阅读说明：本技术 巴伦结构及具有巴伦结构的电子装置 (Balun structure and electronic device with same ) 是由 陈铁钰 林可加 刘叶雨 于 2020-06-30 设计创作，主要内容包括：本发明涉及巴伦结构及具有该巴伦结构的电子装置。所述巴伦结构包括第一微带线、两条第二微带线、一个开路枝节一个输入端口、两个输出端口及多个缺陷地结构,所述第一微带线、第二微带线、开路枝节、输入端口及输出端口设置在电路板的第一层板上,多个缺陷地结构设置在电路板的第二层板上,所述第一微带线与两条所述第二微带线耦合连接,所述第一微带线与所述输入端口连接,每一所述第二微带线与一个所述输出端口连接,所述第一微带线上的预设位置处设置所述开路枝节,所述电路板的第二层板上在与所述第一微带线及每一所述第二微带线的对应位置处设置有至少一个所述缺陷地结构。本发明能够提高巴伦结构的反射系数、带宽等电气特性。(The invention relates to a balun structure and an electronic device with the balun structure. The balun structure comprises a first microstrip line, two second microstrip lines, an open-circuit stub, an input port, two output ports and a plurality of defected ground structures, wherein the first microstrip line, the second microstrip line, the open-circuit stub, the input port and the output port are arranged on a first layer board of a circuit board, the plurality of defected ground structures are arranged on a second layer board of the circuit board, the first microstrip line is coupled with the two second microstrip lines, the first microstrip line is connected with the input port, each second microstrip line is connected with one output port, the open-circuit stub is arranged at a preset position on the first microstrip line, and at least one defected ground structure is arranged at a position, corresponding to the first microstrip line and each second microstrip line, on the second layer board of the circuit board. The invention can improve the electrical characteristics of the balun structure, such as reflection coefficient, bandwidth and the like.)

1. A balun structure is arranged on a circuit board, the circuit board comprises a first layer board and a second layer board, and the balun structure is characterized by comprising a first microstrip line, two second microstrip lines, an open-circuit stub, an input port, two output ports and a plurality of defected ground structures, wherein the first microstrip line, the two second microstrip lines, the open-circuit stub, the input port and the two output ports are arranged on the first layer board of the circuit board, the plurality of defected ground structures are arranged on the second layer board of the circuit board, the first microstrip line is coupled with the two second microstrip lines, the first microstrip line is connected with the input port, each second microstrip line is connected with one output port, the open-circuit stub is arranged at a preset position on the first layer board, and the second layer board of the circuit board is provided with the open-circuit stub at a position corresponding to the first microstrip line and each second microstrip line At least one of the defected ground structures is placed.

2. The balun structure of claim 1, wherein the first microstrip line 11 includes a first sub-microstrip line and a second sub-microstrip line, the first sub-microstrip line is connected to the second sub-microstrip line, a width of the first sub-microstrip line is smaller than a width of the second sub-microstrip line, the input port is connected to an end of the first sub-microstrip line far from the second sub-microstrip line, the open-circuit stub is disposed at a wavelength which is located on the first sub-microstrip line and is distant from 2/5 ± 5% of a target frequency of the second sub-microstrip line, and the target frequency is a frequency of a transmission signal in a transmission medium of the first sub-microstrip line or the second sub-microstrip line.

3. The balun structure of claim 2, wherein the defected ground structure is an i-defected ground structure comprising a first i-defected ground structure and a second i-defected ground structure, wherein the first i-defected ground structure and the second i-defected ground structure are structurally identical and are different in size.

4. The balun structure of claim 3, wherein two first I-shaped defected ground structures are disposed on the second layer board of the circuit board at positions corresponding to 1/8 ± 5% of a target frequency of the first sub microstrip line from the wavelength of the target frequency of the second sub microstrip line, wherein the target frequency is a frequency of a transmission signal in a transmission medium of the first sub microstrip line or the second sub microstrip line.

5. The balun structure of claim 3, wherein a second I-shaped defected ground structure is disposed on a second layer board of the circuit board at a position corresponding to a target area including the second sub-microstrip line and each of the second microstrip line partial areas.

6. A balun structure as claimed in claim 3, wherein the i-shaped defected ground structure comprises two end portions and a shaft portion, the two end portions are connected to two ends of the shaft portion, the end portions and the shaft portion are rectangular, and the length and width of the end portions and the shaft portion can be adjusted.

