A compact integrated directional coupler with a high coupling coefficient

Abstract

The present invention discloses a monolithic integrated directional coupler with a high coupling coefficient, which includes an input port, a through port, a coupling port and an isolation port. The input port and the through port are arranged at two ends of a first microstrip line, and the coupling port and the isolation port are arranged at two ends of a second microstrip line. Both the first microstrip line and the second microstrip line include at least one metal layer, and at least a part of the first microstrip line and at least a part of the second microstrip line are arranged on metal layers of different layers. Since different two layers of metal are used to manufacture the coupling microstrip lines, the coupling line spacing is not restricted by the process rules and can be smaller than the specified minimum spacing of the same-layer metal. Therefore, a very high coupling coefficient can be achieved. Compared with the high-coupling coefficient directional coupler realized by using 6 or 8 same-layer metal coupling lines at present, the high-coupling coefficient directional coupler of the present invention has a much smaller size, which is beneficial to the monolithic integration of a high-performance millimeter-wave communication system.

Description

Technical Field

[0001] The present invention relates to the technical field of monolithic microwave integrated circuits (MMICs), and particularly relates to a compact integrated directional coupler with a high coupling coefficient. Background Art

[0002] With the development of wireless communication technologies, the millimeter-wave band (30 GHz - 300 GHz) has received extensive attention, and related application technologies have also developed vigorously. Compared with the increasingly crowded Sub 6 GHz band, the millimeter-wave band has much richer bandwidth resources and less in-band interference. Therefore, millimeter-wave communication exhibits unparalleled advantages in terms of high speed, low latency, large capacity, and low interference, and has extremely broad future development space.

[0003] Due to the very short wavelength of millimeter waves, millimeter-wave communication systems can be more conveniently monolithically integrated, that is, most circuit components no longer need to be placed on a printed circuit board (PCB), but are fabricated on a semiconductor wafer. Among them, a directional coupler is an important microwave / millimeter-wave circuit component and can be used for power signal distribution, synthesis, and phase shift. In a millimeter-wave communication system, the directional coupler is integrated with other components on the same wafer, thereby reducing insertion loss and parasitic parameters. Currently, the most widely used MMIC technology is the gallium arsenide (GaAs) monolithic integration process. Gallium arsenide semiconductor materials have excellent high-frequency performance, and their linearity and output power density in the millimeter-wave band are superior to those of silicon-based CMOS processes. In recent years, the gallium nitride (GaN) monolithic integration process, known as the "third-generation semiconductor", has been commercialized. It not only has excellent high-frequency performance, but also has an output power density more than 10 times higher than that of silicon-based CMOS processes, so it is particularly suitable for high-power applications such as communication base stations and phased array radars.

[0004] However, current commercial GaAs and GaN monolithic microwave integration processes only include two to three metal layers, and the dielectric layer between the metal layers is very thin (usually < 0.5μm), making it difficult to achieve suitable edge coupling between different metal layers. Therefore, most currently monolithic integrated directional couplers are fabricated using the same-layer metal edge coupling technique, that is, all coupling lines are made of the same-layer metal, and the coupling degree is controlled by adjusting the spacing between the coupling lines. The smaller the spacing, the higher the coupling degree and the larger the voltage coupling coefficient. However, restricted by the process rules, the spacing between the same-layer metals must be greater than a certain minimum value Gmin (for example, for the GaAspHEMT process, Gmin = 5μm), which restricts the achievable coupling coefficient. The voltage coupling coefficient between two same-layer metal coupling lines is generally less than -4dB. Using the Lange coupler structure, that is, using 4 mutually parallel coupling lines to fully utilize the edge stray electric fields on both sides of the coupling lines, the coupling coefficient can be increased to about -3dB. If a higher coupling coefficient is required, more parallel coupling lines need to be used, such as 6 or even 8, which makes the area of the directional coupler become huge and is not conducive to monolithic integration. Summary of the Invention

[0005] To overcome the disadvantages and deficiencies of the prior art, the present invention provides a monolithic integrated directional coupler with a high coupling coefficient to achieve a directional coupler with a high coupling coefficient and a small size.

