JP2002280811A - Microwave circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave circuit with a plurality of degrees of coupling in the case of delivering part of signal power delivered through one transmission line to other transmission line depending on its degree of coupling. SOLUTION: Each input terminal of switches 15, 17 is connected to both ends of a 3rd transmission line 13 placed between 1st and 2nd transmission lines 11, 12 and one of output terminals of the respective switches is connected via resistors 16, 18 to ground and the other of the output terminals is connected directly to ground.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave circuit used for transferring a part of signal power transmitted through one transmission line to another transmission line coupled thereto.

[0002]

2. Description of the Related Art A conventional microwave circuit will be described with reference to FIG. 5 taking a directional coupler having a semi-reentrant structure as an example.

The length of a quarter of the propagation wavelength (λ) (hereinafter λ
/ 4) The first and second transmission lines 41 and 42 are provided in parallel at a predetermined interval. Two transmission lines 4
A third transmission line 43 floating by a length of λ / 4 is provided between the first and second transmission lines 41 and 4 between the first and second transmission lines 41 and 4.
2 is provided in parallel. A signal input terminal IN is connected to one end of the first transmission line 41, and the other end is grounded via a resistor 44 of, for example, 50 ohms. One end of the second transmission line 42 is grounded, and the other end is connected to the output terminal OUT.

In the above configuration, a part of the power of the microwave signal input from the input terminal IN is transmitted to the second transmission line 42 in accordance with the degree of coupling between the first transmission line 41 and the second transmission line 42. It is output to the transition output terminal OUT.

[0005]

The conventional microwave circuit is provided with a third transmission line 43 floating between the first and second two transmission lines 41 and 42.
The configuration is such that a large coupling amount can be obtained for the two transmission lines 41 and 42. However, the degree of coupling between the two transmission lines 41 and 42 is only one, and the degree of freedom of the coupling amount is limited.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks. When a part of signal power transmitted through one transmission line is transferred to another transmission line according to the degree of coupling, a plurality of coupling degrees can be obtained. It is an object of the present invention to provide a microwave circuit.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a transmission wavelength of four.
A first and a second transmission line disposed at a predetermined interval by a length of one-third, and a third and a third transmission line disposed between the first and second transmission lines by a length of a quarter of a propagation wavelength. A first switch circuit having an input end and first and second output ends, the input end of which is connected to one end of the third transmission line; End and first and second output terminals, the input terminal of which is the third terminal.
A second switch circuit connected to the other end of the transmission line,
A resistor having one end connected to the first output terminal of each of the first and second switch circuits is provided, and the other end of the resistor and the second output terminal of each of the first and second switch circuits are connected to each other. It is characterized by being grounded.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1 taking a directional coupler having a semi-reentrant structure as an example. First and second two transmission lines 11 and 12 are provided in parallel at a predetermined interval for a length of λ / 4. A third transmission line 13 having a length of λ / 4 is provided between the two transmission lines 11 and 12 in parallel with the two transmission lines 11 and 12. One end of the first transmission line 11 is connected to an input terminal IN to which a high-frequency signal such as a microwave is input,
The other end is grounded via a resistor 14 of, for example, 50 ohms. One end of the second transmission line 12 is grounded, and the other end is connected to the output terminal OUT.

One end of the third transmission line 13 is connected to a first switch circuit 15, for example, a one-input two-output switch circuit. The first switch circuit 15 has one input terminal 15
i and two output terminals 15 o 1 and 15 o 2, and the input terminal 15 i is connected to one end of the third transmission line 13. One output terminal 15o1 of the first switch circuit 15
Is grounded via a resistor 16 having a high resistance value which is substantially open at high frequencies, and the other output terminal 15o2 is grounded.

The other end of the third transmission line 13 is connected to a second switch circuit 17 having the same configuration as the first switch circuit 15, for example, a one-input two-output switch circuit. The second switch circuit 17 has one input terminal 17i and two output terminals 17o1 and 17o2, and the input terminal 17i is connected to the other end of the third transmission line 13. One output terminal 17o1 of the second switch circuit 17 is grounded via a resistor 18 having a high resistance value which is substantially open at a high frequency, and the other output terminal 17o2 is connected to ground.

The first switch circuit 15 and the second switch circuit 17 are connected to a control circuit 20.
, One of the two output terminals is connected to the input terminal in response to the control signal S output from the other.

In the above configuration, for example, the first switch circuit 15 and the second
Input terminals 15i, 17i of the switch circuit 17 are connected to the respective one output terminals 15o1, 17o1.

At this time, since the output terminals 15o1 and 17o1 are substantially open at a high frequency, the third transmission line 13 is in a floating state at a high frequency, forming a so-called ordinary semi-lentrant directional coupler. , First
And the degree of coupling between the second transmission lines 11 and 12 is, for example, α. Therefore, the microwave signal input from the input terminal IN is transmitted to the first transmission line 11 and the second transmission line 1.
Of the second transmission line 12 according to the degree of coupling α between
And output to the output terminal OUT.

Next, according to the control signal of the control circuit 20,
For example, the input terminals 15i and 17i of the first switch circuit 15 and the second switch circuit 17 are connected to the other output terminals 15o2 and 17o2, respectively.

At this time, both ends of the third transmission line 13 are grounded in terms of high frequency, and the degree of coupling between the first and second transmission lines 11 and 12 is, for example, β. Therefore, the microwave signal input from the input terminal IN is the first signal.
In accordance with the degree of coupling β between the transmission line 11 and the second transmission line 12, part of the power is transferred to the second transmission line 12 and output to the output terminal OUT.

According to the above-described configuration, the termination condition of the third transmission line 13 disposed between the first and second two transmission lines 11 and 12 to be coupled with a predetermined degree of coupling is set to, for example, a floating or ground state. Has been changed to. Thereby, the third transmission line 1 is provided between the two transmission lines 11 and 12.
With the same structure in which 3 are arranged, two bonding amounts can be obtained, and the usage is expanded accordingly.

Next, another embodiment of the present invention will be described with reference to FIG. 2, which shows an example in which the circuit configuration of FIG. In FIG. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals.

First and second two transmission lines 11, 1
2 are provided in parallel at a predetermined interval for the length of λ / 4.
A third transmission line 13 is provided between the two transmission lines 11 and 12.
Are provided in parallel with the two transmission lines 11 and 12 for the length of λ / 4.

One end of the first transmission line 11 is connected to an input terminal IN to which a high frequency signal such as a microwave is input, and the other end is grounded via a resistor 14 of, for example, 50 ohms. One end of the second transmission line 12 is grounded, and the other end is connected to the output terminal OUT. One end of the third transmission line 13 is connected to a first switch circuit 15 such as a one-input two-output switch circuit, and the other end is connected to a second switch circuit 17 such as a one-input two-output switch circuit.

The first switch circuit 15 is composed of, for example, two switches SW1 and SW2 composed of field effect transistors T1 and T2. The first switch circuit 15 has one input terminal 15i and two output terminals 15o1 and 15o2, and the input terminal 15i is connected to the third input terminal 15i.
It is connected to one end of the transmission line 13. One output terminal 15o1 of the first switch circuit 15 is grounded via a resistor 16 having a high resistance value which is substantially open at a high frequency, and the other output terminal 15o2 is grounded.

The second switch circuit 17 is, for example, similar to the first switch circuit 15, for example, a field-effect transistor T
3, two switches SW3, SW4, etc., which are configured by T4, have one input terminal 17i and two output terminals 17o1, 17o2, and the input terminal 17i is the third terminal.
It is connected to the other end of the transmission line 13. One output terminal 17o1 of the second switch circuit 17 is grounded via a resistor 18 having a high resistance value which is substantially open at a high frequency, and the other output terminal 17o2 is connected to ground.

