WO2025225104A1 - Phase shifter - Google Patents

Abstract

In a variable-reactance element (3) of a phase shifter (1), inductors (L1 to L4) are connected in parallel to capacitors (C1 to C4). First switches (Q11 to Q14) connect or disconnect the capacitors (C1 to C4) and a 90-degree hybrid coupler (2). Second switches (Q21 to Q24) connect or disconnect the inductors (L1 to L4) and the 90-degree hybrid coupler (2). A control unit (4) can switch between a first state in which at least one of the capacitors (C1 to C4) is in a connected state and all of the inductors (L1 to L4) are in a disconnected state, and a second state in which all of the capacitors (C1 to C4) are in a disconnected state and at least one of the inductors (L1 to L4) is in a connected state.

Description

phase shifter

The present invention relates to a phase shifter.

Phase shifters that use variable reactance elements for use in microwave circuits are known. Known variable reactance elements include variable capacitors such as variable capacitors, varicaps, and varactor diodes (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 09-074325

When a phase shifter is used at high frequencies, the phase width can become small and losses can become large. Therefore, in order to reduce losses in the phase shifter, a variable capacitor with a larger variable range of reactance (1/2πfc) is required.

However, the variable reactance range of the variable capacitor is limited to the positive side of a phase shift of 0° (no phase shift). As a result, the variable phase range of the phase shifter cannot be made sufficiently wide.

The object of the present invention is to provide a phase shifter with a wide phase variable range.

The phase shifter of the present invention comprises a 90-degree hybrid coupler, a first reactance element, a second reactance element, and a control unit. The 90-degree hybrid coupler has an input terminal, an output terminal, a first reflection terminal, and a second reflection terminal. The first reactance element is connected to the first reflection terminal. The second reactance element is connected to the second reflection terminal. The control unit controls the first reactance element and the second reactance element. Each of the first reactance element and the second reactance element has at least one capacitor, at least one inductor, a first switch, and a second switch. The at least one inductor is connected in parallel to the at least one capacitor. The at least one first switch connects or disconnects the at least one capacitor and the 90-degree hybrid coupler. The at least one second switch connects or disconnects the at least one inductor and the 90-degree hybrid coupler. The control unit is capable of controlling the at least one first switch and the at least one second switch. The control unit is capable of switching between a first state in which at least one capacitor is connected and all of at least one inductor is disconnected, and a second state in which all of at least one capacitor is disconnected and at least one inductor is connected. The control unit transfers a signal input to the input terminal and outputs it from the output terminal.

The phase shifter of the present invention has a wide phase variable range.

FIG. 2 is a circuit diagram of a phase shifter according to the first embodiment. FIG. 2 is a circuit diagram of a first variable reactance element or a second variable reactance element of a phase shifter. 10 is a graph showing a change in the amount of phase shift with respect to a change in normalized characteristic impedance in the first variable reactance element or the second variable reactance element. 10 is a graph showing the magnitudes of S11 and S21 of the capacitor of the first variable reactance element or the second variable reactance element in the phase shifter according to the second embodiment. 10 is a graph showing the magnitudes of S11 and S21 of the inductor of the first variable reactance element or the second variable reactance element. FIG. 11 is an equivalent circuit diagram of a variable inductor in a phase shifter according to a third embodiment. 10 is a graph showing changes in the real part and the imaginary part of the complex permeability of an inductor with respect to frequency in a phase shifter according to a fourth embodiment. FIG. 11 is a circuit diagram of a phase shifter according to a fifth embodiment.

The first embodiment of the present invention will now be described with reference to the accompanying drawings. Note that the same or equivalent parts in each drawing will be designated by the same reference numerals.

1. First Embodiment (1) Schematic Configuration of Phase Shifter A phase shifter 1 according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a circuit diagram of the phase shifter according to the first embodiment.
The phase shifter 1 is a device that shifts the phase of an RF output signal relative to an RF input signal.

The phase shifter 1 mainly comprises a 90-degree hybrid coupler 2, a pair of variable reactance elements 3 (3A, 3B), and a control unit 4.