[0006] To solve the above problems, the present invention provides a monolithic integrated directional coupler with a high coupling coefficient, including an input port, a through port, a coupling port, and an isolation port. The input port and the through port are arranged at both ends of a first microstrip line, the coupling port and the isolation port are arranged at both ends of a second microstrip line. The first microstrip line and the second microstrip line each include at least one metal layer, and at least a part of the first microstrip line and at least a part of the second microstrip line are arranged on different metal layers.

[0007] Further, the horizontal spacing range between the first microstrip line and the second microstrip line is between 0 and 20μm, and the voltage coupling coefficient adjustment range is between -10 and -1.25dB.

[0008] Further, the first microstrip line includes a T1 part, and the second microstrip line includes a T2 part; the T1 part is located on a first metal layer, and the T2 part is located on a second metal layer.

[0009] Further, the first microstrip line includes a T1 part and a T1' part, and the second microstrip line includes a T2 part and a T2' part; the T1 part and the T2' part are located on a second metal layer, the T1' part and the T2 part are located on a first metal layer, and the T1 part and the T1' part, the T2 part and the T2' part are respectively interconnected through vias.

[0010] Further, the first microstrip line includes a T1 portion, a T1' portion, a T3 portion, and a T3' portion, and the second microstrip line includes a T2 portion, a T2' portion, a T4 portion, and a T4' portion; the T1 portion, the T1' portion, the T3 portion, and the T3' portion are all located in the second metal layer, and the T2 portion, the T2' portion, the T4 portion, and the T4' portion are all located in the first metal layer; the T1 portion and the T1' portion, and the T3 portion and the T3' portion are respectively interconnected through vias in the first metal layer; the T1 portion and the T3 portion, the T1' portion and the T3' portion, the T2 portion and the T4 portion, and the T2' portion and the T4' portion are respectively interconnected through an air bridge.

[0011] Further, the first microstrip line includes a T1 portion, a T1' portion, a T3 portion, and a T3' portion, and the second microstrip line includes a T2 portion, a T2' portion, a T4 portion, and a T4' portion; wherein the T1 portion, the T2' portion, the T3 portion, and the T4' portion are located in the second metal layer, and the T1' portion, the T2 portion, the T3' portion, and the T4 portion are located in the first metal layer; the T1 portion and the T1' portion, and the T3 portion and the T3' portion are respectively interconnected through vias in the first metal layer; the T1 portion and the T3 portion, the T1' portion and the T3' portion, the T2 portion and the T4 portion, and the T2' portion and the T4' portion are respectively interconnected through an air bridge.

[0012] Further, a slash transition is used between the via and the corresponding microstrip line.

[0013] Further, the first microstrip line and the second microstrip line are trapezoidal at the ports.

[0014] Further, the first microstrip line and the second microstrip line can be made into a curved shape or a straight shape.

[0015] Further, the monolithic integrated directional coupler with a high coupling coefficient is fabricated by using GaAs pHEMT, GaAs HBT, SiC-based GaN HEMT, or Si-based GaN HEMT process.

[0016] Compared with the prior art, the present invention has the following beneficial effects and advantages:

[0017] In the present invention, it includes an input port, a through port, a coupling port, and an isolation port. The input port and the through port are arranged at two ends of a first microstrip line. The coupling port and the isolation port are arranged at two ends of a second microstrip line. Both the first microstrip line and the second microstrip line include at least one metal layer, and at least a part of the first microstrip line and at least a part of the second microstrip line are arranged on different metal layers. Since different two layers of metals are used to manufacture the coupling microstrip line, the coupling line spacing is not restricted by the process rules and can be smaller than the specified minimum spacing of the same-layer metal. Therefore, a very high coupling coefficient can be achieved. Compared with the high-coupling coefficient directional coupler realized by using 6 or 8 same-layer metal coupling lines currently, the high-coupling coefficient directional coupler provided by the present invention has a much smaller size, which is beneficial to the monolithic integration of a high-performance millimeter-wave communication system. Description of the Drawings

[0018] To more clearly illustrate the technical solution of the present invention, the drawings are provided here for a brief introduction. It should be noted that the following drawings are only used to explain the present invention and do not constitute an improper limitation to the present invention.

