TWI552426B - Adjustable output power ratio compared to branch coupler - Google Patents

Description

Adjustable output power ratio branch coupler

The present invention relates to a branch coupler capable of adjusting an output power ratio, and more particularly to a branch coupler technology applicable to microwave systems of different center frequencies.

As high-frequency microwave circuits are gaining attention, there is a growing demand for applications in the electronics industry, which in turn complicates the application and design trends of integrated circuits, in addition to circuit-level issues and process aspects. The design is also more difficult. The evolution of technology over time, in recent years, wireless communication has become the focus of the development of modern electronic technology, whether in digital TV systems, global satellite systems, or mobile communication systems, people's lives are inseparable for wireless information transmission, branches Couplers (such as Ref. [1]) also play an important role in the above systems. There are many types of branch couplers, and their functions are nothing more than power allocation (eg, [2] [3]) or Power synthesis is used, such as a branch line coupler, a ratrace coupler, and a lange coupler (see Ref. [4] [5]). Among them, the branch coupler is most commonly used. The output power ratio of the circuit output 埠|S21| and the coupled 埠|S31| is mostly designed at half power point (-3dB), and the two output signals are 90 degrees out of phase, and the input is埠|S11| and isolation 埠|S41| and can reach below -15dB, in response to the needs of different environments.

In addition, the geometry of the branch coupler has a high degree of symmetry, since either end can be used as the input port, and the two ends of the output are located on the other side of the input port, the other end on the same side as the input port. It is isolated, and such symmetry can be seen by the scattering coefficient. When all The end turns are matched, and the power entering the input 会 is equally divided into the output 另一 on the other side, and no power is transmitted to the 埠. Although the conventional branch coupler can provide a good input and output impedance matching capability and provide equal power distribution and 90 degree phase difference; however, the conventional branch coupler does not have the function of adjusting the power ratio, so it cannot be applied to different In the microwave system of the center frequency, since the support is low, there is a shortage of the increase in the cost of the construction of the circuit system.

As far as is known, there are no patents or papers that can adjust the output power ratio to be applied to the branch couplers of microwave systems with different center frequencies, and the creators of the present invention are based on the urgent needs of the electronics industry. Under continuous efforts, R&D has finally developed a set of inventions that differ from the technical concepts of the above documents.

The main purpose of the present invention is to provide a branching coupler with adjustable output power ratio, which is mainly based on a conventional 1:2 unequal branching coupler, and the transmission lines at both ends are added to the adjustable T-type equivalent. Capacitor, only need to change the capacitance value to make the circuit output power ratio reach the adjustment range of 1:1 to 1:3, thus achieving the coupler function of achieving multiple output ratios in one circuit, which is equivalent in the system construction. Convenience, the circuit can be applied to a variety of microwave systems with different center frequencies only by changing the capacitance value. Therefore, in addition to high system support, the cost of the entire system can be reduced. The technical means for achieving the above-mentioned purpose is to cover the substrate, and comprises four segments of a first transmission line, a second transmission line, a third transmission line and a fourth transmission line which are vertically connected in a rectangular shape. Wherein, the first transmission line and the second transmission line connection, the second transmission line and the third transmission line connection, the third transmission line and the fourth transmission line connection, and the fourth transmission line and the first transmission line connection are respectively provided with an outward oblique direction Extended extension. And electrically connecting a capacitor to the second transmission line and the fourth transmission line.

10‧‧‧Substrate

20‧‧‧ Transmission line group

21‧‧‧First transmission line

22‧‧‧second transmission line

23‧‧‧ third transmission line

25‧‧‧First conductive block

26‧‧‧Second conductive block

24‧‧‧fourth transmission line

30‧‧‧Extension

31a, 31b, 31c, 31d‧‧‧ triangle segments

32a, 32b, 32c, 32d‧‧‧ long rectangular segments

40‧‧‧First signal埠

41‧‧‧Second signal埠

42‧‧‧ Third signal埠

43‧‧‧fourth signal埠

C ₁ ‧‧‧ capacitor

1 is a schematic diagram of an equivalent circuit of a coupler of the present invention.

2 is a schematic diagram showing an equivalent circuit of a T-type equivalent transmission line of the present invention.

