RF phase shifter

Abstract

The invention provides an RF phase shifter capable of performing high-precision phase control. An RF phase shifter (100) is provided with: a phase shifter (110) for inputting an input RF signal, generating an output RF signal in which the phase of the input RF signal is changed to a set phase in accordance with a control voltage, and outputting the output RF signal; a phase comparator (120) that generates a phase difference voltage corresponding to a phase difference between the input RF signal and the output RF signal; and an arithmetic processing unit (130) that generates a control voltage corresponding to a voltage difference between the phase difference voltage and a reference voltage corresponding to the set phase.

Description

Technical Field

[0001] The present invention relates to RF phase shifters. Background Art

[0002] There is known an RF (high frequency) phase shifter that generates an output RF signal by changing the phase of an input RF signal to a set phase (for example, refer to Patent Document 1).

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 09-074325 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In such an RF phase shifter, high-precision phase control is required. As a method to improve the accuracy of the phase control of the RF phase shifter, fine control of the phase shift can be considered. However, in the previous RF phase shifter, there is an error of several degrees between the set phase and the output phase, and the accuracy of the phase control is low. Therefore, the true value of the output phase is unknown, and it is difficult to ensure the accuracy of the phase control.

[0008] Therefore, an object of the present invention is to provide an RF phase shifter capable of performing high-precision phase control.

[0009] Technical solutions to solve problems

[0010] The RF phase shifter according to the present invention comprises: a phase shifter which receives an input RF signal, generates an output RF signal by changing the phase of the input RF signal to a set phase according to a control voltage, and outputs the output RF signal; a phase comparator which generates a phase difference voltage corresponding to the phase difference between the input RF signal and the output RF signal; and an operation processing unit which generates the control voltage corresponding to the voltage difference between the phase difference voltage and a reference voltage, the reference voltage corresponding to the set phase.

[0011] Another RF phase shifter according to the present invention comprises: a digital phase shifter that receives an input RF signal, generates an output RF signal by changing the phase of the input RF signal to a set phase according to a digital control signal, and outputs the output RF signal; a phase comparator that generates a phase difference voltage corresponding to the phase difference between the input RF signal and the output RF signal; and an arithmetic processing unit that generates the digital control signal corresponding to the voltage difference between the phase difference voltage and a reference voltage, the reference voltage corresponding to the set phase.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to perform high-precision phase control in an RF phase shifter. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 : is a conceptual diagram showing the RF phase shifter according to the present embodiment.

[0015] Figure 2 : is a circuit diagram showing the RF phase shifter (analog type) according to the first embodiment.

[0016] Figure 3 This is a circuit diagram showing an RF phase shifter (digital type) according to the second embodiment.

[0017] Figure 4 It is shown Figure 3 A circuit diagram of an example of a phase shifter (digital) in an RF phase shifter is shown.

[0018] Figure 5 It is shown Figure 3 A circuit diagram of another example of a phase shifter (digital) in an RF phase shifter is shown.

[0019] Figure 6 It is shown Figure 4 or Figure 5 A circuit diagram showing an example of a variable reactance element (digital) in a phase shifter.

[0020] Figure 7 It is shown Figure 4 or Figure 5 A circuit diagram of another example of a variable reactance element (digital) in a phase shifter is shown.

[0021] Figure 8 It is shown Figure 4 or Figure 5 A circuit diagram of another example of a variable reactance element (digital) in a phase shifter is shown. DETAILED DESCRIPTION

[0022] Hereinafter, an example of an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference numerals are attached to the same or corresponding parts.

[0023] [First embodiment]

[0024] (RF Phase Shifter)

[0025] Figure 1 1 is a conceptual diagram showing an RF phase shifter according to the present embodiment. Figure 2 : is a circuit diagram showing the RF phase shifter according to the first embodiment. Figure 1 as well as Figure 2The RF phase shifter 100 shown in FIG. 1 includes an analog phase shifter 110, a phase comparator 120, and an analog operation processing unit 130. Figure 2 As shown, the RF phase shifter 100 may also include splitters 141 and 142 .

[0026] The splitter 141 splits the RF signal input to the input terminal RF_IN of the RF phase shifter 100 into an input RF signal for the phase shifter 110 and an input RF signal for the phase comparator 120 .

[0027] The splitter 142 splits the output RF signal of the phase shifter 110 into an output RF signal for the phase comparator 120 and an RF signal output from the output terminal RF_OUT of the RF phase shifter 110 .

[0028] The phase shifter 110 is an analog phase shifter and receives an input RF signal, generates an output RF signal by changing the phase of the input RF signal to a set phase according to a control voltage, and outputs the output RF signal.

