JPH04288703A - Rat race with built-in absorption resistor and amplifier - Google Patents

Abstract

PURPOSE:To miniaturize the rat race used for distributing/synthesizing of the input/output of microwaves and the balanced amplifier using the rat race by providing isolation terminals and omitting the termination of these terminals concerning the rat race and the amplifier. CONSTITUTION:A transmission line between distributing terminals A and B of the rat race is disconnected, and this part is bridged by a resistor R. The value of the resistor R is made double as large as a characteristic impedance. In this case, the isolation terminals are provided and it is possible to omit the resistance termination of these terminals. This rat race is provided on the input side and/or output side of amplifier circuits 12 and 14 having equal characteristics, and the balanced amplifier is formed. Thus, the compact balanced amplifier can be presented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rat race used for distributing/combining microwave input/output and a balanced amplifier using the same. A strip line is often used as a small and lightweight microwave transmission line, and branch line type or rat race type hybrids (distributor/synthesizer) are examples of circuit elements that utilize this strip line. The present invention relates to this rat race.

0002

2. Description of the Related Art FIG. 5(a) shows a rat race. This is a hybrid with a 180 degree phase difference in which four input/output terminals A to D are provided on a 1.5 wavelength line (ring in the figure). All line characteristic impedances are √2Z0, terminal A~
The characteristic impedance of D is all Z0, terminals D and C, C
and A, and the line lengths between A and B are all λg/4, and the line length between terminals D and B is 3λg/4. The isolation (ISO), coupling degree, and VSWR characteristics of this rat race 10 are shown in FIG. 5(b). The horizontal axis of this figure is the normalized frequency f/
It is f0. As shown in the figure, when the normalized frequency is 1.0, the isolation from B to C is 50 dB or more,
The degree of coupling from B to C and from A to C is 3 dB, and the voltage standing wave ratio VSWR of terminal A is 1.0.

FIG. 6 shows a balanced amplifier using this rat race for input distribution and output synthesis. Reference numerals 12 and 14 denote amplifier circuits having almost the same characteristics; the input terminal of the amplifier circuit 12 is connected to the terminal 10 of the input rat race, the output terminal is connected to the terminal A of the output rat race 10b, and the input terminal of the amplifier circuit 14 is connected to the terminal A of the output rat race 10b. is connected to the terminal A of the input side rat race 10a, and the output end is connected to the terminal D of the output side rat race 10b. The microwave input enters terminal B of rat race 10a, and enters amplifier circuits 12 and 14 through distribution terminals A and D. The amplifier circuit goes into terminals A and D of rat race 10b, and the combined output goes to terminal B.
Output from Dummy loads 14 and 16 are connected to terminals C of rat races 10a and 10b.

0004

As shown in FIG. 6, when the rat race distributes power, an isolation terminal C or an input terminal B exists between the two ports A and D that output the distributed output. Note that the input/output terminal is not limited to B, and may be other terminals. For example, A may be used as an input terminal, and B and C may be used as distribution terminals, and in this case, D may be used as an isolation terminal.

If there is an isolation terminal between the distribution terminals, this terminal is grounded with a dummy load (if the characteristic impedance of the amplifier circuits 12 and 14 is exactly equal to the terminal impedance, this resistance termination is unnecessary, but in reality, this is not the case). (Instead, reflection occurs, so a resistive termination is necessary to absorb this.) When a balanced amplifier is constructed using a rat race as shown in Fig. 6, the amplifier circuit 12,
The dummy loads 14 and 16 are placed between the dummy loads 14 and 14, which hinders miniaturization of the circuit. If miniaturization is not possible, the wiring length becomes long, leading to performance disadvantages such as increased loss. The present invention aims to improve this point, and aims to make it possible to reduce the size by making it possible to omit providing an isolation terminal and terminating it with a resistor.

