JPS61281601A - Coupling rat race ring circuit - Google Patents

Abstract

PURPOSE:To provide a wide band of isolation characteristic by selecting properly the impedance of each connection line and making the length of connection line different in a prescribed rate at each rat race ring. CONSTITUTION:Terminals 2, 3 are provided at an angle of 120 deg. and one set of terminals being isolation terminals mutually and terminals 9 and 12 are similar terminals provided at an angle of 120 deg.. Denoting the input impedance of each terminal as Z0, then connection lines 6, 8 are opposed lines and their impedance are 1.0824Z0. Connection lines 5, 7 are opposed lines and their impedance is 2.6131Z0. The length of connection lines 13, 14 and 15 of the rat race ring R2 is shorter by 5% than the length of the lines 5-7 and the length of the line 16 is shorter than the length of the line 8 by 5%. In connecting two rat race rings to constitute a 3dB hybrid in this way, the isolation characteristic and the branching characteristic are made broader.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention provides iso-isolation over a wide frequency range of rat race rings widely used in microwave integrated circuits (MICs) used in the microwave and millimeter wave frequency bands. The present invention relates to a coupled rat race ring circuit which has ration characteristics and demultiplexing characteristics.

(Prior Art) A conventional rat race ring is constructed as shown in FIG. 4, where 101 is an input terminal, 102 and 1
03 is a coupling output terminal, and 104 is an isolation terminal. 105 to 108 are connection lines between each terminal.

When the input impedance Zo of each terminal is normalized as Z, = 1, the characteristic impedance of the connecting lines 105 to 108 is Fl-, and the length of the connecting lines 105 to 107 is 4.
If the length of the connecting line 108 is three-quarters of a wavelength, a 3-dB splitter is realized.

That is, in the conventional rat race ring, in which the power input from the input terminal 101 is transmitted in half to the combined output terminals 102 and 103, and not to the isolation terminal 104, the two sets of opposing connection lines are the same. It is impedance.

(Problems to be Solved by the Invention) The rat race ring described above is well known, but it has the disadvantage that it cannot be used over a wide range of frequencies because the frequency band is limited as shown in Figure 5. there were. FIG. 5(a) shows the frequency characteristics of the isolation between the input terminal 101 and the isolation terminal 104,
The dotted line in FIG. 5(b) is the frequency characteristic of the degree of coupling from the input terminal 101 to the combined output terminal 102, and the solid line is the frequency characteristic of the degree of coupling from the input terminal 101 to the combined output terminal 103.

In addition, due to problems in manufacturing technology, it is difficult to obtain products with consistent characteristics due to manufacturing errors with design calculation values and variations in repeated manufacturing.

An object of the present invention is to provide a combined rat race ring circuit which has a wider frequency band than the conventional case of a single rat race ring and has less manufacturing variation by combining a plurality of rat race rings. It is something to do.

(Means for Solving the Problems) The coupled rat race ring circuit of the present invention has the following configuration to achieve the above object.

That is, a plurality of terminals are connected by connecting one set of terminals provided at an angle of 120 degrees on the rat race ring of the previous stage to one set of terminals provided at an angle of 120 degrees of the rat race ring of the next stage. A combined rat race ring circuit in which rat race rings are connected in cascade, and the line impedance of each rat race ring is the same for the lines facing each other, but for the line impedance of the lines that are opposite to each other, but The opposing line impedances have a common value that varies depending on the number of rat race rings connected, and the line length of each rat race ring has a different value given in advance to each rat race ring. It is a coupled rat race ring circuit with different lengths depending on the resonant frequency (function) The rat race ring has 4 connection lines connecting each terminal.
However, the connection lines facing each other have the same impedance value, and the connection lines adjacent to each other across the terminal have different impedance values, thereby connecting the input terminal and each coupling output terminal. You can change the degree. On the other hand, when a plurality of rat race rings are connected in cascade so that a 3 dB distribution coupling is obtained as a total characteristic, the coupling degree of each rat race ring is calculated theoretically. As mentioned above, the degree of coupling of the rat race ring is determined by the impedance of the connection line, so the impedance of the connection line is determined so as to obtain the theoretically calculated degree of coupling, and the number of rats, If the race rings are connected in tandem, a combined rat race ring circuit as a 3 dB distributor is obtained.

At this time, instead of making the resonant frequency (the frequency at which the isolation is maximum) of each rat race ring the same, it is slightly shifted, resulting in a resonant circuit characteristic in which there are multiple resonance points at slightly different frequencies. It exhibits characteristics similar to , and the isolation characteristics are broadband.

Since the resonant frequency of the rat race ring is determined by the length of the connection line, if a different resonant frequency is specified for each rat race ring in advance, the specified resonance can be achieved by setting the connection line length according to the resonant frequency. A rat race ring having a frequency is obtained, and by cascading these, a combined rat race ring circuit having broadband isolation characteristics is obtained.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure shows an embodiment of the present invention, and shows a combined rat race ring circuit using two rat race rings R and R2. 1-4 are terminals of rat race ring R, 5-
8 is a connecting line connecting terminals 1 to 4; 9 to 4;
Reference numeral 12 indicates a terminal of the rat race ring R2, and reference numerals 13 to 16 indicate connection lines connecting each of the terminals 9 to 12. Terminals 2 and 3 are a pair of terminals that are placed at an angle of 120 degrees and serve as mutually isolated terminals, and terminals 9 and 12 are also similar terminals that are placed at an angle of 120 degrees. Terminals 3 and 12 are connected, and terminals 2 and 9 are connected.

The impedance relationship will be explained below.

