Coplanar waveguide transmission structure

Abstract

The application discloses a coplanar waveguide transmission structure, comprising: a coplanar waveguide, comprising an upper metal layer, an intermediate dielectric layer, a lower metal layer and a bottom dielectric layer arranged in sequence from top to bottom, the upper metal layer is formed with a transmission line and an upper metal ground, the coplanar waveguide further comprises a first through hole and a second through hole extending in the up-down direction and a wiring groove arranged in the bottom dielectric layer, the wiring groove is communicated with the first through hole and the second through hole; a coaxial cable comprises an inner core, a middle layer dielectric and an outer conductor from inside to outside, the inner core of the first end of the coaxial cable is conductively connected with the transmission line through the first through hole, the outer conductor is conductively connected with the lower metal ground, and the second end of the coaxial cable is connected with a signal input piece to receive a transmission signal. The transmission structure of the application has low loss, small impedance mutation and high signal transmission efficiency, and the coplanar waveguide with the embedded coaxial cable strengthens the integration of the transmission structure.

Description

Technical Field

[0001] This application relates to the field of chip manufacturing technology, and in particular to a coplanar waveguide transmission structure. Background Technology

[0002] In recent years, with the development and popularization of 5G communication technology and consumer electronics technology, semiconductor devices have been continuously miniaturized and integrated, and their operating frequencies have been continuously increasing. Wafer-level testing for high frequencies has gradually become an indispensable part of RF chip production. Traditional coplanar waveguides cannot achieve high-frequency, low-loss transmission structures, making it difficult to meet the needs of wafer testing and analysis. Coaxial cables are a type of transmission line with ultra-low loss and wide bandwidth, but they are difficult to integrate with coplanar waveguides. Summary of the Invention

[0003] To address the challenges of integrating coplanar waveguides and coaxial cables in existing technologies, and the difficulty in meeting the requirements of high frequency and low loss, the purpose of this application is to provide a coplanar waveguide transmission structure.

[0004] To achieve the above objectives, this application adopts the following technical solution: a coplanar waveguide transmission structure, comprising: a coplanar waveguide and a coaxial cable.

[0005] The coplanar waveguide includes: an upper metal layer, an intermediate dielectric layer, a lower metal layer and a bottom dielectric layer arranged sequentially from top to bottom. The upper metal layer forms a transmission line and an upper metal ground separated from the transmission line. The coplanar waveguide has a first through-hole penetrating the intermediate dielectric layer and the lower metal layer, and a routing groove formed in the bottom dielectric layer, and the routing groove is connected to the first through-hole.

[0006] The coaxial cable includes an inner conductor, a middle dielectric layer, and an outer conductor arranged coaxially from the inside to the outside, and at least a portion of the coaxial cable is located within the cable tray;

[0007] The inner conductor of the first end of the coaxial cable passes through the first through hole and is electrically connected to the transmission line. The outer conductor is electrically connected to the lower metal ground. The second end of the coaxial cable is connected to a signal input device to receive the transmitted signal.

[0008] In the above technical solution, a further preferred embodiment is that the coplanar waveguide has a second through hole that simultaneously penetrates the upper metal layer, the intermediate dielectric layer, and the lower metal layer, the wiring groove is connected to the second through hole, and the second end of the coaxial cable is located in the second through hole.

[0009] In the above technical solution, it is further preferred that the signal input device is an RF connector, which is detachably connected to the second end of the coaxial cable.

[0010] In the above technical solution, a third through hole is further preferably formed on the lower metal layer, the third through hole is connected to the first through hole, and the diameter of the third through hole is larger than the diameter of the first through hole and smaller than the diameter of the outer conductor.

[0011] In the above technical solution, it is further preferred that the wiring groove is L-shaped or U-shaped.

[0012] In the above technical solution, it is further preferred that the diameter of the inner conductor is less than or equal to the line width of the transmission line.

[0013] In the above technical solution, a further preferred embodiment is that the coplanar waveguide is further provided with a plurality of metal vias connecting the upper metal layer, the intermediate dielectric layer and the lower metal layer.

[0014] In the above technical solution, it is further preferred that the distance from each of the metal through holes to the transmission line is equal, and the distance between two adjacent metal through holes is equal.

[0015] In the above technical solution, a further preferred embodiment is that an installation groove for installing the transmission line is formed on the upper metal ground, the installation groove is connected to the first through hole, and each of the metal through holes is arranged around the installation groove and is arranged on the periphery of the installation groove.

[0016] Compared with the prior art, this application achieves the following beneficial effects:

[0017] The transmission structure of this application is based on a coplanar waveguide to achieve a back-feed function. This transmission structure has low loss, small impedance change, and high signal transmission efficiency. The coplanar waveguide with embedded coaxial cable enhances the integration of the transmission structure, improves space advantage, and facilitates the docking of the coplanar waveguide with other structures. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a coplanar waveguide transmission structure provided in an embodiment of this application;

[0019] Figure 2 for Figure 1 Top view of the upper metal layer;

[0020] Figure 3 for Figure 1 A three-dimensional structural diagram of part of the transmission structure.

