A D-band waveguide coupled transmission structure

Abstract

The present invention discloses a waveguide coupling transmission structure of D band, including two coupler chips, which are connected by dielectric waveguides; each of the coupler chips includes a coupler body, a coupler feeder and a GSG pad; the coupler body includes a coupler bottom plate, a wedge-shaped waveguide top plate and a mode converter top plate; the mode converter top plate is rectangular, and the wedge-shaped waveguide top plate is a wedge-shaped plate with a gradually narrowing width from near to far; a first metal via array is arranged between the two side edges of the mode converter top plate and the coupler bottom plate, thereby forming a mode converter of the coupler body; a second metal via array is arranged between the two side edges of the wedge-shaped waveguide top plate and the coupler bottom plate, thereby forming a wedge-shaped waveguide of the coupler body. The present invention uses two couplers and dielectric waveguides to complete the design of the signal transmission structure, which increases the working bandwidth and reduces the in-band ripple within the working bandwidth.

Description

Technical Field

[0001] The present invention relates to waveguide coupling, in particular to a D-band waveguide coupling transmission structure. Background Art

[0002] Terahertz (THz) signals hold great potential for applications in imaging, sensing, and communications. Therefore, efficient and stable information transmission between different THz systems is a natural concern for designers. D-band (110-170 GHz) signals are particularly attractive due to their reduced atmospheric absorption and attenuation. However, conventional D-band inter-chip signal transmission structures suffer from significant intra-band fluctuations and narrow bandwidth. Furthermore, the design, manufacturing, and assembly of these transmission structures are cumbersome, making integration difficult and hindering widespread adoption of systems in this frequency band. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a D-band waveguide coupling transmission structure. The design of the signal transmission structure is completed using two couplers and a dielectric waveguide, which increases the operating bandwidth and reduces the in-band ripple within the operating bandwidth.

[0004] The object of the present invention is achieved through the following technical solutions: a D-band waveguide coupling transmission structure, comprising two coupler chips, the two coupler chips being connected by a dielectric waveguide;

[0005] Each coupler chip includes a coupler body, a coupler feed line, and a GSG pad; the coupler body includes a coupler bottom plate, a wedge-shaped waveguide top plate, and a mode converter top plate; the mode converter top plate is rectangular, and the wedge-shaped waveguide top plate is wedge-shaped with a width gradually narrowing from near to far;

[0006] A first metal via array is provided between both side edges of the mode converter top plate and the coupler bottom plate, thereby forming a mode converter of the coupler body;

[0007] A second metal via array is provided between the two side edges of the wedge-shaped waveguide top plate and the coupler bottom plate, thereby forming a wedge-shaped waveguide of the coupler body;

[0008] A first metal via is provided between the mode converter top plate and the wedge waveguide top plate, and the mode converter top plate and the wedge waveguide top plate are connected via the first metal via;

[0009] The coupler feed line includes a waveguide coupling line, a coupler main feed line and a matching stub line; the waveguide coupling line is located above the top plate of the mode converter, the first end of the waveguide coupling line is connected to the top plate of the mode converter via a second metal via, the second end of the waveguide coupling line is connected to the first end of the coupler main feed line, and the second end of the coupler main feed line is connected to the GSG pad; one end of the matching stub line is connected to the coupler main feed line, and the other end is connected to the coupler bottom plate via a third metal via array;

[0010] In each of the coupler chips, a gap is provided in the center of the wedge-shaped waveguide top plate and the mode converter top plate;

[0011] One end of the dielectric waveguide is fixed just above the gap of the wedge-shaped waveguide top plate in one of the coupler chips, and the other end is fixed just above the gap of the wedge-shaped waveguide top plate in the other coupler chip.

[0012] The first metal via array includes seven layers of metal plates arranged in sequence from bottom to top, and any two adjacent layers of metal plates are filled with dielectric and connected through metal vias; the first layer of metal plate and the coupler bottom plate are filled with dielectric and connected through metal vias, and the seventh layer of metal plate and the mode converter top plate are filled with dielectric and connected through metal vias.

