JP2009038499A - Phase shifter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase shifter of smaller size and lower loss. <P>SOLUTION: The phase shifter is provided with an inductor 3 wherein one end is connected to an input/output terminal 1 for inputting/outputting high frequency signals while the other end is connected to an input/output terminal 2 for inputting/outputting high frequency signals, and a capacitor 4 of which one end is connected to the input/output terminal 2. One end of a switch 5 is connected to the other end of the capacitor 4, and the other end of a switch 5 is connected to a ground 6. Thus, smaller size and lower loss are realized. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a phase shifter that can change the passing phase of a high-frequency signal.

For example, a conventional phase shifter disclosed in Non-Patent Document 1 is configured as follows.
(1) First, second and third high impedance lines are connected in series between a first input / output terminal for inputting / outputting a high frequency signal and a second input / output terminal for inputting / outputting a high frequency signal. To do.
(2) Connect the first, second and third both-end bridge type MEMS switches in parallel with the first, second and third high impedance lines.
(3) The first, second and third capacitors are connected between the first, second and third both-end supported bridge type MEMS switches and the ground.

In the conventional phase shifter, when the first, second and third both-end supported bridge type MEMS switches are in the OFF state, the high-frequency signal passing between the first input / output terminal and the second input / output terminal When the phase is set to the reference state and the phase of the high-frequency signal is changed, the first, second and third both-end bridge type MEMS switches are turned on.
When the first, second, and third both-end bridge type MEMS switches are turned on, the first, second, and third capacitors cause the first input / output terminal and the second input / output terminal to be connected. The phase of the high-frequency signal that passes through changes.

Andrea Borgioli "Low-Loss Distributed MEMS Phase Shifter" IEEE Microwave and Guided wave Letters, VOL10, No1, JAN 2000

Since the conventional phase shifter is configured as described above, if the ON / OFF state of the first, second, and third both-end bridge type MEMS switches is switched, the first input / output terminal and the second input / output terminal The phase of the high-frequency signal passing between the input / output terminals can be changed. However, when the dual-support bridge type MEMS switch is mounted, there is a problem that the size of the phase shifter increases.
If a cantilever structure switch is used instead of the double-supported bridge type MEMS switch, the size can be reduced. However, in order to drive the cantilever structure switch, it is necessary to mount a high resistance. In the high-frequency line, there is a problem that a loss of the phase shifter becomes large because a signal flows through a high resistance.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a phase shifter capable of realizing miniaturization and low loss.

  The phase shifter according to the present invention includes an inductor having one end connected to a first input / output terminal that inputs and outputs a high-frequency signal and the other end connected to a second input / output terminal that inputs and outputs a high-frequency signal; Is provided with a capacitor connected to the second input / output terminal, one end of the switch is connected to the other end of the capacitor, and the other end of the switch is connected to the ground.

  According to this invention, one end is connected to a first input / output terminal that inputs and outputs a high-frequency signal, the other end is connected to a second input / output terminal that inputs and outputs a high-frequency signal, and one end is a second. A capacitor connected to the I / O terminal is provided, and one end of the switch is connected to the other end of the capacitor, and the other end of the switch is connected to the ground, so that miniaturization and low loss can be realized. There is an effect that can.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a phase shifter according to Embodiment 1 of the present invention. In the figure, input / output terminal 1 is a terminal for inputting / outputting a high frequency signal, and input / output terminal 1 is a first input / output terminal. Is configured.
The input / output terminal 2 is a terminal for inputting / outputting a high frequency signal, and the input / output terminal 2 constitutes a second input / output terminal.
The inductor 3 has one end connected to the input / output terminal 1 and the other end connected to the input / output terminal 2.
One end of the capacitor 4 is connected to the input / output terminal 2.
The switch 5 has one end connected to the other end of the capacitor 4 and the other end connected to the ground 6.

FIG. 2 is an equivalent circuit showing a reference state of the phase shifter of FIG. 1, and FIG. 3 is an equivalent circuit showing a phase shift state of the phase shifter of FIG.
1 to 3, the normalized reactance of the inductor 3 is represented by X, and the normalized susceptance of the capacitor 4 is represented by B.

Next, the operation will be described.
When the switch 5 is in the OFF state, no high frequency signal flows through the capacitor 4, so the equivalent circuit of the phase shifter is a circuit as shown in FIG.
At this time, when a high-frequency signal is input from the input / output terminal 1, the high-frequency signal undergoes a phase shift due to the action of the inductor 3, and the high-frequency signal after the phase shift is output from the input / output terminal 2.

Hereinafter, this state is referred to as a “reference state”, and the reflection amplitude | S ₁₁ | of the high-frequency signal and the passing phase θ ₁ in this reference state are expressed by the following equations.

Next, when the switch 5 is in the ON state, a high-frequency signal also flows through the capacitor 4, so the equivalent circuit of the phase shifter is a circuit as shown in FIG.
At this time, when a high-frequency signal is input from the input / output terminal 1, the high-frequency signal undergoes phase shift due to the action of the inductor 3 and the capacitor 4, and the high-frequency signal after the phase shift is output from the input / output terminal 2. The

Hereinafter, this state is referred to as a “phase shift state”, and the reflection amplitude | S ₁₁ ′ | and the passing phase θ ₂ of the high-frequency signal in this phase shift state are expressed by the following equations.

Here, assuming that B · X << 1, the phase shift amount Δθ of the phase shifter is expressed as follows.

Therefore, by switching ON / OFF of the switch 5, the passing phases θ ₁ and θ ₂ of the high-frequency signal change, and the difference between the passing phases θ ₁ and θ ₂ is obtained as the phase shift amount Δθ of the phase shifter. I understand.
Further, if the condition of | S ₁₁ | = | S ₁₁ ′ | is imposed in order to reduce the reflection loss in the reference state and the phase shift state, the optimum normalized reactance X and The normalized susceptance B is given by the following equation.
X = B / 2 = tan θ

Hereinafter, a case where the required phase shift amount Δθ is “11.25 °” will be described as an example.
FIG. 4 is an explanatory diagram showing the relationship between the normalized reactance X and the normalized susceptance B when the phase shift amount Δθ is “11.25 °”.
In FIG. 4, the symbols “Δ” and “□” represent the reflection amplitudes in the reference state and the phase shift state.
The solid line represents the worst value of the reflection amplitude in both the reference state and the phase shift state, and the dotted line represents the normalized susceptance B for obtaining the required phase shift amount Δθ = 11.25 °. Yes.

As can be seen from FIG. 4, the reflection amplitude is minimized when X = 0.2.
Accordingly, by appropriately selecting the inductor 3 and the capacitor 4 and switching the ON / OFF of the switch 5, a small phase shifter with a small reflection loss that can obtain the required phase shift amount Δθ is configured.
In addition, since the other end of the switch 5 is connected to the ground 6, it is not necessary to mount a high resistance to drive the switch 5. Therefore, since no signal flows through the high resistance, the loss of the phase shifter does not increase.

  As apparent from the above, according to the first embodiment, one end of the inductor is connected to the input / output terminal 1 for inputting / outputting a high frequency signal, and the other end is connected to the input / output terminal 2 for inputting / outputting the high frequency signal. 3 and a capacitor 4 having one end connected to the input / output terminal 2, one end of the switch 5 is connected to the other end of the capacitor 4, and the other end of the switch 5 is connected to the ground 6. There is an effect that a reduction in size and a reduction in loss can be realized.

Embodiment 2. FIG.
5 is a block diagram showing a phase shifter according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG.
One end of the capacitor 11 is connected to the input / output terminal 1, and the capacitor 11 constitutes a first capacitor.
One end of the capacitor 12 is connected to the input / output terminal 2, and the capacitor 12 constitutes a second capacitor.
The switch 13 has one end connected to the other end of the capacitor 11 and the other end connected to the ground 15, and the switch 13 constitutes a first switch.
The switch 14 has one end connected to the other end of the capacitor 12 and the other end connected to the ground 16, and the switch 14 constitutes a second switch.

6 is an equivalent circuit showing a reference state of the phase shifter of FIG. 5, and FIG. 7 is an equivalent circuit showing a phase shift state of the phase shifter of FIG.
5 to 7, the normalized reactance of the inductor 3 is represented by X, and the normalized susceptance of the capacitors 11 and 12 is represented by B.

Next, the operation will be described.
When the switches 13 and 14 are in the OFF state, the high frequency signal does not flow to the capacitors 11 and 12, so the equivalent circuit of the phase shifter is a circuit as shown in FIG.
At this time, when a high-frequency signal is input from the input / output terminal 1, the high-frequency signal undergoes a phase shift due to the action of the inductor 3, and the high-frequency signal after the phase shift is output from the input / output terminal 2.

Hereinafter, this state is referred to as a “reference state”, and the reflection amplitude | S ₁₁ | of the high-frequency signal and the passing phase θ ₁ in this reference state are expressed by the following equations.

Next, when the switches 13 and 14 are in the ON state, a high-frequency signal also flows through the capacitors 11 and 12, so the equivalent circuit of the phase shifter is a circuit as shown in FIG.
At this time, when a high-frequency signal is input from the input / output terminal 1, the high-frequency signal undergoes a phase shift due to the action of the inductor 3 and the capacitors 11 and 12, and the high-frequency signal after the phase shift is transmitted from the input / output terminal 2. Is output.

Hereinafter, this state is referred to as a “phase shift state”, and the reflection amplitude | S ₁₁ ′ | and the passing phase θ ₂ of the high-frequency signal in this phase shift state are expressed by the following equations.

Here, assuming that B · X << 1, the phase shift amount Δθ of the phase shifter is expressed as follows.

Therefore, by switching ON / OFF of the switches 13 and 14, the passing phases θ ₁ and θ ₂ of the high-frequency signal change, and the difference between the passing phases θ ₁ and θ ₂ is obtained as the phase shift amount Δθ of the phase shifter. I understand that
Further, if the condition of | S ₁₁ | = | S ₁₁ ′ | is imposed in order to reduce the reflection loss in the reference state and the phase shift state, the optimum normalized reactance X and The normalized susceptance B is given by the following equation.
X = B = tan θ

Hereinafter, a case where the required phase shift amount Δθ is “22.5 °” will be described as an example.
FIG. 8 is an explanatory diagram showing the relationship between the normalized reactance X and the normalized susceptance B when the phase shift amount Δθ is “22.5 °”.
In FIG. 8, the symbols “Δ” and “□” represent the reflection amplitudes in the reference state and the phase shift state.
The solid line represents the worst value of the reflection amplitude in both the reference state and the phase shift state, and the dotted line represents the normalized susceptance B for obtaining the required phase shift amount Δθ = 22.5 °. Yes.

As can be seen from FIG. 8, the reflection amplitude is minimized when X = 0.4.
Therefore, by appropriately selecting the inductor 3 and the capacitors 11 and 12, by switching the switches 13 and 14 ON / OFF, a small phase shifter with a small reflection loss that can obtain the required phase shift amount Δθ is configured. The
Since the other ends of the switches 13 and 14 are connected to the grounds 15 and 16, it is not necessary to mount a high resistance in order to drive the switches 13 and 14. Therefore, since no signal flows through the high resistance, the loss of the phase shifter does not increase.

  As apparent from the above, according to the second embodiment, one end of the inductor is connected to the input / output terminal 1 for inputting / outputting a high frequency signal, and the other end is connected to the input / output terminal 2 for inputting / outputting the high frequency signal. 3, a capacitor 11 having one end connected to the input / output terminal 1, and a capacitor 12 having one end connected to the input / output terminal 2, and one ends of the switches 13, 14 are connected to the other ends of the capacitors 11, 12. Since the other ends of the switches 13 and 14 are connected to the grounds 15 and 16, it is possible to achieve a reduction in size and loss.

Embodiment 3 FIG.
FIG. 9 is a block diagram showing a phase shifter according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG.
As with the switch 5 of FIG. 1, the cantilever structure switch 20 has one end connected to the other end of the capacitor 4 and the other end connected to the ground 6.

FIG. 10 is a sectional view showing a cantilever structure switch 20 of a phase shifter according to Embodiment 3 of the present invention.
In the figure, a high frequency line 22 connected to the ground 6 and a high frequency line 23 connected to the capacitor 4 are formed on the substrate 21.
The high-frequency line 22 is formed with a cantilever beam 22 a, and a support end 22 b of the cantilever beam 22 a is supported by the substrate 21. A movable electrode 24 is provided at the free end 22c of the cantilever 22a.

The high-frequency line 23 is provided with a fixed electrode 25, and the fixed electrode 25 is disposed at a position facing the movable electrode 24.
The control power supply 27 controls the bending of the cantilever 22a by controlling the application of voltage to the control electrode 26 formed on the substrate 21, thereby connecting and disconnecting the movable electrode 24 and the fixed electrode 25. Perform the switching process.
The control means is composed of the control electrode 26 and the control power source 27.

Next, the operation will be described.
In the first embodiment, the switch 5 is connected between the capacitor 4 and the ground 6. However, the cantilever structure switch 20 may be used as the switch 5.
FIG. 9 shows that the cantilever structure switch 20 is used as the switch 5, but the cantilever structure switch 20 is used as the switches 13 and 14 in FIG. 5 in the second embodiment. May be.

When the cantilever structure switch 20 is turned on, the control power supply 27 applies a voltage to the control electrode 26.
As a result, electromagnetic force is generated from the control electrode 26 and the movable electrode 24 is attracted to the control electrode 26 with the cantilever 22a as a fulcrum, so that the movable electrode 24 comes into contact with the fixed electrode 25 and the cantilever structure The switch 20 is turned on.
Thus, when the cantilever beam structure switch 20 is turned on, the high frequency line 22 and the high frequency line 23 are connected, so that the capacitor 4 and the ground 6 are connected (see FIG. 3).
In addition, since the support end 22b of the cantilever 22a in the cantilever structure switch 20 is connected to the ground 6, it is not necessary to connect the cantilever structure switch 20 to the ground 6 through a high resistance, and low loss. The phase shifter can be realized.

On the other hand, when the cantilever structure switch 20 is turned off, the control power supply 27 removes the voltage applied to the control electrode 26.
As a result, the electromagnetic force of the control electrode 26 disappears, and the movable electrode 24 is not attracted from the control electrode 26, so that the contact between the movable electrode 24 and the fixed electrode 25 is released, and the cantilever structure switch 20 is turned off. become.
As described above, when the cantilever beam switch 20 is turned off, the high-frequency line 22 and the high-frequency line 23 are opened (see FIG. 2).

  As is apparent from the above, according to the third embodiment, the cantilever structure switch 20 is used as the switch 5, and the support end 22 b of the cantilever 22 a in the cantilever structure switch 20 is connected to the ground 6. Since it comprised as mentioned above, there exists an effect which can implement | achieve a low-loss phase shifter.

Embodiment 4 FIG.
FIG. 11 is a block diagram showing a phase shifter according to Embodiment 4 of the present invention. In the figure, the same reference numerals as those in FIG.
The capacitor switch 30 has one end connected to the input / output terminal 2 and the other end connected to the ground 6.

FIG. 12 is a plan view showing a capacitor switch 30 of a phase shifter according to Embodiment 4 of the present invention.
13 is an XX ′ sectional view of the capacitor switch 30 of FIG. 12, and FIG. 14 is a YY ′ sectional view of the capacitor switch 30 of FIG.
12 to 14, the same reference numerals as those in FIGS. 1 and 10 indicate the same or corresponding parts, and thus the description thereof is omitted.
The strip conductor 31 and the grounds 32 and 33 constitute a coplanar line.
However, FIG. 12 shows the strip conductor 31 constituting a coplanar line, but the strip conductor 31 may constitute a microstrip line.
The insulator 34 has one surface in contact with the strip conductor 31 and the other surface in contact with the fixed electrode 25.

Next, the operation will be described.
In the first embodiment, the switch 5 is connected between the capacitor 4 and the ground 6. However, the capacitor switch 30 may be used as the capacitor 4 and the switch 5.
11 shows the capacitor 4 and the switch 5 using the capacitor switch 30, but the capacitor 11 is used as the capacitors 11 and 12 and the switches 13 and 14 of FIG. 5 in the second embodiment. You may do it.

When the cantilever switch 20 of the capacitor switch 30 is turned on, the control power supply 27 applies a voltage to the control electrode 26 as in the third embodiment.
When the cantilever switch 20 is turned on, the fixed electrode 25 under the strip conductor 31 is electrically connected to the ground 33, so that the strip conductor 31, the insulator 34, and the fixed electrode 25 shunt the coplanar line. That is, the capacitor is formed.

