A coplanar waveguide structure

Abstract

This invention discloses a coplanar waveguide structure, comprising: a top cover film, a substrate, and a bottom cover film sequentially bonded together; the top cover film embeds a top reference ground layer for a microstrip line region; the bottom cover film embeds a bottom ground layer for the microstrip line region; the top reference ground layer for the microstrip line region includes: a microstrip line, a first coplanar waveguide line, a second coplanar waveguide line, an edge reference ground line for the coplanar waveguide region, and a middle reference ground line for the coplanar waveguide region; the edge reference ground line for the coplanar waveguide region is located on both sides of the top cover film; the differential line of the microstrip line region, the first coplanar waveguide line, and the second coplanar waveguide line are located between the edge reference ground line for the coplanar waveguide region; the differential line of the microstrip line region is located at both ends of the top cover film and is divided into two along the middle direction of the top cover film to form the first coplanar waveguide line and the second coplanar waveguide line; transition ground holes are provided at both ends of the middle reference ground line for the coplanar waveguide region. The coplanar waveguide structure of this invention can enhance inter-line coupling.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit boards, and more specifically to a coplanar waveguide structure. Background Technology

[0002] With the popularity of foldable screens and AR / VR / MR devices, the bending and transmission performance of flexible circuit boards at the hinge is becoming increasingly important.

[0003] Currently, the mainstream solutions to improve the bending problem of flexible circuit boards are: air gap structure and coplanar waveguide structure.

[0004] 1. The air gap structure weakens the interaction between layers by removing the interlayer adhesive, and its effect is close to that of a single-layer board. In contrast, the coplanar waveguide structure is a single-layer board, and high-speed signals and all reference grounds are routed on the same layer. Theoretically, the coplanar waveguide has better bending performance than the air gap structure and has a higher lifespan in products. However, its insufficient wiring space and signal instability have hindered the promotion of the coplanar waveguide structure.

[0005] 2. Coplanar waveguides suffer from insufficient wiring space. Besides the cramped wiring space due to their single-layer structure, the lack of upper and lower signal reference layers forces the waveguide to maximize linewidth to increase capacitance and minimize inductance. This linewidth is typically several times, or even ten times, that of a microstrip line. Furthermore, coplanar waveguides also suffer from signal instability. Again, due to the absence of upper and lower reference layers, a significant portion of the electric field of the coplanar waveguide structure diffuses outside the circuit board. Similar to a capacitive sensor, when a hand or other material with a high dielectric constant or metal approaches, the capacitance increases significantly, causing a noticeable drop in impedance. This means the impedance is easily affected by environmental changes, leading to signal instability. Additionally, the electric field divergence results in poor isolation, making it susceptible to electromagnetic interference.

[0006] There is an improved structure that reduces signal instability to some extent by cutting the signal lines far from the reference ground, but it is still far inferior to microstrip lines and striplines; and it does not solve the problem of occupying wiring space. Summary of the Invention

[0007] To overcome the above-mentioned technical defects, the present invention provides a coplanar waveguide structure that can enhance inter-line coupling.

[0008] To solve the above problems, the present invention is implemented according to the following technical solution:

[0009] A coplanar waveguide structure includes: a top cover film, a substrate, and a bottom cover film sequentially bonded together, wherein the top cover film is embedded with a top reference ground layer of a microstrip line region; and the bottom cover film is embedded with a bottom ground layer of a microstrip line region.

[0010] The top reference ground layer of the microstrip line region includes: microstrip line region differential line, first coplanar waveguide region line, second coplanar waveguide region line, coplanar waveguide region edge reference ground line, and coplanar waveguide region middle reference ground line;

[0011] The edge reference ground line of the coplanar waveguide region is located on both sides of the top cover film;

[0012] The microstrip line differential line, the first coplanar waveguide line, and the second coplanar waveguide line are located between the edge reference ground line of the coplanar waveguide region;

[0013] The microstrip line differential lines are located at both ends of the top cover film and are divided into two along the middle direction of the top cover film to form the first coplanar waveguide line and the second coplanar waveguide line;

[0014] The intermediate reference ground line of the coplanar waveguide region is located between the first coplanar waveguide region line and the second coplanar waveguide region line, and transition ground holes are provided at both ends of the intermediate reference ground line of the coplanar waveguide region.