7. The balun structure of claim 2, wherein the second sub-microstrip line includes a first end portion and a second end portion, the first end portion includes a first side and a second side opposite to the first side, the second end portion includes a third side and a fourth side opposite to the third side, the first side and the third side are located on the same side of the second sub-microstrip line, the second side and the fourth side are located on the same side of the second microstrip line, one of the two second microstrip lines is spaced from the first side of the first end portion by a first predetermined distance, and the other second microstrip line is spaced from the fourth side of the second end portion by a first predetermined distance.

8. The balun structure of claim 7, further comprising two third microstrip lines, wherein one of the two third microstrip lines is disposed at a second predetermined distance from the second side of the first end portion, and the other third microstrip line is disposed at a second predetermined distance from the third side of the second end portion.

9. A balun structure according to claim 1, wherein the open-circuit branchknot is a fan-shaped open-circuit branchknot, the fan-shaped open-circuit branchknot having an adjustable fan angle and radial length.

10. An electronic device with a balun structure comprises a circuit board, wherein the balun structure is arranged on the circuit board, the circuit board comprises a first layer board and a second layer board, and the balun structure is characterized by comprising a first microstrip line, two second microstrip lines, an open-circuit stub, an input port, two output ports and a plurality of defected ground structures, the first microstrip line, the two second microstrip lines, the open-circuit stub, the input port and the two output ports are arranged on the first layer board of the circuit board, the plurality of defected ground structures are arranged on the second layer board of the circuit board, the first microstrip line is coupled with the two second microstrip lines, the first microstrip line is connected with the input port, each second microstrip line is connected with one output port, the open-circuit stub is arranged at a preset position on the first microstrip line, at least one defected ground structure is arranged on the second layer plate of the circuit board at the position corresponding to the first microstrip line and each second microstrip line.

Technical Field

The invention relates to the field of electronic circuits, in particular to a Marchand balun structure and an electronic device with the balun structure.

Background

Balun (Balun, Balance to Unbalance) is widely used in radio frequency microwave circuits as a radio frequency device for interfacing a balanced line and an unbalanced line. For example, balun is widely used in radio frequency circuits such as push-pull amplifiers, Double balanced mixers (Double balanced mixers), phase shifters, and Dipole Antenna Feeds (Dipole Antenna Feeds). However, the existing balun is basically composed of two sections of 1/4-wavelength coupled lines, but the bandwidth is realized narrowly, and the performance index of the balun is limited by the manufacturing process of the coupled line spacing.

Disclosure of Invention

In view of the foregoing, it is desirable to provide a balun structure and an electronic device having the balun structure, so as to improve electrical performance such as bandwidth of the balun structure.

The first aspect of the present application provides a balun structure disposed on a circuit board, the circuit board includes a first layer board, a second layer board and an intermediate interlayer, the first layer board and the second layer board are conductive layers, the balun structure includes a first microstrip line, two second microstrip lines, an input port of an open-circuit stub, two output ports and a plurality of defected ground structures, the first microstrip line, the two second microstrip lines, the open-circuit stub, the input port and the two output ports are disposed on the first layer board of the circuit board, the plurality of defected ground structures are disposed on the second layer board of the circuit board, the first microstrip line is coupled to the two second microstrip lines, the first microstrip line is connected to the input port, each of the second microstrip lines is connected to one of the output ports, the open-circuit stub is disposed at a predetermined position on the first microstrip line, at least one defected ground structure is arranged on the second layer plate of the circuit board at the position corresponding to the first microstrip line and each second microstrip line.

Preferably, the first microstrip line 11 includes a first sub-microstrip line and a second sub-microstrip line, the first sub-microstrip line is connected to the second sub-microstrip line, the width of the first sub-microstrip line is smaller than the width of the second sub-microstrip line, the input port is connected to one end of the first sub-microstrip line, which is far away from the second sub-microstrip line, and the open-circuit stub is disposed at a wavelength which is far away from 2/5 ± 5% of a target frequency of the second sub-microstrip line on the first sub-microstrip line, where the target frequency is a frequency of a transmission signal in a transmission medium of the first sub-microstrip line or the second sub-microstrip line.

Preferably, the defected ground structure is an i-shaped defected ground structure, and the defected ground structure comprises a first i-shaped defected ground structure and a second i-shaped defected ground structure, wherein the first i-shaped defected ground structure and the second i-shaped defected ground structure are identical in structure and different in size.

