A transition structure between coplanar waveguide and microstrip line

Abstract

The present invention belongs to the field of semiconductor technology, and specifically discloses a transition structure between a coplanar waveguide and a microstrip line, including: a coplanar waveguide structure and a microstrip line structure; the coplanar waveguide structure includes an upper metal layer, a first dielectric layer and a lower metal layer, the upper metal layer includes a first metal plate with a first notch and a transmission line located in the first notch; the microstrip line structure includes a second dielectric layer, a microstrip layer arranged on a side of the second dielectric layer close to the upper metal layer, and a top metal layer arranged on a side of the second dielectric layer away from the coplanar waveguide structure, the microstrip layer includes a microstrip line and ground wires insulated from the microstrip line on both sides of the microstrip line, and the microstrip line is in electrical contact with the transmission line. The present invention increases the signal return path, avoids the high-frequency band resonance problem, ensures the integrity of the grounding, and at the same time has the function of improving the impedance matching of the transition section, reduces the loss metallization of the high-frequency band, obtains good transmission characteristics, and avoids the high-frequency band resonance problem.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a transition structure between a coplanar waveguide and a microstrip line. Background Art

[0002] In recent years, with the development and popularization of 5G communication technology and consumer electronics technology, semiconductor devices have been continuously developing towards miniaturization and integration, and the operating frequency has been continuously increasing. High-frequency wafer-level testing has gradually become an indispensable part of RF chip production. The cascade of microstrip line structural parts and PCB RF boards is currently an important test solution, which is widely used in high-frequency wafer-level test analysis.

[0003] Microstrip line structures and planar transmission structures such as microstrip lines, coplanar waveguides, and substrate integrated waveguides in PCB RF boards have the advantages of miniaturization and easy integration, and are widely used in microwave integrated circuits and microwave systems. Since various transmission structures have their own characteristics, it is often necessary to achieve transmission transitions between different planes and different transmission lines.

[0004] The PCB board in the prior art is generally composed of a waveguide transmission structure and a microstrip line structure. The microstrip line structure is also a microstrip transmission structure, in which the RF system transition structure is mainly concentrated on a dielectric board to achieve transmission transition through electromagnetic coupling between different transmission structures. This form is not applicable to wafer-level testing. In order to achieve the purpose of wafer-level testing, the designed thin film structure must have a very compact structure, and then connected to the PCB RF board through a type of fixing device, so that the tester can detect the signal. Among the currently used thin film solutions, structures such as microstrip lines and coplanar waveguides are generally used. However, this structure not only has poor RF performance, but the transition structure is also difficult to cover the high-frequency structure and may produce high-frequency resonance, while increasing insertion loss. Summary of the invention

[0005] The present invention provides a transition structure between a coplanar waveguide and a microstrip line, which is used to solve the problems that the radio frequency performance in the current PCB board is poor and the transition structure is difficult to cover the high-frequency structure.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a transition structure between a coplanar waveguide and a microstrip line, which comprises: a coplanar waveguide structure and a microstrip line structure arranged on the coplanar waveguide structure;

[0007] The coplanar waveguide structure comprises an upper metal layer, a first dielectric layer and a lower metal layer arranged from top to bottom, the upper metal layer comprises a first metal plate with a first notch and a transmission line located in the first notch, the transmission line and the first metal plate are insulated from each other;

[0008] The microstrip line structure includes a second dielectric layer, a microstrip layer arranged on a side of the second dielectric layer close to the upper metal layer, and a top metal layer arranged on a side of the second dielectric layer away from the coplanar waveguide structure. The microstrip layer includes a microstrip line and ground lines located on both sides of the microstrip line and insulated from the microstrip line. The microstrip line is in electrical contact with the transmission line.

[0009] In a preferred embodiment of the present invention, the microstrip line includes a gradient line, a contact line and an extension line, the gradient line connects the contact line and the extension line, and the line width of the contact line is greater than that of the extension line.

[0010] In a preferred embodiment of the present invention, the line width of the gradient line at one end connected to the contact line is equal to the line width of the contact line, and the line width of the gradient line at one end in contact with the extension line is equal to the line width of the extension line.

[0011] In a preferred embodiment of the present invention, the contact line is connected to the transmission line via a pad.