[0006]

Means for Solving the Problems As shown in FIG. 1, in the rat race of the present invention, the isolation terminal C is removed and a resistor R is inserted in its place. Similar to Figure 5, the characteristic impedance of terminals A, B, and D is approximately Z0 Ω, and between terminals A and B, B,
The characteristic impedance of the transmission line between D and between D and A is approximately √2Z0 Ω, and the length between A and B is λg/4, B
, D is 3λg/4, and between D and A is λg/2. The resistance value of the resistor R is about 2Z0 Ω, and it is inserted at the A side end of the transmission line between A and D in (a), and at the D side end of the transmission line in (c). Also(
In b), the resistor R is divided into two resistors having a resistance value of approximately Z0, and these resistors are inserted at both ends of the transmission line between A and D.

FIG. 2 shows a balanced amplifier constructed using this rat race. In (a), the amplifier circuit 12,1
Rat race 10a, 10 on both input side and output side of 4
In (c), a rat race is used only on the input side, and a conventional branch line type hybrid 18 is used on the output side. Also, in (b), the amplifier circuits 12 and 14
A rat race is used on the input side and output side of the , but the line connecting terminal A of the input side rat race and the input end of the amplifier circuit 14 is the line connecting the terminal D of the input side rat race and the input end of the amplifier circuit 12. λg/4 longer. Further, the line connecting the terminal A of the output side rat race 10b and the output end of the amplifier circuit 12 is longer by λg/4 than the line connecting the same terminal D and the output end of the amplifier circuit 14.

[0008]

[Operation] As shown in FIG. 1, in the present invention, the rat race isolation terminal C is omitted and the resistance termination of the terminal C is made unnecessary, so that the device can be miniaturized. The reason why inserting the resistor R can eliminate the isolation terminal and eliminate the need for a dummy load will be explained next with reference to FIG.

FIG. 3(a) shows the rat race of FIG.
Transmission lines l1, l2 between terminals BD, DC, CA, AB
The characteristic impedances of b, l2a, and l3 are all approximately Z0
, the line length is l2b, l2a, l3 is λg/4, l1
is 3λg/4. The characteristic impedance of terminals B, A, C, and D is Z0, and in this example, input is made from terminal B, and distributed output is produced at terminals A and D. At this time, terminal C
is an isolation terminal and is terminated with a resistor with a resistance value Z0.

FIG. 3(b) shows the terminals A, C, and D portions taken out. If the circuit in Fig. 3(b) is replaced with a circuit using an equivalent series resistance at the center frequency (equivalent conversion is performed so that the S parameter is the same), Fig. 3(c) to (e
)become. The line l2 consists of lines l2a and l2b, and has a resistance R
1, R4 resistance value is 2Z0 Ω, resistance R2 and R3
The resistance value of each is Z0 Ω. This figure 3(c)~
As is clear from (e), there is no isolation terminal C after equivalent conversion, and no resistor termination is required. The rat race in FIG. 2 corresponds to FIG. 3(e). Therefore, FIG. 3(c) or (d) may be used for the rat race of FIG. 2. Figure 1
(a) corresponds to FIG. 3(c), FIG. 1(b) corresponds to FIG. 3(d), and FIG. 1(c) corresponds to FIG. 3(e).

[0011]

EXAMPLE The rat race shown in FIG. 1 was formed on a Teflon (trade name) glass substrate having a thickness of 0.8 mm and a dielectric constant of 2.5. The pattern shown in FIG. 1 is formed by patterning the front conductor of the substrate, and the back conductor (not shown) of the substrate is left as is and serves as a ground conductor. That is, these constitute a microstrip line. The inner diameter Di of the ring-shaped portion was 7.6 mm, and the width W was 1.2 mm.

A chip resistor was used as the resistor R. Since the characteristic impedance Z0 is 50Ω, Fig. 1(a) and the same (
The resistance R in c) was 100Ω, and the resistance R in (b) was 50Ω. The characteristics of this rat race are shown in Figure 4. As shown in the figure, the center frequency is 11.7 GHz, and the distribution characteristic of inputting from port B and distributing to ports A and D is shown in Figure 4(a).
In addition, isolation between ports A and D and port A
, D is shown in FIG. 4(b). Figure 5 of conventional example
Compared to (b), the characteristics are almost unchanged. In other words, A
The reflection loss of D is slightly worse than the conventional example, and the reflection loss of D is slightly better.

