A broadband bandpass filter power divider structure based on coupled lines

Abstract

This invention relates to a broadband bandpass filter power divider structure based on coupled lines, comprising: a first branch, a second branch, and several isolation networks. The input ports of both the first and second branches are connected to the input ports of the filter power divider. The output port of the first branch serves as the first output port of the filter power divider, and the output port of the second branch serves as the second output port of the filter power divider. Both the first and second branches are formed by cascading N segments of diagonally open-ended coupled lines, and the coupled lines of the same level in the first and second branches are connected by isolation networks, where N is a positive integer greater than or equal to 1. This broadband bandpass filter power divider structure can obtain a broadband bandpass filter response, and also has DC-Block functionality and full-band isolation characteristics. It helps reduce the number of functional components in a wireless communication system, thereby improving system integration, and can reduce interconnect insertion losses and mismatch effects, thereby improving system reliability.

Description

Technical Field

[0001] This invention belongs to the field of microwave passive device technology, specifically relating to a broadband bandpass filter power divider structure based on a coupled line. Background Technology

[0002] With the development of radio frequency (RF) communication technology, its application in wireless communication systems is increasingly trending towards miniaturization and integration, driving the development of RF microwave devices towards high integration. Filters and power dividers are two crucial passive microwave devices in wireless communication systems, and their performance and size constrain the overall system performance and integration. The traditional approach involves miniaturizing these two devices separately and then cascading them together via cables or RF connectors. While this reduces system size to some extent, the overall improvement is limited, and this method introduces additional insertion loss and mismatch effects. Therefore, integrating filters and power dividers into a single, unified design, simultaneously achieving filtering and power distribution, not only reduces the overall system size and design costs but also minimizes losses and mismatches, thereby improving system performance.

[0003] While there have been reports of integrated power divider and filter designs, current technology for implementing filter power dividers has limitations in bandwidth and cannot simultaneously achieve simple structure, good frequency selectivity and port matching, and high isolation, making it unsuitable for use in today's wireless communication systems where frequency resources are increasingly scarce. Therefore, proposing a filter power divider that combines wide bandwidth and high isolation is particularly important. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a broadband bandpass filter power divider structure based on coupled lines. The technical problem to be solved by this invention is achieved through the following technical solution:

[0005] This invention provides a broadband bandpass filter power divider structure based on coupled lines, comprising: a first branch, a second branch, and several isolation networks, wherein...

[0006] The input ports of the first branch and the second branch are both connected to the input ports of the filter power divider. The output port of the first branch serves as the first output port of the filter power divider, and the output port of the second branch serves as the second output port of the filter power divider.

[0007] The first branch and the second branch are both formed by cascading N segments of diagonally open-ended coupling lines, and are connected between the same-level coupling lines of the first branch and the second branch through the isolation network, where N is a positive integer greater than or equal to 1.

[0008] In one embodiment of the present invention, the power divider is a two-way equal-division power divider.

[0009] In one embodiment of the present invention, the coupling line is implemented in the form of parallel line coupling or wide-side coupling.

[0010] In one embodiment of the present invention, the electrical length of the coupling line is 0° to 90°.

[0011] In one embodiment of the present invention, the coupling line includes a first transmission line and a second transmission line, wherein,

[0012] The first transmission line and the second transmission line are arranged in parallel.

[0013] In each stage of coupling line, the first end of the second transmission line is open-circuited. The first end of the first transmission line in the first stage of coupling line is connected to the input port of the filter power divider. In the 2nd to Nth stage coupling lines, the first end of the first transmission line is connected to the second end of the second transmission line in the previous stage coupling line. The second end of the second transmission line in the Nth stage coupling line serves as the output port.

[0014] In the same-level coupling line, the first transmission line of the first branch and the first transmission line of the second branch are connected through the isolation network.

[0015] In one embodiment of the present invention, the first transmission line and the second transmission line are both in the form of one or more of microstrip lines, striplines, dielectric integrated waveguides, and dielectric integrated suspension lines.

[0016] In one embodiment of the invention, the isolation network includes a resistor, wherein,

[0017] One end of the resistor is connected to the second end of the first transmission line in the first branch, and the other end is connected to the second end of the first transmission line in the second branch.

[0018] In one embodiment of the present invention, the isolation network includes a resistor, a capacitor, and an inductor, wherein,

[0019] The resistor, the capacitor, and the inductor are connected in series, with one end of the series circuit connected to the second end of the first transmission line in the first branch and the other end connected to the second end of the first transmission line in the second branch.

