CN115425380B - Broadband transition structure of dielectric integrated suspension parallel strip line-back ground coplanar waveguide - Google Patents

Abstract

The invention discloses a broadband transition structure from a medium-integrated suspended parallel strip line to a back-ground coplanar waveguide, which is divided into a medium-integrated suspended parallel strip line, a stripline and a back-ground coplanar waveguide, and the medium-integrated suspended parallel strip line is distributed in The upper and lower sides of the dielectric substrate; during the transition to the stripline, the line width of the G5 transmission line remains unchanged or gradually decreases to be consistent with the line width of the G5 layer of the strip line, and the line width of the G6 transmission line gradually increases; passing through the air cavity When the cross section of the side boundary is located, the G5 transmission line is connected to the middle metal layer of the stripline; the G6 transmission line is connected to the lower metal layer of the stripline; when transitioning to the back-ground coplanar waveguide, the G5 transmission line is connected to the middle metal layer of the GCPW; the G6 transmission line Connects to the lower metal layer of the GCPW. The invention realizes the integration and interconnection of various transmission lines, can realize various circuit functions, provides guarantee for the circuit package test of SISPSL, and solves the package and loss problems of transition circuits.

Description

Broadband Transition Structure from Dielectric Integrated Suspension Parallel Stripline to Background Coplanar Waveguide

technical field

The invention relates to the technical field of radio frequency microwave circuits, in particular to a broadband transition structure from a dielectric integrated suspension parallel strip line to a back ground coplanar waveguide.

Background technique

With the rapid development of wireless communication technology, multiple communication modes cause mutual interference between systems. Improving the system's anti-interference ability and maintaining the signal-to-noise ratio has become a hot issue. Double-sided parallel stripline is a balanced transmission line commonly used in radio frequency microwave circuits. The balanced circuit has symmetry, which can effectively suppress noise signals and reduce mutual crosstalk between circuit components. The structure of the double-sided parallel strip line includes a dielectric substrate and a metal strip whose upper and lower surfaces are parallel and symmetrical. Double-sided parallel striplines are planar microwave transmission lines whose electromagnetic field distribution is similar to that of microstrip lines. As a transmission line exposed in the air, the double-sided parallel strip line itself needs to be packaged in a metal shell, resulting in a larger circuit size, larger weight, and higher cost for the RF module it constitutes. At the same time, radiation loss is an urgent problem to be solved.

Substrate integrated suspended line (SISL) is a new type of transmission line structure. It usually uses the printed circuit board (PCB) process to obtain a multilayer board structure, and the cavity is excavated inside to further reduce the dielectric loss. The metal through-hole structure is adopted to achieve the effect of the metal side wall equivalently. Substrate integrated suspended parallel strip line (SISPSL) is a method of embedding double-sided parallel strip lines in multi-layer SISL, which can reduce electromagnetic loss, especially radiation loss, while improving the anti-interference ability of the system. , to achieve the characteristics of self-encapsulation.

Since the SISPSL is a balanced bilateral transmission line, it is difficult to directly connect with the commonly used RF coaxial connector in actual testing, and it is not convenient to directly test it. In order to test the SISPSL balanced transmission line and its circuit, it is necessary to design a broadband transition structure. Grounded Coplanar Waveguide (GCPW) is a commonly used transmission line structure. Compared with the balanced transmission line of SISPSL, GCPW is a single-ended circuit type. GCPW is also compatible with commonly used RF coaxial connectors. Therefore, realizing the transition from SISPSL to GCPW has important research significance and application value.

Contents of the invention

The object of the present invention is to provide a broadband transition structure from a dielectric integrated suspension parallel strip line to a back ground coplanar waveguide aiming at the technical defects in the prior art.

The technical scheme adopted for realizing the purpose of the present invention is:

A broadband transition structure from a dielectric-integrated suspended parallel stripline to a back-ground coplanar waveguide, comprising:

Dielectric integrated suspended parallel stripline, stripline (stripine, SL) and back-ground coplanar waveguide; the broadband transition structure is a symmetrical back-to-back structure, and the two symmetrically arranged ports are respectively connected to the symmetrically distributed back-ground coplanar waveguide, and the back-ground coplanar waveguide The waveguide is connected to the symmetrically distributed striplines, and the striplines are connected to the dielectric-integrated suspended parallel striplines in the middle;