[0015] The transition ground hole is provided by penetrating the intermediate reference ground line of the coplanar waveguide region, the substrate, and the bottom layer of the microstrip line region.

[0016] As a further improvement of the present invention, the coplanar waveguide region edge reference ground line includes: a first segment and a second segment, wherein the connection between the first segment and the second segment is set to be arc-shaped;

[0017] The first segment is located outside the differential line of the microstrip line region, and the second segment is located outside the first coplanar waveguide region line and the second coplanar waveguide region line;

[0018] Near the differential line of the microstrip line region, the first segment is provided with a plurality of microstrip line region reference ground vias, which are provided through the first segment, the substrate, and the bottom ground layer of the microstrip line region.

[0019] As a further improvement of the present invention, a set of top-level reference ground planes of the microstrip line region is provided, wherein the first coplanar waveguide region line is the first coplanar waveguide region signal line, and the second coplanar waveguide region line is the second coplanar waveguide region signal line;

[0020] The coplanar waveguide region edge reference ground line, the first coplanar waveguide region signal line, the coplanar waveguide region middle reference ground line, the second coplanar waveguide region signal line, and the coplanar waveguide region edge reference ground line are arranged at intervals.

[0021] As a further improvement of the present invention, the connection points between the differential lines in the microstrip region and the signal lines in the first and second coplanar waveguide regions are all set to be arc-shaped.

[0022] As a further improvement of the present invention, two sets of top-level reference ground planes of the microstrip line region are provided, wherein the first coplanar waveguide region line is a first coplanar waveguide region differential line, and the second coplanar waveguide region line is a second coplanar waveguide region differential line;

[0023] In the top reference ground layer of the first group of microstrip line regions, the edge reference ground line of the coplanar waveguide region, the differential line of the first coplanar waveguide region, the middle reference ground line of the coplanar waveguide region, and the differential line of the second coplanar waveguide region are arranged at intervals. In the top reference ground layer of the second group of microstrip line regions, the edge reference ground line of the coplanar waveguide region, the differential line of the first coplanar waveguide region, the middle reference ground line of the coplanar waveguide region, and the differential line of the second coplanar waveguide region are arranged at intervals.

[0024] As a further improvement of the present invention, the connection between the differential line in the microstrip region and the line in the first coplanar waveguide region is set to be arc-shaped.

[0025] As a further improvement of the present invention, the radius of the transition hole is smaller than W. G1 / 2, where W G1 The linewidth of the intermediate reference ground line in the coplanar waveguide region is given.

[0026] As a further improvement of the present invention, the linewidth of the intermediate reference ground line in the coplanar waveguide region is less than or equal to the linewidth of the first coplanar waveguide region line.

[0027] As a further improvement of the present invention, the two ends of the intermediate reference ground line in the coplanar waveguide region are set as semicircles, and the radius of the semicircles is equal to (W G1 / 2+S1), where S1 is the distance between the first coplanar waveguide region line and the intermediate reference ground line of the coplanar waveguide region.

[0028] As a further improvement of the present invention, it is characterized in that W S2 / (S2+ W S2 )≤0.5, where W S2 S1 is the linewidth of the first coplanar waveguide region line, and S2 is the distance between the first coplanar waveguide region line and the intermediate reference ground line of the coplanar waveguide region.

[0029] Compared with the prior art, the present invention has the following beneficial effects: By using the intermediate reference ground line of the coplanar waveguide region, the coupling can be strengthened, and the differential line of the microstrip line region is divided into two to form the first coplanar waveguide region line and the second coplanar waveguide region line, so as to reduce the line width and thus reduce the waste caused by the region with low electromagnetic intensity due to the large line width, making the electric field more concentrated, while solving the problems of line width occupying space, crosstalk, and signal instability. Attached Figure Description

[0030] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0031] Figure 1 This is an exploded view of the coplanar waveguide structure described in Example 1;

[0032] Figure 2 This is a schematic diagram of the structure of the substrate described in Example 1;

[0033] Figure 3 This is a schematic diagram of the structure of the bottom strata of the microstrip line region described in Example 1;

[0034] Figure 4 This is a schematic diagram of the structure of the top reference stratum of the microstrip line region described in Example 1;

[0035] Figure 5 This is a partial enlarged view of the top reference stratum of the microstrip line region described in Example 1;

[0036] Figure 6 Example 1: Electromagnetic intensity distribution diagram of a conventional coplanar waveguide;