Preferably, two first i-shaped defected ground structures are arranged on a second layer board of the circuit board at positions corresponding to 1/8 ± 5% of the wavelength of a target frequency on the first sub microstrip line away from the second sub microstrip line, wherein the target frequency is the frequency of a transmission signal in a transmission medium of the first sub microstrip line or the second sub microstrip line.

Preferably, the second i-shaped defected ground structure is respectively arranged at a position on the second layer board of the circuit board corresponding to a target area including the second sub-microstrip line and each second microstrip line partial area.

Preferably, the structure of the I-shaped defect comprises two end parts and a shaft part, the two end parts are connected to two ends of the shaft part, the end parts and the shaft part are rectangular, and the length and the width of the end parts and the shaft part can be adjusted.

Preferably, the second sub-microstrip line includes a first end portion and a second end portion, the first end portion includes a first side edge and a second side edge opposite to the first side edge, the second end portion includes a third side edge and a fourth side edge opposite to the third side edge, the first side edge and the third side edge are located on the same side of the second sub-microstrip line, the second side edge and the fourth side edge are located on the same side of the second microstrip line, two of the second microstrip line, the microstrip line and the first side edge of the first end portion are arranged at a first preset distance interval, and the other second microstrip line and the fourth side edge of the second end portion are arranged at a first preset distance interval.

Preferably, the balun structure further includes two third microstrip lines, one of the two third microstrip lines is disposed at a second preset distance from the second side edge of the first end portion, and the other third microstrip line is disposed at a second preset distance from the third side edge of the second end portion.

Preferably, the open-circuit branch is a fan-shaped open-circuit branch, and the fan-shaped angle and the radial length of the fan-shaped open-circuit branch are adjustable.

In a second aspect of the present application, an electronic device with a balun structure includes a circuit board, the balun structure is disposed on the circuit board, the circuit board includes a first layer board and a second layer board, the balun structure includes a first microstrip line, two second microstrip lines, an input port of an open-circuit stub, two output ports, and a plurality of defected ground structures, the first microstrip line, the two second microstrip lines, the open-circuit stub, the input port, and the two output ports are disposed on the first layer board of the circuit board, the plurality of defected ground structures are disposed on the second layer board of the circuit board, the first microstrip line is coupled to the two second microstrip lines, the first microstrip line is connected to the input port, each of the second microstrip lines is connected to one of the output ports, the open-circuit stub is disposed at a preset position on the first microstrip line, at least one defected ground structure is arranged on the second layer plate of the circuit board at the position corresponding to the first microstrip line and each second microstrip line.

The balun structure in the scheme enables odd-mode impedance and even-mode impedance required by the coupling strength of the balun structure to be fine-tuned by arranging the open-circuit branch and the defected ground structure, so that the electrical characteristics of the balun structure, such as the reflection coefficient, the bandwidth and the like, are improved.

Drawings

Fig. 1 is a schematic diagram of an electronic device according to an embodiment of the invention.

Fig. 2 is a schematic diagram of a balun structure in an embodiment of the present invention.

Fig. 3 is a schematic diagram of a structure with an i-shaped defect according to an embodiment of the present invention.

Fig. 4 is a simulation diagram of a balun structure without open-circuit branches and a defected ground structure according to an embodiment of the present invention.

Fig. 5 and 6 are simulation diagrams of balun structures with open-circuit branches and defected ground structures according to an embodiment of the present invention.

Description of the main elements

The following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

Referring to fig. 1, a schematic diagram of an electronic device 100 according to an embodiment of the invention is shown. The electronic device 100 includes a balun structure 1 and a circuit board 2. Referring to fig. 2, a schematic diagram of the balun structure 1 is shown. The balun structure 1 is arranged on a circuit board 2. The circuit board 2 at least includes a first layer board 21, a second layer board and an interlayer dielectric (not shown), the interlayer dielectric is located between the first layer board 21 and the second layer board, and the first layer board and the second layer board are conductor layers. The first laminate 21 is disposed opposite to the second laminate. In this embodiment, the first laminate 21 may be a top layer of the circuit board 2, and the second laminate may be a bottom layer of the circuit board 2. In other embodiments, the first laminate 21 may be a bottom layer of the circuit board 2, and the second laminate may be a top layer of the circuit board 2. In one embodiment, the balun structure 1 may be applied to a base material such as a copper foil printed circuit board for radio frequency, a ceramic substrate, or a GaAs/GaN semiconductor to constitute the circuit board 2.

