A slow-wave Lange coupler chip

Abstract

The present invention discloses a slow-wave Lange coupler chip. It includes a metal coupling line, a port connection line, a metal through hole, a metal connection line, a metal strip, a metal grid and a metal ground, wherein the metal coupling line is connected to the port connection line and is located above the metal ground, and the metal coupling line is connected through the metal through hole and the metal connection line; the metal strip adopts a forked finger structure, which is located below the metal coupling line and connected to the coupling line through the metal through hole; the metal ground is grooved, and the metal grid is located below the metal coupling line, the metal connection line and the metal strip, and is located at the center of the metal ground groove. The present invention realizes the performance of the Lange coupler, and is easy to adjust the characteristic impedance of the coupling line. More importantly, the coupler has a slow-wave effect, which solves the problems of large chip area, high processing cost, and difficulty in on-chip implementation of the Lange coupler.

Description

Technical Field

[0001] The present invention relates to the field of new generation communication technology, and in particular to a slow-wave Lange coupler chip. Background Art

[0002] With the development of new generation communication technology, the operating frequency of communication systems is getting higher and higher, which puts higher requirements on the design of high-performance passive components. In microwave millimeter wave integrated circuit systems, especially in microwave millimeter wave integrated circuit modules such as balanced amplifiers, frequency multipliers, and phase shifters, 90° directional couplers play an indispensable role. As a type of 90° directional coupler, the Lange coupler has the advantages of large bandwidth and low loss, and is widely used in microwave millimeter wave integrated circuits. However, due to its structural principle, the core part of the Lange coupler is one-quarter wavelength of the operating frequency and occupies a large area. At the same time, due to the thinning of the dielectric layer of the high-node integrated circuit process, the design of high-performance Lange couplers becomes more difficult. The traditional microstrip coupled linear Lange coupler will encounter problems such as high return loss, high insertion loss, and poor phase balance under process limitations.

[0003] Slow-wave transmission line is a special transmission line with slow-wave effect. By periodically adding capacitors and inductors to the transmission line, the phase velocity of the transmission signal can be slowed down, making its physical length shorter than that of ordinary microstrip lines at the same electrical length. Slow-wave transmission line can effectively reduce the area of ​​passive devices and realize the miniaturization of integrated circuits, so it has a wide range of applications in microwave and millimeter wave integrated circuits. Summary of the invention

[0004] Technical problem: The purpose of the present invention is to propose a slow-wave Lange coupler chip to address the problems of large area and difficult implementation encountered in the design of traditional Lange couplers in microwave and millimeter-wave integrated circuits. The chip optimizes the performance of the Lange coupler in the integrated circuit, reduces the size, improves the integration of the circuit, and makes it easy to adjust its characteristic impedance.

[0005] Technical solution: To achieve the above purpose, a slow-wave Lange coupler chip of the present invention uses a metal ground as a substrate, a groove is opened in the middle of the metal ground, a metal grid is arranged in the groove, a metal strip is arranged on the metal grid, a metal coupling line and a metal connection line are arranged on the metal strip, and the metal strip is connected to the metal coupling line through a metal through hole;

[0006] The metal coupling lines include a first metal coupling line, a second metal coupling line, a third metal coupling line, a fourth metal coupling line and a fifth metal coupling line; the port connection lines include a first port connection line, a second port connection line, a third port connection line and a fourth port connection line; and the metal connection lines include a first metal connection line, a second metal connection line and a third metal connection line.

[0007] The first metal coupling line, the second metal coupling line, the third metal coupling line, the fourth metal coupling line and the fifth metal coupling line (5) are arranged in sequence on a plane, the first metal coupling line and the fifth metal coupling line are only half the length of the other metal coupling lines, the outer end of the first metal coupling line is aligned with one end of the second metal coupling line, the third metal coupling line and the fourth metal coupling line, and the outer end of the fifth metal coupling line is aligned with the other ends of the second metal coupling line, the third metal coupling line and the fourth metal coupling line; the third metal coupling line is connected to the inner end of the first metal coupling line and the inner end of the fifth metal coupling line through a metal through hole and a first metal connection at the midpoint, and is directly connected to the first metal coupling line and the fifth metal coupling line at both ends of the third metal coupling line; the second metal coupling line is connected to the fourth metal coupling line through a metal through hole, a second metal connection and a third metal connection at both ends.