The gates G1 to G4 of the field effect transistors T1 to T4 constituting the switches SW1 to SW4 are connected to a bias power supply 19, respectively. Bias power supply 1
Reference numeral 9 is connected to the control circuit 20, and applies a predetermined bias voltage to the gates G1 to G4 of the field effect transistors T1 to T4 according to the control signal S of the control circuit 20.

In the above configuration, under the control of the control circuit 20, the bias power supply 19 supplies the field-effect transistors T1,
A bias voltage of 0 V is applied to the gates G1 and G3 of T3, and the first switch SW1 and the third switch SW3 are simultaneously set to the conductive state. On the other hand, the field effect transistor T
2. Apply a bias voltage equal to or less than the pinch-off to the gates G2 and G4 of T4 to set the second switch SW2 and the fourth switch SW4 to the non-conductive state.

In this case, as shown in the sectional view of FIG. 3 taken along the line AA 'of FIG. 2, the third transmission line 13 sandwiched between the first and second two transmission lines 11 and 12 is shown. Are substantially open at both ends. Therefore, the third transmission line 13 is in a state of floating at a high frequency, and a so-called ordinary semi-lentrant directional coupler is formed.
And the degree of coupling between the second transmission lines 11 and 12 is α, for example.

The first to third transmission lines 11 to 13 are formed on a semi-insulating substrate 21 such as a GaAs substrate, and a grounding conductor 22 is provided on the back side of the semi-insulating substrate 21.

In the case of the above switch setting, the input terminal I
A part of the microwave signal input from N is transferred to the second transmission line 12 according to the coupling degree α between the first transmission line 11 and the second transmission line 12, and is output to the output terminal OUT.

Next, a bias voltage of 0 V is applied to the gates G2, G4 of the field effect transistors T2, T4,
The switch SW2 and the fourth switch SW4 are simultaneously turned on. On the other hand, the field effect transistors T1, T
A bias voltage equal to or less than the pinch-off is applied to the gates G1 and G3 of the first switch SW1 and the third switch SW3.
3 is set to a non-conductive state.

In this case, as shown in the cross-sectional view of FIG. 4 taken along the line AA ′ in FIG. 2, both ends of the third transmission line 13 are grounded at a high frequency by through holes 31 and the like. The degree of coupling between the first and second transmission lines 11 and 12 is, for example, β.

In the case of the above switch setting, the input terminal I
A part of the power of the microwave signal input from N is transferred to the second transmission line 12 according to the degree of coupling β between the first transmission line 11 and the second transmission line 12 and output to the output terminal OUT.

According to the above configuration, the termination condition of the third transmission line disposed between the first and second transmission lines coupled with a predetermined degree of coupling is changed to, for example, a floating or ground state. . As a result, two coupling amounts can be obtained with the same structure in which the third transmission line is disposed between the two transmission lines, and the application is expanded.

In the above embodiment, a resistor is connected to one output terminal of each switch circuit, and both ends of the third transmission line are set to an open state at a high frequency. However, the present invention can be applied to a configuration in which one output terminal of each switch circuit is simply opened without connecting a resistor.

[0032]

According to the present invention, when another transmission line is disposed between two transmission lines coupled with a predetermined degree of coupling,
A microwave circuit that can obtain two degrees of coupling between two transmission paths is realized.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram for explaining an embodiment of the present invention.

FIG. 2 is a schematic circuit diagram for explaining another embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view for explaining the operation of the present invention.

FIG. 4 is a schematic cross-sectional view for explaining the operation of the present invention.