[0019] In the drawings:

[0020] Figure 1(a) is a schematic diagram of the basic structure of the high-coupling coefficient integrated directional coupler in Embodiment 1 of the present invention;

[0021] Figure 1(b) is the layout of the high-coupling coefficient integrated directional coupler in Embodiment 1 of the present invention;

[0022] Figure 2(a) is a schematic diagram of the basic structure of the high-coupling coefficient integrated directional coupler in Embodiment 2 of the present invention;

[0023] Figure 2(b) is the layout of the high-coupling coefficient integrated directional coupler in Embodiment 2 of the present invention;

[0024] Figure 3(a) is a schematic diagram of the basic structure of the high-coupling coefficient integrated directional coupler in Embodiment 3 of the present invention;

[0025] Figure 3(b) is the layout of the high-coupling coefficient integrated directional coupler in Embodiment 3 of the present invention;

[0026] Figure 4(a) is a schematic diagram of the basic structure of the high-coupling coefficient integrated directional coupler in Embodiment 4 of the present invention;

[0027] Figure 4(b) is the layout of the high-coupling coefficient integrated directional coupler in Embodiment 4 of the present invention;

[0028] Figure 5 is the layout of the high-coupling coefficient integrated directional coupler in Embodiment 5 of the present invention;

[0029] Figure 6It is the S-parameter curve graph of Embodiment 5;

[0030] Figure 7 It is the phase difference curve graph of the through port and the coupled port of Embodiment 5. Detailed implementation manners

[0031] The high-coupling coefficient monolithic integrated directional coupler of the present invention will be described in more detail below with reference to the schematic diagrams. The preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as a broad guidance for those skilled in the art and not as a limitation to the present invention.

[0032] Embodiment 1

[0033] Embodiment 1 of the present invention provides a high-coupling coefficient monolithic integrated directional coupler. This directional coupler is fabricated using, for example, the GaAs pHEMT process. Referring to FIGS. 1(a) and 1(b), it includes: an input port P1, a through port P2, a coupled port P3, and an isolation port P4. The input port P1 and the through port P2 are disposed at both ends of a first microstrip line, and the coupled port P3 and the isolation port P4 are disposed at both ends of a second microstrip line. Both the first microstrip line and the second microstrip line include at least one metal layer, and at least a part of the first microstrip line and at least a part of the second microstrip line are disposed on different metal layers.

[0034] In this embodiment, the first microstrip line has a T1 part, and both ends of the T1 part are the input port P1 and the through port P2. The second microstrip line has a T2 part, and both ends of the T2 part are the coupled port P3 and the isolation port P4. For ease of description, it is denoted as the first microstrip line T1 and the second microstrip line T2.

[0035] For example, the first microstrip line T1 is disposed on a first metal layer M1, and the second microstrip line T2 is disposed on a second metal layer M2.

[0036] Since two metal layers M1 and M2 are used to fabricate the coupled microstrip line, the coupling line spacing is no longer restricted by the process rules and can be less than the specified minimum spacing of the same-layer metal, and even can be partially overlapped. The voltage coupling coefficient can reach more than -1.25 dB.

[0037] In addition, since the dielectric layer between the M1 and M2 metal layers of the current commercial GaAs and GaN monolithic microwave integrated processes is very thin, it is difficult to achieve proper broadside coupling. Therefore, the coupled microstrip lines located on different metal layers should be edge-coupled, and the broadside coupling should be minimized, that is, large-area overlap should not occur, otherwise the isolation of the coupler will deteriorate.

[0038] Based on this consideration, in Embodiment 1 of the present invention, the horizontal spacing S between the first microstrip line and the second microstrip line preferably ranges from 0 to 20 μm. Correspondingly, the voltage coupling coefficient adjustment range is between -10 and -1.25 dB.

