CN115347342A

CN115347342A - Branch coupler

Info

Publication number: CN115347342A
Application number: CN202110518992.7A
Authority: CN
Inventors: 阙郁智
Original assignee: Nanning Fulian Fugui Precision Industrial Co Ltd
Current assignee: Nanning Fulian Fugui Precision Industrial Co Ltd
Priority date: 2021-05-12
Filing date: 2021-05-12
Publication date: 2022-11-15

Abstract

A branch coupler is suitable for a radio frequency circuit and is characterized by comprising an input end, a first output end, a second output end, an isolation end, a first transmission line, a second transmission line, a first bent branch line and a second bent branch line. The first transmission line is electrically connected between the input end and the first output end and is provided with two open-circuit branch nodes. The second transmission line is electrically connected between the isolation end and the second output end and is provided with two open-circuit branch nodes. The first bending branch line is electrically connected between the input end and the isolation end. The second bending branch line is electrically connected between the first output end and the second output end. The two open circuit branch nodes of the first transmission line and the second transmission line are in a fishbone structure.

Description

Branch coupler

Technical Field

The invention relates to a branch coupler.

Background

In the prior art, microwave circuits typically use directional couplers to address the problems associated with distributing power. With the development of mobile communication technology and satellite communication technology, miniaturization of communication devices is becoming more and more important for portability and mobility. However, the conventional 3dB branch coupler occupies a large circuit board area. Therefore, how to reduce the area of the branch coupler and maintain its performance is a problem to be solved.

Disclosure of Invention

In view of the above, a miniaturized branch coupler is needed to meet the requirements of communication technology, so as to optimize the design of communication products.

The invention provides a branch coupler which is suitable for a radio frequency circuit and is characterized by comprising an input end, a first output end, a second output end, an isolation end, a first transmission line, a second transmission line, a first bent branch line and a second bent branch line. The first transmission line is electrically connected between the input end and the first output end and is provided with two open-circuit branch nodes. The second transmission line is electrically connected between the isolation end and the second output end and is provided with two open-circuit stubs. The first bending branch line is electrically connected between the input end and the isolation end. The second bending branch line is electrically connected between the first output end and the second output end.

According to an embodiment of the present invention, the first bending branch line has a first segment, a second segment and a first U-shaped section interposed between the first segment and the second segment, and the second bending branch line has a third segment, a fourth segment and a second U-shaped section interposed between the third segment and the fourth segment.

According to another embodiment of the present invention, the widths of the first, second, third and fourth sections are greater than the widths of the first and second "U" -shaped sections.

According to another embodiment of the present invention, the opening direction of the first U-shaped section is opposite to the opening direction of the second U-shaped section.

According to another embodiment of the present invention, the two open-circuit stubs of the first and second strip-shaped transmission lines are fishbone-shaped structures.

According to another embodiment of the present invention, the two open-circuit stubs of the first strip-shaped transmission line and the second strip-shaped transmission line are symmetrical along a central vertical line.

According to another embodiment of the present invention, the fishbone structure has one vertical section and four horizontal sections.

According to another embodiment of the invention, the width of the horizontal section at the end of the fishbone is larger than the width of the other horizontal sections.

According to another embodiment of the present invention, the first bent branch line and the second bent branch line are 50 ohm microstrip lines.

According to another embodiment of the present invention, the first and second elongated transmission lines are 53.35 ohm microstrip lines.

Drawings

Fig. 1 is a schematic structural diagram of a branch coupler according to an embodiment of the present invention.

Fig. 2 is a schematic structural dimension diagram of a branch coupler according to an embodiment of the invention.

Fig. 3 is a simulation graph of the S-parameter of the branch coupler according to an embodiment of the invention.

Fig. 4 is a diagram illustrating the phase difference between the first output terminal and the second output terminal of the branch coupler according to an embodiment of the invention.

Fig. 5 is a graph illustrating the difference between the output amplitudes of the first output terminal and the second output terminal of the branch coupler according to an embodiment of the present invention.