If a chip resistor or the like is used for the dummy loads 14 and 16 in FIG. 6, the resistor itself will not become large, but this is because it is connected between the isolation terminal and the ground. , the connection process is troublesome. That is, for example, the surface conductor of the substrate (MIC substrate) is patterned to form a pad, this is connected to the ground conductor on the back side of the substrate through a through hole, and a resistor is connected between this pad and terminal C. This increases the required area and complicates the manufacturing process. In this respect, in the configuration shown in FIG. 1, the resistor R is simply mounted and fixed between the same surface patterns, so it does not take up much space and the installation work is simple and easy.

In FIG. 2(a), lines between terminals D, A of the rat race 10a and input terminals of the amplifier circuits 12, 14, and lines between terminals A, D of the rat race 10b and the amplifiers 12, 1
The characteristic impedance of the line between the output terminal of 4 is Z0
shall be. Further, the phase difference between the distribution terminals of the rat race type hybrid is 180°, and that of the branch line type hybrid is 90°. To make the rat race closer to that of the branch line, change the track length. Figure 2(b)
In this case, the input line length of the amplifier circuit 14 is made longer than that of the amplifier circuit 12 by λg/4, and the output line length of the amplifier circuit 12 is made longer than that of the amplifier circuit 14 by λg/4. In FIG. 2(b), the input impedance can be improved.

Since the resistor inserted into the rat race is small, its power capacity is not large. Therefore, if the hybrid on the output side is a normal branch line type hybrid as shown in FIG. 2(c) and the terminating resistor at the terminal G is externally attached, it can be adapted to the case of high output.

[0016]

As explained above, according to the present invention, it is possible to realize a rat race that does not require providing an isolation terminal and terminating it with a resistor. A balanced amplifier using this rat race is small and has low circuit loss, and can contribute to the realization of small, high-performance wireless devices.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a rat race of the present invention.

FIG. 2 is an explanatory diagram showing a balanced amplifier of the present invention.

FIG. 3 is an explanatory diagram of the principle of replacing a terminating resistor. FIG. 4 is a diagram showing the characteristics of the rat race of the present invention.

FIG. 5 is an explanatory diagram of a conventional rat race.

FIG. 6 is an explanatory diagram of a conventional balanced amplifier.

[Explanation of symbols]

A, B, D terminals R Resistance l1, l2, l3 track 12, 14 Amplifier circuit

Claims (4)

[Claims] Claim 1: First, second, and third terminals each having a characteristic impedance of approximately Z0 Ω, and each having a characteristic impedance of approximately √2Z0 Ω and lengths of approximately 3λg/4 and λg/, respectively.
2, the first, second and third transmission lines of λg/4 and (λg;
A first transmission line (l1) is connected between the first terminal (B) and the second terminal (D), and has a resistance (effective wavelength determined by the medium in which the transmission line is placed) and a resistance. terminal (B
) and the third terminal (A) between the third transmission line (l3)
is connected, and a series circuit of a second transmission line (l2) and a resistor (R) is connected between the second terminal (D) and the third terminal (A). Type rat race. [Claim 2] The total resistance value is approximately 2Z0,
2. The rat race with a built-in absorption resistor according to claim 1, wherein the rat race is connected as a single resistor or divided into two parts in series with the second transmission line between the second and third terminals. [Claim 3] First and second amplifier circuits (12, 14)
and a distributor (10a) that distributes the input to these amplifier circuits.
) and a synthesizer (10
b) and as a distributor and/or combiner for these,
A balanced amplifier characterized by using the rat race according to claim 1 or 2. 4. The first and second amplifier circuits have almost the same characteristics, and the line connecting the second and third terminals (D, A) of the rat race and the first and second amplifier circuits is 4. A balanced amplifier according to claim 3, wherein both have a characteristic impedance of Z0, and the latter has a line length longer by approximately λg/4.