In this embodiment, the balun structure 1 includes one first microstrip line 11, two second microstrip lines 12, one open-circuit stub 13, one input port 14, two output ports 15, and a plurality of defected ground structures 16. The first microstrip line 11, the two second microstrip lines 12, the open-circuit branch 13, the input port 14, and the two output ports 15 are disposed on a first layer board 21 of the circuit board 2, and the plurality of defected ground structures 16 are disposed on a second layer board 22 of the circuit board 2. In this embodiment, the first microstrip line 11 is coupled to the two second microstrip lines 12. The first microstrip line 11 is also connected to the input port 14. Each second microstrip line 12 is connected to an output port 15. The open-circuit branch 13 is arranged at a preset position on the first microstrip line 11. In this embodiment, at least one defected ground structure 16 is disposed on the second layer board of the circuit board 2 at a position corresponding to the first microstrip line 11 and each of the second microstrip lines 12.

In the specific embodiment, the first microstrip line 11 includes a first sub-microstrip line 111 and a second sub-microstrip line 112. The first sub-microstrip line 111 is connected to the second sub-microstrip line 112. The width of the first sub-microstrip line 111 is smaller than that of the second sub-microstrip line 112. In this embodiment, the input port 14 is connected to one end of the first sub-microstrip line 111 far away from the second sub-microstrip line 112, and the open-circuit stub 13 is disposed on the first sub-microstrip line 111 at a wavelength which is away from 2/5 ± 5% of a target frequency of the second sub-microstrip line 112, where the target frequency is a frequency of a transmission signal in a transmission medium of the first sub-microstrip line 111 or the second sub-microstrip line 112. In this embodiment, the input port 14 is an unbalanced interface, and the two output ports 15 are balanced ports. In the present embodiment, a signal is input through the input port 14 of the balun structure 1, and two signals having the same magnitude and a phase difference of 180 degrees are output through the two output ports 15.

In this embodiment, the open-circuit branch 13 is a sector-shaped open-circuit branch, and the sector angle and the radial length of the sector-shaped open-circuit branch are adjustable. In the present embodiment, the adjustment range of the sector angle of the open-sector branch is 60 to 80 degrees. It should be noted that the open stub 13 in the present embodiment is not limited to a fan-shaped open stub, and in the present application, an open stub that can change the return path of the balun structure 1 and enhance the electrical characteristics of the balun structure 1 is within the protection scope of the present application.

In the present embodiment, the electrical characteristics of the balun structure 1 include at least the reflection coefficient and the bandwidth characteristics of the balun structure 1. The open-circuit branch is arranged in the case, odd-mode impedance and even-mode impedance required by the coupling strength of the balun structure 1 are finely adjusted, and therefore the electrical characteristics of the balun structure 1, such as reflection coefficient, bandwidth and the like, are improved.

Referring to fig. 3, a schematic diagram of an i-shaped defective ground structure 16 according to an embodiment of the invention is shown. The i-shaped defected ground structure 16 includes two end portions 161 and a shaft portion 162. Two ends 161 of the i-shaped defected ground structure 16 are connected to two ends of the shaft portion 162. In the present embodiment, the end portion 161 and the shaft portion 162 have a rectangular shape, and the length and width of the end portion 161 and the shaft portion 162 can be adjusted. In the present embodiment, the i-shaped defected ground structure 16 includes a first i-shaped defected ground structure and a second i-shaped defected ground structure, wherein the first i-shaped defected ground structure and the second i-shaped defected ground structure are identical and are different only in size.

In this embodiment, two first i-shaped defected ground structures are disposed on the second layer board of the circuit board 2 at positions corresponding to the wavelengths of 1/8 ± 5% of the target frequency on the first sub-microstrip line 111 away from the second sub-microstrip line 112, where the target frequency is the frequency of signals transmitted in the transmission medium of the first sub-microstrip line or the second sub-microstrip line. In a specific embodiment, two i-shaped copper foils are dug out on the second layer board of the circuit board 2 at positions corresponding to the wavelengths of 1/8 ± 5% of the target frequency on the first sub-microstrip line 111 away from the second sub-microstrip line 112 to form the first i-shaped defected ground structure 16.