The 90-degree hybrid coupler 2 includes an input terminal RF_IN, an output terminal RF_OUT, a first reflection terminal 7_OUT, a second reflection terminal 8_OUT, a first line 5 and a second line 6 which are quarter-wavelength lines with a characteristic impedance of _Z0 , and a third line 7 and a fourth line 8 which are quarter-wavelength lines with a characteristic impedance of _Z0 /√2. One end of the first line 5 is connected to the input terminal RF_IN, and the other end of the first line 5 is connected to the output terminal RF_OUT. One end of the second line 6 is connected to the first reflection terminal 7_OUT, and the other end of the second line 6 is connected to the second reflection terminal 8_OUT. One end of the third line 7 is connected to the input terminal RF_IN, and the other end of the third line 7 is connected to the first reflection terminal 7_OUT. One end of the fourth line 8 is connected to the output terminal RF_OUT, and the other end of the fourth line 8 is connected to the second reflection terminal 8_OUT. The 90-degree hybrid coupler 2 is a circuit that divides and combines an RF input signal.

The first variable reactance element 3A and the second variable reactance element 3B are elements whose reactance changes. The first variable reactance element 3A and the second variable reactance element 3B of the variable reactance element 3 are connected to the first reflection terminal 7_OUT and the second reflection terminal 8_OUT, respectively.

In the 90-degree hybrid coupler 2, the RF signal input from the input terminal RF_IN is distributed among the first line 5, second line 6, third line 7, and fourth line 8, and transmitted to the first reflection terminal 7_OUT and second reflection terminal 8_OUT. Because the first reflection terminal 7_OUT and the second reflection terminal 8_OUT are terminated by the variable reactance element 3 (3A, 3B), the transmitted signal is reflected with a phase change that depends on the reactance of the variable reactance element 3 (3A, 3B). The reflected signal is recombined among the first line 5, second line 6, third line 7, and fourth line 8, and output from the output terminal RF_OUT. At this time, the output signal undergoes a phase change that depends on the reactance of the variable reactance element 3 (3A, 3B), and by changing the reactance of the variable reactance element 3 (3A, 3B), it operates as a phase shift circuit.

(2) Variable Reactance Element The first variable reactance element 3A and the second variable reactance element 3B have the same structure, and therefore, hereinafter, both will be described as the variable reactance element 3.

The variable reactance element 3 will be explained using Figure 2. Figure 2 is a circuit diagram of the first variable reactance element or the second variable reactance element of the phase shifter.

As shown in Figure 2, the variable reactance element 3 is connected to ground G. Ground G refers to a reference conductive part having a reference potential, or refers to the reference potential itself. The reference potential is, for example, 0 V (zero volts). The reference conductive part may be formed using a conductor such as metal.

The variable reactance element 3 has multiple (four in this embodiment) variable capacitors 11 (first to fourth variable capacitors 11A to 11D) connected in parallel, and multiple (four in this embodiment) variable inductors 12 (first to fourth variable inductors 12A to 12D).

The first variable capacitor 11A has a first switch Q11 and a capacitor C1 connected in series. The second variable capacitor 11B has a first switch Q12 and a capacitor C2 connected in series. The third variable capacitor 11C has a first switch Q13 and a capacitor C3 connected in series. The fourth variable capacitor 11D has a first switch Q14 and a capacitor C4 connected in series. The capacitances of the capacitors C1 to C4 are different from one another, and increase in the order of capacitors C1, C2, C3, and C4. The first switches Q11 to Q14 are switching elements such as FETs (Field Effect Transistors). The first switches Q11 to Q14 can be switched between two states, on or off, independently of one another. This allows the variable capacitor 11 to be switched between two values: a first value which is the capacitance of capacitors C1 to C4 (a state in which at least one of the first switches Q11 to Q14 is on, thereby connecting the variable capacitor 11 to the 90-degree hybrid coupler 2), or a second value in which the capacitance is 0 (a state in which the first switches Q11 to Q14 are off, thereby disconnecting the variable capacitor 11 from the 90-degree hybrid coupler 2).