3 is a schematic view showing the circuit structure of the present invention.

4 is a schematic structural view of a physical circuit of the present invention. .

Figure 5a is a schematic diagram of the frequency response of the simulated and measured power ratio of the present invention with a power ratio of 1:2.

Fig. 5b is a schematic diagram showing the results of the simulation and actual measurement of the power ratio of the present invention from 1:1 to 1:2.

Fig. 6a is a schematic diagram showing the comparison between the simulation and the actual measurement of the power ratio of the present invention of 1:1.

Fig. 6b is a schematic diagram showing the results of simulation and actual measurement of the power ratio of the present invention adjusted from 1:2 to 1:1.

Figure 7a is a graphical representation of the simulation and actual measurement of the power ratio of the present invention of 1:3.

Fig. 7b is a schematic diagram showing the results of simulation and actual measurement of the power ratio of the present invention adjusted from 1:2 to 1:3.

The invention is mainly a branching coupler with adjustable power ratio. The circuit is based on a traditional 1:2 unequal branching coupler, and combined with a T-type equivalent of a transmission line, the transmission line at both ends of the coupler is composed of two The group transmission line is replaced with a tunable capacitor. By adjusting the value of the capacitor, the output power ratio of the original output power ratio of the 1:2 coupler can be more power-selected. It is confirmed by the electromagnetic simulation software that the output power ratio can be applied to the operating frequency. : 1 to 1:3 system, the circuit is realized by engraving machine, and finally measured by network analyzer, the simulation data and implementation in the working frequency band do have good electrical characteristics. Since the adjustable structure design of the present invention can be applied to microwave systems of different center frequencies, the present invention is highly supportive, easy to manufacture, and can greatly reduce the cost of system construction.

3 and 4, in order to achieve the main object of the present invention, a substrate 10 and a transmission line group 20 formed on the substrate 10 by printing or etching are included. The transmission line group 20 includes four first transmission lines 21, a second transmission line 22, a third transmission line 23, and a fourth transmission line 24 which are sequentially vertically wound in a rectangular connection to respectively generate characteristic impedances. Wherein, the first transmission line 21 is connected to the second transmission line 22, the second transmission line 22 is connected to the third transmission line 23, the third transmission line 23 is connected to the fourth transmission line 24, and the fourth transmission line 24 is connected to the first transmission line 21. Each of the second transmission line 22 is provided with a first conductive block 25 on the outer side near the middle portion of the second transmission line 22, and a second conductive line 24 is provided on the outer side near the middle portion of the second transmission line 22. The second conductive block 26 is electrically connected to the capacitor C ₁ between the second transmission line 22 and the first conductive block 25, and is electrically connected to the second conductive block 26 to the other capacitor C _{1 .} .

Please refer to the four extensions 30 shown in Figure 3, each containing a triangle Segments 31a, 31b, 31c, 31d and a long rectangular segment 32a, 32b, 32c, 32d. One of the triangular segments 31a is connected to one end of the first transmission line 21, and the other side thereof is connected to a long rectangular section 32a. The two triangular segments 31b are connected to one end of the third transmission line 23, and the other side thereof is connected to the two long rectangular segments 32b. The three triangular segments 31c are connected to the other end of the third transmission line 23, and the other side thereof is connected to the three long rectangular segments 32c. The four triangular segments 31d are connected to the other end of the first transmission line 21, and the other side thereof is connected to the four long rectangular segments 32d. Referring to FIG. 4, a first signal 埠 40 (ie, an isolation 埠) is connected to the end of a long rectangular section 32a, and a second signal 埠 41 (ie, a coupling 埠) is connected to the end of the second rectangular section 32b. A third signal 埠 42 (ie, output 埠) is connected to the end of the three-long rectangular section 32c, and a fourth signal 埠43 (ie, input 埠) is connected to the end of the four-long rectangular section 32d. Specifically, the lengths L1, L2, L3, and L4 of one long rectangular segment 32a, two long rectangular segments 32b, three long rectangular segments 32c, and four long rectangular segments 32d thereof are 15 mm, and widths W1, W2, and W3 are W4 is 6.1mm.

