Balun circuit

Abstract

To provide a balun circuit where the circuit area is easily suppressed.SOLUTION: Provided is a balun circuit in which a transmission line is configured non-annularly. One of a first terminal and a second terminal is functioned as an input section of the balun circuit, and the other of the first terminal and the second terminal is functioned as an output section of the balun circuit. Each of the second terminals is connected to the transmission line, and 2×n pieces of second terminals are disposed so as to be arranged at predetermined intervals therebetween in an extension direction of the transmission line. The 2×n pieces of second terminals include a pair of central terminals positioned closer to a center of the transmission line in the extension direction, and the first terminal is disposed between the pair of central terminals.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a balun circuit. [Background technology]

[0002] In mobile terminals, IoT terminals, base stations, and the like that use millimeter waves or microwaves, a balun circuit (balanced-to-unbalanced converter) is sometimes used to prevent noise from occurring at the connection point between a balanced circuit and an unbalanced circuit (see, for example, Patent Document 1). The balun circuit in Patent Document 1 has a ring structure and is also called a rat-race balun circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-98516 Summary of the Invention [Problem to be solved by the invention]

[0004] In a balun circuit having a ring structure (rat race balun circuit), the inside of the ring structure becomes dead space in the circuit, which raises concerns about an increase in the circuit area.

[0005] An object of the present invention is to provide a balun circuit that can easily reduce the circuit area. [Means for solving the problem]

[0006] According to the present invention, there is provided a balun circuit that performs at least one of power distribution and power combination, comprising a transmission line, a first terminal, and 2×n (n is an integer equal to or greater than 2) second terminals, wherein the transmission line is configured in a non-circular shape, one of the first terminal and the second terminal functions as an input section of the balun circuit, and the other of the first terminal and the second terminal functions as an output section of the balun circuit, each of the second terminals is connected to the transmission line, and the 2×n second terminals are arranged side by side at predetermined intervals in the extension direction of the transmission line, and the 2×n second terminals include a pair of central terminals located toward the center of the transmission line in the extension direction, and the first terminal is arranged between the pair of central terminals.

[0007] According to the present invention, the transmission line is configured in a non-annular shape, which makes it easier to avoid the formation of dead space like the inner part of the annular structure of a conventional rat-race balun circuit, and makes it easier to reduce the circuit area. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 shows an example of a circuit configuration of a balun circuit 100 according to an embodiment. [Figure 2] FIG. 2 is a graph showing the results of a comparative evaluation of the transmission loss of a conventional rat-race balun circuit and the transmission loss of the balun circuit 100 according to the embodiment. [Figure 3] FIG. 3 shows an example of the circuit configuration of a balun circuit 100 according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently.

[0010] 1. Description of the configuration of the embodiment The balun circuit 100 according to the embodiment is configured to be capable of performing at least one of power division and power combination. As will be described later, the balun circuit 100 is capable of both power division and power combination. The balun circuit 100 can be applied to a circuit of a communication device such as a modulation transmitter, for example.

[0011] 1, the balun circuit 100 includes a first terminal 1, 2×n (n is an integer of 2 or more) second terminals 2, and a transmission line 3. Note that, although n=2 in the embodiment, n may be an integer of 3 or more.

[0012] Note that the signal frequencies (GHz) applicable to the balun circuit 100 according to the embodiment are not particularly limited, but specifically include, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, and 1500, and may be within a range between any two of the numerical values ​​exemplified here. The frequencies of signals applicable to the balun circuit 100 may be divided into multiple frequency ranges, such as frequencies above 100 GHz and below 400 GHz, and frequencies above 800 GHz and below 1000 GHz, as defined by the numerical values ​​listed above.

[0013] 1-1. 1st terminal 1 The first terminal 1 is a terminal having a predetermined length and width, and is connected to the transmission line 3. The width of the first terminal 1 can be set to be the same as that of the transmission line 3, for example. The first terminal 1 is formed to extend in a direction perpendicular to the extension direction Dr of the transmission line 3 and away from the second terminal 2, for example.

[0014] The first terminal 1 can function as both a signal output section and a signal input section. The input section is a circuit element (circuit portion) where a signal is input to the balun circuit 100, and the output section is a circuit element (circuit portion) where a signal is output from the balun circuit 100.