[0021] 100. Transmission structure; 1. Coplanar waveguide; 11. Upper metal layer; 111. Transmission line; 112. Upper metal ground; 1120. Mounting slot; 12. Intermediate dielectric layer; 13. Lower metal layer; 131. Lower metal ground; 14. Bottom dielectric layer; 15. First via; 16. Second via; 17. Trace groove; 18. Third via; 19. Metal via; 2. RF connector; 3. Coaxial cable; 31. Inner conductor; 32. Middle dielectric layer; 33. Outer conductor; 4. Screw. Detailed Implementation

[0022] To illustrate the technical content, structural features, achieved objectives, and effects of the application in detail, the technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. In the following description, for illustrative purposes, numerous specific details are set forth to provide a detailed description of various exemplary embodiments or implementations of the invention. However, various exemplary embodiments may also be implemented without these specific details or in one or more equivalent arrangements. Furthermore, the various exemplary embodiments may differ, but are not necessarily exclusive. For example, the specific shape, structure, and characteristics of the exemplary embodiments may be used or implemented in another exemplary embodiment without departing from the inventive concept.

[0023] In the following description, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0024] The terms "upper" and "lower" as used in this application are in accordance with the appendix. Figure 1 The top and bottom.

[0025] In this application, unless otherwise expressly specified and limited, the term "connection" shall be interpreted broadly. For example, "connection" may be a fixed connection, a detachable connection, or an integral part; it may be a direct connection or an indirect connection through an intermediate medium.

[0026] This application provides a coplanar waveguide transmission structure, such as... Figure 1 , 3 As shown, the transmission structure 100 includes a coplanar waveguide 1, a signal input device for transmitting signals, and a coaxial cable 3 disposed within the coplanar waveguide 1. The coaxial cable 3 is embedded within the coplanar waveguide 1, and the signal input device is connected to the coaxial cable 3.

[0027] The coplanar waveguide 1 includes an upper metal layer 11, an intermediate dielectric layer 12, a lower metal layer 13, and a bottom dielectric layer 14 arranged sequentially from top to bottom. The upper metal layer 11 forms a transmission line 111 and an upper metal ground 112, while the lower metal layer 13 forms a lower metal ground 131. Both the upper and lower metal layers 11 and 13 are made of copper. A mounting groove 1120 is formed on the upper metal ground 112 for mounting the transmission line 111, thus separating the transmission line 111 from the upper metal ground 112. The coplanar waveguide 1 can be a PCB board.

[0028] The coplanar waveguide 1 is also provided with a first through-hole 15, a second through-hole 16, and a trace groove 17. The first through-hole 15 is configured to penetrate both the intermediate dielectric layer 12 and the lower metal layer 13. The second through-hole 16 is configured to penetrate both the upper metal layer 11, the intermediate dielectric layer 12, and the lower metal layer 13. The trace groove 17 is formed in the bottom dielectric layer 14 and is L-shaped or U-shaped. The first through-hole 15 and the second through-hole 16 are far apart from each other and are connected to both ends of the trace groove 17. The mounting groove 1120 is connected to the first through-hole 15, and one end of the transmission line 111 arranged in the mounting groove 1120 is located at the first through-hole 15.

[0029] In this application, the signal input component is an RF connector 2, which is detachably disposed on the upper metal layer 11 and located at the second through-hole 16. In this application, the RF connector 2 is detachably connected to the coplanar waveguide 1 by a plurality of screws 4.

[0030] like Figure 1-3 As shown, the coplanar waveguide 1 is also provided with a number of metal vias 19 that connect the upper metal ground 112, the intermediate dielectric layer 12 and the lower metal ground 131. The number of metal vias 19 are distributed around the periphery of the mounting groove 1120. The distance from each metal via 19 to the transmission line 111 is equal, and the distance between two adjacent metal vias 19 is equal.

[0031] A third through hole 18 is also provided on the lower metal layer 13. The third through hole 18 is coaxially arranged with the first through hole 15 and is interconnected with it. The diameter of the third through hole 18 is larger than the diameter of the first through hole 15.

[0032] The coaxial cable 3 includes an inner conductor 31, a middle dielectric 32, and an outer conductor 33 arranged coaxially from the inside to the outside. Part of the coaxial cable 3 is accommodated in a wiring groove 17. The depth of the wiring groove 17 is greater than or equal to the diameter of the coaxial cable 3 so that the coaxial cable 3 can be completely embedded in the coplanar waveguide 1. Alternatively, epoxy resin can be filled in the wiring groove 17 to integrate the coaxial cable 3 inside the coplanar waveguide 1.

[0033] The coaxial cable 3 has a first end and a second end that are far apart from each other. The inner conductor 31 of the first end passes through the third through hole 18 and the first through hole 15 and is electrically connected to the transmission line 111. The outer conductor 33 of the first end passes through the wiring groove 17 and is electrically connected to the lower metal ground 131. The second end of the coaxial cable 3 is located in the second through hole 16 and is connected to the RF connector 2 to receive external transmission signals from the RF connector 2.