The first variable inductor 12A has a second switch Q21 and an inductor L1 connected in series. The second variable inductor 12B has a second switch Q22 and an inductor L2 connected in series. The third variable inductor 12C has a second switch Q23 and an inductor L3 connected in series. The fourth variable inductor 12D has a second switch Q24 and an inductor L4 connected in series. The inductances of inductors L1 to L4 are different from one another and increase in the order of L1, L2, L3, and L4. The second switches Q21 to Q24 are switching elements such as FETs (Field Effect Transistors). The second switches Q21 to Q24 can be switched between two states, on or off, independently of one another. This allows the variable inductor 12 to be switched between two values: a first value which is the inductance of inductors L1 to L4 (a state in which at least one of the second switches Q21 to Q24 is on and the variable inductor 12 is connected to the 90-degree hybrid coupler 2), and a second value in which the inductance is zero (a state in which all of the second switches Q21 to Q24 are off and the variable inductor 12 is disconnected from the 90-degree hybrid coupler 2).

(3) Control Configuration The control unit 4 changes the gate voltages applied to the first switches Q11 to Q14 and the second switches Q21 to Q24, thereby switching the first switches Q11 to Q14 and the second switches Q21 to Q24 between two states: on and off. As a result, the variable reactance element 3 switches the impedance with respect to the RF signal. As a result, the reflection coefficients seen from the first reflection terminal 7_OUT and the second reflection terminal 8_OUT change, causing the phase shifter 1 to change the phase of the RF signal.

The control unit 4 is a computer system having a processor (e.g., a CPU), a storage device (e.g., a ROM, RAM, HDD, SSD, etc.), and various interfaces (e.g., an A/D converter, a D/A converter, a communication interface, etc.). The control unit 4 performs various control operations by executing programs stored in the storage unit (corresponding to part or all of the storage area of the storage device).

(4) Operation (4-1) Switching Between Connection and Disconnection of Variable Capacitor and Variable Inductor The state switching operation of the variable reactance element 3 by the control unit 4 will be described. When a gate voltage is applied to the first switches Q11 to Q14 and the second switches Q21 to Q24 in response to a command from the control unit 4 (when the gate voltage reaches or exceeds the threshold voltage level), the variable capacitor 11 and the variable inductor 12 enter a connected state. When the gate voltage to the first switches Q11 to Q14 and the second switches Q21 to Q24 is released in response to a command from the control unit 4 (when the gate voltage falls below the threshold voltage level), the variable capacitor 11 and the variable inductor 12 enter a disconnected state.

(4-2) State Switching of Variable Reactance Elements The change in the amount of phase shift when the state of the variable reactance element 3 (3A, 3B) is switched will be described using Figures 2 and 3. Figure 3 is a graph showing the change in the amount of phase shift with respect to the change in normalized characteristic impedance in the first variable reactance element or the second variable reactance element. In Figure 3, as an example, L is in the range of 0.06 nH to 28 nH (e.g., L1 = 0.06 nH, L4 = 28 nH in Figure 2), C is 0.1 pF to 22 pF (e.g., C1 = 0.1 pF, C4 = 22 pF), and the frequency is 5.8 GHz.

The control unit 4 can switch the variable reactance element 3 between the following three states.
In the first state (capacitance state), only one of the first to fourth variable capacitors 11A to 11D is in a connected state, and all of the first to fourth variable inductors 12A to 12D are in a disconnected state. In this case, the reactance of one of the capacitors C1, C2, C3, and C4 that is in a connected state becomes the reactance of the variable reactance element 3. If a state in which there is no phase shift is defined as a phase shift amount of 0°, then in this case the phase shift amount becomes positive.

In the second state (inductance state), all of the first to fourth variable capacitors 11A to 11D are disconnected, and one of the first to fourth variable inductors 12A to 12D is connected. In this case, the reactance of one of the inductors L1, L2, L3, and L4 that is connected becomes the reactance of the variable reactance element 3. If a state with no phase shift is considered to have a phase shift amount of 0°, then in this case the phase shift amount is negative.

