KR19980047740A - T-branchline hybrid power divider architecture - Google Patents

Abstract

The 90 ° hybrid branchline power divider, circular hybrid power divider, and its modified structures, which are widely used in existing (ultra) high frequency circuits or systems, are generally composed of two or more kinds of characteristic impedances. While there is a discontinuous dissipation effect in the connection part, the power divider of the present invention can be composed of transmission lines having one kind of characteristic impedance, which can be a simple structure, thereby reducing the discontinuous part of the circuit, and the existing power divider. While the circuit parameters are determined, the power divider of the present invention can design a variety of circuits because four parameters are selected out of eight circuit parameters, and the remaining four parameters are selected. It can reduce the effect. In addition, it is possible to reduce the mutual coupling between transmission lines having low characteristic impedance that may occur in a high frequency band such as a millimeter wave band.

Description

T-branchline hybrid power divider architecture

The present invention relates to a T-branchline hybrid power divider that can be widely used in in-phase shifters, balanced mixers, modulators, balanced amplifiers, power dividers, and the like that constitute RF systems such as satellite communication, mobile communication, and personal communication. will be.

In general, a power divider is a very important element in an (ultra) high frequency circuit or system that can divide a signal in (ultra) high frequency circuit or system application and synthesize the signal in the reverse direction. Wilkinson published the 1960 IRE Trans. Microwave Theory Tech., Vol. Since the introduction of the N-way power divider in the MTT-8, numerous power dividers in various forms, including power splitters, 90 ° hybrid branch line power splitters, circular hybrid power splitters, and range combiners, have been modified from the Wilkins N-way power splitter. Although the results of these studies have been published, the present invention is the first in the form of a symmetric T-branchline hybrid power divider.

The 90 ° hybrid branchline power divider, the circular hybrid power divider, and its modified structures, which are commonly used in prior art (ultra) high frequency circuits or systems, are generally composed of two kinds of characteristic impedances to connect the transmission lines. There is a discontinuous dispersion effect at, and the electrical length of the transmission line between nodes is 90 °, so the overall circuit size is determined at a given frequency. In addition, in a high frequency band such as a millimeter wave band, mutual coupling between opposing transmission lines having low characteristic impedance may occur.

In addition, the existing power divider has a predetermined circuit parameter, so the overall size of the circuit is determined by one.

In order to solve the above problems, by using the present invention to solve the fine phase difference between the output terminal that can occur in the microstrip type power synthesis circuit configuration by fine tuning of the matching stubs, the characteristic impedance of all transmission lines in the circuit By doing the same, the discontinuity effect of the line connection part is reduced, and the overall circuit size is reduced to be useful in power synthesis circuit configuration.

Specifically, a 90 ° hybrid branchline power divider, a circular hybrid power divider, and its modified structures, which are commonly used in existing (ultra) high frequency circuits or systems, are generally composed of two or more kinds of characteristic impedances. While there is a discontinuous dispersion effect in the connection part between transmission lines at, the power divider of the present invention can be composed of transmission lines having one kind of characteristic impedance, which can be a simple structure, thereby reducing the discontinuous parts of the circuit. .

The existing power divider is a circuit parameter is determined, whereas the power divider of the present invention can be selected a variety of circuit design, because the remaining four parameters are selected if four parameters among the eight circuit parameters are selected, low frequency band Can also reduce the circuit size.

In addition, it is possible to reduce the mutual coupling between transmission lines having low characteristic impedance that may occur in a high frequency band such as a millimeter wave band.

1 is a structural diagram of a symmetric T-branchline hybrid power divider of the present invention.

2 is a structural diagram of a power divider of the present invention according to the embodiment of FIG.

3 shows simulation results of all electrical performance expected at each output stage of the power divider when the output power distribution ratio is 1: 1.

3A illustrates matching (or input / output return loss) characteristics at each input / output terminal;

3b illustrates the input / output insertion loss (or conversion loss) characteristic,

3C shows the isolation (or isolation) characteristics between the terminals, respectively.

Explanation of symbols on the main parts of the drawings

TL-1 ~ TL-8: Transmission line constituting the closed loop of the circuit (the electrical length of the transmission line is less than 90 °)

SL-1 ~ SL-4: Matching stub

R-1 to R-4: Equivalent characteristic impedance observed toward the input and output terminals