[0039] The width of the first microstrip line T1 located in the M1 layer is W1, and the width of the second microstrip line T2 located in the M2 layer is W2. W1 is used to adjust the matching impedance Z01 of the input port P1 and the through port P2, and is preferably 3 to 30 μm. W2 is used to adjust the matching impedance Z02 of the coupling port P3 and the isolation port P4, and is preferably 3 to 30 μm. Increasing / decreasing the width will cause the matching impedance to decrease / increase accordingly. If Z01 = Z02 is required, then W1 = W2 can be set. However, in the actual selected process, there may be some differences in the thickness of the M1 and M2 metals and the distance from the ground plane. Therefore, W1 and W2 can be finely adjusted to ensure Z01 = Z02. The length L of the coupled microstrip line is used to adjust the center operating frequency of the directional coupler. The smaller L is, the higher the center frequency is, and it is preferably 100 to 2000 μm. In addition, to ensure good odd-mode and even-mode symmetry, the two coupled microstrip lines should have the same length L. The spacing S between the coupled microstrip lines is used to adjust the coupling coefficient. The smaller S is, the larger the coupling coefficient is. As described above, the spacing S between the M1 and M2 metals is not restricted by the process rules and can be set to any value. However, since the dielectric layer between the M1 and M2 metal layers in the current commercial GaAs and GaN monolithic microwave integrated processes is very thin, it is difficult to achieve proper broadside coupling. If S < 0, that is, the coupled lines partially overlap, the introduced broadside coupling will cause the isolation of the coupler to deteriorate. Therefore, S should be ≥ 0.

[0040] As an example, the length L of T1 and T2 is 320 μm, and the widths W1 = W2 = 8 μm.

[0041] To conveniently connect with a 50 Ω (or other specifications) microstrip line, as shown in FIG. 1, trapezoidal lines are added to all four ports of this directional coupler, and the widths of their ends are all 35 μm.

[0042] The electromagnetic simulation results show that the center frequency of this directional coupler is 80 GHz, the voltage coupling coefficient at the center frequency reaches -3.4 dB, the port impedance is 51 Ω, the return loss > 25 dB, the isolation > 21 dB, and the phase difference between the through end and the coupling end is 92°.

[0043] Embodiment 2

[0044] This Embodiment 2 can be further implemented based on Embodiment 1, or can exist without being based on Embodiment 1. Among them, the same or similar modules are marked with the same or similar marks, and their descriptions are omitted.

[0045] The directional coupler is fabricated using, for example, a SiC-based GaN HEMT process. As shown in FIGS. 2(a) and 2(b), in the monolithic integrated directional coupler with a high coupling coefficient of this embodiment, it can be divided into two centrosymmetric left and right parts, and each part is composed of 2 parallel coupled microstrip lines. The first microstrip line includes a T1 part and a T1' part. The T1 part is located in the second metal layer M2, and the T1' part is located in the first metal layer M1. The T1 part and the T1' part are interconnected through vias. The second microstrip line includes a T2 part and a T2' part. The T2' part is located in the second metal layer M2, and the T2 part is located in the first metal layer M1. The T2 part and the T2' part are interconnected through vias.

[0046] The overall structure of the coupler is a centrosymmetric structure, and the through port P2 and the coupled port P3 are located on the same metal layer, thereby eliminating the slight deviation in impedance between the through port and the coupled port caused by separately using M1 and M2 to fabricate the coupled lines.

[0047] All the microstrip lines have the same length to maintain good odd and even mode symmetry. The width is finely adjusted based on W1 = W2 to ensure the best performance, and the spacing S is used to adjust the coupling coefficient.

[0048] As an example, the length L of both the first microstrip line and the second microstrip line is 186 μm, the width W1 = W2 = 12 μm, and the spacing S is 1 μm.

[0049] The via structure includes the first metal layer M1, the second metal layer M2, and the via metal layer V. Therefore, the distance G between the via and other same-layer metals must follow the process rules, that is, it is not less than the minimum spacing Gmin of the same-layer metals specified by the process rules. However, to achieve a high coupling coefficient, S is usually less than Gmin. Therefore, a slant transition is required between the via and the coupled line. To reduce the discontinuity of the microstrip line corner, the slant angle θ should be ≤ 45°. But θ should also be ≥ 30°, otherwise the transition line is too long, reducing the proportion of the tightly coupled line segment and resulting in a decrease in the coupling coefficient.

[0050] As an example, a slant transition with θ = 40° is used between the via and the coupled line.

[0051] To facilitate the connection with a 50 Ω microstrip line, trapezoidal lines are added to all four ports of the directional coupler, and the width of the end is 54 μm.