[0029] The phase comparator 120 is a high-precision phase comparator. The phase comparator 120 compares the phase of the input RF signal and the phase of the output RF signal, and generates a voltage having a voltage value corresponding to the phase difference between them. This voltage is referred to as a phase difference voltage.

[0030] The operation processing unit 130 is an analog operation processing unit, and includes an operational amplifier 132. One input of the operational amplifier 132 is connected to the output of the phase comparator 120. The other input of the operational amplifier 132 is connected to the middle point of resistors 133 and 134 connected in series between the reference voltage line V_Phase ref and the ground line GND. In addition, the output of the operational amplifier 132 is feedback-connected to one input of the operational amplifier 132 in series via a capacitor 136.

[0031] The phase difference voltage V_Δphase is input to one input of the operational amplifier 132. The reference voltage V_Phase ref is input to the other input of the operational amplifier 132. Specifically, the reference voltage V_Phase ref divided by the resistors 133 and 134 is input. The reference voltage V_Phase ref is a voltage corresponding to the set phase of the phase shifter 110 (for example, the set phase of the output RF signal).

[0032] With such a configuration, the calculation processing unit 130 generates a voltage corresponding to the voltage difference between the phase difference voltage V_Δphase and the reference voltage V_Phase ref. Specifically, the calculation processing unit 130 performs integration processing of the differential voltage between the phase difference voltage V_Δphase and the reference voltage V_Phase ref as shown in the following equation.

[0033] V_control=∫(V_Δphase-V_Phase ref)dt

[0034] The calculation processing unit 130 feeds back the voltage to the phase shifter 110 as a control voltage V_control.

[0035] As described above, according to the RF phase shifter 100 of the first embodiment, the output phase and input phase of the phase shifter 110 are compared by the high-precision phase comparator 120, the difference between the phase difference and the set phase difference (V_Phaseref) is integrated and fed back to the phase shifter 110, and the output phase is adjusted to the set phase. Thus, high-precision phase control can be performed. In addition, the output phase of the output RF signal can be stabilized for a long time.

[0036] In particular, since the arithmetic processing unit 130 performs integration processing, even if the frequency of the phase shift target signal increases, high-precision phase control can be performed, and the output phase of the output RF signal can be stabilized for a long period of time.

[0037] [Second embodiment]

[0038] (RF Phase Shifter)

[0039] Figure 1 1 is a conceptual diagram showing an RF phase shifter according to the present embodiment. Figure 3 : is a circuit diagram showing an RF phase shifter according to the second embodiment. Figure 1 as well as Figure 3 The RF phase shifter 100A shown is Figure 1 as well as Figure 2 Compared with the RF phase shifter 100 of the first embodiment shown in the figure, the RF phase shifter 100 is different in that a digital phase shifter 110A and a digital calculation processing unit 130 are provided instead of the analog phase shifter 110 and the analog calculation processing unit 130 .

[0040] The phase shifter 110A is a digital phase shifter and receives an input RF signal, generates an output RF signal by changing the phase of the input RF signal to a set phase according to a digital control signal, and outputs the output RF signal.

[0041] The operation processing unit 130A is a digital operation processing unit, and includes an operation processor such as a PU (Processing Unit), a DSP (Digital Signal Processor), and an FPGA (Field-Programmable Gate Array). The functions of the operation processing unit 130A are realized by executing a given software (program) stored in a memory. In addition, the functions of the operation processing unit 130A can be realized by the cooperation of hardware and software, or can be realized only by hardware (electronic circuit).

[0042] An input of the arithmetic processing unit 130A is connected to the output of the phase comparator 120 , and another input of the arithmetic processing unit 130A is connected to a reference voltage line V_Phase ref. An output of the arithmetic processing unit 130A is connected to the phase shifter 110A.

[0043] The phase difference voltage V_Δphase is input to the input of the arithmetic processing unit 130A. The reference voltage V_Phase ref is input to the other input of the arithmetic processing unit 130A. The reference voltage V_Phase ref is a voltage corresponding to the set phase of the phase shifter 110A (for example, the set phase of the output RF signal).

[0044] The calculation processing unit 130A generates a signal according to the voltage difference between the phase difference voltage V_Δphase and the reference voltage V_Phase ref. Specifically, the calculation processing unit 130A performs integration processing of the differential voltage between the phase difference voltage V_Δphase and the reference voltage V_Phase ref as shown in the following equation.

[0045] V_control=∫(V_Δphase-V_Phase ref)dt

[0046] The arithmetic processing unit 130A converts the voltage into a bit code, and feeds back the converted signal to the phase shifter 110A as a digital control signal V_control (bit code).