Z ₁ ~ Z ₈ : Characteristics impedance of transmission line

θ ₁ ~ θ ₈ : Electrical length of transmission line

Z _S1 to Z _S4 : Characteristic impedance of the matching stub

θ _S1 ~ θ _S4 : Electrical length of matching stub

M, N: output power distribution ratio on the output terminal side

1 ~ 8: Node point in circuit

In order to achieve the above object, the symmetrical T-branch line power divider of the present invention includes an M power output terminal and an N power output terminal having a first equivalent characteristic impedance (R-1), M: N power distribution ratio observed toward the input terminal. Between the second and third equivalent characteristic impedances (R-2, R-3) and the fourth equivalent characteristic impedance (R-4) observed toward the termination (isolated) terminal and the equivalent characteristic impedances observed between the node Transmission lines formed by connecting closed loops of arbitrary shape, having the same characteristic of transmission line characteristic impedance (Z ₁ to Z ₈ ) and reducing symmetry of the discontinuous dispersion effect of the connection part between transmission lines. First to eighth transmission lines TL-1 to TL-8 having electrical lengths θ ₁ to θ _{8 of the} furnace; And the characteristic impedances Z _S1 to Z _S4 of each matching stub and the electrical lengths θ _S1 to _S4 of the matching stubs;

A central portion of a branch line between each of the first transmission line and the second transmission line, the third transmission line and the fourth transmission line, the fifth transmission line and the sixth transmission line, and the seventh transmission line and the eighth transmission line; Characterized in that the first to fourth impedance matching stub (SL-1 ~ SL-4) is inserted into the.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a general structural diagram of a T-branchline hybrid power divider.

This structure is a planar structure, and at the center frequency, theoretically perfect matching performance (or input / output return loss performance) and separation performance (or isolation performance) at all input and output terminals are perfect.

In the power divider structure shown in FIG. 1, the input terminal is connected to node 1, two output terminals are connected to node 2 and 3, and the terminal (or isolation terminal) is connected to node 4. It is arbitrarily shown assuming the connected parts. Here, when implementing the power divider, the node points 1 to 4 may have a 50 ohm characteristic impedance and an optional transmission line with an electrical length. The length varies only with the phase difference of the input / output signal at the center frequency, but the main performance (input / output return loss, insertion loss, isolation between terminals, etc.) does not change.

Referring to the symbols for each of the parts shown in Figure 1 as follows.

(R-1) to (R-4) are equivalent characteristic impedances observed toward the input / output terminals and generally use 50 ohms. (TL-1) to (TL-8) represent transmission lines constituting the closed loop of the power divider circuit. (Z ₁ ) to (Z ₈ ) represent characteristic impedances of the transmission lines, and all of them may be set to values having the same characteristic impedance, thereby reducing the discontinuous dispersion effect of the connection portions between the transmission lines. θ ₁ to θ ₈ represent electrical lengths of transmission lines, and the electrical lengths of each transmission line have a value smaller than 90 ° in left and right (up and down) symmetry. (SL-1) to (SL-4) indicate impedance matching stubs inserted into the center portion of each branch line. Z _S1 to Z _S4 represent the characteristic impedance of the matching stub, and θ _S1 to θ _S4 represent the electrical lengths of the matching stub, and the characteristic impedance and the electrical length of the stub can be set arbitrarily because they have a correlation with each other. M and N represent the output power distribution ratios on the respective output terminals.

In order to operate the power divider as shown in FIG. 1 with an M: N power divider having a 90 ° phase difference between the output terminals, a closed loop and a reference numeral composed of 1, 5, 2, 6, 3, 7, 4, and 8 are shown. Matching stubs attached to 5, 6, 7, and 8 must have the following electrical characteristics:

Electrical Characteristics of (TL-1), (TL-2), (TL-5), (TL-6):

Electrical Characteristics of (TL-3), (TL-4), (TL-7), (TL-8):

Electrical Characteristics of (SL-1), (SL-3):

Electrical characteristics of (SL-2), (SL-4):

Here, Z ₀ means the same characteristic impedance as the equivalent characteristic impedance shown in the symbols (R-1) to (R-4). (TL-1), (TL-2), (TL-5), and (TL-6) have the same electrical characteristics, and the characteristic impedance Z _a and the electrical length θ _a are dependent on each other, so that any one of the two variables If is selected, the other variable is determined automatically. Similarly, (TL-3), (TL-4), (TL-7), and (TL-8) have the same electrical properties, and the characteristic impedance Z _b and the electrical length θ _b are also dependent on each other. When you select one variable, the other is automatically determined. In addition, (SL-1) and (SL-3) are the same, and the characteristic impedance Z _Sa and the electrical length θ _Sa are also dependent on each other, and when one of the two variables is selected, the other one is automatically determined. Similarly, (SL-2) and (SL-4) are the same, and the characteristic impedance Z _Sb and the electrical length θ _Sb are also dependent on each other, so that if one of the two variables is randomly selected, the other one is automatically determined. As such, the present invention has four optional design variables not found in the existing power divider, thereby allowing more flexible circuit design.

For example, when the impedance Z ₀ of each input and output terminal is 50 ohm and the power distribution ratio (M: N) at each output terminal is 1: 1, to make all transmission lines in the closed loop constituting the power divider circuit 50 ohm. The eight design variables (Z _a , Z _b , Z _S2 , Z _Sb , θ _a , θ _b , θ _Sa , θ _Sb ) are determined as follows.