[0052] The electromagnetic simulation results show that the center frequency of the directional coupler is 65 GHz, the voltage coupling coefficient at the center frequency is as high as -2.7 dB, the port impedance is 52 Ω, the return loss > 27 dB, the isolation > 22 dB, and the phase difference between the through end and the coupled end is 90°.

[0053] Embodiment 3

[0054] This Embodiment 3 can be further implemented based on Embodiment 1 or Embodiment 2, or it can exist without being based on Embodiment 1 or Embodiment 2. Among them, the same or similar modules are marked with the same or similar marks, and their descriptions are omitted.

[0055] This directional coupler is fabricated using, for example, the GaAs HBT process. As shown in Figures 3(a) and 3(b), for the monolithic integrated directional coupler with a high coupling coefficient in this embodiment, the first microstrip line includes a T1 part, a T1' part, a T3 part, and a T3' part, all of which are located in the second metal layer M2. The T1 part and the T1' part, and the T3 part and the T3' part are respectively interconnected through vias in the first metal layer M1; the second microstrip line includes a T2 part, a T2' part, a T4 part, and a T4' part, all of which are located in the first metal layer M1; the T1 part and the T3 part, the T1' part and the T3' part, the T2 part and the T4 part, and the T2' part and the T4 part are respectively interconnected through an air bridge.

[0056] This directional coupler can be divided into two centrosymmetric left and right parts, and each part is composed of four mutually parallel and interleaved coupled microstrip lines, which can make full use of the edge stray electric fields on both sides of the coupled lines to further improve the coupling coefficient.

[0057] In this Embodiment 3, several microstrip lines need to be interconnected by bridging. In order to reduce the broadside coupling caused by the overlap of the M1 and M2 metals during the bridging interconnection, the bridging interconnection between the second metal layers M2 uses an air bridge. At the same time, the process rules of the MMIC prohibit the same-layer metals from being connected into a closed loop, so the bridging interconnection between the first metal layers M1 also uses an air bridge. The air bridge is fabricated using the elevated second metal layer M2, and there is an air layer below it. The width B of the air bridge needs to follow the process rules and cannot be less than the minimum value Bmin specified by the process rules.

[0058] The via structure includes the first metal layer M1, the second metal layer M2, and the via metal layer V. Therefore, the distance G between the via and other same-layer metals must follow the process rules, that is, it is not less than the minimum distance Gmin between the same-layer metals specified by the process rules. However, in order to achieve a high coupling coefficient, S is usually less than Gmin. Therefore, a slant transition is required between the via and the coupled line. In order to reduce the discontinuity of the microstrip line corner, the slant angle θ should be ≤ 45°. But θ should also be ≥ 30°, otherwise the transition line is too long, reducing the proportion of the tightly coupled line segment and resulting in a decrease in the coupling coefficient.

[0059] As an example, a slant transition with θ = 40° is used between the via and the coupled line.

[0060] As an example, the width W1 of the coupled microstrip line of the first metal layer M1 is 8 μm, the width W2 of the coupled microstrip line of the second metal layer M2 is 8 μm, and the coupling line spacing S is 0 μm. The overall length L of the directional coupler is 540 μm.

[0061] As an example, the spacing G between the via structure and the other first metal layer M1 is 5 μm.

[0062] As an example, the width B of the air bridge is 10 μm.

[0063] As an example, a 45° diagonal line transition is used between the air bridge structure and the coupled line.

[0064] In order to facilitate connection with a 50 Ω microstrip line, trapezoidal lines with a width of 34 μm are added to all four ports of the directional coupler.

[0065] The electromagnetic simulation results show that the center frequency of the directional coupler is 50 GHz, the voltage coupling coefficient at the center frequency is as high as -1.25 dB, the port impedance is 40 Ω, the return loss > 25 dB, the isolation > 21 dB, and the phase difference between the through port and the coupled port is 93°.

[0066] Embodiment 4

[0067] This Embodiment 4 can be further implemented based on Embodiment 1 or Embodiment 2 or Embodiment 3, or can exist without being based on Embodiment 1 or Embodiment 2 or Embodiment 3. Among them, the same or similar modules are marked with the same or similar labels, and their descriptions are omitted.