[0020] In one embodiment of the present invention, the isolation network includes a resistor, a capacitor, and an inductor, wherein,

[0021] The resistor, the capacitor, and the inductor are connected in parallel, with one end of the parallel circuit connected to the second end of the first transmission line in the first branch and the other end connected to the second end of the first transmission line in the second branch.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] In the power divider structure of this invention, the first and second branches are formed by cascading N coupling lines. The operating bandwidth of the power divider can be expanded by increasing the number of coupling line stages in the two branches. The open-circuit coupling line at the diagonal end of each stage adds DC-Block functionality and full-band isolation characteristics to the power divider. The inherent bandpass response of the coupling line brings a broadband bandpass filter response to the power divider. Therefore, this broadband bandpass filter power divider structure based on coupling lines is not only simple in structure, but also obtains a broadband bandpass filter response, and has DC-Block functionality and full-band isolation characteristics. It helps to reduce the number of functional devices in the wireless communication system, thereby improving the system integration, and can reduce the impact of interconnect insertion loss and mismatch, thereby improving the system reliability. Attached Figure Description

[0024] Figure 1 A circuit schematic diagram of a broadband bandpass filter power divider structure based on a coupled line is provided for an embodiment of the present invention.

[0025] Figures 2a-2c A circuit structure diagram of an isolation network provided in an embodiment of the present invention;

[0026] Figure 3 A circuit schematic diagram of another broadband bandpass filter power divider structure based on coupled lines provided in this embodiment of the invention;

[0027] Figure 4 A circuit diagram of a three-stage cascaded broadband bandpass filter power divider structure provided in an embodiment of the present invention;

[0028] Figure 5 Return loss and transmission loss curves of a simulated three-stage coupled-line broadband bandpass filter power divider provided in an embodiment of the present invention;

[0029] Figure 6 The output port isolation curve is shown in the simulation diagram of the three-stage coupled-line broadband bandpass filter power divider provided in the embodiment of the present invention. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0031] Example 1

[0032] Please see Figure 1 , Figure 1 The circuit diagram shows a broadband bandpass filter power divider structure based on a coupled line, provided for an embodiment of the present invention.

[0033] The broadband bandpass filter power divider structure based on coupled lines includes a first branch, a second branch, and several isolation networks. The input ports of the first branch and the second branch are both connected to the input port 1 of the filter power divider. The output port of the first branch serves as the first output port 2 of the filter power divider, and the output port of the second branch serves as the second output port 3 of the filter power divider. The first branch and the second branch are both formed by cascading N segments of coupled lines with open diagonal terminals. The coupled lines of the same level in the first branch and the second branch are connected by isolation networks, where N is a positive integer greater than or equal to 1.

[0034] Specifically, the input power of the power divider is input to the first branch and the second branch, where it is split into two paths and output from the output terminals of the first and second branches respectively. The power of the first and second branches can be equal or unequal. For example, if the power of the first and second branches is equal, then the power divider is a two-way equal-splitting power divider.

[0035] Specifically, the number of coupling lines in the first and second branches is at least one segment. When the number of coupling lines is greater than or equal to two segments, multiple coupling lines are cascaded sequentially. There is a one-to-one correspondence between the N coupling lines in the first branch and the N coupling lines in the second branch, and coupling lines of the same level in the two branches are connected by isolation networks. Multi-level coupling lines are connected by multiple isolation networks. It can be understood that the number of coupling lines in the first branch, the number of coupling lines in the second branch, and the number of isolation networks are all equal.

[0036] Specifically, each coupling line has two parallel transmission lines, and each transmission line has two ports. In this embodiment, one set of diagonal ports of the two transmission lines is open-circuited, and the other set of diagonal ports is used to connect the coupling lines, thereby realizing a coupling line with open-circuited diagonal terminals. Furthermore, the open-circuited ports of the first branch and the second branch are connected through an isolation network to achieve isolation between the first branch and the second branch.

[0037] In one specific embodiment, the coupling line includes a first transmission line and a second transmission line. The first and second transmission lines are arranged in parallel. In each stage of the coupling line, the first end of the second transmission line is open-circuited. The first end of the first transmission line in the first stage of the coupling line is connected to the input port of the filter power divider. The first end of the first transmission line in the 2nd to Nth stage coupling lines is connected to the second end of the second transmission line in the previous stage coupling line. The second end of the second transmission line in the Nth stage coupling line serves as the output port. In coupling lines of the same stage, the first transmission line of the first branch and the first transmission line of the second branch are connected through an isolation network.