Z _a = Z _Sa = Z ₀ , θ _a = θ _Sa = 35.26 °

Z _b = Z ₀ , Z _Sb = 0, θ _b = 90 °, θ _Sb = 0 °

2 is an exemplary diagram of a power divider having the design values.

The result of computer simulation of the theoretical electrical performances of the power divider shown in FIG. 2 is shown in FIG. 3.

3A shows matching (or I / O return loss) characteristics at each input / output terminal, FIG. 3B shows input / output insertion loss (or conversion loss) characteristics, and FIG. 3C shows isolation (or isolation) characteristics between the terminals. The simulation results show satisfactory output characteristics in the constant frequency band as well as the center frequency.

If the power divider is implemented in a circular structure as described above, the effect of discontinuous dispersion in the connection portions between the transmission lines is reduced, thereby reducing the transmission characteristics and the circuit size. The T-branchline hybrid power divider is useful for implementing rectangular as well as circular structures, and in low frequency applications, matching stubs can be inserted into the closed loop to reduce circuit size.

In the present invention, since the characteristic impedance of all transmission lines in a circuit can be unified as one type, the discontinuous dispersion effect generated at the connection part between the transmission lines can be eliminated, and the mutual coupling phenomenon between transmission lines having low characteristic impedance can be solved. Therefore, it can be used as a power divider useful for high frequency bands such as millimeter wave bands. In addition, power dividers invented in relatively low frequency bands, such as UHF or L bands, can reduce the overall circuit size, thereby solving the circuit size problem of conventional power dividers. In particular, when used in low frequency bands, suitable lumped capacitors can be used instead of matching stubs.

In summary, the main effects of the present invention will be described as follows.

First, it reduces discontinuous dispersion effect between transmission lines in high frequency band application, and second, reduces the mutual coupling between transmission lines with low characteristic impedance in high frequency band application, and third, reduces circuit size in low frequency band application. Can be reduced.

In addition, the secondary effect of the present invention will be described.

Firstly, it is possible to use a suitable concentrator capacitor instead of matching stub in low frequency band applications, and secondly, it is possible to fine tune the matching stub to improve the electrical performance of the output stage.

Since the present invention can unify the characteristic impedance of all transmission lines in a circuit as a kind, mutual coupling between transmission lines having low characteristic impedance that can occur in a high frequency band can be eliminated by discontinuous dispersion effect generated at the connection part between transmission lines. It solves the phenomena, and it is possible to variably design the electrical length of the transmission line in the circuit less than 90 °, reducing the overall circuit size and tuning the fine phase difference that can occur during power synthesis because it has matching stubs between the transmission lines. The goal is to provide a new type of T-branchline hybrid power divider that can be tuned to improve output performance.

Claims (6)

In a symmetric T-branchline hybrid power divider, First equivalent characteristic impedance (R -1) observed toward the input terminal, M: N power output terminal having an N power distribution ratio and second and third equivalent characteristic impedances (R -2, R − observed toward the N power output terminal); 3) and a fourth equivalent characteristic impedance (R-4) observed toward the termination (isolated) terminal; Any equivalent closed loop is formed between the equivalent characteristic impedances and the node, and the same characteristic of the transmission line characteristic impedance (Z ₁ to Z ₈ ) is used to reduce the discontinuous dispersion effect of the connection portion between the transmission lines. First to eighth transmission lines TL-1 to TL-8 having electrical lengths θ ₁ to θ ₈ of transmission lines that are symmetrical to the left and right (up and down); And Each matching stub has a characteristic impedance (Z _S1 to Z _S4 ) and an electrical length (θ _S1 to θ _S4 ) of the matching stub, A central portion of a branch line between each of the first transmission line and the second transmission line, the third transmission line and the fourth transmission line, the fifth transmission line and the sixth transmission line, and the seventh transmission line and the eighth transmission line; T-branch line hybrid power splitter, characterized in that consisting of the first to fourth impedance matching stub (SL-1 ~ SL-4) inserted in the. The method of claim 1, wherein the transmission line T-branchline hybrid power distributor characterized in that the closed loop of a circular or rectangular structure. The method of claim 1, wherein the transmission line T-branch line hybrid power divider characterized in that the electrical length of the transmission line is configured to have a value smaller than 90 ° in symmetry. According to claim 1, wherein the first to fourth impedance matching stub is T-branchline hybrid power divider, inserted into the closed loop for applications in the low frequency band. According to claim 1, wherein the first to fourth impedance matching stub is T-branchline hybrid power divider, inserted outside the closed loop for high frequency applications. 2. The T-branch line hybrid power divider according to claim 1, A T-branch line hybrid power divider characterized by operating in a reverse direction to use as a power synthesizer.