On the other hand, when the cantilever switch 20 of the capacitor switch 30 is turned off, the voltage applied to the control electrode 26 by the control power supply 27 is removed as in the third embodiment.
When the cantilever structure switch 20 is turned off, the fixed electrode 25 under the strip conductor 31 is not electrically connected to the ground 33, so that the coplanar line is passed.

  As apparent from the above, by switching ON / OFF the cantilever structure switch 20 of the capacitor switch 30, the same operation as in the third embodiment can be obtained, and a low-loss phase shifter can be realized. There is an effect that can be done.

It is a block diagram which shows the phase shifter by Embodiment 1 of this invention. It is an equivalent circuit which shows the reference | standard state of the phase shifter of FIG. It is an equivalent circuit which shows the phase-shift state of the phase shifter of FIG. It is explanatory drawing which shows the relationship between the normalized reactance X and the normalized susceptance B when phase shift amount (DELTA) (theta) is "11.25 degrees." It is a block diagram which shows the phase shifter by Embodiment 2 of this invention. 6 is an equivalent circuit showing a reference state of the phase shifter of FIG. 5. It is an equivalent circuit which shows the phase-shift state of the phase shifter of FIG. It is explanatory drawing which shows the relationship between the normalized reactance X and the normalized susceptance B when the amount of phase shift Δθ is “22.5 °”. It is a block diagram which shows the phase shifter by Embodiment 3 of this invention. It is sectional drawing which shows the cantilever structure switch 20 of the phase shifter by Embodiment 3 of this invention. It is a block diagram which shows the phase shifter by Embodiment 4 of this invention. It is a top view which shows the capacitor switch 30 of the phase shifter by Embodiment 4 of this invention. It is X-X 'sectional drawing in the capacitor switch 30 of FIG. FIG. 13 is a Y-Y ′ sectional view of the capacitor switch 30 of FIG. 12.

Explanation of symbols

1 input / output terminal (first input / output terminal), 2 input / output terminal (second input / output terminal), 3 inductor, 4 capacitor, 5 switch, 6 ground, 11 capacitor (first capacitor), 12 capacitor ( Second capacitor), 13 switch (first switch), 14 switch (second switch), 20 cantilever switch, 21 substrate,
22, 23 High-frequency line, 22a Cantilever, 22b Support end, 22c Free end, 24 Movable electrode, 25 Fixed electrode, 26 Control electrode (control means), 27 Control power supply (control means), 30 Capacitor switch, 31 Strip conductor 32, 33 Ground, 34 Insulator.

Claims (5)

  An inductor having one end connected to a first input / output terminal that inputs and outputs a high-frequency signal and the other end connected to a second input / output terminal that inputs and outputs a high-frequency signal; and one end connected to the second input / output terminal A phase shifter comprising a connected capacitor and a switch having one end connected to the other end of the capacitor and the other end connected to the ground.   An inductor having one end connected to a first input / output terminal that inputs and outputs a high-frequency signal and the other end connected to a second input / output terminal that inputs and outputs a high-frequency signal; and one end connected to the first input / output terminal A first capacitor connected, a second capacitor having one end connected to the second input / output terminal, one end connected to the other end of the first capacitor, and the other end connected to the ground; A phase shifter comprising: a first switch; and a second switch having one end connected to the other end of the second capacitor and the other end connected to the ground.   The phase shifter according to claim 1 or 2, wherein a cantilever structure switch is used as a switch, and a support end of the cantilever beam in the cantilever structure switch is connected to a ground.   The cantilever structure switch includes a movable electrode provided at a free end of a cantilever whose supporting end is connected to the ground, a fixed electrode provided at a position facing the movable electrode, and the cantilever The control unit according to any one of claims 1 to 3, wherein the control unit switches between connection and non-connection between the movable electrode and the fixed electrode by controlling bending. Phase shifter.   5. A strip conductor constituting a coplanar line or a microstrip line, and an insulator having one surface in contact with the strip conductor and the other surface in contact with a fixed electrode. Phase shifter.

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