[0037] Figure 7 This is a comparison diagram of the electric field intensity 5 μm above the signal line in Example 1;

[0038] Figure 8 This is a comparison diagram of the electric field intensity 60 μm above the signal line in Example 1;

[0039] Figure 9 This is an exploded view of the coplanar waveguide structure described in Example 2;

[0040] Figure 10 This is a schematic diagram of the structure of the substrate described in Example 2;

[0041] Figure 11 This is a schematic diagram of the structure of the bottom strata of the microstrip line region described in Example 2;

[0042] Figure 12 This is a schematic diagram of the structure of the top reference stratum of the microstrip line region described in Example 2;

[0043] Figure 13 This is a partial enlarged view of the top reference stratum of the microstrip line region described in Example 2;

[0044] Figure 14 This is a TDR comparison diagram between the structure of the present invention and the prior art;

[0045] Figure 15 This is a comparison diagram of the insertion loss between the present invention and the prior art structure;

[0046] Figure 16 This is a comparison diagram of the isolation degree between the structure of the present invention and the prior art;

[0047] Figure 17 This is a comparison diagram of impedance after interference from a 3mm*3mm grounded metal block at 20μm above the structure of the present invention and the prior art.

[0048] Figure 18 The insertion loss comparison diagram shows the result of interference from a 3mm*3mm grounded metal block at the top 20μm of the structure of this invention and that of the prior art.

[0049] Explanation of reference numerals in the attached figures:

[0050] Example 1: 101, Top cover film; 102, Substrate; 103, Bottom cover film; 104, Top reference ground plane of microstrip line region; 1041, Differential line of microstrip line region; 1042, Signal line of first coplanar waveguide region; 1043, Signal line of second coplanar waveguide region; 1044, Edge reference ground line of coplanar waveguide region; 10441, First segment; 10442, Second segment; 10443, Reference ground via of microstrip line region; 1045, Middle reference ground line of coplanar waveguide region; 105, Bottom ground plane of microstrip line region; 106, Transition ground via.

[0051] Example 2: 201, Top cover film; 202, Substrate; 203, Bottom cover film; 204, Top reference ground plane of microstrip line region; 2041, Differential line of microstrip line region; 2042, Differential line of first coplanar waveguide region; 2043, Differential line of second coplanar waveguide region; 2044, Edge reference ground line of coplanar waveguide region; 20441, First segment; 20442, Second segment; 20443, Reference ground via of microstrip line region; 2045, Middle reference ground line of coplanar waveguide region; 205, Bottom ground plane of microstrip line region; 206, Transition ground via. Detailed Implementation

[0052] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0053] Example 1

[0054] This invention provides a coplanar waveguide structure, which is a single-ended coplanar waveguide structure, such as... Figures 1 to 3As shown, it includes: a top cover film 101, a substrate 102, and a bottom cover film 103 sequentially bonded together. The top cover film 101 is embedded with a top reference ground layer 104 for the microstrip line region; the bottom cover film 103 is embedded with a bottom ground layer 105 for the microstrip line region; the top reference ground layer 104 for the microstrip line region includes: a microstrip line 1041, a first coplanar waveguide line, a second coplanar waveguide line, a coplanar waveguide edge reference ground line 1044, and a coplanar waveguide middle reference ground line 1045; the coplanar waveguide edge reference ground line 1044 is located on both sides of the top cover film 101; the microstrip line differential line 1041, the first coplanar waveguide line, and the second coplanar waveguide line are also present. The waveguide region line and the second coplanar waveguide region line are located between the edge reference ground line 1044 of the coplanar waveguide region; the microstrip line region differential line 1041 is located at both ends of the top cover film 101 and is divided into two along the middle direction of the top cover film 101 to form the first coplanar waveguide region line and the second coplanar waveguide region line; the middle reference ground line 1045 of the coplanar waveguide region is located between the first coplanar waveguide region line and the second coplanar waveguide region line, and transition ground holes are provided at both ends of the middle reference ground line 1045 of the coplanar waveguide region; the transition ground holes are provided through the middle reference ground line 1045 of the coplanar waveguide region, the substrate 102, and the bottom layer 105 of the microstrip line region.