[0012] In a preferred embodiment of the present invention, a plurality of interconnected first through holes are provided on the upper metal layer, the lower metal layer and the first dielectric layer.

[0013] In a preferred embodiment of the present invention, the top metal layer, the second dielectric layer and the microstrip layer are provided with a plurality of interconnected second through holes.

[0014] In a preferred embodiment of the present invention, the top metal layer includes a second metal plate with a second notch, and the second notch corresponds to the first notch in position and has the same shape.

[0015] In a preferred embodiment of the present invention, a connecting bridge spanning the second notch is provided on the second metal plate.

[0016] In a preferred embodiment of the present invention, there are at least two connecting bridges and the intervals between two adjacent connecting bridges are equal.

[0017] In a preferred embodiment of the present invention, the coplanar waveguide structure is a PCB board, and the microstrip line structure is a flexible film.

[0018] The technical solution provided by the present invention has the following advantages compared with the prior art:

[0019] The present invention increases the signal return path, avoids the high-frequency band resonance problem, ensures the integrity of the grounding, and simultaneously improves the impedance matching of the transition section, reduces the loss metallization of the high-frequency band, and obtains good transmission characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, drawings of other embodiments can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is an exploded schematic diagram of a transition structure between a coplanar waveguide and a microstrip line according to an embodiment of the present invention;

[0022] Figure 2 is an exploded schematic diagram of a microstrip line structure in a transition structure between a coplanar waveguide and a microstrip line according to an embodiment of the present invention;

[0023] Figure 3 It is a matching response simulation diagram of a PCB board in the prior art;

[0024] Figure 4 This is a matching response simulation diagram of a transition structure between a coplanar waveguide and a microstrip line described in one embodiment of the present invention.

[0025] As shown in the figure:

[0026] 1-lower metal layer; 2-first dielectric layer; 21-first through hole; 3-upper metal layer; 31-transmission line; 4-microstrip layer; 41-ground line; 42-microstrip line; 43-gradient line; 5-second dielectric layer; 51-second through hole; 6-top metal layer; 61-second notch; 62-connecting bridge. DETAILED DESCRIPTION

[0027] For ease of understanding, a transition structure between a coplanar waveguide and a microstrip line is described below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0028] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation and positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0031] like Figure 1-2 As shown, the present invention discloses a transition structure between a coplanar waveguide and a microstrip line, comprising: a coplanar waveguide structure and a microstrip line structure arranged on the coplanar waveguide structure, wherein the microstrip line structure is a flexible film.

[0032] Among them, Figure 1 As shown, the coplanar waveguide structure includes a lower metal layer 1 , an upper metal layer 3 , and a first dielectric layer 2 arranged between the lower metal layer 1 and the upper metal layer 3 .

[0033] The lower metal layer 1 is a rectangular metal plate. The upper metal layer 3 includes a first metal plate and a transmission line 31. The first metal plate is provided with a first notch, and the transmission line 31 is embedded in the first notch. The transmission line 31 is insulated from the first metal plate by making the transmission line 31 not in contact with the first metal plate.

[0034] A plurality of interconnected first through holes are provided on the upper metal layer 3 and the lower metal layer 1, a metallized first through hole 21 is etched on the first dielectric layer 2, and a first through hole 21 is provided on the second dielectric layer 2 to connect the lower metal layer 1 and the first metal plate, so in this embodiment, the first through hole 21 is located between the first metal plate and the lower metal layer 1. The interior of the first through hole 21 is plated with a metal layer, which can not only enhance the signal transmission between the ground wire 41 and the top metal layer 6, but also resist oxidation and facilitate welding.

[0035] The first through holes 21 are divided into two columns, one column is located on one side of the transmission line 31, and the other column is located on the other side of the transmission line 31. The number of first through holes 21 in each column is at least two. In this embodiment, the number of first through holes 21 in each column is 4, and the total number of first through holes 21 is 8, which can fully meet the requirements of signal transmission.

[0036] Furthermore, since the first through hole 21 is used to transmit signals between the lower metal layer 1 and the first metal plate, the first through hole 21 is completely located between the lower metal layer 1 and the first metal plate, that is, the inner diameter of the first through hole 21 is not greater than the width of a single first metal plate.