[0008] There are four port connection lines in total, which serve as the input end, the through end, the coupling end and the isolation end of the Lange coupler respectively; the port connection lines are directly connected to the two ends of the metal coupling line respectively and are located above the metal ground, wherein the first port connection line is connected to one end of the second metal coupling line, the second port connection line is connected to one end of the third metal coupling line and the fifth metal coupling line respectively, the third port connection line is connected to one end of the fourth metal coupling line, and the fourth port connection line is connected to one end of the first metal coupling line and the third metal coupling line respectively.

[0009] The metal strip is a multi-layer interdigitated structure formed by metal layers interlaced with each other.

[0010] The metal grid is composed of a plurality of metal thin strips and is distributed periodically. The metal grid is located in the same layer of the metal ground or between the metal ground and the metal strip. The metal grid is connected to the metal ground or is suspended.

[0011] The metal strips, metal through holes and metal grids constitute a slow-wave unit, which is distributed periodically or non-periodically on the lower side of the metal coupling line; the lower sides of the first metal coupling line, the second metal coupling line, the third metal coupling line, the fourth metal coupling line and the fifth metal coupling line all have the slow-wave unit structure with the same or different periods.

[0012] The slow-wave effect of the slow-wave Lange coupler increases with the increase of the width of the metal strip, the increase of the number of metal strip layers, and the increase of the length of the metal grid.

[0013] The coupling strength of the metal coupling line of the slow-wave Lange coupler increases with the growth of the metal grid.

[0014] The characteristic impedance of the metal coupling line of the slow-wave Lange coupler increases with the growth of the metal grid, decreases with the increase of the width of the metal strip, and decreases with the increase of the number of metal strip layers.

[0015] The physical length of the metal coupling line of the slow-wave Lange coupler is smaller than the physical length corresponding to a quarter wavelength of the operating frequency.

[0016] Beneficial effects: The advantages of the present invention are that it provides a slow-wave Lange coupler chip, which is composed of metal coupling lines, port connection lines, metal wires, metal through-holes, metal strips, metal grids and metal grounds. The metal strips are multi-layer interdigitated structures, located on the lower side of the metal coupling lines, and vertically connected to the metal coupling lines through metal through-holes, so as to introduce the capacitance required for the slow-wave effect without affecting the coupling performance of the coupling lines; the slots of the metal grids and the metal grounds increase the ground return path without affecting signal transmission and causing signal leakage to the substrate, and introduce the inductance required for the slow-wave effect; under the joint action of the metal strips, metal grids and slotted metal grounds, the phase velocity of the coupling lines is reduced, and a slow-wave effect is generated. At the same time, by adjusting the metal strips, metal grids and slotted metal grounds, it is possible to break through the performance of traditional microstrip coupling lines under some process limitations, and achieve the coupling strength and impedance required for the metal coupling lines in the Lange coupler. Compared with the traditional Lange coupler, the above-mentioned slow-wave Lange coupler realizes the slow-wave effect through the capacitors and inductors introduced by the new structure, so that the quarter-wavelength coupling line in the Lange coupler can be replaced by a coupling line with a shorter physical length, which can improve the performance of the coupler while achieving miniaturization, and solves the problems of large chip area, high processing cost, and difficult on-chip implementation of the coupler in radio frequency integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a slow-wave Lange coupler according to an embodiment of the present invention;

[0018] FIG2( a ) is a front view of a slow-wave Lange coupler according to an embodiment of the present invention;

[0019] FIG2( b ) is a top view of a slow-wave Lange coupler according to an embodiment of the present invention;

[0020] Figure 3 A size comparison diagram of a slow-wave Lange coupler according to an embodiment of the present invention and a conventional Lange coupler;

[0021] FIG4( a ) is a schematic diagram of S-parameter simulation amplitude of a slow-wave Lange coupler according to an embodiment of the present invention;

[0022] FIG4( b ) is a schematic diagram of S-parameter simulation amplitude of a conventional microstrip Lange coupler according to an embodiment of the present invention;

[0023] Figure 5 A comparison diagram of simulation results of phase differences between the through end and the coupled end of a slow-wave Lange coupler in one embodiment of the present invention and a traditional microstrip Lange coupler;

[0024] Figure 6 A schematic diagram of the structure of a slow-wave Lange coupler according to an embodiment of the present invention;

[0025] FIG. 7( a ) is a schematic diagram of S-parameter simulation amplitude of a slow-wave Lange coupler according to an embodiment of the present invention;

[0026] FIG. 7( b ) is a schematic diagram of a simulation result of a phase difference between a through end and a coupled end of a slow-wave Lange coupler according to an embodiment of the present invention;

[0027] Figure 8 Schematic diagram of the structure of a slow-wave Lange coupler according to an embodiment of the present invention.