[0055] like Figure 4 As shown, the coplanar waveguide region edge reference ground line 1044 includes: a first segment 10441 and a second segment 10442, the connection between the first segment 10441 and the second segment 10442 is set in an arc shape; the first segment 10441 is located outside the microstrip line region differential line 1041, and the second segment 10442 is located outside the first coplanar waveguide region line and the second coplanar waveguide region line; near the microstrip line region differential line 1041, the first segment 10441 is provided with a plurality of microstrip line region reference ground vias 10443, the microstrip line region reference ground vias 10443 are provided through the first segment 10441, the substrate, and the microstrip line region bottom ground layer 105 to ensure signal return at the edge of the coplanar waveguide.

[0056] In this embodiment, a set of microstrip line region top layer reference ground 104 is provided, the first coplanar waveguide region line is the first coplanar waveguide region signal line 1042, and the second coplanar waveguide region line is the second coplanar waveguide region signal line 1043; the coplanar waveguide region edge reference ground line 1044, the first coplanar waveguide region signal line 1042, the coplanar waveguide region middle reference ground line 1045, the second coplanar waveguide region signal line 1043, and the coplanar waveguide region edge reference ground line 1044 are arranged at intervals.

[0057] In this embodiment, a set of coplanar waveguide edge reference ground lines 1044 are added at each of the two sides, so that the signal lines at both ends of the coplanar waveguide structure are wrapped by ground (return path).

[0058] Specifically, the signal line 1042 in the first coplanar waveguide region and the signal line 1043 in the second coplanar waveguide region are connected in parallel. The impedance of the signal line 1042 in the first coplanar waveguide region is Z1, and the impedance of the signal line 1043 in the second coplanar waveguide region is Z2. At this time, we have... Where Z0 is the characteristic impedance required for the transmission line. Considering the symmetry of the overall structure, Z1 = Z2 = 2Z0 is generally taken.

[0059] like Figure 5 As shown, the connections between the microstrip differential line 1041 and the signal lines 1042 and 1043 in the first and second coplanar waveguide regions are all designed as arcs. Specifically, the connections are implemented using double transition arcs. The microstrip differential line 1041 first expands outward through the first transition arc and then retracts inward through the second transition arc. The radius of the first transition arc is R1 = W. G1 + S1+ W S2 The radius of the second transition arc, R1 = W G1 + S1+ W S2 .

[0060] The radius of the transition hole 106 is less than W. G1 / 2, where W G1 This represents the linewidth of the reference ground line in the middle of the coplanar waveguide region.

[0061] The linewidth of the intermediate reference ground line 1045 in the coplanar waveguide region is smaller than that of the first coplanar waveguide region line, which facilitates the processing of the transition ground hole 106.

[0062] The two ends of the intermediate reference ground line 1045 in the coplanar waveguide region are set as semicircles, and the radius of the semicircles is equal to (W). G1 / 2+S1), where S1 is the distance between the signal line of the first coplanar waveguide region and the intermediate reference ground line of the coplanar waveguide region, and is uniformly coupled with the transition ground hole disk.

[0063] In this embodiment, in order to concentrate the electric field, W S2 / (S2+ W S2 When W ≤ 0.5, the metal utilization rate reaches near its maximum value. S2 W is the linewidth of signal line 1042 in the first coplanar waveguide region. S3 W is the linewidth of the signal line in the first coplanar waveguide region. G3S1 is the linewidth of the second segment 10442 of the edge reference ground line 1044 of the coplanar waveguide region; S2 is the distance between the first coplanar waveguide region line and the middle reference ground line 1045 of the coplanar waveguide region; S1 is the distance between the middle reference ground line 1045 of the coplanar waveguide region and the signal line 1043 of the second coplanar waveguide region; S3 is the distance between the signal line 1043 of the second coplanar waveguide region and the second segment 10442 of the edge reference ground line 1044 of the coplanar waveguide region; and S4 is the distance between the signal line 1042 of the first coplanar waveguide region and the second segment 10442 of the edge reference ground line 1044 of the coplanar waveguide region.