[0047] As described above, in the RF phase shifter 100A of the second embodiment, the output phase and input phase of the phase shifter 110A are also compared by the high-precision phase comparator 120, and the difference between the phase difference and the set phase difference (V_Phase ref) is fed back to the phase shifter 110A, and the output phase is adjusted to the set phase. In this way, high-precision phase control can be performed. In addition, the output phase of the output RF signal can be stabilized for a long time.

[0048] In particular, since the arithmetic processing unit 130A performs integration processing, even if the frequency of the phase shift target signal increases, high-precision phase control can be performed, and the output phase of the output RF signal can be stabilized for a long period of time.

[0049] (Digital Phase Shifter)

[0050] The following, Figure 3 An example of a digital phase shifter 110A is shown for explanation.

[0051] Figure 4 is a circuit diagram showing an example of a phase shifter according to the present embodiment. Figure 5 : is a circuit diagram showing another example of the phase shifter according to this embodiment. Figure 4 as well as Figure 5 The phase shifter 10 shown can be used as Figure 3 The digital phase shifter 110A is shown.

[0052] Figure 4 The phase shifter 10 shown is a hybrid coupled type high frequency (RF) phase shifter including 1 / 4 wavelength lines 11 and 12 with characteristic impedance Z0 and 1 / 4 wavelength lines 13 and 14 with characteristic impedance Z0 / √2. The phase shifter 10 sets one end side of the line 11 as an input terminal RF_IN and the other end side of the line 11 as an output terminal RF_OUT. The phase shifter 10 has a variable reactance element 1 (1A, 1B) that terminates the output terminal 13_OUT on the line 13 side and the output terminal 14_OUT on the line 14 side, respectively. The details of the variable reactance element 1 (1A, 1B) will be described later.

[0053] In the phase shifter 10, the RF signal input from the input terminal RF_IN is distributed by the hybrid coupled lines 11, 12, 13, and 14, and transmitted to the output terminal 13_OUT on the line 13 side and the output terminal 14_OUT on the line 14 side. These output terminals 13_OUT and 14_OUT are terminated by the variable reactance element 1 (1A, 1B), so the signals transmitted to these output terminals are reflected by the phase change depending on the reactance of the variable reactance element 1 (1A, 1B). The signals reflected at these output terminals 13_OUT and 14_OUT are synthesized again by the hybrid coupled lines 11, 12, 13, and 14, and output from the output terminal RF_OUT. At this time, the output signal is subjected to the phase change depending on the reactance of the variable reactance element 1 (1A, 1B), and the reactance of the variable reactance element is changed, thereby operating as a phase shifter.

[0054] In addition, Figure 4 , an example in which a variable reactance element 1 (1A, 1B) is applied to a hybrid coupled phase shifter 10 is shown, but it is also possible to Figure 5 As shown, the variable reactance element 1 ( 1A, 1B) is applied to a loaded line type phase shifter 10 including a quarter wavelength line 11 having a characteristic impedance of Z0.

[0055] As described above, according to the high-frequency phase shifter using the digital variable reactance element described later, the reactance can be greatly changed to both capacitive and inductive properties, so a high-frequency (RF) phase shifter with a large phase shift width can be realized with low loss.

[0056] (Digital variable reactance element)

[0057] The following, Figure 4 as well as Figure 5 An example of a variable reactance element is shown in FIG.

[0058] Figure 6 FIG. 1 is a circuit diagram showing a digital variable reactance element according to the present embodiment. Figure 6 As shown, the digital variable reactance element 1 is an element that digitally makes reactance variable. The digital variable reactance element 1 includes a plurality of digital capacitors 2 and a plurality of digital inductors 4. In addition, the digital variable reactance element 1 may also include a digital resistor 6. In the digital variable reactance element 1, the plurality of digital capacitors 2, the plurality of digital inductors 4, and the digital resistor 6 are connected in parallel.

[0059] The digital capacitor 2 has a capacitor C1 and a digital switch (first digital switch) Q connected in series. The digital switch Q is not particularly limited, and a switching element such as a FET (Field Effect Transistor) can be used. The digital switch Q can be switched to two states: an on state and an off state. Thus, the digital capacitor 2 can be switched to two values: a first value of the capacitance of the capacitor C1 (the digital switch Q is in the on state) or a second value of 0 capacitance (the digital switch Q is in the off state). That is, the digital capacitor 2 can switch the capacitance digitally.

[0060] The digital inductor 4 includes an inductor L1 and a digital switch (second digital switch) Q connected in series. The digital switch Q is not particularly limited, and a switch element such as a FET (Field Effect Transistor) can be used. The digital switch Q can be switched to two states: an on state and an off state. Thus, the digital inductor 4 can be switched to two values: a first value of the inductance of the inductor L1 (the digital switch Q is in the on state) or a second value of 0 inductance (the digital switch Q is in the off state). That is, the digital inductor 4 can digitally switch the inductance.

[0061] The digital resistor 6 has a resistor R1 and a digital switch Q connected in series. The digital switch Q is not particularly limited, and a switch element such as a FET (Field Effect Transistor) can be used. The digital switch Q can be switched to two states: an on state and an off state. Thus, the digital resistor 6 can be switched to two values, a first value (the digital switch Q is in the on state) which is the resistance value of the resistor R1, or a second value (the digital switch Q is in the off state) which is 0. That is, the digital resistor 6 can switch the resistance value digitally.

[0062] Thus, the variable reactance element 1 can digitally make the reactance variable by switching the on state or the off state of each digital switch Q.

[0063] Furthermore, the variable reactance element 1 can digitally make impedance (particularly, impedance to RF signals (high frequency signals)) variable by switching the on state or the off state of each digital switch Q.

[0064] According to the digital variable reactance element 1, the reactance generated by the plurality of capacitors C1 and the plurality of inductors L1 is digitally made variable by control using the digital switch Q. In addition, according to the digital variable reactance element 1, the impedance generated by the plurality of capacitors C1, the plurality of inductors L1, and the resistor R1 is digitally made variable by control using the digital switch Q.

[0065] Furthermore, not only capacitance but also inductance can be made variable, and reactance can be greatly varied from capacitive (1 / 2πfc) to inductive (2πfL). Therefore, the variable range of reactance (1 / 2πfc+2πfL) can be widened.

[0066] Furthermore, there is no need to use a plurality of variable capacitors or a plurality of variable inductors, and there is no problem that control signals of the plurality of variable capacitors or a plurality of variable inductors become complicated.

[0067] In addition, a high frequency (RF) phase shifter with a large phase shift amplitude can be realized with low loss.

[0068] In the above-mentioned embodiment, the following variable reactance element 1 is exemplified, that is, each digital capacitor 2 has a capacitor C1 and a digital switch Q connected in series, each digital inductor 4 has an inductor and a digital switch connected in series or in parallel, and a plurality of digital capacitors 2 and a plurality of digital inductors 4 are connected in parallel. However, the present invention is not limited thereto, and can also be applied to the following various variable reactance elements, that is, each digital capacitor has a capacitor and a digital switch connected in series or in parallel, each digital inductor has an inductor and a digital switch connected in series or in parallel, and a plurality of digital capacitors and a plurality of digital inductors are connected in series or in parallel. For example, the following exemplifies Modification 1 and Modification 2 of the present embodiment.

[0069] (Digital variable reactance element of modification 1)

[0070] Figure 7 FIG. 1 is a circuit diagram showing a digital variable reactance element according to a first variation of the present embodiment. Figure 7 As shown, the digital variable reactance element 1A is an element that digitally makes reactance variable. The digital variable reactance element 1A includes a plurality of digital capacitors 2A and a plurality of digital inductors 4A. In addition, the digital variable reactance element 1A may also include a digital resistor 6A. In the digital variable reactance element 1A, the plurality of digital capacitors 2A, the plurality of digital inductors 4A, and the digital resistor 6A are connected in series.

[0071] The digital capacitor 2A has a capacitor C1 and a digital switch (first digital switch) Q connected in series, and also has a capacitor C2 and the digital switch Q connected in parallel. Specifically, in the digital capacitor 2A, a series circuit of the capacitor C1 and the digital switch Q is connected in parallel with the capacitor C2. The digital switch Q is the same as described above. Thus, the digital capacitor 2A can switch between two values, namely, the first value as the combined capacitance of the capacitor C1 and the capacitor C2 (the digital switch Q is in the on state) or the second value as the capacitance of the capacitor C2 (the digital switch Q is in the off state). That is, the digital capacitor 2A can switch the capacitance digitally.

[0072] The digital inductor 4A includes an inductor L1 and a digital switch (a second digital switch) Q connected in series, and also includes an inductor L2 and the digital switch Q connected in parallel. Specifically, in the digital inductor 4A, a series circuit of the inductor L1 and the digital switch Q is connected in parallel to the inductor L2. The digital switch Q is the same as described above. Thus, the digital inductor 4A can switch between two values: a first value (the digital switch Q is in the on state) which is a combined inductance of the inductor L1 and the inductor L2, or a second value (the digital switch Q is in the off state) which is an inductance of the inductor L2. That is, the digital inductor 4A can digitally switch the inductance.