In a specific embodiment, the first transmission line 21 and the third transmission line 23 have the same width and length and are rectangular, and the second transmission line 22 and the fourth transmission line 24 have the same width and length and are elongated and rectangular, and the second The widths of the transmission line 22 and the fourth transmission line 24 are smaller than the first transmission line 21 and the third transmission line 23. Further, the lengths L5 and L6 of the first transmission line 21 and the third transmission line 23 are both 43.8 mm, the widths W5 and W6 are both 8.44 mm, and the lengths L7 of the second transmission line 22 and the fourth transmission line 24 are both 31.4 mm. The width W7 is 0.75mm. The two capacitors C ₁ are all variable capacitors. One end of the capacitor C _{1 is} electrically connected to the middle of the second transmission line 22 , and the other end of the capacitor C ₁ is electrically connected to the first conductive block 25 (ie, the ground end). The second capacitor C _{1 is} electrically connected to the middle of the fourth transmission line 24, and the other end is electrically connected to the second conductive block 26 (ie, the ground end), and the capacitance of the two capacitors C ₁ can be adjusted. Between 0.7 and 1.8 pF.

The circuit of the invention is a conventional 1:2 unequal branching coupler (such as reference text) [6-9]) is the architecture, the transmission lines at both ends are added with adjustable capacitance by T-type equivalent (such as reference [10]), and the circuit can change the capacitance value so that the output power ratio of the circuit can be 1:1 to 1. : 3 adjustability. The advantage of this circuit design is that it realizes a coupler with multiple output ratios in one circuit. It is quite convenient in the system construction. The circuit can be applied to a variety of microwave systems with different center frequencies only by changing the capacitance value. The circuit not only has a high degree of height. System support can reduce the cost of the entire system.

The circuit structure of the present invention is shown in FIG. 1. The circuit is based on a conventional 1:2 dry coupler, and the two transmission lines in the circuit structure are equivalent to T-type, and the equivalent structure is shown in FIG. The circuit of the present invention changes the output power ratio of its output 埠|S21| to the coupled 埠|S31| by a variable capacitance in the T-equivalent. Therefore, the T-equivalent and transmission line relationship matrix must be obtained first, as shown in equation (1):

From the above matrix, the equivalent post-impedance values Zo and B (the admittance of the capacitive reactance) can be obtained as shown in equation (2)(3):

Given the equivalent electrical length θ o , the original transmission line impedance value Z and the electrical length θ are respectively brought into the equation (2) (3), and the equivalent transmission line impedance value Zo and the capacitance value can be obtained. The obtained parameters are brought into the circuit and simulated by the electromagnetic software IE3D. The selected substrate 10 (such as a plate) is FR4 (about 3.2 mm), and the structure is optimized by the corresponding length of the line tool of the software tool Linegauge. Adjust as shown in Figure 3, the circuit dimensions are as shown. The lengths L1, L2, L3, and L4 of the three long rectangular segments 32 and the four long rectangular segments 32 are all 15 mm, and the widths W1, W2, W3, and W4 are all 6.1 mm; the first transmission line 21 and the third transmission line 23 are The lengths L5 and L6 are both 43.8 mm, the widths W5 and W6 are all 8.44 mm; the lengths L7 of the second transmission line 22 and the fourth transmission line 24 are both 31.4 mm, and the width W7 is 0.75 mm; as for the capacitor C1, 1.3pF.