[0013] The second metal via array includes eight layers of metal plates arranged sequentially from bottom to top, and any two adjacent layers of metal plates are filled with dielectric and connected through metal vias; the first layer of metal plate and the coupler bottom plate are filled with dielectric and connected through metal vias, and the eighth layer of metal plate and the wedge waveguide top plate are filled with dielectric and connected through metal vias.

[0014] The third metal via array includes eight layers of metal plates arranged sequentially from bottom to top, and any two adjacent layers of metal plates are filled with dielectric and connected through metal vias; the first layer of metal plate and the coupler bottom plate are filled with dielectric and connected through metal vias, and the eighth layer of metal plate and the matching branch line are filled with dielectric and connected through metal vias.

[0015] The present invention achieves the following beneficial effects: By employing an on-chip waveguide coupler chip-bonded with a dielectric waveguide, it achieves the design of a D-band signal inter-chip transmission structure. The on-chip coupler chip utilizes a mode converter coupled to a wedge-shaped waveguide. Compared to traditional antenna radiation schemes, this increases the system's operating bandwidth, reduces passband ripple, and reduces the difficulty of precise alignment between the transmitter and receiver. The on-chip matching structure is simple, easy to design and manufacture, and does not affect broad passband performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the coupler chip;

[0017] Figure 2 is a schematic structural diagram of a second metal via array;

[0018] Figure 3 Schematic diagram of the assembly scheme of the chip-to-chip signal transmission system based on wedge-shaped waveguide couplers;

[0019] Figure 4 This is a schematic diagram of the signal transmission structure probe station test;

[0020] Figure 5 Schematic diagram of the simulation model of the inter-chip signal transmission system based on wedge-shaped waveguide coupler;

[0021] Figure 6 Schematic diagram of the two-port S11 parameter test and simulation comparison results of the inter-chip signal transmission system of the wedge-shaped waveguide coupler;

[0022] Figure 7 Schematic diagram of the two-port S21 parameter test and simulation comparison results of the inter-chip signal transmission system of the wedge-shaped waveguide coupler. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0024] The present invention designs an on-chip waveguide coupler operating in the D-band based on the CMOS 65nm process library, and uses two coupler chips to paste dielectric waveguides to complete the design of the signal transmission structure, which increases the operating bandwidth and reduces the in-band ripple within the operating bandwidth. At the same time, on the waveguide coupler chip, a coupler feed line is used to feed the signal, and the impedance matching section is arranged near the GSG pad, which reduces the design complexity without affecting the bandwidth and in-band ripple. Finally, a rectangular dielectric waveguide made of Rogers 3006 is pasted on the top of the two waveguide coupler chips using photosensitive resin (commonly known as UV glue) to complete the connection between the two coupler chips, reducing manufacturing and assembly costs. Finally, the S-parameter test of the present invention was carried out on a probe station, and the test results were consistent with the simulation results.

[0025] The invention consists of two identical waveguide coupler chips and a dielectric waveguide mounted on the two identical waveguide coupler chips. The chips adopt CMOS 65nm technology. Figure 1 The structure of the waveguide coupler chip is shown, which includes two wedge-shaped waveguide couplers connected by a dielectric waveguide.

[0026] Each coupler chip includes a coupler body, a coupler feed line, and a GSG pad 11; the coupler body includes a coupler bottom plate 1, a wedge-shaped waveguide top plate 2, and a mode converter top plate 3; the mode converter top plate 3 is rectangular, and the wedge-shaped waveguide top plate 2 is wedge-shaped with a width gradually narrowing from near to far.

