JPS6216568B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a 3 dB power divider suitable for integrated circuits or printed board circuits that distributes the power of signals in ultra-high frequency circuits in the same phase. Conventionally, power dividers are coupler circuits that use coupled lines, trapezoidal circuits or rattrace circuits that use loop lines, magic T circuits that use slot lines, and a lumped constant circuit that connects the other end of a T-branched line proposed by EJ Wilkinson. It consisted of a circuit bridged by resistive elements. Among these, an in-phase power divider using a microstrip transmission line structure of an integrated circuit or a printed circuit board is a Wilkinson
A shaped circuit is suitable. This circuit has fewer distributed constant elements than other circuits and is suitable for miniaturization. However, in order to avoid coupling between the two distributed constant elements, this circuit must be constructed with the lines sufficiently separated when forming the pattern, so miniaturization had to be sacrificed. Examples of this pattern are as shown in Figure 1 a, b, and c.
The lines 1 and 2 were constructed with a considerable distance from each other. In addition, as shown in Fig. 1d, the T-branched line 1,
A circuit type in which the two are actively coupled has been considered, but this results in a long and narrow pattern in the signal transmission direction. In the figure, 3 is a resistance element, and 4 to 6 are input/output terminals. When these patterns are used in balanced amplifiers, mixers, filters, etc., it is difficult to miniaturize the entire circuit. An object of the present invention is to enable extremely miniaturization when configured with integrated circuits or printed circuit board circuits,
For example, it is an object of the present invention to provide a power divider that is effective in downsizing when configuring balanced amplifiers, mixers, and filters. Hereinafter, the present invention will be explained in detail with reference to the drawings. FIGS. 2a and 2b are block diagrams showing a 3 dB power divider for one-stage and two-stage lines according to an embodiment of the present invention. In the figure, a pair of two-wire distributed coupled lines 1, 2 and a lumped constant resistance element 3, which have the same electrical length and the same degree of coupling and are interconnected at one end, are sequentially connected in a cyclic manner to form a closed set. A circuit is constructed, and branch lines 4, 5, and 6 are provided at each connection point.
Note that Fig. 1a shows the tracks 1 and 2 bent close to each other, and Fig. 1b shows the tracks 1 and 2 made up of adjacent tracks 11 and 21 and slightly separated tracks 12 and 22. . A branch line 4 with a characteristic impedance Z ₀₁ is provided at the connection point of these distributed coupling lines 1 and 2, and a branch line 5 with a characteristic impedance Z ₀₂ is provided at the other two connection points.
The distributed coupling lines 1 and 2 have the same electrical length and coupling degree, have a characteristic impedance of √2 _{01 02} , and have a resistance value of the lumped resistance element 3 of 2Z ₀₂ . The transmission characteristics of these circuits can be explained by breaking them down into even and odd modes. That is, when input voltages of the same phase are applied to the branch lines 5 and 6, the mode becomes an even mode as shown in the explanatory diagram of FIG. As shown in the figure, the mode becomes odd mode. In these even and odd modes, if the reflection coefficient at input end 5 is Γ _e and Γ _p , then (1) Reflection loss at branch point 4: -20log | Γ _e | (2) Branch point 5 or Reflection loss at 6: -20log | Γ _e + Γ _p |/2 (3) Isolation between branch points 5 and 6: -
20log | Γ _e + Γ _p |/2 (4) Separation from branch point 4 to branch point 5 or 6: It is known that -10 log 1 - | Γ _e | ² /2. Therefore, Γ _e =Γ _p =
At the frequency where the frequency becomes 0, the power distributed from the branch line 4 to the branch lines 5 and 6 becomes 1/2, and the mutual transmission power between the branch lines 5 and 6 becomes 0.
and become isolated from each other. The reflected power at the branch points of these branch lines 4, 5, and 6 is 0, and impedance matching is established. In a single-stage coupled line, Γ _e and Γ _p can be expressed by the following equations, where l is the electrical length of the distributed coupled line, k is the coupling degree, and λ is the transmission signal wavelength. However, j=√−1. The electrical length l of the distributed coupling line is defined as the transmission signal wavelength λ.