[0064] The effective electric field of a coplanar waveguide structure is mainly concentrated between the signal line and ground. Increasing or decreasing the linewidth at other locations yields minimal impedance gains. Considering capacitance, the further away from the reference layer, the greater the spacing between the capacitor plates. Let x be the distance between a point on the signal line and the reference layer; then, as x increases, the rate of change of capacitance... (where a is a constant), starting close to 0, as x increases, The impedance decreases rapidly, and since the decrease in characteristic impedance depends on the increase in capacitance, the result is that reducing impedance by 10Ω requires an increase in linewidth of x1, while reducing impedance by 20Ω requires a linewidth x2 >> x1. Figure 6 As shown, the same pattern can be observed from the calculation of the electric field strength. Clearly, although the linewidth of the coplanar waveguide is large, the portion directly opposite the signal line, i.e., the area within the box, has the greatest impact on the signal or impedance. What we need to address is increasing the proportion of the electric field strength in the box section. Increasing the copper thickness is the most direct approach, but it's unsuitable for products requiring bending resistance. Reducing the line spacing is also unsuitable due to etching limitations. Ultimately, the best remaining approach is to reduce the weak electric field areas while increasing the number of strong electric field areas, thus increasing the electric field strength between the two points. (in, The potential difference between two points. (The distance between the two points), at point A. Since E is relatively constant, E at point B is the same as... When the relationship is close to a direct proportion, As the linewidth increases, E decreases rapidly, but the electric field strength decreases by only half of its original value. Continuing to increase the linewidth results in an excessively large area occupied while the impedance change remains small. Therefore, the ideal design is ≤0.5.

[0065] At the coplanar waveguide port location, due to the increased linewidth, the impedance usually decreases. Therefore, it is necessary to reduce the linewidth of the ground wire to reduce the parasitic capacitance of the coplanar waveguide port, while still preserving the effect of the return path. The linewidth can be slightly smaller than the signal line spacing S.

[0066] like Figure 7 and Figure 8As shown, when close to the signal line, the electric field strength of the design of this invention is greater than that of the traditional design. However, at a slightly greater distance, the electric field strength of the traditional coplanar waveguide is greater, indicating that the electric field of the traditional coplanar waveguide is more emitted. Furthermore, the design of this invention has a minimum electric field strength of about half of the maximum electric field strength when close to the signal line, which meets the design expectation. That is, by adjusting the line width, the second requirement is met, and the line width utilization is close to the maximum. Similarly, the electric field change can be concentrated inside the PCB, which can improve the stability of the signal line and reduce crosstalk between signal lines.

[0067] Example 2

[0068] This embodiment provides another coplanar waveguide structure, which is a differential coplanar waveguide structure, such as... Figures 9 to 11 As shown, it includes: a top cover film 201, a substrate 202, and a bottom cover film 203 sequentially bonded together. The top cover film 201 is embedded with a top reference ground layer 204 for the microstrip line region; the bottom cover film 203 is embedded with a bottom ground layer 205 for the microstrip line region; the top reference ground layer 204 for the microstrip line region includes: a microstrip line 2041, a first coplanar waveguide line, a second coplanar waveguide line, a coplanar waveguide edge reference ground line 2044, and a coplanar waveguide middle reference ground line 2045; the coplanar waveguide edge reference ground line 2044 is located on both sides of the top cover film 201; the microstrip line differential line 2041, the first coplanar waveguide line, and the second coplanar waveguide line are also present. The waveguide region line and the second coplanar waveguide region line are located between the edge reference ground line 2044 of the coplanar waveguide region; the microstrip line region differential line 2041 is located at both ends of the top cover film 201, and is divided into two along the middle direction of the top cover film 201 to form the first coplanar waveguide region line and the second coplanar waveguide region line; the middle reference ground line 2045 of the coplanar waveguide region is located between the first coplanar waveguide region line and the second coplanar waveguide region line, and transition ground holes are provided at both ends of the middle reference ground line 2045 of the coplanar waveguide region; the transition ground holes are provided through the middle reference ground line 2045 of the coplanar waveguide region, the substrate 202, and the bottom layer 205 of the microstrip line region.

[0069] like Figure 12 and Figure 13 As shown, the coplanar waveguide region edge reference ground line 2044 includes: a first segment 20441 and a second segment 20442, the connection between the first segment 20441 and the second segment 20442 is set in an arc shape; the first segment 20441 is located outside the microstrip line region differential line 2041, and the second segment 20442 is located outside the first coplanar waveguide region line and the second coplanar waveguide region line; near the microstrip line region differential line 2041, the first segment 20441 is provided with a plurality of microstrip line region reference ground vias 20443, the microstrip line region reference ground vias 20443 are provided through the first segment 20441, the substrate, and the microstrip line region bottom ground layer 205.