After the circuit of the invention is simulated, it can indeed meet the expected result. Therefore, the circuit can be output to the engraving machine to process the physical circuit and measure the result. The finished product of the circuit after engraving machine is shown in Figure 4, and measured by Anritsu-MS2034A network analyzer. Compared with the simulation results, the frequency response of IE3D and physical circuit is shown in Figure 5(a) and (b). The measurement frequency ranges from 0 to 4 GHz, and the size ranges from 0 to -40 dB. In the operating frequency band (fo=0.925 GHz) |S ₁₁ | and |S ₄₁ | are all below -15 dB, and the output 埠|S21| and the coupling 埠| The output power ratio of S31| is 2:1, and in Fig. 5(b), the phase difference between |S ₂₁ | and |S ₃₁ | is 90 degrees. With this good characteristic, change the capacitance value of the capacitor C ₁ of the circuit in Figure 1, from 1.3pF to 1.8pF, and then the output power ratio is 1:1, and then the network analyzer The measured IE3D and physical circuit frequency response is shown in Figure 6 (a), (b), the measurement frequency is from 0 to 4 GHz, the size is from 0 to -40 dB, and the input coefficient S scattering coefficient |S ₁₁ | The scattering coefficient |S ₄₁ | is below -15dB, and the output power ratio |S ₂₁ | and |S ₃₁ | of the output 埠 and the coupled 埠 are 1:1, in Fig. 6(b), |S ₂₁ | The phase difference from |S ₃₁ | is 90 degrees, and the above simulation and measurement results are indeed quite close to expectations. Finally, the capacitance value of circuit C ₁ in Figure 1 is changed again, from 1.8pF to 0.7pF, and the output power ratio is 3:1. The frequency response of IE3D and the physical circuit is measured by the network analyzer. (a), (b), the measurement frequency is from 0 to 4 GHz, and the size is from 0 to -40 dB. In the working frequency band, both |S ₁₁ | and |S ₄₁ | are below -15 dB, and the output power ratio of both ends is | S ₂₁ | and |S ₃₁ | are 3:1, and in Fig. 7(b), the phase difference between |S ₂₁ | and |S ₃₁ | is 90 degrees. From the above design and simulation results, it is confirmed that the present invention can be realized by a dry coupler by adjusting the variable capacitance value to achieve an output power ratio of 1:1 to 1:3.

Therefore, with the description of the above specific embodiments, the present invention is not 1:2 The averaging branch coupler is an architecture, and the transmission lines at both ends are added to the adjustable capacitor by T-type equivalent, and only the capacitance value needs to be changed to make the output power ratio of the circuit reach the adjustment range of 1:1 to 1:3, thereby Achieving the coupler function of realizing multiple output ratios with one circuit is quite convenient in the system construction. The circuit can be applied to a variety of microwave systems with different center frequencies only by changing the capacitance value. Therefore, in addition to the system with high altitude In addition to support, it can reduce the cost of the entire system.

The above description is only a possible embodiment of the present invention, and is not intended to limit the present invention. The equivalent scope of the invention, which is based on the content, the features and the spirit of the invention, is to be included in the scope of the invention. Specific to the present invention The structural features defined in the request item are not found in similar items, and they are practical and progressive. They have met the requirements of the invention patents and have applied for it according to law. Please ask the bureau to approve the patents in accordance with the law to protect the applicant's legality. rights and interests.

references

[1] Reed, J; Wheeler, GJ; "A Method of Analysis of Symmetrical Four-Port Networks", Microwave Theory and Techniques, IRE Transactions on Volume: 4, Issue: 4, pp.246-252, October 1956

[2] Cohn, Seymour B.; “A Class of Broadband Three-Port TEM-Mode Hybrids,” Microwave Theory and Techniques, IEEE Transactions on Volume: 16, Issue: 2, pp. 110-116, Feb 1968.

[3] EJ Wilkinson; “An N-way hybrid power divider”, IRE Trans. Microwave Theory and Techniques , vol. MTT-8, pp.116 -118 1960

[4] Luzzatto, G.; Marconi Italiana SpA; “A General 180-Degree Hybrid Ring”, Broadcasting, IEEE Transactions on Volume: BC-14, Issue: 1, pp.41-43, March 1968.

[5] Lange, J.; “Interdigitated Stripline Quadrature Hybrid”, Microwave Theory and Techniques, IEEE Transactions on Volume: 17, Issue: 12, pp.1150-1151, Dec 1969.

[6] Yong-Beom Kim, Hyun-Tai Kim, Kwi-Soo Kim, Jong-Sik Lim, and Dal Ahn; “A Branch line hybrid having arbitrary power division ratio and port impedances”, Microwave Conference, 2006. APMC 2006. Asia-Pacific, pp.1376-1379, 12-15 Dec. 2006.

[7] Tseng, C.-H.; Dept. of Electron. Eng., Nat. Taiwan Univ. of Sci. & Technol., Taipei, Taiwan; Wu, C.-H.; “Design of compact branch-line Couplers using π-equivalent artificial transmission lines”, Microwaves, Antennas & Propagation, IET, Volume: 6, Issue: 9, pp. 969 - 974, June 19 2012.

