JP3171915B2 - Monolithic microwave phase shifter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic microwave phase shifter constituted by a monolithic integrated circuit for controlling the phase of a microwave signal.

[0002]

2. Description of the Related Art As is well known, a microwave phase shifter controls a phase of a microwave signal input from an input terminal to a desired phase and transmits the signal to an output terminal, and is often used for a phased array antenna. Can be

FIG. 4 shows a configuration of a conventional microwave phase shifter. In the figure, a microstrip line 11 has a reference phase for an input microwave signal. The first FET 12 has a drain electrode connected to the input terminal 15, a source electrode connected to one end of the microstrip line 11, and a gate electrode connected to the first control terminal 19. The second FET 13 has a source electrode connected to the other end of the microstrip line 11, a drain electrode connected to the output terminal 16, and a gate electrode connected to the first control terminal 19. The third FET 14
The drain electrode is connected to the input terminal 15, the source electrode is connected to the output terminal 16, and the gate electrode is connected to the second control terminal 14.

That is, the FETs 12, 13, and 14 are used as switching elements, respectively, and the microstrip line 11 is used to determine the phase amount of a phase shifter. Now, a control voltage of 0 V is applied to the FETs 12 and 13 from the first control terminal 19, and a control voltage equal to or less than the pinch-off voltage is applied to the FET 14 from the second control terminal 20. At this time, the FETs 12 and 13 are turned on, and the FET 1
4 is turned off. Therefore, the microwave signal input from the input terminal 15 is
Will pass by the side. As a result, a reference state as a phase shifter is formed, and the FET 12,
A signal having a phase amount determined by the passing phase of the microstrip line 11 and the FET 13 is output.

On the other hand, a control voltage lower than the pinch-off voltage is applied to the FETs 12 and 13 from the first control terminal 19 to
A control voltage of 0 V is applied from the second control terminal 20 to T14. At this time, the FETs 12 and 13 are turned off,
The FET 14 is turned on. Therefore, input terminal 1
The microwave signal input from 5 passes through the FET 14 side. As a result, a phase shift state as a phase shifter is formed, and a signal having a passing phase of the FET 14 is output from the output terminal 16.

That is, by selectively switching the first and second control voltages applied to the FETs 12, 13, and 14, the reference state and the phase shift state can be switched, and a constant phase change is given to the microwave signal. be able to.

However, the conventional microwave phase shifter as described above is a line switching type, and the FETs 12, 13 and F
Since the same gate width is usually used for ET14,
When switching between T12 and T13 and the FET 14, impedance mismatch occurs between the FET and the external circuit due to the equivalent resistance of the FET in the ON state. For this reason, conventionally,
Good matching could not be achieved in both the reference state and the phase shift state, and the input / output VSWR characteristics could not be improved over a wide band. For this reason, it was difficult to realize a wideband microwave phase shifter with the above configuration.

Recently, gallium arsenide (GaAs) has been used.
Monolithic circuit with active elements such as FETs, resistors, capacitors, inductors, etc. formed on a semi-insulating substrate such as
Microwave integrated circuits have been put into practical use and are expected to develop in the future in order to reduce the size of microwave phase shifters.
In order to realize the phase shifter having the above configuration with this integrated circuit, FE
A matching circuit for the equivalent resistance in the ON state of T must be mounted outside the phase shifter circuit. For this reason, the overall chip size becomes large, and it can be said that the above configuration is not suitable as a phase shifter using a monolithic microwave integrated circuit.

[0009]

As described above, in the conventional line-switching type microwave phase shifter, the resistance of the FET used as a switch in the ON state is determined by the resistance.
The phase shifter circuit cannot be matched with the external circuit,
Output VSWR characteristics are degraded, and it is not possible to realize a wide band. If a matching circuit is provided outside the phase shifter circuit, when a phase shifter is formed by a monolithic / microwave integrated circuit, the chip size becomes large, and miniaturization cannot be realized.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has a good input / output VSWR over a wide band, and can realize a monolithic microwave integrated circuit with a small chip size. It is intended to provide a phase shifter.

[0011]

In order to achieve the above object, a monolithic microwave phase shifter according to the present invention comprises:
A microstrip line having a reference phase, one controlled electrode is connected to an input terminal, the other controlled electrode is connected to one end of the microstrip line, and a control electrode is connected to a first control terminal. A first switch element, one controlled electrode is connected to the other end of the microstrip line, the other controlled electrode is connected to an output terminal, and a control electrode is connected to the first control terminal. And a third switch in which one controlled electrode is connected to the input terminal, the other controlled electrode is connected to the output terminal, and the control electrode is connected to the second control terminal. An element, and first and second resistors respectively connected between the input terminal and the reference potential point and between the output terminal and the reference potential point, wherein the first and second switch elements are provided. In the on state Wherein the valence resistance was set to a substantially double the equivalent resistance in the on state of the third switch element.

[0012]

In the monolithic microwave phase shifter having the above configuration, in order to match the external circuit when each switch element is on, the first and second switch elements forming the reference state are simultaneously turned on. The equivalent resistance in the ON state of the third switch element forming the phase shift state is made equal to the series equivalent resistance, and the input terminal and the output terminal are grounded via the respective resistors, and the reference state and the phase shift state are set. In any case, the π-type circuit is formed by the equivalent resistance in the ON state of each switch element and the first and second resistances connected to the input side and the output side, thereby achieving impedance matching in both states and widening the bandwidth. In this manner, the input / output VSWR characteristics are improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. However, in FIG. 1, the same portions as those in FIG. 4 are denoted by the same reference numerals, and different portions will be mainly described here.