[0068] The directional coupler is fabricated using, for example, the Si-based GaN HEMT process. As shown in FIGS. 4(a) and 4(b), for the monolithic integrated directional coupler with a high coupling coefficient in this embodiment, the first microstrip line includes a T1 part, a T1' part, a T3 part, and a T3' part, where the T1 part, the T2' part, the T3 part, and the T4' part are located in the second metal layer M2, the T1' part, the T2 part, the T3' part, and the T4 part are located in the first metal layer M1. The T1 part and the T1' part, the T3 part and the T3' part are respectively interconnected through vias in the first metal layer M1. The T1 part and the T3 part, the T1' part and the T3' part, the T2 part and the T4 part, the T2' part and the T4' part are respectively interconnected through an air bridge.

[0069] The directional coupler can be divided into two centrosymmetric left and right parts, each part consisting of four mutually parallel and interleaved coupled microstrip lines, which can make full use of the edge stray electric fields on both sides of the coupled lines to further improve the coupling coefficient.

[0070] The through port P2 and the coupled port P3 are located on the same M1 metal layer, thus eliminating the slight impedance deviation between the through port and the coupled port caused by separately using M1 and M2 to fabricate the coupled line.

[0071] The via structure includes the first metal layer M1, the second metal layer M2, and the via metal layer V. Therefore, the distance G between the via and other same-layer metals must follow the process rules, that is, not less than the minimum pitch Gmin of the same-layer metals specified by the process rules. However, in order to achieve a high coupling coefficient, S is usually less than Gmin. Therefore, a diagonal transition is required between the via and the coupled line. To reduce the discontinuity of the microstrip line corner, the diagonal angle θ should be ≤ 45°. But θ should also be ≥ 30°, otherwise the transition line is too long, reducing the proportion of the tightly coupled segment and resulting in a decrease in the coupling coefficient.

[0072] As an example, a 45° diagonal transition is used between the air bridge structure and the coupled line.

[0073] As an example, the width W1 of the coupled microstrip line in the first metal layer M1 is 11 μm, the width S2 of the coupled microstrip line in the second metal layer M2 is 11 μm, and the coupling line pitch S is 1 μm. The overall length L of the directional coupler is 540 μm.

[0074] As an example, the distance G between the via structure and other M1 layer metals is 5 μm.

[0075] As an example, the air bridge width B is 10 μm.

[0076] To facilitate connection with a 50 Ω microstrip line, trapezoidal lines with a width of 45 μm are added to all four ports of this directional coupler.

[0077] The electromagnetic simulation results show that the center frequency of this directional coupler is 50 GHz, the voltage coupling coefficient at the center frequency is as high as -1.8 dB, the port impedance is 45 Ω, the return loss > 26 dB, the isolation > 20 dB, and the phase difference between the through end and the coupled end is 90°.

[0078] Embodiment 5

[0079] This Embodiment 5 can be further implemented on the basis of Embodiments 1 - 4, or it can exist without relying on the above embodiments. Among them, the same or similar modules are marked with the same or similar labels, and their descriptions are omitted.

[0080] For the high-coupling coefficient directional coupler provided in this embodiment, for the sake of description, improvements based on Embodiment 2 are exemplarily described. This directional coupler is fabricated using the GaAs pHEMT process, and its structure is as Figure 5 shown.

[0081] To achieve a more compact layout, the coupled lines are bent while still maintaining a centrosymmetric layout. The layout can be divided into two centrosymmetric upper and lower parts, each part consisting of two parallel bent coupled microstrip lines. Among them, the T1 part and the T2' part are located in the second metal layer M2, and the T2 part and the T1' part are located in the first metal layer M1. The T1 part is interconnected with the T1' part, and the T2 part is interconnected with the T2' part through vias.

[0082] The through port P2 and the coupled port P3 are located in the same metal layer M1, thus eliminating the slight impedance deviation between the through port and the coupled port caused by using M1 and M2 respectively to fabricate the coupled lines.

[0083] As an example, the length of all coupled microstrip lines is 310 μm, the width is 7 μm, and the spacing is 1 μm.

[0084] To facilitate the connection with a 50 Ω microstrip line, trapezoidal lines with a width of 35 μm are added to the four ports of this directional coupler.