[0070] In this embodiment, two sets of microstrip line region top-level reference ground layers 204 are provided. The first coplanar waveguide region line is the first coplanar waveguide region differential line 2042, and the second coplanar waveguide region line is the second coplanar waveguide region differential line 2043. In the first set of microstrip line region top-level reference ground layers 204, the coplanar waveguide region edge reference ground line 2044, the first coplanar waveguide region differential line 2042, the coplanar waveguide region middle reference ground line 2045, and the second coplanar waveguide region differential line 2043 are arranged at intervals. In the second set of microstrip line region top-level reference ground layers 204, the coplanar waveguide region edge reference ground line 2044, the first coplanar waveguide region differential line 2042, the coplanar waveguide region middle reference ground line 2045, and the second coplanar waveguide region differential line 2043 are arranged at intervals.

[0071] The connection points between the microstrip differential line 2041 and the differential line in the first coplanar waveguide region are all designed as arcs. Specifically, the connection is achieved using a double transition arc. The microstrip differential line 2041 first expands outward through the first transition arc, and then retracts inward through the second transition arc. The radius of the first transition arc is R1 = W. G1 + S1+ W S2 The radius of the second transition arc, R1 = W G1 + S1+ W S2 .

[0072] The radius of the transition hole 206 is less than W. G1 / 2, where W G1 This represents the linewidth of the reference ground line in the middle of the coplanar waveguide region.

[0073] The linewidth of the intermediate reference ground line 2045 in the coplanar waveguide region is smaller than that of the first coplanar waveguide region line, which facilitates the processing of the transition ground hole 206.

[0074] The two ends of the intermediate reference ground line 2045 in the coplanar waveguide region are set as semicircles, and the radius of the semicircles is equal to (W G1 / 2+S1), where S1 is the distance between the signal line of the first coplanar waveguide region and the intermediate reference ground line of the coplanar waveguide region, and is uniformly coupled with the transition ground hole disk.

[0075] In this embodiment, in order to concentrate the electric field, W S2 / (S2+ W S2 When W ≤ 0.5, the metal utilization rate reaches near its maximum value. S2 W is the linewidth of the differential line in the first coplanar waveguide region. S3 W is the linewidth of the differential line 2042 in the first coplanar waveguide region. G3S1 is the linewidth of the second segment of the edge reference ground line of the coplanar waveguide region; S2 is the distance between the first coplanar waveguide region line and the middle reference ground line 2045 of the coplanar waveguide region; S1 is the distance between the middle reference ground line 2045 of the coplanar waveguide region and the differential line 2043 of the second coplanar waveguide region; S3 is the distance between the differential line 2043 of the second coplanar waveguide region and the second segment 20442 of the edge reference ground line 2044 of the coplanar waveguide region; S4 is the distance between the differential line 2042 of the first coplanar waveguide region and the second segment 20442 of the edge reference ground line 2044 of the coplanar waveguide region.

[0076] For other implementation methods of this embodiment, please refer to Embodiment 1, which will not be described in detail here.

[0077] like Figures 14 to 18 As shown, the present invention has the following beneficial effects:

[0078] 1. Significantly reduced linewidth: Under the same impedance and line spacing conditions, the total occupancy of this invention is only 1 / 10 to 1 / 7 of that of a traditional coplanar waveguide.

[0079] 2. Low crosstalk between lines: The isolation level of this design is 20-30dB higher than that of conventional designs. Figure 16 As shown.

[0080] 3. Strong anti-interference capability: Under interference-free conditions, the insertion loss performance is slightly worse than that of ordinary designs (due to the smaller linewidth and larger conductor loss, this shortcoming is difficult to avoid); under external interference conditions, such as the simultaneous presence of a 3mm*3mm grounded metal block interference at a distance of 20μm above, see below. Figure 17 and Figure 18 Therefore, the TDR mutation and insertion loss of this design are much smaller than those of traditional coplanar waveguides, which is of great significance for the application and promotion of coplanar waveguide products.

[0081] 4. The line spacing of this design is consistent with that of traditional coplanar waveguides, and the required etching capability is similar to that of traditional coplanar waveguides, which will not significantly increase the process cost.

[0082] 5. The metal layer and dielectric can be made thinner, while maintaining signal stability and good bending ability.