In the third state (state without phase shift control), all of the first to fourth variable capacitors 11A to 11D are disconnected, and all of the first to fourth variable inductors 12A to 12D are disconnected. In this state, no phase shift control is performed.

In this embodiment, by using the variable reactance element 3 (3A, 3B) as described above, its susceptance can be varied from -∞ to ∞, at which point the phase shifter 1's phase change amount is 360 degrees. In other words, by using the first to fourth variable capacitors 11A to 11D and the first to fourth variable inductors 12A to 12D, each with a finite variable range, a phase shift circuit that provides a 360-degree phase change amount in one stage can be realized.

As shown in Figure 3, the capacitances of capacitors C1 to C4 and inductors L1 to L4 are all set to values that do not result in a signal phase shift of 0° or a predetermined range near 0°, the predetermined range being -5° to +5°. As a result, resonance near the phase shift of 0° in phase shifter 1 can be suppressed, thereby reducing losses.

(5) Effects A number of effects of this embodiment will be described below. These effects may be obtained individually or in combination.

As mentioned above, the capacitor and inductor are selectively connected. Specifically, when setting the phase shift amount, only one capacitor or one inductor is selected. Between the first state in which the capacitor is connected and the second state in which the inductor is connected, the phase can be shifted to the opposite side of the 0° phase shift amount. In other words, not only can the capacitance be varied, but the inductance can also be varied, allowing the reactance to be varied over a wide range, from capacitive (1/2πfc) to inductive (2πfL). This makes it possible to widen the variable range of the reactance (1/2πfc + 2πfL). As a result, a low-loss, high-frequency (RF) phase shifter with a large phase shift range can be realized, for example, a phase shift of 360°.

In the variable reactance element 3 (3A, 3B), the first to fourth variable capacitors 11A to 11D and the first to fourth variable inductors 12A to 12D are configured in a single stage. In other words, the first to fourth variable capacitors 11A to 11D and the first to fourth variable inductors 12A to 12D are not connected in series with other variable reactance elements, but are connected to ground G. As a result, the phase shifter 1 has low loss and can be reduced in size. Previously, it was not possible to achieve a 360° phase shift without using a multi-stage configuration or a configuration using resonance, for example. This resulted in problems such as increased loss in the phase shifter and a large size.

2. Second Embodiment A second embodiment will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a graph showing the magnitudes of S11 and S21 of the capacitor of the first variable reactance element or the second variable reactance element in a phase shifter according to the second embodiment. Fig. 5 is a graph showing the magnitudes of S11 and S21 of the inductor of the first variable reactance element or the second variable reactance element.

Figure 4 shows the changes in S11 (reflection coefficient) and S21 (transmission coefficient) relative to the capacitance of the capacitors in phase shifter 1. As is clear from the figure, the S parameters of capacitors C1 to C4 are S21 > S11. This relationship is maintained even if the capacitance of capacitors C1 to C4 changes. By maintaining this relationship, the phase shifter can achieve a more appropriate phase shift. The difference between S21 and S11 is preferably in the range of 80 to 95°, and even more preferably in the range of 85 to 95°.

Figure 5 shows the changes in S11 and S21 with respect to the inductance of the inductors. In the S parameters of inductors L1 and L2, S11 > S21. Even if the capacitance of inductors L1 to L4 changes, the relationship S11 > S21 is maintained. By maintaining this relationship, the phase shifter can achieve a more appropriate phase shift amount. The difference between S11 and S21 is preferably in the range of 80 to 95 degrees, and more preferably in the range of 85 to 95 degrees.
With the above configuration, the phase width of the phase shifter 1 can be ensured to be wide.

3. Third Embodiment A third embodiment will be described with reference to Fig. 6. Fig. 6 is an equivalent circuit diagram of a variable inductor in a phase shifter according to the third embodiment.

In Figure 6, the first variable inductor 12A is shown. Specifically, the second switch Q21 is shown in an equivalent circuit and consists of a resistance R and a parasitic capacitance C.