[0027] A first metal via array 4 is provided between the two side edges of the mode converter top plate 3 and the coupler bottom plate 1, thereby forming a mode converter of the coupler body;

[0028] A second metal via array 5 is provided between the two side edges of the wedge-shaped waveguide top plate 2 and the coupler bottom plate 1, thereby forming a wedge-shaped waveguide of the coupler body;

[0029] A first metal via 6 is provided between the mode converter top plate 3 and the wedge waveguide top plate 2, and the mode converter top plate 3 and the wedge waveguide top plate 2 are connected via the first metal via 6;

[0030] The coupler feed line includes a waveguide coupling line 7, a coupler main feed line 8 and a matching branch line 9; the waveguide coupling line 7 is located above the mode converter top plate 3, the first end of the waveguide coupling line 7 is connected to the mode converter top plate 3 through a second metal via 10, the second end of the waveguide coupling line 7 is connected to the first end of the coupler main feed line 8, and the second end of the coupler main feed line 8 is connected to the GSG pad 11; one end of the matching branch line 9 is connected to the coupler main feed line, and the other end is connected to the coupler bottom plate 1 through a third metal via array 12;

[0031] In each of the coupler chips, a gap is provided in the center of the wedge-shaped waveguide top plate 2 and the mode converter top plate 3;

[0032] One end of the dielectric waveguide is fixed just above the gap of the wedge-shaped waveguide top plate 2 in one of the coupler chips, and the other end is fixed just above the gap of the wedge-shaped waveguide top plate 2 in the other coupler chip.

[0033] like Figure 1 As shown in the figure, the waveguide coupler consists of a mode converter at the near end and a wedge-shaped waveguide at the far end. Their base plates are identical, using the same base plate as the waveguide coupler chip and designed using the first metal layer (M1) in the process library. Their top plates are made of different materials: the mode converter's top plate uses the ninth metal layer (M9) in the process library, while the wedge-shaped waveguide's top plate uses the tenth metal layer (AP). Furthermore, their top plates differ in shape: the mode converter's is rectangular, while the wedge-shaped waveguide's is a wedge-shaped plate that tapers from near to far.

[0034] The present application has a gap of equal width in the middle of the mode converter and the top plate of the wedge-shaped waveguide, which runs through the top plates of the two structures. The top plates of the mode converter and the wedge-shaped waveguide are connected by a via metal RV between the metal M9 and the metal AP, and the connection position is only located at the junction of the end of the mode converter and the starting end of the wedge-shaped waveguide. In addition, a metal-via array is used to connect the top plate and the bottom plate at the left and right edges of the two structures, without any metal in the middle, to form a waveguide structure. The structure of the second metal via array 5 and the third metal via array 12 is as shown in FIG. Figure 2 As shown in the figure: In the process library used, via metal is provided between each adjacent metal layer, Mx represents the x-th metal layer in the CMOS 65nm process library, and VIAx represents the x-th via metal layer; for the first metal via array 4, its structure is Figure 2 Structure below M9.

[0035] Immediately adjacent to the interface between the mode converter and the wedge-shaped waveguide is a feeder-waveguide coupling line, constructed from metal AP. One end is connected to the mode converter top plate below it using a metal RV, and the other end is connected to the GSG pad via a waveguide coupler feeder line. The waveguide coupler feeder line consists of a main coupler feeder line and a grounded matching stub line, both constructed from metal AP. The feeder's reference ground is the coupler chip backplane, and the grounding method uses a metal-via array to connect the matching stub line to the coupler chip backplane. Compared to existing rectangular waveguide solutions, this solution, due to the gradually narrowing width of the wedge-shaped waveguide from its starting point to its end, maximizes energy coupling into the dielectric waveguide above within a relatively short waveguide length. This improves coupling efficiency, reduces chip area, and increases the structure's integration potential. Furthermore, as the wedge-shaped waveguide width gradually narrows, the structure's cutoff frequency also increases, gradually extending the operating frequency to higher frequencies and broadening the structure's operating bandwidth. Furthermore, compared to other non-waveguide structures, this waveguide structure exhibits lower in-band ripple. In addition, compared with the solution of matching elements on the waveguide part, the branch line matching solution adopted by the present invention is easier to design and control. During the design, it is only necessary to adjust the length and width of the branch line to meet the matching requirements. The shape of the branch line is regular, which is more in line with the process during manufacturing and does not introduce additional manufacturing difficulties.