Description of the main elements

Axes of symmetry Ax1, ax2

Structural dimensions D1-D12

Input terminal P1

First output terminal P2

Second output terminal P3

Isolated terminal P4

Transmission line segments S1-S6

First open-circuit stubs St1, st2

Second open-circuit stubs St3, st4

First transmission line T1

Second transmission line T2

First bending branch line T3

Second bending branch line T4

Detailed Description

Further areas of applicability of the present systems and methods will become apparent from the detailed description provided hereinafter. It should be understood that the following detailed description and specific examples, while indicating exemplary embodiments of the branch coupler, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a branch coupler according to an embodiment of the invention. In the embodiment of the present invention, the branch coupler 100 is axisymmetric based on the Ax1 axis and the Ax2 axis. As shown in fig. 1, the branch coupler 100 at least includes an input end P1, a first output end P2, a second output end P3, an isolation end P4, a first transmission line T1, a second transmission line T2, a first bent branch line T3, and a second bent branch line T4. The transmission line configurations of the input end P1, the first output end P2, the second output end P3 and the isolation end P4 in fig. 1 can select transmission lines with different impedances according to the port matching requirements of users, and the configuration structure of the ports is not limited by the present invention and can be defined according to actual use.

The first transmission line T1 is electrically connected between the input end P1 and the first port P2, and the second transmission line T2 is electrically connected between the second port P3 and the isolation end P4. In addition, the first transmission line T1 has a first open stub St1 and a first open stub St2, and the first open stub St1 and the first open stub St2 are axisymmetric based on the Ax 1. The second transmission line T2 has a second open stub St3 and a second open stub St4, and the second open stub St3 and the second open stub St4 are also axisymmetric based on Ax 1. In addition, the first transmission line T1 and the second transmission line T2 are axisymmetrical based on Ax2, and the first open branch St1, the first open branch St2, the second open branch St3, and the second open branch St4 are all disposed between the first transmission line T1 and the second transmission line T2.

The third bending branch line T3 is electrically connected between the input end P1 and the isolation end P4, and the fourth bending branch line T4 is electrically connected between the first port P3 and the second port P4. The third bending branch T3 has a first segment S1, a second segment S2 and a first U-shaped segment S10, and the fourth bending branch T4 has a third segment S3, a fourth segment S4 and a second U-shaped segment S20. Wherein, the third bending branch line T3 and the fourth bending branch line T4 are axisymmetric based on Ax 1. In addition, the first "U" -shaped section S10 of the third branch T3 and the second "U" -shaped section S20 of the fourth branch T4 have open/closed surfaces. In other words, the first "U" -shaped section S10 has the second "U" -shaped section S20 with opposite open/close directions. It should be noted that the "U" shaped region structure of the third bending branch T3 and the fourth bending branch T4 is not intended to limit the present invention, and it is consistent with the spirit of the present invention as long as the area of the coupler is reduced by bending. In addition, according to an embodiment of the present invention, the transmission line may be a microstrip line or other transmission lines.

According to an embodiment of the present invention, the first transmission line T1 and the second transmission line T2 are equivalent to 35.35 ohm transmission lines, and the third meander branch line T3 and the fourth meander branch line T4 are equivalent to 50 ohm transmission lines. It should be noted that the selection of the transmission line parameters may be adaptively selected according to the impedance matching, and the invention is not limited thereto.

Fig. 2 is a schematic structural dimension diagram of a branch coupler according to an embodiment of the invention. As shown in fig. 2, a length D1 between the input terminal P1 and the first output terminal P2 is smaller than a length D2 between the input terminal P1 and the isolation terminal P4. The line width of the first U-shaped section S10 is smaller than the line widths of the first section S1 and the second section S2. The fishbone-shaped structures of the first open branch section St1, the first open branch section St2, the second open branch section St3 and the second open branch section St4 all have a trunk perpendicular to the first transmission line T1 and the second transmission line T2, and four branches perpendicular to the trunk, one end of the trunk of the first open branch section St1 and the first open branch section St2 is connected with the main body of the first transmission line T1, and the other end is connected with one of the four branches. The line width of the branch connected to the tail end of the main body is larger than the line widths of the remaining three branches.

According to an embodiment of the present invention, the length D1 between the input end P1 and the first output end P2 is preferably 4.48mm, and the length D2 between the input end P1 and the isolation end P4 is preferably 4mm5.32mm. The line width between the first open stub St1 and the first port and the line width between the first open stub St2 and the first output port are both 0.46mm. The total length D7 of the first open branch St1, the first open branch St2, the second open branch St3, and the second open branch St4 is 1.67mm, the line width D8 of the trunk is 0.2mm, and the lengths D6 of the four branches are all 1.2mm. The line width D10 of the branch connected to the end of the trunk was 0.47mm, and the line widths D9 of the remaining three branches were 0.2mm. In addition, the line widths D4 of the first open branch St1 and the first open branch St2 on the first transmission line T1 are both 0.25mm, and the distance D5 therebetween is 1.42mm. The first "U" shaped section S10 has an open inner width D11 of 0.2mm and an outer width D12 of 0.7mm. It should be noted that, since the structure of the second transmission line T2 is identical and symmetrical to the first transmission line T1, and the structure of the second bent branch line T4 is identical and symmetrical to the first bent branch line T3, the structure size of the second transmission line T2 is identical to the structure size of the first transmission line T1, and the structure size of the second bent branch line T4 is identical to the structure size of the first bent branch line T3, which is not repeated herein for brevity. In addition, in the embodiment of fig. 2, the area size of the branch coupler is 4.48mm × 6.24mm =27.9552mm ² And the area size of the traditional branch coupler is 7.4mm multiplied by 9.14mm =67.636mm ² The area of the branch coupler of the present invention is saved by 58.7% compared to the area of the branch coupler of the present invention.