[0028] The figure includes: a first metal coupling line 1, a second metal coupling line 2, a third metal coupling line 3, a fourth metal coupling line 4, a fifth metal coupling line 5, a first port connecting line 6, a second port connecting line 7, a third port connecting line 8, a fourth port connecting line 9, a first metal connection line 10, a second metal connection line 11, a third metal connection line 12, a metal strip 13, a metal through hole 14, a metal grid 15, and a metal ground 16. DETAILED DESCRIPTION

[0029] The present invention is further explained below in conjunction with the accompanying drawings and examples. The implementation methods of the present invention include but are not limited to the following examples.

[0030] This embodiment provides a slow-wave Lange coupler chip, such as Figure 1 As shown in FIG2 . As shown in the figure, it includes metal coupling lines, port connection lines, metal through holes 14, metal wires, metal strips 13, metal grids 15 and metal grounds 16, wherein the metal coupling lines include a first metal coupling line 1, a second metal coupling line 2, a third metal coupling line 3, a fourth metal coupling line 4 and a fifth metal coupling line 5, the port connection lines include a first port connection line 6, a second port connection line 7, a third port connection line 8 and a fourth port connection line 9, and the metal wires include a first metal wire 10, a second metal wire 11 and a third metal wire 12;

[0031] The first metal coupling line 1, the second metal coupling line 2, the third metal coupling line 3, the fourth metal coupling line 4 and the fifth metal coupling line 5 are arranged in sequence, the first metal coupling line 1 and the fifth metal coupling line 5 are only half the length of the other metal coupling lines, the first metal coupling line 1 is aligned with one end of the second metal coupling line 2, the third metal coupling line 3 and the fourth metal coupling line 4, and the fifth metal coupling line 5 is aligned with the other ends of the second metal coupling line 2, the third metal coupling line 3 and the fourth metal coupling line 4; the third metal coupling line 3 is connected to the first metal coupling line 1 and the fifth metal coupling line 5 at the midpoint through the metal through hole 14 and the first metal connection line 10, and is directly connected to the first metal coupling line 1 and the fifth metal coupling line 5 at both ends; the second metal coupling line 2 is connected to the fourth metal coupling line 4 at both ends through the second metal connection line 11, the third metal connection line 12 and the metal through hole 14;

[0032] There are four port connection lines, which can be used as the input end, the through end, the coupling end and the isolation end of the Lange coupler respectively; the port connection lines are directly connected to the metal coupling lines and are located above the metal ground 16, wherein the first port connection line 6 is connected to one end of the second metal coupling line 2, the second port connection line 7 is connected to one end of the fifth metal coupling line 5, the third port connection line 8 is connected to one end of the fourth metal coupling line 4, and the fourth port connection line 9 is connected to one end of the first metal coupling line 1;

[0033] The metal strip 13 is located at the lower side of the metal coupling line and is connected to the metal coupling line through the metal through hole 14;

[0034] The metal ground 16 is grooved, and the metal grid 15 is located at the lower side of the metal coupling line, the metal connection line and the metal strip 13 and at the center of the groove of the metal ground 16 .

[0035] Specifically, the metal strip 13 is a multi-layer interdigitated structure formed by metal interlacing, providing the required capacitance for the slow wave effect of the coupling line. The metal grid 15 is composed of a plurality of metal strips and is periodically distributed. The metal grid 15 is located in the same layer as the metal ground 16 or between the metal ground 16 and the metal strip 13. The metal grid 15 is connected to the metal ground 16 or suspended in the air, providing the required inductance for the slow wave effect of the coupling line. It should be particularly noted that if the lengths of the individual units are unequal, that is, they are cascaded according to a non-periodic rule, the slow wave effect can still be brought to the slow wave Lange coupler.