[0015] The relationship between the first terminal 1 and the second terminal 2 and the output section and the input section is selective. That is, one of the first terminal 1 and the second terminal 2 functions as the input section of the balun circuit 100, and the other of the first terminal 1 and the second terminal 2 functions as the output section of the balun circuit 100. In other words, if the first terminal 1 is the input section, the second terminal 2 is the output section, and if the first terminal 1 is the output section, the second terminal 2 is the input section.

[0016] 1-2.Second terminal 2 The second terminal 2 has a plurality of terminals. Specifically, the second terminal 2 has a second terminal 2a, a second terminal 2b, a second terminal 2c, and a second terminal 2d. These multiple terminals (the second terminals 2a, the second terminal 2b, the second terminal 2c, and the second terminal 2d) are an example of 2×n second terminals. The second terminals 2a, the second terminal 2b, the second terminal 2c, and the second terminal 2d each have a predetermined length and width. In the embodiment, these lengths are the same. That is, the 2×n (n is an integer greater than or equal to 2) second terminals 2 (the second terminals 2a, the second terminal 2b, the second terminal 2c, and the second terminal 2d) have the same length. The second terminals 2a, the second terminal 2b, the second terminal 2c, and the second terminal 2d also have the same width. The widths of the second terminals 2a, the second terminal 2b, the second terminal 2c, and the second terminal 2d can be set to the same width as the transmission line 3, for example.

[0017] The second terminals 2 (second terminals 2a, 2b, 2c, and 2d) are formed, for example, to extend in a direction perpendicular to the extension direction Dr of the transmission line 3 and away from the first terminal 1.

[0018] Each of the second terminals 2a, 2b, 2c, and 2d is connected to a transmission line 3. These second terminals 2a, 2b, 2c, and 2d (2×n terminals) are arranged side by side at a predetermined interval D in the extension direction Dr of the transmission line 3.

[0019] In the embodiment, the above-mentioned predetermined interval D is the wavelength λ of the transmission signal transmitted through the transmission line 3. Note that the interval D preferably matches the wavelength λ, but does not have to match exactly. Specifically, the interval D can be, for example, 0.90×λ, 0.95×λ, 1.0×λ, 1.05×λ, or 1.10×λ, and may be within a range between any two of the values ​​exemplified here.

[0020] Here, the 2×n terminals (second terminals 2a, 2b, 2c, 2d) include a pair of central terminals located toward the center of the extension direction Dr of the transmission line 3. In the embodiment, the second terminals 2b and 2c are an example of a pair of central terminals. In addition, the first terminal 1 is disposed between this pair of central terminals (second terminals 2b and 2c) in the extension direction Dr. For example, if six (n=3) second terminals are arranged in the left-right direction at an interval D, the third (nth) and fourth (n+1th) second terminals from the left (or right) correspond to a pair of central terminals, and the first terminal 1 is disposed between this pair of central terminals. The same is basically true for eight or more lines (n≧4). That is, the n-th and (n+1)-th second terminals from one end in the direction in which the second terminals are arranged (extension direction Dr in this embodiment) correspond to a pair of central terminals, and the first terminal 1 is disposed between this pair of central terminals (the n-th and (n+1)-th second terminals from one end).

[0021] Each of the second terminals 2a, 2b, 2c, and 2d is connected to a circuit (referred to as a second terminal connection circuit) having the same function, although not shown in the figure. This second terminal connection circuit can be configured with, for example, a harmonic mixer, an amplifier, or the like.

[0022] 1-3. Transmission line 3 The transmission line 3 is configured in a non-cyclic shape. As described above, in the embodiment, since the transmission line 3 is not a circular (rat race) line, it is easy to reduce the area of ​​the circuit, and as a result, it is easy to improve the mountability in a microdevice. In the embodiment, the transmission line 3 extends linearly from one end to the other end. In other words, the transmission line 3 is configured in a bus shape. That is, in the embodiment, the transmission line 3 does not have any bent portions as in a rat-race circuit, so the circuit area can be more reliably reduced, and the mountability of microdevices can be improved. In addition, if the transmission line has bent portions as in a rat-race circuit, signal loss is likely to occur at the bent portions. However, in the embodiment, since the transmission line 3 is linear, such signal loss can also be effectively reduced. In the embodiment, the transmission line 3 is described as extending linearly from one end to the other end, but this is not limiting. As long as the transmission line 3 is non-circular, the effects of the embodiment can be obtained even if it has a curved portion.