[0037] Reference Figure 2 As shown, the microstrip line structure includes a second dielectric layer 5, a microstrip layer 4 arranged on a side of the second dielectric layer 5 close to the coplanar waveguide structure, a top metal layer 6 arranged on a side of the second dielectric layer 5 away from the coplanar waveguide structure, and a plurality of second through holes arranged on the second dielectric layer 5. The microstrip layer in the microstrip line structure layer overlaps with the upper metal layer 3 in the PCB board.

[0038] The microstrip line 42 includes a gradient line 43, a contact line and an extension line (not marked in the figure), the gradient line 43 connects the contact line and the extension line, and the line width of the contact line is greater than the extension line. The line width of the gradient line 43 at one end connected to the contact line is equal to the line width of the contact line, and the line width of the gradient line 43 at one end in contact with the extension line is equal to the line width of the extension line. The contact line is connected to the transmission line through a pad, and here, the microstrip line 42 does not directly contact the transmission line, and insulation is achieved where there is no pad.

[0039] The microstrip layer includes two ground wires 41 arranged in parallel and a microstrip line 42 located between the two ground wires 41. A contact layer is provided on one side of the ground wire 41 and the microstrip line 42 close to the upper metal layer 3. The contact layer is an insulating member to insulate the microstrip layer and the upper metal layer 3 from each other to prevent signal short circuit or other safety hazards.

[0040] The contact layer can be a contact surface covering the entire ground line 41 and the upper metal layer 3 or the contact surface between the entire microstrip line 42 and the upper metal layer 3, or it can be a small contact surface layer arranged on the ground line 41 and the microstrip line 42. As long as the contact layer can be in full contact with the coplanar waveguide structure, the microstrip line 42 can be prevented from contacting the ground line in the coplanar waveguide structure to cause a signal short circuit.

[0041] When a small contact layer is provided on the microstrip line 42, the microstrip line 42 also includes a small gradient line 43 in the middle. The different widths at both ends of the microstrip line 43 result in different impedances. The impedance mutation is improved through the gradient method, and the signal transmission is enhanced.

[0042] Reference Figure 2 As shown, a plurality of second through holes 51 are provided on the second dielectric layer 5, and the second through holes 51 are all through holes, and the second through holes 51 are located between the ground wire 41 and the top metal layer 6. The interior of the second through hole 51 is plated with a metal layer to enhance the signal transmission between the ground wire 41 and the top metal layer 6, and also to resist oxidation and facilitate welding.

[0043] The second through holes 51 are divided into two columns, respectively located on the two ground lines 41, and the number of the second through holes 51 in each column is at least two. In this embodiment, the number of the second through holes 51 in each column is 4, and the total number of the second through holes 51 is 8, which is the same as the number of the first through holes 21, and can fully meet the requirements of signal transmission.

[0044] Since the through hole on the second dielectric layer 5 is to enhance signal transmission between the ground line 41 and the top metal layer 6 , the second through hole 51 is completely located between the ground line 41 and the top metal layer 6 , that is, the inner diameter of the second through hole 51 is smaller than the width of the ground line 41 .

[0045] Continue to refer to Figure 2 As shown, the top metal layer 6 includes a second metal plate with a second notch 61, and the second notch 61 corresponds to the position of the first notch and has the same shape as the top metal layer. A connecting bridge 62 is provided on the second metal plate, spanning the second notch 61. There are at least two connecting bridges 62, and the spacing between two adjacent connecting bridges 62 is equal.

[0046] That is, the second notch 61 on the body corresponds to the second notch 61 on the first metal plate in position and has the same shape, the second notch 61 is axially symmetrical along the center line of the body, and the two ends of the connecting bridge 62 are connected to two symmetrical points on the second notch 61. In this embodiment, the second notch 61 and the connecting bridge 62 are provided to improve impedance matching of signal transmission.

[0047] The microstrip line structure and the PCB board are assembled by external pressure. After assembly, the ground line 41 is connected to the first metal plate in the upper metal layer 3, thus forming a complete path for signal transmission. The ground line 41, the through hole, and the upper metal layer 3 as parts of the microstrip line structure ensure the integrity of the ground phase signal in the transition section. Compared with the ground phase structure without the second notch 61 and the connecting bridge 62, the structure in this embodiment can improve the impedance matching of signal transmission.

