layered schematic diagram of a duplexer based on SISL and DGS in the present invention;

[0015] Figure 2 A top view of the stacking of the G1, G2 and sub1 layers of the duplexer of the present invention;

[0016] Figure 3 A top view of the stacking of the G3, G4 and sub2 layers of the duplexer of the present invention;

[0017] Figure 4 A top view of the stacking of the G5, G6 and sub3 layers of the duplexer of the present invention;

[0018] Figure 5 A top view of the stacking of the G7, G8 and sub4 layers of the duplexer of the present invention;

[0019] Figure 6 A top view of the stacking of the G9, G10 and sub5 layers of the duplexer of the present invention;

[0020] Figure 7 This is a simulation result diagram of the duplexer in the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The present invention proposes a duplexer based on SISL and DGS, such as Figure 1 As shown, the duplexer includes: five dielectric substrates arranged in sequence from top to bottom, namely sub1-sub5; the upper surface and the lower surface of each dielectric substrate are covered with a metal layer, and there are ten metal layers G1-G10 from top to bottom, and the metal layers covering the upper and lower surfaces of the dielectric substrates are exactly the same in shape and size as the corresponding dielectric substrates.

[0023] The top view of the stack of each dielectric layer and the metal layer it covers is shown in Figure 2-Figure 6 As shown; three rectangular parts are cut off from the edges of the dielectric substrate sub1 and the dielectric substrate sub2, and the dielectric substrate sub1 and the dielectric substrate sub2 overlap; the five dielectric substrates and the ten metal layers are provided with a first metal through-hole square array, and each dielectric substrate and each metal layer square array of metal through holes overlap; two G-shaped DGS resonators are provided in the metal layer G2. The G-shaped DGS resonator designed by the present invention can reduce losses, and the size of the device can be reduced by bending the DGS resonator into a G shape, thereby achieving miniaturization.

[0024] The multi-layer dielectric substrates of the duplexer are stacked and assembled to form a dielectric integrated suspension line. The uppermost and lowermost dielectric substrates and metallized through holes connected up and down around form a metal shielding structure, which reduces radiation loss.

[0025] Preferably, a second square array of metal through holes is arranged around the two G-shaped DGS resonators in the metal layer G2 to form an integrated DGS and reduce the radiation loss of the G-shaped DGS resonator.

[0026] Preferably, three GCPW transition to T-shaped feeding structures are arranged on the metal layer G5. The GCPW transition to T-shaped feeding structure includes a GCPW structure, a transition structure and a T-shaped feeding branch; the GCPW structure is arranged directly below the rectangular portion cut off from the edge of the dielectric substrate sub1, the T-shaped feeding branch is connected to the GCPW structure through the transition structure, and the T-shaped feeding branch is located inside the square array of metal through holes.

[0027] like Figure 2-Figure 4 As shown, in the duplexer, three rectangular parts are cut off from the edges of the dielectric substrate sub1 and the dielectric substrate sub2, and there are three GCPW transitions to T-shaped feeding structures set on the corresponding metal layer G5; the metal layer G5 has one input port and two output ports, that is, one GCPW structure is used as an input port, and the other two GCPW structures are used as output ports, and the two ports are on the same straight line.

[0028] Preferably, an air cavity is provided in the middle of the dielectric substrate sub2 and the dielectric substrate sub4, the air cavity is inside the square array of metal through holes, and the air cavity of the dielectric substrate sub4 overlaps with the air cavity of the dielectric substrate sub2; preferably, the air cavity is a cavity formed by removing a rectangular dielectric substrate from the middle of the original dielectric substrate.

[0029] Preferably, a step impedance suspension line resonator with a center-loaded short-circuit branch is provided on the metal layer G6, and the resonator is used to generate a low-frequency filtering passband.

[0030] Preferably, fixed through holes are provided on the five-layer dielectric substrate and the ten-layer metal layer for fixing the duplexer.