It is assumed that the input impedance of each terminal is Zo. Connection lines 6 and 8 are opposing lines, and their impedances are both 1.0824zo. Similarly, the impedance of both connection lines 14 and 16 is 1.
．． It is 0824zo. On the other hand, connection lines 5 and 7 are also opposing lines, and their impedances are both 2.61.
It is 31Zo. Similarly, the impedances of the connecting lines 13 and 15 are both 2.6131 Zo. These impedances are equal to the impedances for cascading two rat race rings to form a 3 dB divider.

Next, the length of the connection line will be explained. The lengths of the connecting lines 5, 6 and 7 of the rat race ring R1 are one quarter wavelength of the resonant frequency, and the length of the connecting line 8 is three quarter wavelengths. be. On the other hand, the lengths 2 of the connection lines 13, 14 and 15 of the rat race ring R2 are 5% shorter than the lengths of the connection lines 5 to 7, and the length of the connection line 16 is the connection line 8. It is 5% shorter than the length of . Therefore, the rat race ring R2 has all the connecting lines 5% shorter than the rat race ring R1, so the resonant frequency is correspondingly higher, which makes it suitable for the isolation frequency band of the coupled rat race ring circuit. exhibits broadband characteristics similar to the characteristics of a resonant circuit in which there are two resonance points slightly apart.

FIG. 2(a) is a diagram showing the frequency characteristics of isolation between terminal 1 and terminal 4 in this embodiment. Figure 2 (a
), the frequency range in which the isolation is 20 dB is from 25 GHz to 350 H2. This is because the frequency range in which the isolation of the conventional rat race ring shown in Figure 5(a) is 20 dB is 25 GHz.
It shows that the band is about 1.2 times wider than that of ~33,3 GH2.

FIG. 2(b) is a diagram showing the frequency characteristics of the degree of coupling in this example, where the dotted line is the frequency characteristic of the degree of coupling between terminals 1 and 11, and the solid line is the frequency characteristic of the degree of coupling between terminals 1 and 10. It is a frequency characteristic. Comparing this with the coupling degree frequency and characteristics of the conventional rat race ring shown in Figure 5(b), it can be seen that the bandwidth is wider.In this way, two rat race rings are connected to create a 3 dB hybrid. If configured, the isolation characteristics and demultiplexing characteristics can be made broadband.0 Line impedance of this embodiment, connection line 5, 7, 1
3, and the impedance of 15 is 2.6131xZ
,, The impedance of the connecting lines 6, 8, 14 and 16 was set to 1.0824X Zo, but the impedance of the former was (2 to 4) X Zo, and the impedance of the latter was (0,9 to 1 .3) Wideband characteristics can be obtained even with XZo.

Although the case where two rat race rings are connected has been described above, the same effect can be obtained even if three or more rat race rings are connected.

A connection example in the case of three is shown in FIG. In this case, the connection lines 5, 7, 13, 15, 21 and 2 are used.
3 impedance is 3.5781xZo, connection line 6
, 8, 14, 16, 22 and 24 can be set to 1.0383Zo. Even in the case of 3 pieces, if you shift the length of the connection line by about 5%, the impedance of 2 pieces, As in the case, the isolation characteristic becomes wider. This shows that by connecting rat race rings in multiple stages, it is possible to obtain multi-stage resonant circuit characteristics and obtain broader band characteristics than a single rat race ring.

(Effects of the Invention) The coupled rat race ring circuit of the present invention maintains an appropriate degree of coupling by selecting the impedance of the connection line between the terminals of each rat race ring even when a plurality of rat race rings are connected in series. The impedance of each connection line is appropriately selected, focusing on the fact that the desired degree of coupling can be obtained by setting the desired degree of coupling, and the length of the connection line is varied at a constant rate for each rat race ring. In addition, each rat race ring has a different resonance frequency. Similar to the characteristics of a multi-stage resonant circuit with different slanted resonant frequencies, there is an advantage that a broader frequency characteristic can be obtained than when one rat race ring has one resonant frequency. In addition, since it is composed of multiple rat race rings, variations in the characteristics of one rat race ring have no effect on the overall characteristics. As a result, the variation tolerance for individual rat race rings is increased, which has the advantage of increasing the degree of freedom in design and manufacturing.

[Brief explanation of drawings]

Fig. 1 is a connection diagram of an embodiment of the present invention, Fig. 2 is a frequency characteristic diagram of the embodiment of Fig. 1, Fig. 3 is a connection diagram of another embodiment of the invention, and Fig. 4 is a conventional rat FIG. 5 is a diagram showing an example of the frequency characteristics of a conventional rat lace ring. 1.2.3.4...Terminal, 5.6.7.8.
..., ... connection line, 9,10.11.12...
...terminal, 13.14.15.16...connection line, 17.18,19.20...terminal, 21
, 22.23.24... Connection line, 101.
... Input terminal, 102.103 ... Combined output terminal, 104 ... Isolation terminal, 105, 106.107.108 ... Connection line agent Patent attorney Yoshihiro Hachiman $4 Figure (a) Surrounding tear relief ((3Hz) Cb) Figure 2

Claims (1)

[Claims] Connect one set of terminals provided at a 120 degree angle on the previous stage rat race ring to the 120 degree angle on the next stage rat race ring.
A combined rat race ring circuit in which a plurality of rat race rings are connected in series by connecting to a set of terminals provided at a degree angle, and the line impedance of each rat race ring is opposite to each other. The impedance values of the two lines are the same, but the impedance of the other pair of opposing lines adjacent to each other across the terminal has a common value that differs depending on the number of rat race rings connected, and A combined rat race ring circuit characterized in that the line length of each rat race ring is different depending on the different resonance frequencies given in advance to each rat race ring.