Distributed in the area between the NN' section and the LL' section is the dielectric integrated suspended parallel strip line, the G5 transmission line and the G6 transmission line of the dielectric integrated suspended parallel strip line are wired in parallel, and the width of the G5 transmission line remains unchanged or The narrowed gradient structure transitions from the middle to the striplines on both sides, the width of the G6 transmission line increases, and the widened gradient structure transitions from the middle to the striplines on both sides. At the section N-N', the G5 transmission line and The width of the G6 transmission line is the same; at the section M-M' between the NN' section and the LL' section, the width of the G6 transmission line is wider than the G5 transmission line;

When passing through the section L-L', the G5 transmission line is connected to the middle metal layer of the stripline at the section L-L'; the G6 transmission line is widened, and then connected to the lower metal layer of the stripline at the section L-L';

When passing through the section L-L', the transmission line transitions from a dielectric-integrated suspended parallel stripline to a stripline structure;

When passing through section K-K', the middle metal layer of the stripline is connected to the middle metal layer of the back ground coplanar waveguide; the lower metal layer of the strip line is connected to the lower metal layer of the back ground coplanar waveguide;

When passing through the section K-K', the transmission line transitions from the stripline to the structure of the back-ground coplanar waveguide;

Among them, the section NN' is the symmetry axis of the entire back-to-back transition structure, which divides the medium-integrated suspension parallel strip line into two symmetrical parts, and the section L-L' is the same as the air cavity inside the medium-integrated suspension parallel strip line The boundaries coincide, the section MM' is located between the section LL' and the section NN', and the section K-K' is located at the junction of the stripline and the back-ground coplanar waveguide.

Among them, after the G6 transmission line extends from the symmetry line N-N' to both sides for a certain distance, it gradually widens symmetrically from the middle to both sides in a triangular structure, gradually covers the dielectric substrate where it is located, and connects with the boundary of the air cavity. Form a symmetrical hourglass-shaped structure.

Among them, after the G6 transmission line extends from the symmetry line NN' to both sides for a certain distance, it gradually widens symmetrically from the middle to both sides in a stepped transition manner, gradually covers the dielectric substrate where it is located, and connects with the boundary of the air cavity , forming a symmetrical ladder-like structure.

Among them, after the G6 transmission line extends from the symmetrical line NN' to both sides for a certain distance, it gradually widens symmetrically from the middle to both sides in a chamfered manner, and gradually covers the dielectric substrate where it is located, and connects with the boundary of the air cavity. Form a symmetrical chamfer structure.

The SISPSL of the present invention uses the SISL to realize low loss and self-encapsulation, effectively reduces electromagnetic loss, reduces the overall size of the circuit, and is beneficial to miniaturized and highly integrated circuit design.

The transition from SISPSL to GCPW provided by the invention realizes the integration and interconnection of multiple transmission lines on the same multilayer printed circuit board platform, can realize multiple circuit functions, and provides guarantee for the circuit package test of SISPSL.

The transition structure provided by the present invention can also adjust the bandwidth of the transition circuit, the working frequency band and realize other functions by adjusting the transition form of the topology and encapsulating a part of the topology, and has design flexibility.

Compared with the double-sided parallel strip line circuit that needs to be packaged, the entire circuit of the transition structure provided by the present invention has a smaller physical length, and can reduce the area and size of the corresponding circuit module.

The transition structures in the prior art have relatively large radiation loss because their transition structures are exposed in the air. The present invention solves the problem of radiation loss by introducing a self-encapsulation structure, and the self-encapsulation can avoid the effect of adding a metal shell later on the performance of the transition circuit.

Compared with the transition circuit that needs to be encapsulated, the transition structure provided by the present invention has the characteristics of self-encapsulation and integration, and does not need to introduce the effect of external metal shielding to reduce loss, thereby effectively avoiding the influence of circuit performance after encapsulating the metal shell.

Description of drawings

FIG. 1 is a top view of a metal layer G5 in a transition structure from a dielectric integrated suspended parallel strip line (SISPSL) to a back ground coplanar waveguide (GCPW) according to the present invention.

Fig. 2 is a top view of the metal layer G6 in the transition structure from the dielectric integrated suspended parallel strip line (SISPSL) to the back ground coplanar waveguide (GCPW) of the present invention.

Fig. 3 is a three-part schematic diagram (completely symmetrical) of the metal layer G5 in the transition structure from the dielectric integrated suspended parallel strip line (SISPSL) to the back ground coplanar waveguide (GCPW) of the present invention.