Fig. 3 is a simulation graph of S-parameters of a branch coupler according to an embodiment of the invention. As can be seen from FIG. 3, the attenuation of the branch coupler S11 of the present invention is greater than 10dB, which is approximately 4.6GHz-6.4GHz, corresponding to a center frequency of 5.5GHz. S12, S13 have a 3dB power loss in the frequency band. The parameters S22, S33, and S44 of the first output terminal, the second output terminal, and the isolation terminal are similar to the input terminal S11, and are not shown in the drawings. According to the content of fig. 3, the branch coupler of the present invention can be implemented with similar effect as the conventional branch coupler.

Fig. 4 is a diagram illustrating the phase difference between the first output terminal P2 and the second output terminal P3 of the branch coupler according to an embodiment of the invention. As can be seen from the curve C1 in fig. 4, the first output port P2 and the second output port P3 of the branch coupler of the present invention have a smaller output phase difference in the frequency band of 4.9GHz-6.2GHz, specifically, the output phase difference between the first output port P2 and the second output port P3 is less than 10 °.

Fig. 5 is a diagram illustrating the difference between the output amplitudes of the first output terminal P2 and the second output terminal P3 of the branch coupler according to an embodiment of the invention. As can be seen from the curve C2 in fig. 5, the first output end P2 and the second output end P3 of the branch coupler of the present invention have a smaller amplitude output difference between the frequency bands of 4.9GHz to 6.2GHz, specifically, the output amplitude difference between the first output end P2 and the second output end P3 is smaller than 2dB.

In summary, the branch coupler according to some embodiments of the present invention is formed by using the transmission line with a bent shape, so as to reduce an area by 58.7% compared to the conventional branch coupler. In addition, the branch coupler has better performance in a frequency band of 4.6GHz-6.4GHz, S11 attenuation is larger than 10dB, and the output amplitude and the phase difference of the two output ports are smaller. After overcoming the defect that the prior art occupies a large area of the PCB, the PCB has better characteristics and is suitable for being applied to mobile communication products.

It should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A branch coupler for use in radio frequency circuits, said branch coupler comprising:

an input end;

a first output terminal;

a second output terminal;

an isolation end;

the first transmission line is electrically connected between the input end and the first output end and is provided with two first open-circuit branch sections;

the second transmission line is electrically connected between the isolation end and the second output end and is provided with two second open-circuit branch nodes;

the first bending branch line is electrically connected between the input end and the isolation end; and

and the second bending branch line is electrically connected between the first output end and the second output end, wherein the first open branch knot and the second open branch knot are fishbone-shaped structures.

2. The branch coupler of claim 1, wherein the first bent branch line has a first section, a second section, and a first "U" shaped section between the first section and the second section, and the second bent branch line has a third section, a fourth section, and a second "U" shaped section between the third section and the fourth section.

3. The branch coupler of claim 2, wherein the widths of the first, second, third and fourth sections are greater than the widths of the first and second "U" -shaped sections.

4. The branch coupler of claim 3, wherein the opening direction of the first "U" shaped section is opposite to the opening direction of the second "U" shaped section.

5. The branch coupler of claim 1, wherein the first open stub and the second open stub are symmetrical along a central vertical line.

6. The branch coupler of claim 1, wherein the fishbone structure has one vertical section and four horizontal sections.

7. The branch coupler of claim 1, wherein the horizontal section at the end of the fishbone has a width greater than the width of the other horizontal sections.

8. The branch coupler of claim 1, wherein the first meander-shaped branch line and the second meander-shaped branch line are 50 ohm microstrip lines.

9. The branch coupler of claim 1, wherein the first transmission line and the second transmission line are 53.35 ohm microstrip lines.