In this embodiment, a second i-shaped defected ground structure is disposed on the second layer board of the circuit board 2 at a position corresponding to a target area including the second sub-microstrip line 112 and a partial area of each second microstrip line 12. In the specific embodiment, two i-shaped copper foils are dug out on the second layer board of the circuit board 2 at positions corresponding to the target area including the second sub-microstrip line 112 and the partial area of each second microstrip line 12 to form the second i-shaped defected ground structure 16.

In the present embodiment, a plurality of grounding points (not shown) are further disposed on the second layer board of the circuit board 2, and the grounding points are formed at the positive and negative (+/-) ends of the port of the balun structure 1. For example, grounding points are respectively provided on the second plate of the circuit board 2 at positions corresponding to the input port 14 and the output port 15, and the grounding points are respectively formed at two ends of the ports of the input port 14 and the output port 15 of the balun structure 1. In this embodiment, the board material of the circuit board 2 is RO4003C, and the board thickness is 0.8 mm.

Referring to fig. 2, in an embodiment, the second sub-microstrip line 112 includes a first end 1121 and a second end 1122. The two second microstrip lines 12 are respectively coupled to the first end 1121 and the second end 1122 of the second sub-microstrip line 112. Specifically, the second end portion 1121 includes a first side 11211 and a second side 11212 opposite to the first side 11211. The second end 1122 includes a third side 11221 and a fourth side 11222 opposite the third side 11221. In this embodiment, the first side 11211 of the first end portion 1121 and the third side 11221 of the second end portion 1122 are located on the same side of the second sub-microstrip line 112, and the second side 11212 of the first end portion 1121 and the fourth side 11222 of the second end portion 1122 are located on the same side of the second sub-microstrip line 112. In this embodiment, one of the two second microstrip lines 12 is disposed at a first predetermined distance from the first side 11211 of the first end portion 1121, and the other second microstrip line 12 is disposed at a first predetermined distance from the fourth side 11222 of the second end portion 1122, so that the two second microstrip lines 12 are respectively coupled to the first end portion 1121 and the second end portion 1122 of the second sub-microstrip line 112.

In an embodiment, the balun structure 1 further includes two third microstrip lines 17. The two third microstrip lines 17 are respectively coupled to the first end 1121 and the second end 1122 of the second sub-microstrip line 112. Specifically, one third microstrip line 17 of the two third microstrip lines 17 is disposed at a second predetermined distance from the second side edge 11212 of the first end portion 1121, and the other third microstrip line 17 is disposed at a second predetermined distance from the third side edge 11221 of the second end portion 1122, so that the two third microstrip lines 17 are respectively coupled to the first end portion 1121 and the second end portion 1122 of the second sub-microstrip line 112. It should be noted that the first preset distance and the second preset distance in the present disclosure may be preset as needed, and the first preset distance and the second preset distance may be the same or different.

In an embodiment, the circuit board 2 is a two-layer circuit board, and the first microstrip line 11 and the second microstrip line 12 are respectively added with one microstrip line and are disposed on the two-layer board of the circuit board 2 in a coupled manner. In another embodiment, the first microstrip line 11, the second microstrip line 12 and the third microstrip line are respectively added with upper and lower microstrip lines coupled to a three-layer board of the circuit board 2.

In the present embodiment, the electrical characteristics such as the bandwidth of the balun structure 1 are evaluated based on the amplitude balance specification and the phase balance specification of the two output signals of the two output ports 15 of the balun structure 1. Wherein the amplitude balance specification is not more than-1.0 dB, and the phase balance specification is not more than 10 degrees. The amplitude balance specification is that the difference between the amplitude of the two output signals and an ideal amplitude output value is not more than-1.0 dB, and the phase balance specification is that the difference between the phase of the two output signals and an ideal phase output value is not more than 10 degrees. Referring to fig. 4, a simulation diagram of a balun structure without open-circuit branches and a defected ground structure is shown in an embodiment of the present invention. As can be seen from FIG. 4, on the premise of meeting the amplitude balance specification and the phase balance specification, the bandwidth of the balun structure is within 3.443-3.524 GHz, and the bandwidth is 81 Mhz. Referring to fig. 5 and fig. 6, simulation diagrams of balun structures with open-circuit branches and defected ground structures are shown in an embodiment of the present invention. As can be seen from FIGS. 5 and 6, on the premise of meeting the amplitude balance specification and the phase balance specification, the bandwidth of the balun structure is within 3.354-3.919 GHz, and the bandwidth is 565 Mhz. According to the comparison result, the balun structure can improve the electrical performances such as bandwidth.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention.