JPH0799457A - High frequency power switching device - Google Patents

Abstract

(57) [Abstract] [Purpose] In order to obtain a high-frequency power switching device that is compact and does not easily generate distortion, a microwave power switching switch is formed by a circulator so that reversal of the rotation direction in the circulator is not necessary at the time of switching. To do. [Arrangement] The impedance of the output section of the amplifier circuit connected to the connection port of the circulator is adjusted to be "0" when the amplifier circuit is in the inoperative state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave power switching device, and more particularly to a high frequency power switching device.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional device of this type, in which a high-frequency signal from an input terminal 1 is switched by an input changeover switch 2 to input the first amplifier circuit 3 or a second amplifier circuit. Is connected to the input terminal of the amplifier circuit 4. The outputs of these amplifier circuits 3 and 4 are switched by the output selector switch 10 and output through the output terminal 6. In the example described below, the amplifier circuit 3 is a microwave power amplifier circuit that outputs relatively high microwave power (provisionally referred to as high output power), and the amplifier circuit 4 is also a microwave power amplifier circuit, but its output is amplified. An output smaller than the output of the circuit 3 (provisionally referred to as medium output power) is output.

Input selector switch 2 and output selector switch 1
When the high frequency signal of the input terminal 1 is connected to the input terminal of the amplifier circuit 3, the output terminal of the amplifier circuit 3 is connected to the output terminal 6 via the output selector switch 10, Output power is output. When the high frequency signal of the input terminal 1 is connected to the input terminal of the amplifier circuit 4, the output terminal of the amplifier circuit 4 is connected to the output terminal 6 via the output changeover switch 10, and the medium output power is output. That is, the output power is switched by interlocking the input changeover switch 2 and the output changeover switch 10. Also,
Although not shown in the drawing, a power switch for cutting off the power of the amplifier circuit which is not operating is provided.

By the way, in the case of power amplification in the microwave band, a microwave power transmission path from the amplifier circuits 3 and 4 to the output selector switch 10 and a microwave power transmission path from the output selector switch 10 to the output terminal 6, etc. Are normally composed of distributed constant circuits, and the wave impedances of these distributed constant circuits are set to the same value. Assuming that the value of this impedance is Z, the amplifier circuits 3 and 4 are designed so that the maximum power is output when the impedance viewed from the output terminals of the amplifier circuits 3 and 4 is Z. This condition is achieved when a load of impedance Z is connected to the output terminal 6. Output terminal 6
Connect the antenna via a matching circuit (not shown) from
The antenna load viewed from the output terminal 6 is matched so as to be equal to Z.

However, the amplifier circuit 3 or 4 may operate in a state where the antenna is not connected, or in a state where the matching is insufficient even if the antenna is connected. Alternatively, there is a risk that a part of the electric power is reflected and the semiconductor of the amplifier circuit is damaged by the reflected power. In order to prevent such a danger, it is common to provide an isolator that blocks reflected power from entering the amplifier circuit. FIG. 5 is a block diagram showing an example in which an isolator is provided. In FIG.
The same reference numerals denote the same or corresponding parts, 8 is a terminating resistor, and 9 is an isolator circulator.

The circulator 9 has three connection ports A,
Equipped with B and C, input from connection port A is connection port B
And the input from the connection port B is output to the connection port C. Therefore, even if there is power reflected from the output terminal 6 and input to the connection port B due to load mismatch at the output terminal 6, this power is output from the connection port C and absorbed by the terminating resistor 8. , Does not enter the output changeover switch 10. The resistance value of the terminating resistor 8 is set equal to the wave impedance of the distributed constant circuit forming the circulator 9.

[0007]

In the conventional high frequency power switching device as described above, the structure of the output changeover switch 10 poses a problem. That is, if it is attempted to configure this switch by a mechanical changeover switch, it is necessary to prevent discontinuity in the microwave transmission line, resulting in a complicated and large structure. Further, when the semiconductor switch is used, there is a problem that a large distortion occurs in a high frequency waveform and an insertion loss also increases.

In order to solve such a problem, a prior art in which the output changeover switch is constituted by a circulator, Japanese Utility Model Application No. 61-35, which is disclosed in Japanese Utility Model Application Laid-Open No. 63-335333.
127819 "High-frequency switching circuit" (hereinafter referred to as prior art 1) and "Transmission section active standby switching device" disclosed in JP-A-63-208332 (hereinafter referred to as prior art 2).
There is). However, in both the above-mentioned Prior Art 1 and Prior Art 2, the rotation direction of the circulator is reversed at the time of switching, and when the rotation direction of the circulator is reversed, the structure of the circulator itself is complicated and the rotation direction of the circulator is also changed. The problem remains that the control mechanism for reversing is complicated.

The present invention has been made in order to solve the above problems and provides a high frequency power switching device in which the output changeover switch is constituted by a circulator, but which changes the rotation direction of the circulator without changing it. With the goal.

[0010]

A high frequency power switching device according to the present invention includes a first amplification circuit and a second amplification circuit for amplifying high frequency power, and a high frequency signal input from an input terminal to a first amplification circuit. An input selector switch that is connected by switching to the input terminal of the circuit or the input terminal of the second amplifier circuit;
It is composed of a distributed constant circuit and has three connection ports A, B and C. High frequency power input to the connection port A is output to the connection port B, and high frequency power input to the connection port B is connected to the connection port C. The circulator configured to output the high frequency power input to the connection port C to the connection port A, and connect the high frequency signal of the input terminal to the input of the second amplification circuit by the input selector switch The output circuit of the first amplifier circuit from the port A is characterized in that the impedance circuit is configured so that the impedance of the output circuit is sufficiently lower than the wave impedance of the distributed constant circuit. It is a thing.

The output of the first amplifier circuit is larger than the output of the second amplifier circuit.

Further, the impedance constituting means is designed so that the impedance of the output circuit when the first amplifier circuit is in the inoperative state is sufficiently lower than the wave impedance of the distributed constant circuit as seen from the connection port A. It is characterized by.

Further, the impedance forming means, when the input selector switch connects the high frequency signal of the input terminal to the input of the second amplifier circuit, the impedance seen from the connection port A by the switch interlocked with the input selector switch is a distributed constant. The output circuit of the first amplifier circuit is switched so as to be sufficiently smaller than the wave impedance of the circuit.

The load connected to the connection port B is
The resistance is the same as the wave impedance of the circulator.

Further, the first contact of the second changeover switch is connected to the connection port C of the circulator through a distributed constant circuit having the same wave impedance as that of the circulator, and the second changeover switch is connected. Operates in conjunction with the input selector switch, and when the input selector switch connects the high frequency signal at the input terminal to the input of the second amplifier circuit, connects the output of the second amplifier circuit to the first contact and When the changeover switch connects the high frequency signal of the input terminal to the input terminal of the first amplifier circuit, the terminating resistor is connected to the first contact.

Further, an isolator circulator is inserted between the connection port C of the circulator and the output of the first amplifying circuit, and the isolator circulator has three connection ports A, B, C. A
The high frequency power input to the connection port B is output to the connection port B, the high frequency power input to the connection port B is output to the connection port C, and the connection port A is connected to the output of the first amplifier circuit. A connection port C of the circulator according to the first aspect is connected to the connection port B, and a terminating resistor is connected to the connection port C of the circulator for the isolator.

[0017]

In the present invention, the rotation direction of the circulator having the connection ports A, B and C is A-B-C-A,
The output of the first amplifier circuit is connected to the connection port A,
If a load is connected to the connection port C and the output of the second amplification circuit is connected to the connection port C, the first amplification circuit is operated, and the second amplification circuit is deactivated, the output of the first amplification circuit is It is input from the connection port A and supplied to the load of the connection port B. Next, when the first amplifier circuit is made inoperative and the second amplifier circuit is operated, the output of the second amplifier circuit enters from the connection port C and is output to the connection port A. At this time, if the impedance looking at the output of the first amplifier circuit from the connection port A is set to a sufficiently low impedance, almost 100% of the power output from the connection port A is reflected and input to the connection port A again. Therefore, the electric power input to the connection port A is output from the connection port B. That is, the electric power from the connection port C comes to be output from the connection port B.