[0083] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A coplanar waveguide structure, characterized in that, include: A top cover film, a substrate, and a bottom cover film are sequentially bonded together, wherein the top cover film is embedded with a microstrip line region top reference layer; The underlying cover film is embedded with a microstrip line area of ​​the underlying stratum; The top reference ground layer of the microstrip line region includes: microstrip line region differential line, first coplanar waveguide region line, second coplanar waveguide region line, coplanar waveguide region edge reference ground line, and coplanar waveguide region middle reference ground line; The edge reference ground line of the coplanar waveguide region is located on both sides of the top cover film; The microstrip line differential line, the first coplanar waveguide line, and the second coplanar waveguide line are located between the edge reference ground line of the coplanar waveguide region; The microstrip line differential lines are located at both ends of the top cover film and are divided into two along the middle direction of the top cover film to form the first coplanar waveguide line and the second coplanar waveguide line; The intermediate reference ground line of the coplanar waveguide region is located between the first coplanar waveguide region line and the second coplanar waveguide region line, and transition ground holes are provided at both ends of the intermediate reference ground line of the coplanar waveguide region. The transition ground hole is provided by penetrating the intermediate reference ground line of the coplanar waveguide region, the substrate, and the bottom ground layer of the microstrip line region; The coplanar waveguide region edge reference ground line includes: a first segment and a second segment, wherein the connection between the first segment and the second segment is set to be arc-shaped; The first segment is located outside the differential line of the microstrip line region, and the second segment is located outside the first coplanar waveguide region line and the second coplanar waveguide region line; Near the differential line of the microstrip line region, the first segment is provided with a plurality of microstrip line region reference ground vias, which are provided through the first segment, the substrate, and the bottom ground layer of the microstrip line region.

2. The coplanar waveguide structure according to claim 1, characterized in that, A set of top-level reference ground planes for the microstrip line region is provided, the first coplanar waveguide region line is the first coplanar waveguide region signal line, and the second coplanar waveguide region line is the second coplanar waveguide region signal line; The coplanar waveguide region edge reference ground line, the first coplanar waveguide region signal line, the coplanar waveguide region middle reference ground line, the second coplanar waveguide region signal line, and the coplanar waveguide region edge reference ground line are arranged at intervals.

3. The coplanar waveguide structure according to claim 2, characterized in that, The connections between the differential lines in the microstrip region and the signal lines in the first and second coplanar waveguide regions are all designed to be arc-shaped.

4. The coplanar waveguide structure according to claim 1, characterized in that, Two sets of top-level reference ground planes for the microstrip line regions are provided, the first coplanar waveguide region line is the first coplanar waveguide region differential line, and the second coplanar waveguide region line is the second coplanar waveguide region differential line; In the top reference ground layer of the first group of microstrip line regions, the edge reference ground line of the coplanar waveguide region, the differential line of the first coplanar waveguide region, the middle reference ground line of the coplanar waveguide region, and the differential line of the second coplanar waveguide region are arranged at intervals. In the top reference ground layer of the second group of microstrip line regions, the edge reference ground line of the coplanar waveguide region, the differential line of the first coplanar waveguide region, the middle reference ground line of the coplanar waveguide region, and the differential line of the second coplanar waveguide region are arranged at intervals.

5. The coplanar waveguide structure according to claim 4, characterized in that, The connection points between the differential lines in the microstrip region and the lines in the first coplanar waveguide region are all designed to be arc-shaped.

6. The coplanar waveguide structure according to claim 1, characterized in that, The radius of the transition hole is less than W. G1 / 2, where W G1 The linewidth of the intermediate reference ground line in the coplanar waveguide region is given.

7. The coplanar waveguide structure according to claim 1, characterized in that, The linewidth of the intermediate reference ground line in the coplanar waveguide region is less than or equal to the linewidth of the first coplanar waveguide region line.

8. The coplanar waveguide structure according to claim 1, characterized in that, The two ends of the intermediate reference ground line in the coplanar waveguide region are set as semicircles, and the radius of the semicircles is equal to (W G1 / 2+S1), where S1 is the distance between the first coplanar waveguide region line and the intermediate reference ground line of the coplanar waveguide region.

9. The coplanar waveguide structure according to claim 1, characterized in that, W S2 / (S2+ W) S2 )≤0.5, where W S2 S1 is the linewidth of the first coplanar waveguide region line, and S2 is the distance between the first coplanar waveguide region line and the intermediate reference ground line of the coplanar waveguide region.

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