[0036] Figure 3The present invention demonstrates an assembly scheme for inter-chip signal transmission. First, the distance between the two waveguide coupler chips is determined on the printed circuit board. Drying film is then laid at the corresponding locations. The waveguide coupler chips are placed on the film and placed in an incubator for heat curing. This completes the bonding of the waveguide coupler chips to the printed circuit board. Next, rectangular dielectric waveguides made of Rogers 3006, 1 mm in length, and with a cross-sectional area of ​​0.635 mm x 1.300 mm are bonded using photosensitive resin (UV adhesive) directly above the gap between the wedge-shaped waveguides on the top plates of the two coupler chips. This completes the assembly of the entire signal transmission structure, a simple and easy-to-use solution. Compared to existing dielectric waveguide solutions using silicon, Rogers 3006 dielectric waveguides offer a certain degree of flexibility, unlike silicon, which is hard and brittle. This allows for signal transmission even under certain curvatures and is less prone to breakage during installation. Furthermore, silicon waveguides of the same size and shape are more expensive per unit length than the dielectric waveguides used in the present invention. Compared with traditional wireless solutions, due to the continuity and uniformity of signal energy leakage, the dielectric waveguide can transmit signals as long as it is attached above the gap of the wedge-shaped waveguide top plate of the coupler chip, avoiding the problem of remote precise alignment of the transceiver system.

[0037] The S parameters of the signal transmission structure are measured based on the probe test. Figure 4 As shown, waveguide coupler chip I serves as the transmitter, while waveguide coupler chip II serves as the receiver. First, the input signal is connected to probe I, which serves as the external signal input port; the data processing equipment is connected to probe II, which serves as the output port. The entire signal transmission structure is then placed on a probe station, with probe I connected to the GSG pads of waveguide coupler chip I and probe II connected to the GSG pads of waveguide coupler chip II. The input signal is then transmitted through the probes to the coupler feed line and waveguide coupling line of waveguide coupler chip I, and then through the gap in the top plate of the mode converter below it into the wedge-shaped waveguide. After the signal enters the wedge-shaped waveguide of waveguide coupler chip I, due to the leakage effect of the gap in its top plate, the signal will gradually and evenly leak into the dielectric waveguide above it. After being transmitted through the dielectric waveguide, it leaks through the gap in the top plate of the wedge-shaped waveguide below the other side into the wedge-shaped waveguide of waveguide coupler chip II. It is then transmitted to the mode converter, waveguide coupling line, waveguide coupler feed line and GSG pad of chip II in sequence, and finally transmitted to the data processing equipment through probe II, ultimately obtaining the amplitude-frequency characteristic curve of the S parameter of the entire structure. Figure 5 The simulation model of the entire signal transmission structure is shown. Figure 6-Figure 7 It is the simulation and measured S parameter diagram of the entire structure, where Figure 6 is the amplitude-frequency characteristic curve of S11, Figure 7The following are the amplitude-frequency characteristics of S21. In both figures, the horizontal axis represents frequency, and the vertical axis represents the relative logarithmic amplitude of the S-parameter. The measured in-band 3dB bandwidth is 32.1GHz (137.9GHz-170GHz). At a center frequency of 140GHz, the corresponding relative bandwidth reaches 23%. The maximum in-band ripple is 2.9dB, and the simulated and measured results agree well.

[0038] This invention achieves the design of a D-band signal inter-chip transmission structure by employing an on-chip waveguide coupler chip-bonded with a dielectric waveguide. The on-chip coupler chip utilizes a mode converter coupled to a wedge-shaped waveguide. Compared to traditional antenna radiation schemes, this increases the system's operating bandwidth, reduces passband ripple, and reduces the difficulty of precise alignment between the transmitter and receiver. The on-chip matching structure is simple, easy to design and manufacture, and does not affect much of the passband performance. The installation scheme is simple and easy to operate. The Rogers 3006 dielectric waveguide material is highly flexible and has a regular rectangular shape. Compared to silicon waveguide solutions, it is less prone to breakage and has a lower manufacturing cost. Furthermore, the rectangular dielectric waveguide employed in this invention is also less expensive per unit length than silicon waveguides of the same size.