[0031] The working principle of the duplexer is as follows: the input signal is transferred to the input T-shaped branch of SSL through the structural GCPW, the T-shaped feeding structure located in the G5 layer couples and transmits energy to the G-shaped DGS resonator located in the G2 metal layer through the upper air cavity, the G-shaped DGS resonators transmit energy through coupling, the G-shaped DGS resonator couples energy to the T-shaped branch of output port 2 through the air cavity, and finally transitions to the GCPW of output port 2, the entire transmission forms the second passband, the T-shaped feeding of input port 1 transfers energy to the step impedance resonator of the center-loaded short-circuit branch of the G6 layer through coupling, the resonator couples energy to the T-shaped feeding end of output port 3, the entire transmission forms the first passband, two T-shaped feeding structures are used to introduce source-load coupling, a transmission zero is introduced on the left side of the first passband and the second passband, and two transmission zeros are introduced on the right side of the passband to achieve higher selectivity. The center frequency of the second passband can be adjusted by the overall length of the G-shaped DGS resonator, while the center frequency of the first passband can be adjusted by the overall length of the suspension line resonator.

[0032] The simulation results of the dual-frequency filter are shown in Figure 7 As shown in the simulation results, it can be seen that the first filter passband is 1.95-3.09GHz, the second filter passband is 4.93-5.41GHz, and a transmission zero is introduced in the lower stopband of the first / second passband, and two transmission zeros are introduced in the upper stopband. The input return loss (S11) in the two passbands is better than 20dB, and the insertion loss (S21) of the two passbands is better than 0.03dB and 0.36dB respectively. The overall stopband reaches 12GHz below -20dB (4.9f0, f0 is the center frequency of the first passband) and the overall center circuit size is 15mm*14mm (0.12λ g *0.115λ g ), the isolation between output port 2 and output port 3 is also lower than -28dB, it can be seen that the simulation example of the present invention has excellent out-of-band suppression performance, smaller circuit size and wider stopband range. Compared with the simulation effect of the duplexer of the same dielectric integrated suspension line document "A High Isolationand Low Loss Duplexer Based on SISL Platform", the structure of the present invention has better out-of-band suppression effect, smaller size and wider stopband range.

[0033] In summary, the duplexer designed by the present invention based on the suspended line resonator and the integrated DGS realizes a wide stopband effect in the S parameter, and introduces three transmission zeros in the transmission coefficient of each passband, which greatly improves the selectivity of the dual passband; the circuit is placed on the G2 layer and a 3D stacked resonator structure is adopted, so that the duplexer is smaller in size under the same performance conditions, and the present invention has better performance.

[0034] The above embodiments further illustrate the purpose, technical solutions and advantages of the present invention in detail. It should be understood that the above embodiments are only preferred implementation modes of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A duplexer based on SISL and DGS, characterized in that: include: The five dielectric substrates arranged in sequence from top to bottom are sub1-sub5 respectively; the upper surface and the lower surface of each dielectric substrate are covered with metal layers, and there are ten metal layers G1-G10 from top to bottom; three rectangular parts are cut off from the edges of the dielectric substrate sub1 and the dielectric substrate sub2, and the dielectric substrate sub1 and the dielectric substrate sub2 overlap; the five dielectric substrates and the ten metal layers are provided with a first metal through-hole square array penetrating therethrough, and the metal through-hole square arrays of each dielectric substrate and each metal layer overlap; two G-shaped DGS resonators are arranged in the metal layer G2.

2. A duplexer based on SISL and DGS according to claim 1, characterized in that: A second square array of metal through holes is arranged around the two G-shaped DGS resonators in the metal layer G2.

3. The duplexer based on SISL and DGS according to claim 1, characterized in that: Three GCPW transition to T-shaped feeding structures are arranged on the metal layer G5.

4. A duplexer based on SISL and DGS according to claim 3, characterized in that: The GCPW transition to the T-shaped feeding structure includes a GCPW structure, a transition structure and a T-shaped feeding branch; the GCPW structure is arranged directly below the rectangular part cut off from the edge of the dielectric substrate sub1, the T-shaped feeding branch is connected to the GCPW structure through the transition structure, and the T-shaped feeding branch is located inside the metal through-hole square array.

5. The duplexer based on SISL and DGS according to claim 1, characterized in that: An air cavity is disposed in the middle of both the dielectric substrate sub2 and the dielectric substrate sub4. The air cavity is inside the square array of metal through holes, and the air cavity of the dielectric substrate sub4 overlaps with the air cavity of the dielectric substrate sub2.

6. The duplexer based on SISL and DGS according to claim 1, characterized in that: A step impedance suspended line resonator with a center-loaded short-circuit branch is arranged on the metal layer G6.

7. The duplexer based on SISL and DGS according to claim 1, characterized in that: Fixed through holes are arranged on the five-layer dielectric substrate and the ten-layer metal layer for fixing the duplexer.

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