[0036] The slow-wave unit composed of the metal strips 13, metal through holes 14 and metal grids is periodically or non-periodically distributed on the lower side of the metal coupling line; the lower sides of the first metal coupling line 1, the second metal coupling line 2, the third metal coupling line 3, the fourth metal coupling line 4 and the fifth metal coupling line 5 all have the unit structure with the same or different periods.

[0037] Furthermore, the slow-wave effect of the slow-wave Lange coupler increases with the increase of the width of the metal strip 13 , increases with the increase of the number of layers of the metal strip 13 , and increases with the increase of the length of the metal grid 15 .

[0038] Furthermore, the coupling strength and characteristic impedance of the metal coupling line of the slow-wave Lange coupler are not only related to the line width and spacing of the metal coupling line itself, but also to the size of the metal strip 13 and the metal grid 15. The above structural dimensions can be adjusted according to needs during design to meet design requirements.

[0039] The physical length of the metal coupling line of the slow-wave Lange coupler is less than the physical length corresponding to a quarter wavelength of the operating frequency.

[0040] Furthermore, the above-mentioned slow-wave Lange coupler can be realized by any process that can meet the requirements of multi-layer metal, and can be applied to various semiconductor processes including but not limited to CMOS, LTCC and other processes.

[0041] In one embodiment, under the same process and the same frequency band, the slow-wave Lange coupler has a significantly smaller area than the traditional Lange coupler and can achieve better performance under processing constraints, such as Figure 3 The amplitude simulation results of the slow-wave Lange coupler and the traditional microstrip Lange coupler are shown in FIG4 ; the phase difference simulation results of the two output ports of the slow-wave Lange coupler and the traditional microstrip Lange coupler are shown in Figure 5 . In FIG4(a), the horizontal axis represents the frequency, and the vertical axis represents the amplitude of the S parameter of the slow-wave Lange coupler; in FIG4(b), the horizontal axis represents the frequency, and the vertical axis represents the amplitude of the S parameter of the traditional microstrip Lange coupler; Figure 5 The horizontal axis represents the frequency, and the vertical axis represents the phase difference between the through end and the coupled end of the slow-wave Lange coupler and the traditional microstrip Lange coupler.

[0042] In this example, within the frequency range of 110-170 GHz, the insertion loss of the slow-wave Lange coupler at the through end and the coupled end is less than 1.4 dB, the imbalance is less than 0.5 dB, the return loss is better than 12 dB, and the isolation is greater than 13 dB; within the frequency range of 110-170 GHz, the phase difference between the through end and the coupled end is 90°±5°.

[0043] In one embodiment, by setting the length of the metal grid 15 to be longer, the slow wave effect and the coupling strength of the metal coupling line are improved, and the coupler performance is also achieved. The slow wave Lange coupler achieves a greater slow wave effect with a longer grid, which greatly shortens the length of its metal coupling line, and has its unique advantages in certain circuit designs. The basic structure of the slow wave Lange coupler with long metal grid 15 is as follows: Figure 6 The amplitude and phase simulation results are shown in Figure 6. In FIG7(a), the horizontal axis represents the frequency, and the vertical axis represents the amplitude of the S parameter; in FIG7(b), the horizontal axis represents the frequency, and the vertical axis represents the phase difference between the through end and the coupled end of the Lange coupler.

[0044] In one embodiment, two slow-wave Lange couplers share the same grid bar, and adjust the line length, line spacing and other parameters to achieve the normal performance of the coupler. The slow-wave Lange coupler is reused by the metal grid bar 15, which saves area and improves integration to a greater extent. The basic structure of the slow-wave Lange coupler with the reuse of the metal grid bar 15 is as follows Figure 8 shown.