[0073] The digital resistor 6A includes a resistor R1 and a digital switch Q connected in parallel. The digital switch Q is the same as described above. Thus, the digital resistor 6A can switch between two values: a first value of 0 (the digital switch Q is in the on state) or a second value of the resistance value of the resistor R1 (the digital switch Q is in the off state). That is, the digital resistor 6A can digitally switch the resistance value.

[0074] Thus, the variable reactance element 1A can digitally make the reactance variable by switching the on state or the off state of each digital switch Q.

[0075] Furthermore, the variable reactance element 1A can digitally change impedance (particularly, impedance to RF signals (high frequency signals)) by switching the on state or the off state of each digital switch Q.

[0076] The digital variable reactance element 1A of this modification 1 also has the same advantages as the digital variable reactance element 1 of the present embodiment described above.

[0077] (Digital variable reactance element of modification 2)

[0078] Figure 8 FIG. 2 is a circuit diagram showing a digital variable reactance element according to a second variation of the present embodiment. Figure 8 As shown, the digital variable reactance element 1B is an element that digitally makes reactance variable. The digital variable reactance element 1B includes a plurality of the above-mentioned digital capacitors 2A and a plurality of the above-mentioned digital inductors 4. In the digital variable reactance element 1B, the plurality of digital capacitors 2A are connected in series, the plurality of digital inductors 4 are connected in parallel, and the series circuit of the digital capacitors 2A and the parallel circuit of the digital inductors 4 are connected in series.

[0079] Thus, the variable reactance element 1B can digitally make the reactance variable by switching the on state or the off state of each digital switch Q.

[0080] Furthermore, the variable reactance element 1B can digitally make impedance (particularly, impedance to RF signals (high frequency signals)) variable by switching the on state or the off state of each digital switch Q.

[0081] The digital variable reactance element 1B of this modification 2 also has the same advantages as the digital variable reactance element 1 of the present embodiment described above.

[0082] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various changes and modifications are possible. In addition, the RF phase shifter of the above embodiments can be applied to technical fields such as phased array radar, synthesizer, and communication.

[0083] Description of Reference Numerals

[0084] 1, 1A, 1B: digital variable reactance element;

[0085] 2. 2A: Digital capacitor;

[0086] 4. 4A: Digital inductor;

[0087] 6. 6A: Digital resistor;

[0088] C1, C2: capacitors;

[0089] L1, L2: inductors;

[0090] R1: resistor;

[0091] Q: Digital switch;

[0092] 10, 110, 110A: phase shifter;

[0093] 100, 100A: RF phase shifter;

[0094] 120: phase comparator;

[0095] 130, 130A: calculation processing unit;

[0096] 132: Operational amplifier;

[0097] 133, 134: resistor;

[0098] 136: Capacitor;

[0099] 141, 142: splitter.

Claims

1. An RF phase shifter, comprising: a phase shifter that receives an input RF signal, generates an output RF signal by changing the phase of the input RF signal to a set phase according to a control voltage, and outputs the output RF signal; a phase comparator for generating a phase difference voltage corresponding to a phase difference between the input RF signal and the output RF signal; as well as The calculation processing unit generates the control voltage according to the voltage difference between the phase difference voltage and a reference voltage corresponding to the set phase.

2. An RF phase shifter, comprising: a digital phase shifter that receives an input RF signal, generates an output RF signal by changing the phase of the input RF signal to a set phase according to a digital control signal, and outputs the output RF signal; a phase comparator that generates a phase difference voltage corresponding to a phase difference between the input RF signal and the output RF signal; and The arithmetic processing unit generates the digital control signal according to a voltage difference between the phase difference voltage and a reference voltage corresponding to the set phase.

3. The RF phase shifter according to claim 2, wherein: The digital phase shifter has a digital variable reactance element that digitally makes reactance variable. The digital variable reactance element has a plurality of digital capacitors and a plurality of digital inductors. The plurality of digital capacitors and the plurality of digital inductors are connected in series or in parallel, Each of the plurality of digital capacitors includes a capacitor connected in series or in parallel and a first digital switch, wherein the first digital switch can be switched between two states: an on state and an off state. Each of the plurality of digital inductors includes an inductor connected in series or in parallel and a second digital switch that can be switched between two states: an on state and an off state.

4. The RF phase shifter according to any one of claims 1 to 3, wherein: The calculation processing unit performs integration processing of a differential voltage between the phase difference voltage and the reference voltage.

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