Fig. 4 is a three-part schematic diagram (completely symmetrical) of the metal layer G6 in the transition structure from the dielectric integrated suspended parallel strip line (SISPSL) to the back ground coplanar waveguide (GCPW) of the present invention.

Fig. 5 is a schematic cross-sectional view of a dielectric integrated suspended parallel strip line (SISPSL) at the N-N' section in Fig. 1 of the present invention.

Fig. 6 is a schematic cross-sectional view of the dielectric integrated suspended parallel strip line (SISPSL) at the M-M' section in Fig. 1 of the present invention.

Fig. 7 is a schematic cross-sectional view of the stripline (SL) at the L-L' section in Fig. 1 of the present invention.

Fig. 8 is a schematic cross-sectional view of the back-ground coplanar waveguide (GCPW) at the K-K' section in Fig. 1 of the present invention.

FIG. 9 is a top view of the diagonal transition structure of the metal layer G6 of the present invention.

FIG. 10 is a top view of the stepped transition structure of the metal layer G6 of the present invention.

FIG. 11 is a top view of the arc-shaped transition structure of the metal layer G6 of the present invention.

12 is a top view of metal layers G5 and G6 in the transition structure from dielectric integrated suspended parallel strip line (SISPSL) to back ground coplanar waveguide (GCPW) according to the present invention.

Fig. 13 is a schematic diagram of simulation of scattering parameters of a back-to-back structure transitioning from a dielectric integrated suspended parallel strip line (SISPSL) to a back ground coplanar waveguide (GCPW).

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The transitional back-to-back structure of the dielectric-integrated suspended parallel stripline (SISPSL) to the back-ground coplanar waveguide (GCPW) in the embodiment of the present invention includes a dielectric-integrated suspended parallel stripline, a stripline and a back-ground coplanar waveguide, as shown in Figure 3 and 4. For the self-encapsulated transmission line structure, parallel-aligned metal strip lines are printed on the upper and lower surfaces of the dielectric substrate, and the double-sided parallel strip lines are packaged in an equivalent metal shielding shell by using a multilayer board structure and a printed circuit board process, including 10 metal layers, namely metal layer G1, metal layer G2, metal layer G3, metal layer G4, metal layer G5, metal layer G6, metal layer G7, metal layer G8, metal layer G9, metal layer G10, there are 5 layers Dielectric substrates (refer to the network-shaped line coverage areas in Figures 5, 6, 7, and 8), respectively, dielectric substrate Sub1, dielectric substrate Sub2, dielectric substrate Sub3, dielectric substrate Sub4, dielectric substrate Sub5, metal layer G1, and metal layer G2 Located on both sides of the dielectric substrate Sub1, the metal layer G3 and the metal layer G4 are located on both sides of the dielectric substrate Sub2, the metal layer G5 and the metal layer G6 are located on both sides of the dielectric substrate Sub3, the metal layer G7 and the metal layer G8 are located on the sides of the dielectric substrate Sub4 On both sides, the metal layer G9 and the metal layer G10 are located on both sides of the dielectric substrate Sub5, and the middle of the dielectric substrate Sub2 and the dielectric substrate Sub4 is hollowed out to form two vertically symmetrical air cavities separated by the dielectric substrate Sub3, as shown in Figure 5 and Figure 6 The two white areas in the middle are shown.

Wherein, the metal layer G2, the metal layer G9 and the metallized through holes are equivalent to achieve the electromagnetic shielding effect. Its structural topology adopts a multi-layer board structure, and uses different combinations of metallized vias to achieve self-encapsulation effects. At present, PCB technology has been widely used, with unique advantages such as high density, high reliability, and designability. Referring to Figures 1 to 4, the shaded area represents the metal layer, the unshaded round hole arranged on the metal layer represents the metallized through hole, and the white area inside the metal layer represents the bare dielectric substrate, as shown in Figure 5, The strip-shaped rectangular white areas arranged vertically in 6, 7, and 8 indicate metallized through holes.