[0048] Reference Figure 3-4 The simulation results of its matching response are shown in Figure 4 As shown, in this embodiment, the -20dB return loss frequency band is 41.7GHz, and the insertion loss within the bandwidth is within -2.3dB, wherein the substrate dielectric constant used by the PCB board is 3.49, and the microstrip line structure is a polyimide material. Therefore, the transition structure of the designed microstrip line structure microstrip line 42 and the PCB coplanar waveguide obtains good transmission characteristics, and the -20dB return loss bandwidth can cover 41.7GHz, corresponding to an insertion loss of -2.3dB, which greatly improves the system performance.

[0049] In summary, the -20dB return loss in the prior art reaches 41.7GHz, and the insertion loss after improvement by the solution of the present invention is -2.3dB, which obtains good transmission characteristics. In addition, the setting of the ground wire 41 ensures the integrity of the grounding and avoids the resonance problem in the high frequency band.

[0050] When the present invention is working, the radio frequency signal enters through the coplanar waveguide port of the PCB, the signal is transmitted in the transmission line 31, and is transmitted to the microstrip structure of the film through the microstrip line 42. When the signal passes through the discontinuous point of the microstrip line 42, the impedance will suddenly change and introduce parasitic capacitance and inductance. The second notch 61 of the top metal layer 6 is used to regulate the impedance change of the transition section and improve the parasitic effect. A small section of the gradient line 43 in the microstrip line 42 also improves the impedance mutation of the transition structure. The broadband transmission characteristics benefit from the matching of the upper metal layer 3 and the microstrip line 42. In order to further reduce the high-frequency insertion loss, the connecting bridge 62 is introduced, which can significantly improve the electromagnetic leakage problem caused by the existence of the second notch 61 and reduce the loss in the high-frequency band.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A transition structure between a coplanar waveguide and a microstrip line, characterized in that: include: A coplanar waveguide structure and a microstrip line structure arranged on the coplanar waveguide structure; The coplanar waveguide structure comprises an upper metal layer, a first dielectric layer and a lower metal layer arranged from top to bottom, the upper metal layer comprises a first metal plate with a first notch and a transmission line located in the first notch, the transmission line and the first metal plate are insulated from each other; The microstrip line structure comprises a second dielectric layer, a microstrip layer arranged on a side of the second dielectric layer close to the upper metal layer, and a top metal layer arranged on a side of the second dielectric layer away from the coplanar waveguide structure, the microstrip layer comprises a microstrip line and ground lines insulated from the microstrip line on both sides of the microstrip line, and the microstrip line is in electrical contact with the transmission line; The top metal layer includes a second metal plate with a second notch, wherein the second notch corresponds to the first notch in position and has the same shape; The second metal plate is provided with a connecting bridge spanning the second notch.

2. A transition structure between a coplanar waveguide and a microstrip line according to claim 1, characterized in that: The microstrip line includes a gradient line, a contact line and an extension line. The gradient line connects the contact line and the extension line. The line width of the contact line is greater than that of the extension line.

3. The transition structure between a coplanar waveguide and a microstrip line according to claim 2, characterized in that: The line width of the end where the gradient line is connected to the contact line is equal to the line width of the contact line, and the line width of the end where the gradient line is in contact with the extension line is equal to the line width of the extension line.

4. The transition structure between a coplanar waveguide and a microstrip line according to claim 2, characterized in that: The contact line is connected to the transmission line through a pad.

5. The transition structure between a coplanar waveguide and a microstrip line according to claim 1, characterized in that A plurality of interconnected first through holes are arranged on the upper metal layer, the lower metal layer and the first dielectric layer.

6. The transition structure between a coplanar waveguide and a microstrip line according to claim 1, characterized in that: The top metal layer, the second dielectric layer and the microstrip layer are provided with a plurality of interconnected second through holes.

7. The transition structure between a coplanar waveguide and a microstrip line according to claim 1, characterized in that: There are at least two connecting bridges, and the intervals between two adjacent connecting bridges are equal.

8. The transition structure between a coplanar waveguide and a microstrip line according to claim 1, characterized in that: The coplanar waveguide structure is a PCB board, and the microstrip line structure is a flexible film.

Images