[0034] The inner conductor 31 of the coaxial cable 3 is longer than the middle layer dielectric 32, and the diameter of the inner conductor 31 is less than or equal to the line width of the transmission line 111. The length of the middle layer dielectric 32 is the same as the length of the outer conductor 33, and the inner conductor 31 at the first end is exposed outside the middle layer dielectric 32 and the outer conductor 33.

[0035] The outer conductor 33 at the first end is soldered to the lower metal layer 13 at the third through-hole 18, and the outer conductor 33 at the second end passes through the second through-hole 16 and is connected to the RF connector 2. In this embodiment, the coaxial cable 3 is a semi-steel wire, which connects the coplanar waveguide and the RF connector 2. The transmitted signal enters through the RF connector 2 and is then transmitted to the transmission line 111 through the coaxial cable 3, forming a complete signal transmission path. To improve the efficiency of signal transmission and the impedance stability and continuity of the signal circuit, the transmission structure 100 requires a coplanar waveguide with a low dielectric constant. In this application, the dielectric constant of the coplanar waveguide 1 is in the range of 3-5, and the thickness of the coplanar waveguide 1 is 0.1mm-0.3mm.

[0036] The diameter of the third through hole 18 is larger than the diameter of the first through hole 15 and smaller than the diameter of the outer conductor 33. The appropriately sized third through hole 18 forms the back feed channel of the inner conductor 31, so that the transmission structure 100 is in an impedance-matched state, reducing signal transmission loss and improving signal transmission efficiency.

[0037] The intermediate dielectric layer 12 is configured to be compressibly disposed between the upper metal layer 11 and the lower metal layer 13 in the vertical direction. When the thickness of the intermediate dielectric layer 12 decreases, the length of the first via 15 decreases, thereby reducing the parasitic inductance effect caused by the via in the inner conductor 31 and reducing the loss of the transmission structure 100. The return loss of the transmission structure 100, which is impedance matched and reduces parasitic inductance, is reduced to -20dB, and the -20dB return loss reaches 65GHz. The insertion loss is -0.23dB. The reduced loss improves the signal transmission efficiency of the transmission structure 100.

[0038] The transmission structure of this application is based on a coplanar waveguide 1 to realize a back-feed function. This transmission structure has low loss, small impedance change, and high signal transmission efficiency. The coplanar waveguide 1 with embedded coaxial cable 3 enhances the integration of the transmission structure, improves space advantage, and facilitates the docking of coplanar waveguide 1 with other structures.

[0039] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made without departing from the spirit and scope of this application. The scope of protection claimed by this application is defined by the appended claims, specification, and their equivalents.

Claims

1. A coplanar waveguide transmission structure, characterized in that, include: Coplanar waveguides and coaxial cables The coplanar waveguide includes: an upper metal layer, an intermediate dielectric layer, a lower metal layer and a bottom dielectric layer arranged sequentially from top to bottom. The upper metal layer forms a transmission line and an upper metal ground separated from the transmission line. The coplanar waveguide has a first through-hole penetrating the intermediate dielectric layer and the lower metal layer, and a routing groove formed in the bottom dielectric layer, and the routing groove is connected to the first through-hole. The coaxial cable includes an inner conductor, a middle dielectric layer, and an outer conductor arranged coaxially from the inside to the outside, and at least a portion of the coaxial cable is located within the cable tray; The inner conductor of the first end of the coaxial cable passes through the first through hole and is electrically connected to the transmission line. The outer conductor is electrically connected to the lower metal layer. The second end of the coaxial cable is connected to a signal input device to receive the transmitted signal.

2. The transmission structure according to claim 1, characterized in that, The coplanar waveguide has a second through-hole that simultaneously penetrates the upper metal layer, the middle dielectric layer, and the lower metal layer. The wiring groove communicates with the second through-hole, and the second end of the coaxial cable is located in the second through-hole.

3. The transmission structure according to claim 1 or 2, characterized in that, The signal input device is an RF connector, which is detachably connected to the second end of the coaxial cable.

4. The transmission structure according to claim 1, characterized in that, A third through hole is formed on the lower metal layer. The third through hole communicates with the first through hole. The diameter of the third through hole is larger than the diameter of the first through hole and smaller than the diameter of the outer conductor.

5. The transmission structure according to claim 1, characterized in that, The cable trays are L-shaped or U-shaped.

6. The transmission structure according to claim 1, characterized in that, The diameter of the inner conductor is less than or equal to the line width of the transmission line.

7. The transmission structure according to claim 1, characterized in that, The coplanar waveguide is also provided with several metal vias that connect the upper metal layer, the intermediate dielectric layer and the lower metal layer.

8. The transmission structure according to claim 7, characterized in that, The distance from each of the metal vias to the transmission line is equal, and the distance between any two adjacent metal vias is equal.

9. The transmission structure according to claim 8, wherein an installation groove for mounting the transmission line is formed on the upper metal ground, the installation groove is connected to the first through hole, and each of the metal through holes is arranged around the installation groove and is arranged on the periphery of the installation groove.

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