Distributed in the area between the NN' section and the LL' section is the dielectric integrated suspended parallel strip line (including the upper metal layer of the SISPSL and the lower metal layer of the SISPSL, that is, the conduction band of the metal layer G5 or the G5 transmission line , the conduction band of the metal layer G6 or the G6 transmission line, which are distributed in parallel on the upper and lower sides of the dielectric substrate in the middle, forming a structure of dielectric integrated suspended parallel strip lines), the conduction band of the metal layer G5 is parallel to the conduction band of the metal layer G6 Wiring, in the process of transitioning from dielectric integrated suspended parallel stripline to stripline, the width of the conduction strip of metal layer G5 does not change when it extends to both sides, or adopts a structure that narrows from width, and gradually decreases to the stripline The line width of the G5 layer remains consistent, and the conduction band of the metal layer G6 adopts a structure from narrow to wide, and the width gradually increases.

At the section NN', the conduction band widths of the metal layer G5 and the metal layer G6 are the same; at the section MM', the conduction band width of the metal layer G6 is wider than that of the metal layer G5, as shown in Figures 5 and 6 shown.

When passing through the section LL', the conduction band of the metal layer G5 is connected to the middle metal layer (metal layer G5) of the stripline at the section LL', and the conduction band of the metal layer G6 widens, and then connects with the stripline The lower metal layer of the line (metal layer G6) is connected at section LL'. When passing through the section L-L', the transmission line transitions from a dielectric-integrated suspended parallel stripline to a stripline structure, and the cross-section of the stripline is shown in Figure 7.

When passing through the section K-K', the metal layer G5 is connected to the middle metal layer of the back ground coplanar waveguide and the metal layers on both sides (metal layer G5); that is, the middle metal layer of the stripline is connected to the back ground coplanar waveguide (GCPW) The middle metal layer is connected; the metal layer G6 is connected to the lower metal layer (metal layer G6) of the back-ground coplanar waveguide, that is, the lower metal layer of the stripline is connected to the lower metal layer of the back-ground coplanar waveguide. When passing through the section K-K', the transmission line transitions from the stripline to the back-ground coplanar waveguide structure, and the cross-section of the back-ground coplanar waveguide is shown in Figure 8.

In the embodiment of the present invention, the entire transition structure is a symmetrical back-to-back structure. Port 1 and port 2 are connected to the back-ground coplanar waveguide, the back-ground coplanar waveguide is connected to the stripline, and the stripline is connected to the dielectric-integrated suspension parallel stripline in the middle.

It should be noted that, in the embodiment of the present invention, the N-N' section is the section perpendicular to the SISPSL at the symmetry axis of the SISPSL, and the M-M' section is a certain section in the process of the gradual transition from the SISPSL to the stripline, and N- The N' section is parallel, the LL' section is the section of the SL structure, which is parallel to the NN' section, and the K-K' section is the section of the GCPW structure, which is parallel to the NN' section.

Figures 1 and 2 show the top view of the wiring diagram of the G5 transmission line and the G6 transmission line of this transition structure, where the dielectric integrated suspended parallel strip line is between the NN' and LL' sections, and the LL' and K- The stripline is between the K' sections, and the back-ground coplanar waveguide is between the K-K' section and the boundary of the entire transition structure, as shown in Figures 3 and 4.

Fig. 5, Fig. 6, Fig. 7, Fig. 8 represent respectively the cross-sectional schematic view of N-N', M-M', L-L', K-K' section in Fig. 1. Wherein, FIG. 5 shows a cross-sectional view of a cross-section at the axis of symmetry of the SISPSL. Figure 6 shows a cross-sectional view of a certain section during the transition from SISPSL to stripline, and its G6 transmission line gradually increases in width until it gradually changes to cover the dielectric substrate. FIG. 7 shows a cross-sectional view of a stripline, and FIG. 8 shows a cross-sectional view of a back-ground coplanar waveguide.

In the transition structure of the embodiment of the present invention, three transition forms are proposed, and other transition forms are used as topologies. As shown in FIG. 9 , with oblique transition, the width of the G5 transmission line remains unchanged, and the G6 transmission line is connected to the boundary of the cavity through a triangular structure. As shown in Figure 10, the width of the G5 transmission line remains unchanged for the step transition. The G6 transmission line is connected to the boundary of the cavity through a stepped structure. As shown in FIG. 11 , the arc-shaped transition, the width of the G5 transmission line remains unchanged, and the G6 transmission line is connected to the boundary of the cavity through an arc-shaped chamfer structure.

Finally, a back-to-back single-ended transition based on a circular-arc chamfer structure was simply designed, as shown in Figure 12. The simulation results of scattering parameters were obtained using electromagnetic simulation software, and a frequency bandwidth greater than 40 GHz was achieved, as shown in Figure 13.