[0038] Specifically, for the first branch, the first end of the first transmission line in the first-stage coupling line is connected as the input port of the first branch to the input port 1 of the filter power divider, and the second end of the second transmission line in the Nth-stage coupling line is connected as the output port of the first branch to the first output port 2 of the filter power divider. For the second branch, the first end of the first transmission line in the first-stage coupling line is connected as the input port of the second branch to the input port 1 of the filter power divider, and the second end of the second transmission line in the Nth-stage coupling line is connected as the output port of the second branch to the second output port 3 of the filter power divider. In the same-stage coupling line, the second ports of the first transmission lines in the two branches are connected through an isolation network.

[0039] In one specific embodiment, the coupling line is implemented in the form of parallel line coupling or wide-side coupling.

[0040] Specifically, parallel-line coupling refers to the first and second transmission lines being located on the same layer and arranged in parallel. Wide-edge coupling refers to the first and second transmission lines being located on opposite upper and lower layers, with the two transmission lines partially or completely overlapping.

[0041] In one specific embodiment, both the first transmission line and the second transmission line can be one or more of the following: microstrip line, stripline, dielectric integrated waveguide, and dielectric integrated suspension line.

[0042] It should be noted that the form of the first transmission line and the second transmission line is not limited to the above-mentioned transmission line forms, and can also be any other transmission line forms.

[0043] In one specific embodiment, the electrical length of the coupling line is 0° to 90°.

[0044] Specifically, in the two branches of the filter power divider, the odd-mode impedances of the coupling lines from the first stage to the Nth stage are Z0 and Z1 respectively. 1o Z 2o ...Z io ...Z No The even-mode impedances of the coupling lines from the first stage to the Nth stage are respectively Z 1e Z 2e ...Z ie ...Z Ne The electrical lengths of the coupling lines from the first stage to the Nth stage are θ1, θ2, ..., θ3, respectively. i ……θ N , where i is a positive integer greater than or equal to 1 and less than or equal to N. The electrical length of the coupling line ranges from 0° to 90°, and based on this, the odd-mode impedance and even-mode impedance are optimized.

[0045] Please see Figures 2a-2c , Figures 2a-2cThe circuit structure diagram of the isolation network provided in the embodiment of the present invention.

[0046] like Figure 2a As shown, the isolation network includes a resistor, wherein one end of the resistor is connected to the second end of the first transmission line in the first branch, and the other end of the resistor is connected to the second end of the first transmission line in the second branch.

[0047] like Figure 2b As shown, the isolation network includes a resistor, a capacitor, and an inductor, wherein the resistor, capacitor, and inductor are connected in series, and one end of the series circuit, i.e. the end of the resistor, is connected to the second end of the first transmission line in the first branch, and the other end of the series circuit, i.e. the end of the inductor, is connected to the second end of the first transmission line in the second branch.

[0048] like Figure 2c As shown, the isolation network includes a resistor, a capacitor, and an inductor, wherein the resistor, capacitor, and inductor are connected in parallel, and one end of the parallel circuit is connected to the second end of the first transmission line in the first branch, and the other end is connected to the second end of the first transmission line in the second branch.

[0049] It should be noted that for a broadband bandpass filter power divider structure based on coupled lines, the isolation network can adopt any of the three forms mentioned above, such as... Figure 3 As shown, Figure 3 The circuit diagram shows another broadband bandpass filter power divider structure based on coupled lines provided in this embodiment of the invention; any two or all three forms mentioned above can also be used, and this embodiment does not impose further restrictions.

[0050] In the power divider structure of this embodiment, the first and second branches are formed by cascading N coupling lines. The operating bandwidth of the power divider can be expanded by increasing the number of coupling line stages in the two branches. The open-circuit coupling line at the diagonal end of each stage adds DC-Block functionality and full-band isolation characteristics to the power divider. The inherent bandpass response of the coupling line brings a broadband bandpass filter response to the power divider. Therefore, this broadband bandpass filter power divider structure based on coupling lines is not only simple in structure, but also obtains a broadband bandpass filter response and has DC-Block functionality and full-band isolation characteristics. It helps to reduce the number of functional components in wireless communication systems, thereby improving system integration. It can reduce the impact of interconnect insertion loss and mismatch, thereby improving system reliability. It will be widely used in wireless communication systems.

[0051] Example 2

[0052] Based on Embodiment 1, this embodiment discloses a broadband bandpass filter power divider structure consisting of three cascaded coupling lines, such as... Figure 4 As shown, Figure 4The circuit diagram shows a three-stage cascaded broadband bandpass filter power divider structure provided in an embodiment of the present invention.