In this embodiment, when the second switch Q21 is in a connected state, current flows on the second switch Q21 side of the inductor L5, and no current or a small amount of current flows on the side of the inductor L5 opposite the second switch Q21.

The current flowing on the side of inductor L1 opposite to second switch Q21 is preferably 0 to 50% of the current flowing on the second switch Q21 side of inductor L1, and more preferably 1 to 10%.

As a result, the loss in inductor L1 can be reduced, which in turn reduces the loss as a reflective phase shifter. This allows the inductor to be made smaller. Note that the above configuration can also be applied to the second to fourth variable inductors 12B to 12D.

4. Fourth Embodiment A fourth embodiment will be described with reference to Fig. 7. Fig. 7 is a graph showing changes in the real part and imaginary part of the complex permeability of an inductor with respect to frequency in a phase shifter according to the fourth embodiment.
The fourth embodiment is based on the configuration and operation of the first, second or third embodiment, and further restricts other configurations.

Figure 7 shows the changes in the real part (μ') and imaginary part (μ'') of the complex permeability of the inductance with changes in frequency. As is clear from the figure, in the low-frequency region there is a first frequency region 101 where the real part is larger than the imaginary part. In the high-frequency region there is a second frequency region 102 where the imaginary part is larger than the real part.

As shown in Figure 7, the self-resonant frequency SRF of the inductor of phase shifter 1 falls outside drive frequency range A. Drive frequency range A is the frequency range between 0.9 x (c/λ) and 1.1 x (c/λ). c is the speed of light, measured in m/sec. λ is measured in m. The center frequency of drive frequency range A is (c/λ). Therefore, in drive frequency range A, the ideal impedance state can be achieved in phase shifter 1, resulting in a stable reduction in loss.

Furthermore, at least one of the real and imaginary parts of the inductor's complex permeability is set so that the amount of change is 10% or less in drive frequency range A. This makes it possible to achieve the ideal impedance state for a reflective phase shifter, and consistently reduces losses in drive frequency range A.

Furthermore, in the second frequency domain 102, the imaginary part of the complex permeability has at least a portion of a value greater than the maximum value of the real part of the complex permeability in the first frequency domain 101. As a result, it is possible to suppress the decrease in the amount of phase shift at high frequencies above 3 GHz.

5. Fifth Embodiment In the first embodiment, the variable reactance element includes a plurality of variable capacitors and a plurality of variable inductors. However, the variable reactance element may include one variable capacitor and one variable inductor, and the two may be selected alternatively.

Such an example will be described as the fifth embodiment using Figure 8. Figure 8 is a circuit diagram of a phase shifter according to the fifth embodiment.

As shown in FIG. 8, the variable reactance element 3E has one variable capacitor 11E and one variable inductor 12E connected in parallel.

The variable capacitor 11E has a first switch Q15 and a capacitor C5 connected in series.

The variable inductor 12E has a second switch Q25 and an inductor L5 connected in series.

The control unit can switch the variable reactance element 3E between the following three states.
In the first state (capacitance state), the variable capacitor 11E is connected and the variable inductor 12E is disconnected. In this case, the reactance of the variable capacitor 11E becomes the reactance of the variable reactance element 3E. If a state without phase shift is defined as a phase shift amount of 0°, in this case the phase shift amount is positive.

In the second state (inductance state), variable capacitor 11E is disconnected and variable inductor 12E is connected. In this case, the reactance of variable inductor 12E becomes the reactance of variable reactance element 3E. If a state with no phase shift is considered to have a phase shift amount of 0°, then in this case the phase shift amount is negative.

In the third state (state without phase shift control), the variable capacitor 11E is off and the variable inductor 12E is off. In this state, no phase shift control is being performed.

6. Sixth Embodiment In the first to fifth embodiments, among the plurality of capacitors and the plurality of inductors, only one capacitor or only one inductor is in a connected state.

In other embodiments, multiple capacitors or multiple inductors may be connected. In this case, the multiple capacitors may include two or more capacitors with the same capacitance, and the multiple inductors may include two or more inductors with the same inductance.