[Formula] times, or

If [Equation] is selected twice, Γ _e =Γ _p = 0 is satisfied, and therefore, it can be seen that the circuit of the present invention works as a 3 dB power divider. 4a, b, c, and d are examples of the circuit patterns of FIG. 2 which are integrated circuits. In addition, Figure 4 a,
c corresponds to Figure 2 a and b, but in Figure 4 b, another line is inserted between lines 1 and 2 to increase the degree of coupling, shortening the length of lines 1 and 2. FIG. 4d is a diagram in which the line spacing of FIG. 4c is reversed. Compared to the circuit pattern shown in Fig. 1, these circuit patterns show that the degree of miniaturization of the circuit of the present invention is different in the case of a 2 GHz band 3 dB power divider constructed using an alumina ceramic substrate with a thickness of 0.635 mm. The area occupied by the pattern excluding the lines is approximately 0.4 to 0.7 times smaller. The relationship between the coupling degree (coupling loss) and the electrical length (wavelength unit) of these coupled distribution lines 1 and 2 is, for example,
The line length is 0.188λ (for example, 14.3mm at 1.5GH) with a coupling degree of 3dB in one stage, and 0.167λ with a coupling degree of 6dB in one stage, 1
For a stage of 20 dB, the line length is 0.132λ, and in the case of two stages, the combination of 3 dB and 6 dB coupling results in a line length of 0.094 λ and 0.083 λ. Figures 5a and 5b are characteristic diagrams of calculation examples when Z ₀₁ = Z ₀₂ = 50Ω, where a is the isolation between branch lines 5 and 6, and b is the isolation from branch line 4 to 5 or 6. Shows separation. In the figure, 7 is 1 stage of coupling
6dB characteristic line, 8 is 1 stage coupling 10dB characteristic line, 9 is
Wilkinson type one-stage characteristic line, 10 and 11 are coupling 2
Characteristic lines for stages 10-6dB and 6-10dB are shown, respectively. When the distributed coupling line has one stage, the ratio band tends to narrow as the coupling becomes denser, so the degree of coupling k becomes
It is desirable to have a configuration of around 20dB (0.1) to 6dB (0.5), but if there is no need to use a wide special band,
Even if it is 0.5 or more, it is sufficiently practical and can be made small. Also, when the distributed coupling line is two stages,
Making the coupling in the first stage denser than the coupling in the next stage will widen the fractional bandwidth than in the opposite case. However, in view of the circuit pattern configuration, it is more ideal to make the connections in the first stage coarser than those in the next stage. As explained above, the present invention allows the circuit to be patterned on a plane, is sufficiently smaller than conventional circuits, and is short in the signal transmission direction.
When used for power distribution and synthesis in balanced amplifiers, mixers, filters, etc., the overall circuit size can be reduced. Although this embodiment has been explained using a transmission line with a microstrip structure, it is not limited to this and can also be applied to a coaxial line, etc.
It can also be realized using any distributed constant element capable of transmitting TEM waves. Moreover, the number of stages of the distributed coupling line may be further increased. Furthermore, this power divider can also be used as a power combiner by inputting transmission signals from branch lines 5 and 6.

[Brief explanation of the drawing]

Figures 1a, b, c, and d are plan views of a conventional hybrid power divider, Figures 2a and b are configuration diagrams of an embodiment of the present invention, and Figures 3a and b are diagrams of signal transmission characteristic modes. Explanatory diagrams, Figures 4a, b, c, and d are plan views of hybrid patterns to which the present invention is applied, and Figures 5a and b are isolation diagrams when Z ₀₁ = Z ₀₂ = 50Ω in Figure 3. and a calculation characteristic diagram of separation. In the figure, 1, 2...branch line, 3...resistance element, 4,
5, 6...input/output terminals, 7-11...characteristic lines.

Claims (1)

[Claims] 1. First and second distributed coupling lines whose one ends are commonly connected to the first branch line, and the other ends of the first and second distributed coupling lines. a lumped constant resistance element connecting between second and third branch lines respectively connected to and the other ends of the first and second distributed coupling lines; In a power divider with bent lines, the characteristic impedances of the second and third branch lines are made equal to each other, and the characteristic impedance of the first and second distributed coupling lines is made equal to the characteristic impedance of the first branch line. The resistance value of the lumped constant resistance element is set to be equal to the square root of twice the product of the characteristic impedance and the characteristic impedance of the second or third branch line, and the resistance value of the lumped constant resistance element is equal to the characteristic impedance of the second or third branch line. A power divider characterized in that the interval between each bent portion of the first and second distributed coupling lines is narrowed so that the distance is equal to twice the distance between the bent portions of the first and second distributed coupling lines. 2. The power divider according to claim 1, characterized in that the power divider is constituted by a multi-stage line in which the intervals between the bent portions of the first and second distributed coupling lines are different.