[0023] As shown in FIG. 1 , with the transmission line 3 as the boundary, the region on one side is designated as a first region Rg1, and the region on the other side is designated as a second region Rg2. The first terminal 1 is arranged in the first region Rg1, and the second terminal 2 is arranged in the second region Rg2. Thus, unlike conventional rat-race circuits, the embodiment allows the circuit portion serving as the input or output side to be arranged in the first region Rg1, and the opposite circuit portion (the output or input side) to be arranged in the second region Rg2, making circuit layout easier. In other words, in conventional rat-race circuits, each circuit portion is arranged radially from the circular transmission line 3, making circuit layout difficult and increasing the circuit area. The embodiment has the advantage of easily avoiding such problems.

[0024] The transmission line 3 has a total length w1 based on the wavelength λ of the transmission signal transmitted to the input port. Note that the total length w1 corresponds to the line length of the transmission line 3, and if the transmission line 3 is linear, it is the distance from one end to the other end. Here, the total length w1 can be 0.80×λ×m, 0.85×λ×m, 0.90×λ×m, 0.95×λ×m, 1.00×λ×m, 1.05×λ×m, 1.10×λ×m, 1.15×λ×m, or 1.20×λ×m, and may be within a range between any two of the values ​​exemplified here, where m is an odd number equal to or greater than 3. For example, the total length w1 can be set to 0.8×λ×m (m is an odd number equal to or greater than 3) or 1.2×λ×m or less. Most preferably, the total length w1 is 1.00×λ×m, but even with the values ​​listed above, it is possible to expect effects similar to those of the embodiment.

[0025] As shown in FIG. 1, in one example of the embodiment, the number of second terminals 2 is four (n=2), so the total length w1 is 3×the spacing D=3λ, and m=3. Furthermore, for example, if the number of second terminals 2 is six (n=3), the total length w1 is 5 × spacing D=5λ, and m=5, and if the number of second terminals 2 is eight (n=4), the total length w1 is 7 × spacing D=7λ, and m=7. The relationship between m and n is m=2n-1.

[0026] The first terminal 1 is arranged in the extension direction Dr at a distance w2 based on the wavelength λ of the transmission signal transmitted to the input section from one of the pair of central terminals (in the embodiment, the second terminal 2b). Here, the spacing w2 can be 0.80×λ / 4, 0.85×λ / 4, 0.90×λ / 4, 0.95×λ / 4, 1.00×λ / 4, 1.05×λ / 4, 1.10×λ / 4, 1.15×λ / 4, or 1.20×λ / 4, or can be within a range between any two of the values ​​exemplified here. For example, the spacing w2 can be 0.8×λ / 4 or greater and 1.2×λ / 4 or less. Most preferably, the spacing w2 is 1.00×λ / 4, but effects similar to those of the embodiment can be expected even with the values ​​listed above.

[0027] 2. Description of the operation of the embodiment 2-1.Power coupling The balun circuit 100 is a balanced-to-unbalanced circuit conversion circuit that can convert a balanced signal into an unbalanced signal and output it as an unbalanced signal. In other words, the balun circuit 100 can combine balanced signals and output an unbalanced signal. Balanced signals are pairs of signals with opposite phases. The transmission signals input to the second terminals 2a and 2b and the transmission signals input to the second terminals 2c and 2d correspond to balanced signals. Here, a case will be described in which a positive phase wave Z0(+) is input to the second terminals 2a and 2b, and a negative phase wave Z0(-) is input to the second terminals 2c and 2d.

[0028] The transmission signals input to the second terminal 2a and the second terminal 2b have a wavelength difference of λ along the transmission path (the transmission path from each of the second terminals 2a, 2b to the first terminal 1) and are in phase, so the noise of these transmission signals is added together. Similarly, the transmission signals input to the second terminal 2c and the second terminal 2d have a wavelength difference of λ along the transmission path (the transmission path from each of the second terminals 2c, 2d to the first terminal 1) and are in phase, so the noise of these transmission signals is also added together.