FIG. 1 shows an embodiment of a monolithic microwave phase shifter according to the present invention. In FIG. 1, resistors 17 and 18 are matching resistors. The other functions are the same as those in FIG. Resistors 17 and 18 are connected to FETs 12 and 1
3 or a resistor when the FET 14 is in an on state and a π-type matching circuit are formed.

FIG. 2A shows first and second FETs 12 and 1.
FIG. 2B shows a π-type matching circuit when the third FET 14 is turned on and the third FET 14 is turned on. In FIG. 2A, a resistor 31 is an equivalent resistance of the first FET 12 in an on state, and a resistor 32 is an equivalent resistance of the second FET 13 in an on state. Further, in FIG.
Reference numeral 3 denotes an equivalent resistance of the third FET 14 in an ON state.

The gate width of the FET 14 is approximately twice the gate width of the first and second FETs 12 and 13. In this case, the series resistance value of the resistance 31 and the resistance 32
3 can be made the same. Therefore, the resistors 17 and 18
Indicates that when the FETs 12 and 13 are turned on,
Even when 14 is turned on, it can be set so that matching can be obtained with an external circuit.

FIG. 3 shows the input / output VSWR characteristics of the monolithic microwave phase shifter having the above configuration in comparison with the characteristics of the conventional phase shifter. Note that the first and second FETs 12,
13 have a gate width of 1200 [micron], and the third FET 14 has a gate width of 600 [micron]. The resistances 17 and 18 are each 1 kΩ, and the phase shift through the phase shifter is 11.25 degrees. In the figure, the dotted line indicates the input / output VSWR when the matching circuit is not provided, and the solid line indicates the input / output VSWR when the matching circuit which is a feature of the present invention is provided. When the matching circuit is provided, it can be seen that the input and output VSWR values are reduced over a wide band in both the reference state and the phase shift state.

Therefore, the monolithic microwave phase shifter having the above configuration switches between the equivalent resistance in the ON state of the first and second FETs 12 and 13 used for forming the reference state and the microstrip line 11. In this case, the mismatch between the third FET 14 used to form the phase shift state and the external circuit due to the equivalent resistance in the ON state of the third FET 14 can be reduced, thereby improving the input / output VSWR characteristics over a wide band. Can be realized.
Moreover, since there is no need to provide a matching circuit outside the phase shifter circuit, the chip size can be reduced, and a wideband monolithic microwave phase shifter can be realized. It goes without saying that various modifications can be made without departing from the scope of the present invention.

[0019]

As described above, according to the present invention, there is provided a monolithic / microwave phase shifter which has a good input / output VSWR over a wide band and can realize a monolithic / microwave integrated circuit with a small chip size. Can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a monolithic microwave phase shifter according to the present invention.

FIG. 2 is an equivalent circuit diagram for explaining the operation of the embodiment.

FIG. 3 is a characteristic diagram showing characteristics of the monolithic microwave phase shifter of the embodiment in comparison with characteristics of a conventional phase shifter.

FIG. 4 is a circuit diagram showing a configuration of a conventional microwave phase shifter.

[Explanation of symbols]

11 ... microstrip line, 12,13,14 ... F
ET, 15: input terminal, 16: output terminal, 17, 18 ...
Resistance, 19, 20 ... control terminals.

Claims (2)

(57) [Claims] 1. A microstrip line having a reference phase, one controlled electrode is connected to an input terminal, the other controlled electrode is connected to one end of the microstrip line, and the control electrode is connected to a first electrode. A first switch element connected to the control terminal of the microstrip line, one controlled electrode is connected to the other end of the microstrip line, the other controlled electrode is connected to the output terminal, and the control electrode is connected to the first terminal. Connected to the control terminal of
Of a switching element, is connected to one of the control electrodes the input terminal is connected to the other of the control electrode and the output terminal, and a third switching element control electrode connected to the second control terminal And providing an ON signal to the first control terminal to provide the first and second control terminals.
The two switch elements are simultaneously turned on, and the second
To the control terminal of the third switch element
To an off state, and the marker is connected between the input terminal and the output terminal.
First connection state where only the cross trip line is connected
Providing an off signal to the first control terminal,
And the second switch element are simultaneously turned off,
An ON signal is supplied to a second control terminal to switch the third switch
The element is turned on, and from between the input terminal and the output terminal.
A second microstrip line that is separated and directly connected
To selectively switch the connection state of the
Of the microwave signal output from the output terminal
Line switching type monolithic microwave transfer
In the phaser, first and second resistors are connected between the input terminal and the reference potential point and between the output terminal and the reference potential point, respectively.
In the first connection state and the second connection state, respectively.
And a shape matching circuit is formed between the input terminal and the output terminal in the first connection state.
The input terminal and the output in the second connection state with an equivalent resistance.
Impedance in both states by equalizing the equivalent resistance between
A monolithic microwave phase shifter characterized by dance matching . 2. The first, second and third switch elements are field-effect transistors, and the gate width of each of the first and second switch element field-effect transistors is reduced by the electric field of the third switch element. By setting the gate width of the effect transistor to approximately twice the gate width , the first connection state can be reduced.
An equivalent resistance between the input terminal and the output terminal and the second contact;
And the equivalent resistance between the input terminal and the output terminal in the
2. The monolithic microwave phase shifter according to claim 1, wherein said phase shifters are equal .