[0045] Based on the basic structure and several embodiments of the above slow-wave Lange coupler, the slow-wave Lange coupler of the present invention, on the basis of realizing the basic performance of the Lange coupler, introduces the slow-wave effect by adding the slow-wave structure formed by the metal strip 13, the metal through hole 14, the metal grid 15 and the slotted metal ground 16, and breaks through the limitations of the traditional microstrip coupling line in some processes while realizing miniaturization. The method described in the present invention has a relatively simple structure, is more flexible to adjust, and is relatively easy to implement, providing a solution for the miniaturization design of the Lange coupler in microwave millimeter wave integrated circuits.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A slow-wave Lange coupler chip, characterized in that: The coupler chip uses a metal ground (16) as a substrate, a groove is opened in the middle of the metal ground (16), a metal grid (15) is arranged in the groove, a metal strip (13) is arranged on the metal grid (15), a metal coupling line and a metal connection line are arranged on the metal strip (13), and the metal strip (13) is connected to the metal coupling line through a metal through hole (14); The metal coupling line comprises a first metal coupling line (1), a second metal coupling line (2), a third metal coupling line (3), a fourth metal coupling line (4) and a fifth metal coupling line (5); the port connection line comprises a first port connection line (6), a second port connection line (7), a third port connection line (8) and a fourth port connection line (9); and the metal connection line comprises a first metal connection line (10), a second metal connection line (11) and a third metal connection line (12); The first metal coupling line (1), the second metal coupling line (2), the third metal coupling line (3), the fourth metal coupling line (4) and the fifth metal coupling line (5) are arranged in sequence on a plane; the first metal coupling line (1) and the fifth metal coupling line (5) are only half the length of the other metal coupling lines; the outer end of the first metal coupling line (1) is aligned with one end of the second metal coupling line (2), the third metal coupling line (3) and the fourth metal coupling line (4); the outer end of the fifth metal coupling line (5) is aligned with the second metal coupling line (2), the third metal coupling line (3) and the fourth metal coupling line (4); (3) and the other end of the fourth metal coupling line (4); the third metal coupling line (3) is connected to the inner end of the first metal coupling line (1) and the inner end of the fifth metal coupling line (5) at the midpoint through a metal through hole (14) and the first metal connection line (10), and is directly connected to the first metal coupling line (1) and the fifth metal coupling line (5) at both ends of the third metal coupling line (3); the second metal coupling line (2) is connected to the fourth metal coupling line (4) at both ends through a metal through hole (14) and the second metal connection line (11) and the third metal connection line (12); There are four port connection lines in total, and the four port connection lines serve as the input end, the through end, the coupling end and the isolation end of the Lange coupler respectively; the port connection lines are directly connected to the two ends of the metal coupling line respectively and are located above the metal ground (16), wherein the first port connection line (6) is connected to one end of the second metal coupling line (2), the second port connection line (7) is respectively connected to one end of the third metal coupling line (3) and one end of the fifth metal coupling line (5), the third port connection line (8) is connected to one end of the fourth metal coupling line (4), and the fourth port connection line (9) is respectively connected to one end of the first metal coupling line (1) and one end of the third metal coupling line (3).

2. The slow-wave Lange coupler chip according to claim 1, characterized in that: The metal strip (13) is a multi-layer interdigitated structure formed by metal layers interlaced with each other.

3. The slow-wave Lange coupler chip according to claim 1, characterized in that: The metal grid (15) is composed of a plurality of metal thin strips and is distributed periodically. The metal grid (15) is located in the same layer as the metal ground (16) or between the metal ground (16) and the metal strip (13). The metal grid (15) is connected to the metal ground (16) or is suspended in the air.

4. The slow-wave Lange coupler chip according to any one of claims 1 to 3, characterized in that: The metal strips (13), metal through holes (14) and metal grids (15) constitute a slow-wave unit, which is distributed periodically or non-periodically on the lower side of the metal coupling line; the lower sides of the first metal coupling line (1), the second metal coupling line (2), the third metal coupling line (3), the fourth metal coupling line (4) and the fifth metal coupling line (5) all have the slow-wave unit structure with the same or different periods.

5. The slow-wave Lange coupler chip according to claim 4, characterized in that: The slow-wave effect of the slow-wave Lange coupler increases with the increase of the width of the metal strip (13), increases with the increase of the number of layers of the metal strip (13), and increases with the increase of the length of the metal grid (15).

6. The slow-wave Lange coupler chip according to claim 5, characterized in that: The coupling strength of the metal coupling line of the slow-wave Lange coupler increases with the growth of the metal grid (15).

7. The slow-wave Lange coupler chip according to claim 6, characterized in that: The characteristic impedance of the metal coupling line of the slow-wave Lange coupler increases with the growth of the metal grid (15), decreases with the increase of the width of the metal strip (13), and decreases with the increase of the number of layers of the metal strip (13).

8. The slow-wave Lange coupler chip according to claim 7, characterized in that: The physical length of the metal coupling line of the slow-wave Lange coupler is smaller than the physical length corresponding to a quarter wavelength of the operating frequency.

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