[0039] The foregoing description is a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present invention can be used in other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

Claims

1. A D-band waveguide coupling transmission structure, characterized in that: The invention comprises two coupler chips, and the two coupler chips are connected by a dielectric waveguide; Each of the coupler chips comprises a coupler body, a coupler feed line and a GSG pad (11); the coupler body comprises a coupler bottom plate (1), a wedge-shaped waveguide top plate (2) and a mode converter top plate (3); the mode converter top plate (3) is rectangular, and the wedge-shaped waveguide top plate (2) is wedge-shaped with a width gradually narrowing from near to far; A first metal via array (4) is provided between the two side edges of the mode converter top plate (3) and the coupler bottom plate (1), thereby forming a mode converter of the coupler body; A second metal via array (5) is provided between the two side edges of the wedge-shaped waveguide top plate (2) and the coupler bottom plate (1), thereby forming a wedge-shaped waveguide of the coupler body; A first metal via (6) is provided between the mode converter top plate (3) and the wedge-shaped waveguide top plate (2); the mode converter top plate (3) and the wedge-shaped waveguide top plate (2) are connected via the first metal via (6); The coupler feed line comprises a waveguide coupling line (7), a coupler main feed line (8) and a matching branch line (9); the waveguide coupling line (7) is located above the mode converter top plate (3); a first end of the waveguide coupling line (7) is connected to the mode converter top plate (3) via a second metal via (10); a second end of the waveguide coupling line (7) is connected to a first end of the coupler main feed line (8); and a second end of the coupler main feed line (8) is connected to a GSG pad (11); one end of the matching branch line (9) is connected to the coupler main feed line, and the other end is connected to the coupler bottom plate (1) via a third metal via array (12); In each of the coupler chips, a gap is provided in the center of the wedge-shaped waveguide top plate (2) and the mode converter top plate (3); One end of the dielectric waveguide is fixed just above the gap of the wedge-shaped waveguide top plate (2) in one of the coupler chips, and the other end is fixed just above the gap of the wedge-shaped waveguide top plate (2) in the other coupler chip.

2. A D-band waveguide coupling transmission structure according to claim 1, characterized in that: The dielectric waveguide is a rectangular dielectric waveguide.

3. The D-band waveguide coupling transmission structure according to claim 1, characterized in that: The first metal via array (4) comprises seven layers of metal plates arranged in sequence from bottom to top, and any two adjacent layers of metal plates are filled with dielectric and connected via metal vias; the first layer of metal plate and the coupler bottom plate (1) are filled with dielectric and connected via metal vias, and the seventh layer of metal plate and the mode converter top plate (3) are filled with dielectric and connected via metal vias.

4. The D-band waveguide coupling transmission structure according to claim 1, characterized in that: The second metal via array (5) comprises eight layers of metal plates arranged in sequence from bottom to top, and any two adjacent layers of metal plates are filled with a dielectric and connected via metal vias; the first layer of metal plates and the coupler bottom plate (1) are filled with a dielectric and connected via metal vias, and the eighth layer of metal plates and the wedge-shaped waveguide top plate (2) are filled with a dielectric and connected via metal vias.

5. The D-band waveguide coupling transmission structure according to claim 1, characterized in that: The third metal via array (12) comprises eight layers of metal plates arranged in sequence from bottom to top, and dielectric is filled between any two adjacent layers of metal plates and connected via metal vias; dielectric is filled between the first layer of metal plate and the coupler bottom plate (1) and connected via metal vias, and dielectric is filled between the eighth layer of metal plate and the matching branch line (9) and connected via metal vias.

6. The D-band waveguide coupling transmission structure according to claim 1, characterized in that: The material used for the dielectric waveguide is Rogers 3006.

7. The D-band waveguide coupling transmission structure according to claim 1, characterized in that: The dielectric waveguide is fixed to the two coupler chips by means of photosensitive resin bonding.

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