[0029] The above-described transmission signal reaches the first terminal 1, where the above-described noises cancel each other out. In other words, a differential signal is supplied to the first terminal 1, reducing noise components due to common-mode signals. As a result, an unbalanced signal with reduced noise is output from the first terminal 1. In this way, the balun circuit 100 according to the embodiment has a different configuration from a conventional rat-race balun circuit, but can achieve a power coupling function similar to that of the conventional rat-race balun circuit.

[0030] 2-2.Power distribution The balun circuit 100 is capable of outputting an unbalanced signal as a balanced signal, i.e., the balun circuit 100 is capable of dividing an unbalanced signal and outputting it as a balanced signal. The basic operation is the reverse of the operation described in "2-1. Power Coupling", where an unbalanced signal is input to the first terminal 1, and a balanced signal can be extracted from the second terminal 2a, the second terminal 2b, the second terminal 2c, and the second terminal 2d.

[0031] 3. Functions and Effects of the Embodiments The balun circuit 100 according to the embodiment maintains the same performance (power coupling and power distribution) as a conventional rat-race balun circuit, but the circuit area can be easily reduced because the transmission line 3 is non-annular. In other words, the balun circuit 100 makes it easier to avoid the formation of dead space like the inside of the annular structure of a conventional rat-race balun circuit, and therefore makes it easier to reduce the circuit area.

[0032] In particular, since large second-terminal-connected circuits such as amplifiers and mixers are connected to the second terminal 2, facilitating circuit layout leads to reduced circuit area. The balun circuit 100 of the embodiment allows the second-terminal-connected circuits to be arranged together in the second region Rg2, facilitating circuit layout and effectively reducing the circuit area. Furthermore, since the transmission line 3 is non-cyclic (straight in the embodiment), there are no bends in the line, making it possible to effectively reduce signal loss.

[0033] Referring to Figure 2, the transmission loss in a conventional circuit configuration (rat race balun) (dashed line graph in Figure 2) and the transmission loss in the balun circuit 100 according to the embodiment (solid line graph in Figure 2) were evaluated, and the results will be briefly described below. The inventors have confirmed that the transmission loss of the balun circuit 100 has performance roughly equivalent to that of a conventional circuit configuration, as shown in Fig. 2. Therefore, by replacing the conventional circuit configuration (rat-race balun circuit) with the balun circuit 100 according to the embodiment, it is possible to reduce the circuit area while maintaining the same functionality as the conventional circuit.

[0034] 4. Variations 3, the balun circuit 100 may have two first terminals. That is, the first terminal 1 includes a first terminal 1a and a first terminal 1b. Both the first terminal 1a and the first terminal 1b are disposed between a pair of center terminals (second terminals 2b and 2c). The first terminal 1a as one of the first terminals 1 is arranged at a distance w2 from one of the central terminals (here, the second terminal 2b). The first terminal 1b as the other of the first terminals 1 is arranged at a distance w2 from the other central terminal (here, the second terminal 2c). The balun circuit 100 according to this modification can also have the same function as a conventional double rat-race circuit. The distance w2 is the same as that described in the embodiment.

[0035] Here, a case will be described in which a positive phase wave Z0(+) is input to the second terminals 2a and 2b, and a negative phase wave Z0(-) is input to the second terminals 2c and 2d. The balun circuit 100 according to the modified example shown in FIG. 3 has two output ports (first terminals 1a and 1b), and can output different phase outputs from each of the first terminals 1a and 1b. That is, an unbalanced signal with a positive phase wave is output from the first terminal 1a, and an unbalanced signal with a negative phase wave is output from the first terminal 1b. Note that, as in the embodiment, noise from these unbalanced signals is canceled out and suppressed.

[0036] Furthermore, in the above description, an example (power coupling) has been described in which a balanced signal is input from the second terminal 2 and an unbalanced signal is extracted from the first terminal 1a or the first terminal 1b, but even in the modified example, it is possible to input an unbalanced signal to the first terminal 1a or the first terminal 1b and extract a balanced signal from the second terminal 2, thereby distributing power. Also in the modified example, the number of second terminals 2 is not limited to four, and can be 2×n (n is an integer equal to or greater than 2), as in the embodiment.