[8] Arriola, W.; Dept. of Radio Eng., Kyung Hee Univ., Yongin, South Korea; Ihn Seok Kim; “Wideband Branch Line Coupler with Arbitrary Coupling Ratio”, Microwave Conference Proceedings (APMC), 2011 Asia- Pacific, pp. 1758-1761, 5-8 Dec. 2011.

[9] Chun-Han Yu; Inst. of Comput. & Commun. Eng., Nat. Cheng Kung Univ., Tainan, Taiwan; Yi-Hsin Pang; “Dual-Band Unequal-Power Quadrature Branch-Line Coupler With Coupled Lines Microwave and Wireless Components Letters, IEEE Volume: 23, Issue: 1, pp. 10-12, Jan. 2013.

[10] Tae-Soon Yun; Ki-Byoung Kim; Jong-Chul Le, “Research on Size Reduction of a Branch-line Power Divider Using Shunt-Stub,” Microwave Conference Proceedings, 2005. APMC 2005. Asia-Pacific Conference Proceedings , Vol.1, Feb.2005.

20‧‧‧ Transmission line group

21‧‧‧First transmission line

22‧‧‧second transmission line

23‧‧‧ third transmission line

24‧‧‧fourth transmission line

25‧‧‧First conductive block

26‧‧‧Second conductive block

30‧‧‧Extension

31a, 31b, 31c, 31d‧‧‧ triangle segments

32a, 32b, 32c, 32d‧‧‧ long rectangular segments

C ₁ ‧‧‧ capacitor

Claims (4)

A branching coupler capable of adjusting an output power ratio, comprising a substrate, and a transmission line group disposed on the substrate, the transmission line group comprising four segments sequentially vertically surrounding a rectangular connection to respectively generate characteristic impedance a first transmission line, a second transmission line, a third transmission line, and a fourth transmission line, wherein the first transmission line and the second transmission line, the second transmission line and the third transmission line, the third transmission line, and the fourth The transmission line and the connection between the fourth transmission line and the first transmission line and the like are respectively provided with an extending portion extending obliquely outwardly. The second transmission line is provided with a first conductive block outside, and a second conductive line is disposed outside the second transmission line. a capacitor, and a capacitor is electrically connected between the second transmission line and the first conductive block, and another capacitor is electrically connected to the second conductive block and the second conductive block; wherein the first transmission line And the third transmission line has the same width and length and has a long rectangular shape, and the second transmission line and the fourth transmission line have the same width and length and are respectively elongated and rectangular, and the second transmission And the width of the fourth transmission line is smaller than the first transmission line and the third transmission line; wherein the four extensions each comprise a triangular segment and a long rectangular segment, and one of the triangular segments is connected to one end of the first transmission line. The other side is connected to one of the long rectangular segments; the other side of the triangular segment is connected to one end of the third transmission line, and the other side is connected to the two rectangular segments; the third side of the triangular segment is connected to the third transmission line An end connection, the other side of which is connected to the three long rectangular segments; four of the triangular segments are connected to the other end of the first transmission line, and the other side is connected to the four long rectangular segments; the first capacitor and the second The capacitors are respectively variable capacitors. By adjusting the capacitance of the two capacitors between 0.7 and 1.8 pF, the output power ratio is adjusted from 1:1 to 1:3. The adjustable output power ratio of the branch coupler according to claim 1, wherein the first transmission line and the third transmission line have a length of 43.8 mm and a width of 8.44 mm, and the second transmission line and the first transmission line The four transmission lines have a length of 31.4 mm and a width of 0.75 mm. The adjustable output power ratio of the branching coupler according to claim 1, wherein a first signal 埠 is connected to one end of the long rectangular segment, and a second signal 接 is connected to the end of the long rectangular segment. A third signal 埠 is connected to the end of the long rectangular section, and a fourth signal 埠 is connected to the end of the long rectangular section. The adjustable output power ratio of the branch coupler according to claim 3, wherein a length of the long rectangular segment, the two long rectangular segments, three of the long rectangular segments, and four of the long rectangular segments are 15mm and width is 6.1mm.