It should be noted here that other methods of utilizing the natural transition of the electromagnetic field to transition the structure of the self-encapsulated double-sided parallel strip line to the structure of the GCPW also belong to the expansion method of the invention.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or fundamentals of the present invention. In the case of features, the invention can be implemented in other specific forms;

Accordingly, the embodiments should be regarded in all points of view as exemplary and not restrictive, the scope of the invention being defined by the appended claims rather than the foregoing description, and it is therefore intended that the scope of the invention be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in the invention, and any reference sign in a claim shall not be construed as limiting the claim concerned.

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only includes an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art.

Claims (4)

1. The broadband transition structure from the dielectric integrated suspension parallel strip line to the back-to-ground coplanar waveguide is characterized by comprising the dielectric integrated suspension parallel strip line, the strip line and the back-to-ground coplanar waveguide; the broadband transition structure is a symmetrical back-to-back structure, two ports which are symmetrically arranged are respectively connected with symmetrically distributed back-to-ground coplanar waveguides, the back-to-ground coplanar waveguides are connected with symmetrically distributed strip lines, and the strip lines are connected with medium integrated suspension parallel strip lines in the middle part;

distributed in the area between the N-N ' section and the L-L ' section is a medium integrated suspension parallel strip line, a G5 transmission line and a G6 transmission line of the medium integrated suspension parallel strip line are arranged in parallel, the width of the G5 transmission line is unchanged or a narrowing gradual change structure is transited from the middle to two side strip line parts, the width of the G6 transmission line is increased, a widening gradual change structure is transited from the middle to two side strip line parts, and the widths of the G5 transmission line and the G6 transmission line are consistent at the section N-N '; the section M-M ' between the N-N ' section and the L-L ' section is provided with a G6 transmission line width ratio G5 transmission line width;

when passing through the section L-L ', the G5 transmission line is connected with the middle metal layer of the strip line at the section L-L ', the G6 transmission line is widened, and then is connected with the lower metal layer of the strip line at the section L-L ';

when the cross section L-L 'is passed, the transmission line is transited to the structure of the strip line by the medium integrated suspension parallel strip line, and when the cross section K-K' is passed, the middle metal layer of the strip line is connected with the middle metal layer of the back-to-ground coplanar waveguide; the lower metal layer of the strip line is connected with the lower metal layer of the back-to-ground coplanar waveguide;

when the section K-K' is passed, the transmission line is transited from the strip line to the back ground coplanar waveguide structure;

the medium integrated suspension parallel strip line is divided into two symmetrical parts, the cross section N-N 'is a cross section vertical to the medium integrated suspension parallel strip line along the symmetry axis, the cross section L-L' coincides with the boundary of an air cavity inside the medium integrated suspension parallel strip line, the cross section M-M 'is positioned between the cross section L-L' and the cross section N-N ', and the cross section K-K' is positioned at the junction of the strip line and the back-to-ground coplanar waveguide.

2. The broadband transition structure from the dielectric integrated suspension parallel strip line to the back ground coplanar waveguide according to claim 1, wherein after the G6 transmission line extends from the symmetry axis N-N' to two sides for a certain distance, the dielectric substrate where the G6 transmission line is located is gradually and symmetrically widened from the middle to two sides in a triangular structure and gradually covered on the dielectric substrate, and is connected with the boundary of the air cavity to form a symmetrical hourglass structure.

3. The broadband transition structure from the dielectric integrated suspension parallel strip line to the back ground coplanar waveguide according to claim 1, wherein after the G6 transmission line extends from the symmetry axis N-N' to two sides for a certain distance, the dielectric substrate where the G6 transmission line is gradually and symmetrically widened from the middle to two sides in a step transition manner and gradually covers the dielectric substrate is connected with the boundary of the air cavity to form a symmetrical step-shaped structure.

4. The broadband transition structure from the dielectric integrated suspension parallel strip line to the back-to-ground coplanar waveguide according to claim 1, wherein after the G6 transmission line extends from the symmetry axis N-N' to two sides for a certain distance, the dielectric substrate where the G6 transmission line is gradually and symmetrically widened from the middle to two sides in a chamfering manner and gradually covers the G6 transmission line is connected with the boundary of the air cavity through an arc chamfer to form a symmetrical chamfer structure.

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