[0018]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a first embodiment of the present invention, in which the same reference numerals as those in FIG. 4 denote the same or corresponding parts.
Is a circulator used as an output changeover switch, equipped with connection ports A, B, C, and rotating in the direction of AB-
It is C-A. The output of the first amplifier circuit 3 is the connection port A
, The load is connected to the connection port B via the output terminal 6, and the output of the second amplifier circuit 4 is connected to the connection port C.

The operation of the first embodiment shown in FIG. 1 will be described below. When outputting the high output power which is the output of the first amplifier circuit 3, the high frequency signal of the input terminal 1 is connected to the input of the amplifier circuit 3 by the input changeover switch 2, and the amplifier circuit 3 is put into an operating state and amplified. The circuit 4 is made inoperative. The output of the amplifier circuit 3 is input from the connection port A, is output from the connection port B, and is input to the load (not shown) via the output terminal 6. Next, the high frequency signal of the input terminal 1 is connected to the input of the amplifier circuit 4 by the input changeover switch 2 to activate the amplifier circuit 4 and deactivate the amplifier circuit 3. The electric power input from the connection port C is output from the connection port A and enters the output side of the amplifier circuit 3. In this case, the output of the amplifier circuit 3 in the inoperative state is adjusted so that the impedance viewed from the connection port A becomes "0". With this adjustment, the power output from connection port A is 100%.
The reflected light returns to the connection port A and is input from the connection port A. The power input from the connection port A is output from the connection port B.

When the amplifier circuit 3 is in a non-operational state, the impedance viewed from the connection port A to the amplifier circuit 3 is set to "0". Therefore, a changeover switch (not shown) interlocked with the input changeover switch 2 when necessary. Can be used to switch the circuit constant of the output portion of the amplifier circuit 3.

In the prior arts 1 and 2 described above, when the amplifying circuit 4 is in the operating state and the amplifying circuit 3 is in the inoperative state, the rotation direction of the circulator 5 is reversed and the input of the connection port C is changed to the connection port. Although it is controlled to output to the B port, in the present invention, since the output of the connection port C is output to the connection port B without changing the rotation direction of the circulator 5, the device configuration and control can be made much simpler. . However, in the case of the present invention, since it goes through the path of C-A-B, there is an increase in the insertion loss of half the circumference of the circulator as compared with the case of reversing the rotation direction to form the path of C-B. Although the insertion loss will be added because the reflection at A cannot be 100%, the increase of the insertion loss to this extent does not pose a problem when it is used for switching for the purpose of medium output power.

In order to absorb the reflected power when the impedance of the load is not matched, the isolator circulator 9 shown in FIG. 5 can be inserted between the connection port B of the circulator 5 and the output terminal 6. It goes without saying that other circuit configurations are also possible for obtaining similar effects.

Example 2. 2 is a block diagram showing a second embodiment of the present invention. In FIG. 2, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions, 7 is a second changeover switch, and 8
Is a terminating resistor, but when the amplifier circuit 4 is in operation, the output of the amplifier circuit 4 is connected to the connection port C of the circulator 5 via the switch 7, and the circuit of FIG. 2 is similar to the circuit of FIG. When the amplifier circuit 3 operates, the connection port C of the circulator 5 is connected to the terminating resistor 8 via the switch 7, so that the power reflected from the output terminal 6 and input from the connection port B is It is output from C and absorbed by the terminating resistor 8.