[0053] In this embodiment, the broadband bandpass filter power divider is a two-way equal-division power divider. Each of the two branches is composed of three cascaded coupling lines with open diagonal terminations. The odd-mode impedances of the three cascaded coupling lines are Z0, ... 1o Z 2o and Z 3o The even-mode impedances are Z 1e Z 2e and Z 3e The coupling lines of the two branches of the broadband bandpass filter power divider are connected by isolation resistors R1, R2, and R3, respectively. Specifically, the circuit parameter values ​​of the broadband bandpass filter power divider consisting of three cascaded coupling lines are as follows: Z 1o =201.7Ω, Z 2o =177.4Ω, Z 3o =149.1Ω; Z 1e =21.3Ω, Z 2e =18.2Ω, Z 3e =21.1Ω; θ1=θ2=θ3=90°; R1=178Ω, R2=220Ω, R3=300Ω.

[0054] Please see Figure 5 and Figure 6 , Figure 5 The return loss and transmission loss curves of the simulated three-stage coupled-line broadband bandpass filter power divider provided in the embodiment of the present invention are shown. Figure 6 The output port isolation curve is shown in the simulation diagram of the three-stage coupled-line broadband bandpass filter power divider provided in the embodiment of the present invention. Figure 5 and Figure 6 As can be seen, the three-stage coupled-line broadband bandpass filter power divider in this embodiment exhibits good bandpass and frequency selectivity in the 6GHz to 14GHz operating frequency band. The simulated input and output return losses are both better than 20dB, and it exhibits an isolation of more than 18dB across the entire frequency band.

[0055] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A broadband bandpass filter power divider structure based on coupled lines, characterized in that, include: The first branch road, the second branch road, and several isolation networks, among which, The input ports of the first branch and the second branch are both connected to the input ports of the filter power divider. The output port of the first branch serves as the first output port of the filter power divider, and the output port of the second branch serves as the second output port of the filter power divider. The first branch and the second branch are both formed by cascading N segments of diagonally open-ended coupling lines, and are connected by the isolation network between the same-level coupling lines of the first branch and the second branch, where N is a positive integer greater than or equal to 2. The coupling line includes a first transmission line and a second transmission line, wherein... The first transmission line and the second transmission line are arranged in parallel. In each stage of coupling line, the first end of the second transmission line is open-circuited. The first end of the first transmission line in the first stage of coupling line is connected to the input port of the filter power divider. In the 2nd to Nth stage coupling lines, the first end of the first transmission line is connected to the second end of the second transmission line in the previous stage coupling line. The second end of the second transmission line in the Nth stage coupling line serves as the output port. In the same-level coupling line, the first transmission line of the first branch and the first transmission line of the second branch are connected through the isolation network.

2. The broadband bandpass filter power divider structure based on coupled lines according to claim 1, characterized in that, The power divider is a two-way equal-division power divider.

3. The broadband bandpass filter power divider structure based on coupled lines according to claim 1, characterized in that, The coupling line can be implemented in the form of parallel line coupling or wide-side coupling.

4. The broadband bandpass filter power divider structure based on coupled lines according to claim 1, characterized in that, The electrical length of the coupling line is 0°~90°.

5. The broadband bandpass filter power divider structure based on coupled lines according to claim 1, characterized in that, Both the first transmission line and the second transmission line can be one or more of the following: microstrip line, stripline, dielectric integrated waveguide, and dielectric integrated suspension line.

6. The broadband bandpass filter power divider structure based on coupled lines according to claim 1, characterized in that, The isolation network includes resistors, wherein, One end of the resistor is connected to the second end of the first transmission line in the first branch, and the other end is connected to the second end of the first transmission line in the second branch.

7. The broadband bandpass filter power divider structure based on coupled lines according to claim 1, characterized in that, The isolation network includes resistors, capacitors, and inductors, wherein, The resistor, the capacitor, and the inductor are connected in series, with one end of the series circuit connected to the second end of the first transmission line in the first branch and the other end connected to the second end of the first transmission line in the second branch.

8. The broadband bandpass filter power divider structure based on coupled lines according to claim 1, characterized in that, The isolation network includes resistors, capacitors, and inductors, wherein, The resistor, the capacitor, and the inductor are connected in parallel, with one end of the parallel circuit connected to the second end of the first transmission line in the first branch and the other end connected to the second end of the first transmission line in the second branch.

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