[0037] Various embodiments are exemplified below, and the embodiments shown below can be combined with each other. [Appendix 1] A balun circuit for performing at least one of power division and power combination, comprising: a transmission line, a first terminal, and 2×n (n is an integer of 2 or more) second terminals; the transmission line is configured in a non-circular shape; one of the first terminal and the second terminal functions as an input section of the balun circuit, and the other of the first terminal and the second terminal functions as an output section of the balun circuit; each of the second terminals is connected to the transmission line, and the 2×n second terminals are arranged to be aligned at predetermined intervals in the extension direction of the transmission line, and the 2×n second terminals include a pair of central terminals located toward the center of the transmission line in the extension direction; The first terminal is disposed between the pair of center terminals. [Appendix 2] 2. The balun circuit according to claim 1, the transmission line has a total length based on a wavelength λ of a transmission signal transmitted to the input port; The balun circuit has a total length of 0.8×λ×m (m is an odd number of 3 or more) or more and 1.2×λ×m or less. [Appendix 3] 1. A balun circuit according to claim 1 or 2, the first terminal is disposed in the extension direction with respect to one of the pair of central terminals at a distance based on a wavelength λ of a transmission signal transmitted to the input port, The balun circuit, wherein the spacing is equal to or greater than 0.8×λ / 4 and equal to or less than 1.2×λ / 4. [Appendix 4] 4. The balun circuit according to claim 3, two of the first terminals; one of the first terminals is disposed at the interval with respect to the one of the central terminals, the other first terminal is disposed at the distance from the other central terminal. [Appendix 5] The balun circuit according to any one of Supplementary Note 1 to Supplementary Note 4, The 2×n (n is an integer of 2 or more) second terminals have the same length. [Appendix 6] The balun circuit according to any one of Supplementary Note 1 to Supplementary Note 5, The balun circuit, wherein the transmission line extends linearly from one end to the other end. [Appendix 7] A balun circuit according to any one of Supplementary Note 1 to Supplementary Note 6, When the region on one side of the transmission line is defined as a first region and the other side as a second region, The balun circuit, wherein the first terminal is disposed in the first region and the second terminal is disposed in the second region. [Explanation of symbols]

[0038] 100: Balun circuit 1: 1st terminal 1a: 1st terminal 1b: 1st terminal 2: 2nd terminal 2a: 2nd terminal 2b: 2nd terminal 2c: 2nd terminal 2d: 2nd terminal 3: Transmission line Dr: Stretching direction Rg1: 1st area Rg2: Second area w1 : full length w2 : interval

Claims

1. A balun circuit for performing at least one of power division and power combination, comprising: a transmission line, a first terminal, and 2×n (n is an integer of 2 or more) second terminals; the transmission line is configured in a non-circular shape; one of the first terminal and the second terminal functions as an input section of the balun circuit, and the other of the first terminal and the second terminal functions as an output section of the balun circuit; each of the second terminals is connected to the transmission line, and the 2×n second terminals are arranged to be aligned at predetermined intervals in the extension direction of the transmission line, and the 2×n second terminals include a pair of central terminals located toward the center of the transmission line in the extension direction; The balun circuit, wherein the first terminal is disposed between the pair of center terminals.

2. 2. The balun circuit according to claim 1, the transmission line has a total length based on a wavelength λ of a transmission signal transmitted to the input port; The balun circuit has a total length of 0.8×λ×m (m is an odd number of 3 or more) or more and 1.2×λ×m or less.

3. 3. The balun circuit according to claim 1, the first terminal is disposed in the extension direction with respect to one of the pair of central terminals at a distance based on a wavelength λ of a transmission signal transmitted to the input port, A balun circuit, wherein the spacing is equal to or greater than 0.8×λ / 4 and equal to or less than 1.2×λ / 4.

4. 4. The balun circuit according to claim 3, two of the first terminals; one of the first terminals is disposed at the interval with respect to the one of the central terminals, the other first terminal is disposed at the distance from the other central terminal.

5. 3. The balun circuit according to claim 1, The 2×n (n is an integer of 2 or more) second terminals have the same length.

6. 3. The balun circuit according to claim 1, The balun circuit, wherein the transmission line extends linearly from one end to the other end.

7. 3. The balun circuit according to claim 1, When the region on one side of the transmission line is defined as a first region and the other side is defined as a second region, The balun circuit, wherein the first terminal is disposed in the first region and the second terminal is disposed in the second region.

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