Example 3. 3 is a block diagram showing a third embodiment of the present invention, and the same reference numerals as those in FIGS. 2 and 5 designate the same or corresponding parts. That is, the second changeover switch 7 of FIG.
Is replaced with an isolator circulator 9. The output of the amplifier circuit 4 is input from the connection port A of the circulator 9, is output to the connection port B, and is input to the connection port C of the circulator 5. Therefore, regarding the input power, the circuit of FIG. 3 is the same as the circuit of FIG. Become. The power reflected from the output terminal 6 and input to the connection port B of the circulator 5 is output from the connection port C of the circulator 5 through the connection port B of the circulator 9 and is absorbed by the terminating resistor 8. .

[0025]

As described above, according to the high-frequency power switching device of the present invention, the high-frequency power can be switched by the circulator without reversing the rotation direction in the circulator, which is small in size and less likely to cause distortion. There is an effect that an inexpensive device can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

FIG. 4 is a block diagram showing an example of a conventional device.

FIG. 5 is a block diagram showing another example of a conventional device.

[Explanation of symbols]

 1 Input Terminal 2 Input Selector Switch 3 First High Frequency Power Amplifier Circuit 4 Second High Frequency Power Amplifier Circuit 5 Circulator 6 Output Terminal 7 Second Selector Switch 8 Termination Resistor 9 Isolator Circulator

Claims (7)

[Claims] 1. A first amplifier circuit and a second amplifier circuit for amplifying high-frequency power, and a high-frequency signal input from an input terminal is used as an input terminal of the first amplifier circuit or an input terminal of the second amplifier circuit. It is composed of a distributed constant circuit and an input selector switch that connects and switches to, and has three connection ports A, B, and C. High-frequency power input to connection port A is output to connection port B and to connection port B. A circulator configured such that the input high-frequency power is output to the connection port C and the high-frequency power input to the connection port C is output to the connection port A. The input changeover switch outputs the high-frequency signal from the input terminal to the second terminal. When connecting to the input of the amplifier circuit, the impedance of the output circuit of the first amplifier circuit seen from the connection port A is higher than the wave impedance of the distributed constant circuit. A high-frequency power switching device, comprising: an impedance composing means for composing the output circuit so that the output circuit has a sufficiently low value. 2. The output of the first amplifier circuit is larger than the output of the second amplifier circuit.
The high frequency power switching device according to the item. 3. The impedance composing means ensures that the impedance seen from the connection port A of the output circuit when the first amplifier circuit is inactive is sufficiently lower than the wave impedance of the distributed constant circuit. The high frequency power switching device according to claim 1, wherein the high frequency power switching device is designed according to claim 1. 4. The impedance composing means is characterized in that the input changeover switch outputs the high frequency signal of the input terminal to the second terminal.
Of the first amplifier circuit so that the impedance seen from the connection port A becomes sufficiently smaller than the wave impedance of the distributed constant circuit by connecting with the input of the amplifier circuit. The high frequency power switching device according to claim 1, wherein the output circuit is switched. 5. The load connected to the connection port B is
The high frequency power switching device according to claim 1, wherein the circulator is a resistor having the same resistance value as the wave impedance of the circulator. 6. The first contact of the second changeover switch is connected to the connection port C of the circulator via a distributed constant circuit having the same wave impedance as the wave impedance of the circulator, and the second changeover switch is connected. The switch operates in conjunction with the input selector switch, and when the input selector switch connects the high frequency signal at the input terminal to the input of the second amplifier circuit, the output of the second amplifier circuit is changed to the first output. A terminating resistor is connected to the first contact when the input selector switch connects the high frequency signal of the input terminal to the input terminal of the first amplifier circuit. The high frequency power switching device according to item 1. 7. An isolator circulator is inserted between the connection port C of the circulator and the output of the first amplifier circuit, and the isolator circulator includes three connection ports A, B, and C. The high frequency power input to the connection port A is output to the connection port B, the high frequency power input to the connection port B is output to the connection port C, and the output of the first amplifier circuit is output to the connection port A. Is connected, and the connection port B is claimed in claim 1.
The high frequency power switching device according to claim 1, wherein a connection port C of the circulator according to the above item is connected, and a terminating resistor is connected to the connection port C of the circulator for an isolator.