FIG. 5 is a schematic circuit diagram for explaining a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... 1st transmission path 12 ... 2nd transmission path 13 ... 3rd transmission path 14 ... resistance 15 ... 1st switch circuit 15i ... input terminal of 1st switch circuit 15o1 ... 1st output terminal of 1st switch circuit 15o2: second output terminal of the first switch circuit 16: resistor 17: second switch circuit 17i: input terminal of the second switch circuit 17o1: first output terminal of the second switch circuit 17o2: second output of the second switch circuit End 18: Resistor 19: Bias circuit 20: Control circuit

Claims (6)

[Claims] A first transmission line and a second transmission line which are arranged at a predetermined interval by a length of a quarter of a propagation wavelength, and a transmission line having a length of four
A third transmission line disposed between the first and second transmission lines for a length of one-half, and having an input terminal and first and second output terminals. A first switch circuit having an input terminal connected to one end of the third transmission line, an input terminal and first and second output terminals, the input terminal of which is connected to the other end of the third transmission line; A second switch circuit connected thereto; and a resistor having one end connected to a first output terminal of each of the first and second switch circuits. The other end of the resistor and the first and second switch circuits are provided.
Wherein the second output terminal of each of the switch circuits is grounded. 2. A transmission line according to claim 1, wherein said first and second transmission lines are arranged at a predetermined interval corresponding to a quarter of the propagation wavelength.
A third transmission line disposed between the first and second transmission lines for a length of one-half, and having an input terminal and first and second output terminals. A first switch circuit having an input terminal connected to one end of the third transmission line, an input terminal and first and second output terminals, the input terminal of which is connected to the other end of the third transmission line; A second switch circuit connected to the first and second switch circuits.
A microwave circuit, wherein a first output terminal of each of the switch circuits is open and a second output terminal of each of the first and second switch circuits is grounded. 3. A first state in which the input terminals of the first and second switch circuits are connected to respective first output terminals, and the input terminal of the first and second switch circuits is connected to a respective second terminal. 3. The microwave circuit according to claim 1, further comprising a control circuit for switching to a second state connected to an output terminal of the microwave. 4. The device according to claim 1, wherein each of the first and second switch circuits has a field-effect transistor, and a bias power supply for applying bias voltages having different magnitudes to gate electrodes of the field-effect transistor is provided. Item 3. The microwave circuit according to Item 2. 5. A first transmission line and a second transmission line which are arranged at a predetermined interval by a length of a quarter of a propagation wavelength;
A microwave circuit comprising a third transmission line disposed between the first and second transmission lines for one-half the length, one side of which is connected to the input terminal via the first field-effect transistor And the other side is grounded via a resistor.
And a second terminal connected to the input terminal on one side via the second field-effect transistor and the other side grounded.
And a first switch circuit having an input terminal connected to one end of the third transmission line, and one end connected to a third switch circuit.
A first output terminal connected to the input terminal via a field effect transistor and the other side grounded via a resistor; and one side connected to the input terminal via a fourth field effect transistor and the other side grounded And a second switch circuit having an input terminal connected to the other end of the third transmission line and the first field effect transistor and the third field effect transistor. Or a state in which the conduction and non-conduction of the second field effect transistor and the fourth field effect transistor are controlled to either one of the non-conduction state and the conduction state or non-conduction state of the second field effect transistor and the third field effect transistor. And a control circuit for controlling the microwave circuit. 6. A first transmission line and a second transmission line which are arranged at a predetermined interval by a length of a quarter of a propagation wavelength,
A microwave circuit comprising a third transmission line disposed between the first and second transmission lines for one-half the length, one side of which is connected to the input terminal via the first field-effect transistor A first output terminal whose other side is open, and a second output terminal whose one side is connected to the input terminal via the second field effect transistor and whose other side is grounded, and whose input terminal is A first switch circuit connected to one end of the third transmission line, a first output terminal connected on one side to an input terminal via a third field-effect transistor and open on the other side; and Has a second output terminal connected to an input terminal via a fourth field-effect transistor and the other side grounded, and has a second output terminal connected to the other end of the third transmission line. A switch circuit;
The field-effect transistor and the third field-effect transistor are simultaneously controlled to be either conductive or non-conductive, and the second field-effect transistor and the fourth field-effect transistor are controlled to be conductive or non-conductive by the first field-effect transistor.
A microwave circuit comprising: a field effect transistor; and a control circuit for controlling a state opposite to that of the third field effect transistor.