[0085] The S-parameter curve of the electromagnetic simulation results is shown in Figure 6 , and the phase difference curve between the coupled end and the through end is shown in Figure 7 . The center frequency of this directional coupler is 40 GHz. At the center frequency, the voltage coupling coefficient is as high as -2.3 dB, the port impedance is 51 Ω, the return loss > 23 dB, the isolation > 18 dB, and the phase difference between the through end and the coupled end is 91°.

[0086] For the structures in Embodiment 1 and Embodiments 3-4, the relevant microstrip lines can also be bent, which can be implemented by those skilled in the art based on this embodiment, and the description is omitted here.

[0087] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0088] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A monolithic integrated directional coupler with a high coupling coefficient, characterized in that, It includes an input port, a through port, a coupling port, and an isolation port. The input port and the through port are disposed at two ends of a first microstrip line. The coupling port and the isolation port are disposed at two ends of a second microstrip line. Both the first microstrip line and the second microstrip line include at least one metal layer. At least a part of the first microstrip line and at least a part of the second microstrip line are disposed on different metal layers, so that the coupling part is always located on different metal layers to increase the coupling coefficient. The horizontal spacing range between the first microstrip line and the second microstrip line is between 0 and 20 μm, and the coupling coefficient adjustment range is between -10 and -1.25 dB. By means of vias, under the condition of ensuring that the coupling part is located on different metal layers, the through port and the coupling port are placed on the same metal layer to reduce the impedance deviation between the through port and the coupling port.

2. The monolithic integrated directional coupler with a high coupling coefficient according to claim 1, characterized in that, The first microstrip line includes a T1 part, and the second microstrip line includes a T2 part; the T1 part is located on a first metal layer, and the T2 part is located on a second metal layer.

3. The monolithic integrated directional coupler with a high coupling coefficient according to claim 1, wherein The first microstrip line includes a T1 part and a T1' part, and the second microstrip line includes a T2 part and a T2' part; the T1 part and the T2' part are located on a second metal layer, and the T2 part and the T1' part are located on a first metal layer; the T1 part and the T1' part, and the T2 part and the T2' part are interconnected through vias respectively.

4. The monolithic integrated directional coupler with a high coupling coefficient according to claim 1, characterized in that, The first microstrip line includes a T1 part, a T1' part, a T3 part, and a T3' part, and the second microstrip line includes a T2 part, a T2' part, a T4 part, and a T4' part; The T1 part, the T1' part, the T3 part, and the T3' part are all located on a second metal layer, and the T2 part, the T2' part, the T4 part, and the T4' part are all located on a first metal layer; the T1 part and the T1' part, and the T3 part and the T3' part are interconnected through vias on the first metal layer respectively; The T1 part and the T3 part, the T1' part and the T3' part, the T2 part and the T4 part, and the T2' part and the T4' part are interconnected through an air bridge respectively.

5. The monolithic integrated directional coupler with a high coupling coefficient according to claim 1, characterized in that, The first microstrip line includes a T1 part, a T1' part, a T3 part, and a T3' part, and the second microstrip line includes a T2 part, a T2' part, a T4 part, and a T4' part; wherein the T1 part, the T2' part, the T3 part, and the T4' part are located on a second metal layer, and the T1' part, the T2 part, the T3' part, and the T4 part are located on a first metal layer; The T1 part and the T1' part, and the T3 part and the T3' part are interconnected through vias on the first metal layer respectively, and the T1 part and the T3 part, the T1' part and the T3' part, the T2 part and the T4 part, and the T2' part and the T4' part are interconnected through an air bridge respectively.

6. The monolithic integrated directional coupler with a high coupling coefficient according to any one of claims 2-5, characterized in that A diagonal transition is used between the via and the corresponding microstrip line.

7. The monolithic integrated directional coupler with a high coupling coefficient according to any one of claims 2-5, characterized in that The first microstrip line and the second microstrip line are trapezoidal at the port.

8. The monolithic integrated directional coupler with a high coupling coefficient according to any one of claims 2-5, characterized in that, The first microstrip line and the second microstrip line are made into a curved shape or a straight shape.

9. The monolithic integrated directional coupler with a high coupling coefficient according to claim 1, wherein The monolithic integrated directional coupler with a high coupling coefficient is fabricated by using GaAs pHEMT, GaAs HBT, SiC-based GaN HEMT or Si-based GaN HEMT technology.

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