In this embodiment, multiple capacitors are connected simultaneously, allowing for finer phase shifts depending on the combination. In addition, in this embodiment, multiple inductors are connected simultaneously, allowing for finer phase shifts depending on the combination.

7. Modifications Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes and modifications are possible.

The number of variable capacitors and variable inductors in the variable reactance elements is not limited to the above embodiment.

The number of variable capacitors and the number of variable inductors may be different.

1 Phase shifter 2 90-degree hybrid coupler 3 Variable reactance element 3A First variable reactance element 3B Second variable reactance element 11 Variable capacitor 11A First variable inductor 11B Second variable inductor 11C Third variable inductor 11D Fourth variable inductor 12 Variable inductor 12A First variable inductor 12B Second variable inductor 12C Third variable inductor 12D Fourth variable inductor Q1 First switch Q2 Second switch

Claims (9)

a 90-degree hybrid coupler having an input terminal, an output terminal, a first reflecting terminal, and a second reflecting terminal;
a first variable reactance element connected to the first reflection terminal;
a second variable reactance element connected to the second reflection terminal;
a control unit that controls the first variable reactance element and the second variable reactance element;
Equipped with
Each of the first variable reactance element and the second variable reactance element is
at least one capacitor;
at least one inductor connected in parallel with the at least one capacitor;
at least one first switch for connecting or disconnecting the at least one capacitor and the 90-degree hybrid coupler;
at least one second switch for connecting or disconnecting the at least one inductor and the 90-degree hybrid coupler;
and
The control unit
the at least one first switch and the at least one second switch are controllable, and are switchable between a first state in which the at least one capacitor is in a connected state and all of the at least one inductor is in a disconnected state, and a second state in which all of the at least one capacitor is in a disconnected state and the at least one inductor is in a connected state;
A signal input to the input terminal is transferred and output from the output terminal.
Phase shifter. the control unit, in the first state, causes only one of the at least one capacitor to be in a connected state;
the control unit, in the second state, causes only one of the at least one inductor to be in a connected state;
2. The phase shifter according to claim 1. each of the first variable reactance element and the second variable reactance element is connected to ground;
3. The phase shifter according to claim 1 or 2. In the S-parameters of the at least one capacitor, S21 (transmission coefficient)>S11 (reflection coefficient),
In the S-parameters of the at least one inductor, S11 (reflection coefficient)>S21 (transmission coefficient),
4. The phase shifter according to claim 1. the 90-degree hybrid coupler comprises: a first line having a line length of λ/4 and a characteristic impedance of Z0, connected between the input terminal and the output terminal; a second line having a line length of λ/4 and a characteristic impedance of Z0, connected between the first reflecting terminal and the second reflecting terminal; a third line having a line length of λ/4 and a characteristic impedance of Z0/√2, connected between the input terminal and the first reflecting terminal; and a fourth line having a line length of λ/4 and a characteristic impedance of Z0/√2, connected between the output terminal and the second reflecting terminal,
The self-resonant frequency of the at least one inductor is outside the frequency range of 0.9×(c/λ) to 1.1×(c/λ).
5. The phase shifter according to claim 1. At least one of the real part and the imaginary part of the complex permeability of the at least one inductor is set so that the amount of change is 10% or less in a frequency range of 0.9 × (c/λ) or more and 1.1 × (c/λ) or less.
6. The phase shifter according to claim 1. In a first frequency range, the value of the imaginary part of the complex permeability of the at least one inductor is smaller than the value of the real part;
In a second frequency range higher than the first frequency range, the imaginary part of the complex permeability of the at least one inductor has at least a part that is greater than a maximum value of the real part of the complex permeability in the first frequency range.
7. The phase shifter according to claim 6. When the second switch is on, a current flows through the at least one inductor on the second switch side, and no current or a small amount of current flows through the at least one inductor on the opposite side to the second switch.
The phase shifter according to any one of claims 1 to 7. the capacitance of the at least one capacitor and the inductance of the at least one inductor are set to values that do not realize a phase shift of the signal of 0° or a predetermined range around 0°;
The phase shifter according to any one of claims 1 to 8.