JP2001168668A - Phase shifter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase shifter which reduces loss and can be made small to be more inexpensive by reducing components such as distributors, variable attenuators and adders used by a 2 πphase shifter in the 2π phase shifter changing the phases of a high frequency signal and to provide communication equipment using the phase shifter. SOLUTION: A π distributor divides a signal whose phase is to be changed into two paths and a π/2 distributor further divides each of the signals. In the outputs of variable attenuators connected to the four paths being the outputs of two π/2 distributors, the optional phase shift quantity of 0 to 2 π rad can be adjusted by changing the attenuation quantity of the variable attenuators.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear compensation circuit for compensating for non-linearity of a power amplifier of a transmission apparatus for performing radio transmission using a linear modulation method, and more particularly to a phase shifter.

[0002]

2. Description of the Related Art A conventional example of a phase shifter will be described with reference to FIG. FIG. 4 is a block diagram showing the configuration of the phase shifter. 1 is an input terminal, 21, 25, 29 and 33 are π / 2 dividers, 22, 23 and 26,
27 and 30, 31, 34 and 35 are variable attenuators (ATT), 24, 28 and 32
And 36 are adders, 16 is an output terminal, and 37 and 38 are control voltage input terminals. In FIG. 4, a signal input from an input terminal 1 is input to a π / 2 distributor 21. The in-phase signal (0 rad) is generated by the hybrid π / 2 distributor 21.
And are distributed to quadrature signals (π / 2 rad) and output. The distributed in-phase signal (I1) is provided to the variable attenuator 22, and the quadrature signal (Q1) is provided to the variable attenuator 23. The output P1 of the variable attenuator 22 and the output P2 of the variable attenuator 23 are respectively supplied to an adder 24, and are added by the adder 24. The output P3 of the adder 24 is supplied to the π / 2 distributor 25, which distributes the output P3 into an in-phase signal (0 rad) and a quadrature signal (π / 2 rad) and outputs the same. The distributed in-phase signal (I2) is a variable attenuator
26, and the quadrature signal (Q2) is applied to variable attenuators 27, respectively. The outputs of the variable attenuator 26 and the variable attenuator 27 are respectively supplied to an adder 28, and are added by the adder 28. The output of the adder 28 is provided to a π / 2 divider 29,
The signal is divided into an in-phase signal (0 rad) and a quadrature signal (π / 2 rad) and output. The distributed in-phase signal (I3) is provided to the variable attenuator 30, and the quadrature signal (Q3) is provided to the variable attenuator 31. The outputs of the variable attenuator 30 and the variable attenuator 31 are respectively supplied to an adder 32, and are added by the adder 32. The output of the adder 32 is supplied to a π / 2 divider 33, which outputs an in-phase signal (0 rad) and a quadrature signal (π / 2ra).
Distributed to d) and output. In-phase signal (I4) distributed
Is provided to the variable attenuator 34, and the quadrature signal (Q4) is provided to the variable attenuator 35. Variable attenuator 34 and variable attenuator
The outputs of 35 are given to the adders 36, respectively, and are added by the adders 36. The output of the adder 36 is output from the output terminal 16. The control voltage input terminal 37 is connected to the variable attenuators 22, 26, 30, and 34, receives the control voltage V1, and
26, 30, and 34 are controlled. The control voltage input terminal 38 is connected to the variable attenuators 23, 27, 31, and 35, and the control voltage V2
To control the variable attenuators 23, 27, 31, and 35.

First, the operation from the input terminal 1 to the adder 24 will be described. For example, the attenuation amounts of the variable attenuators 22 and 23 are each set to 0 to 30 dB, and the output signal of the variable attenuator 22 is
P1, the output signal of the variable attenuator 23 is P2, and the output signal of the adder 24 is P3. To simplify the explanation, the attenuation of the two variable attenuators (ATT) 22 and 23 is set to 0 dB (ATT = 0 dB, that is, P1 = P
If 2 = 1), the output signal state of the adder 24 is as shown in FIG. 5A, and a composite vector P3 of two orthogonal vectors P1 and P2 is output. Therefore, by changing the magnitude of P1 and P2 (ie, changing the attenuation of the variable attenuator), the phase angle of the composite vector P3 (the output of the adder 24) can be changed. In the output signal of the adder 24, the control voltages V1 and V2 and the phase angle θ for changing the phase angle while keeping the signal level constant are given by the following equations.

However, the attenuation of the variable attenuator is proportional to the logarithm of the input voltage. Further, k is a proportional constant that gives the sensitivity of the variable attenuator.

[0005]

(Equation 1)

The control voltages V1 and V2 given by equation (1)
Is input from control voltage input terminals 37 and 38, respectively, is applied to variable attenuators 22 and 23, and is set to different attenuation amounts, respectively, with reference to FIG. 5B. By adjusting the control voltages V1 and V2, the variable attenuator 22
Is 0 dB and the attenuation of the variable attenuator 23 is 30 dB, the phase angle θ of the output of the adder 24 is 0 rad. Also,
Assuming that the attenuation of the variable attenuator 22 is 30 dB and the attenuation of the variable attenuator 23 is 0 dB, the phase angle θ is π / 2 rad. As described above, by setting the two variable attenuators 22 and 23 to appropriate values, the phase angle θ can be set to 0 to π / 2 rad while the output level is kept constant.
Can be set to any value within the range.

Further, as shown in FIG. 6, the output signal of the adder 28 has the same phase as the output signal A of the adder 24 and the variable attenuator 26
And the output signal A attenuated by the variable attenuator 27 is output as a signal d of a composite vector of a signal c having a phase shift of π / 2. As described above, the output signal of the adder 28 can be set to the phase angle 2θ, that is, an arbitrary phase angle from 0 rad to π rad. And the output signal of the adder 32 is
By the same operation up to the adder 28, the phase angle 3θ, that is, 0
A phase angle from rad to 3π / 2 rad can be set. The output signal of the adder 36 can also set the phase angle 4θ, that is, the phase angle of 0 rad to 2π rad, by the same operation as the operation up to the adder 28. As described above, at the output terminal 16, the phase shift amount can be made to correspond in all regions (0 rad to 2π rad).

[0008] The above-mentioned distributor requires four distributors composed of hybrids.
Assuming that there is a loss of 3 dB, the cascade connection of the four splitters results in a total loss of 12 dB, which is a large loss.

[0009]

The above-mentioned prior art includes the following:
Four distributors composed of hybrids are required, and there is a disadvantage that the loss increases. Further, there is a disadvantage that the number of required variable attenuators is large, and it is difficult to reduce the size and simplify the adjustment.

An object of the present invention is to eliminate the above-mentioned drawbacks and to reduce components such as a distributor, a variable attenuator, and an adder, thereby reducing loss, enabling downsizing and a more inexpensive transfer. A communication device using a phase shifter and a phase shifter is provided.

[0011]

In order to achieve the above-mentioned object, the phase shifter of the present invention has a π divider that shifts the phase by π rad, and outputs the signals of the opposite phases to the π / 2 phase shifters, respectively. By inputting, a phase shifter in which an output signal corresponds to all phase angles of 0 rad to 2π rad is realized.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the phase shifter of the present invention. Components having the same functions as those described above are denoted by the same reference numerals. In addition, 2 is a π divider, 3 and 4 are π / 2 dividers, 5 to 8 are variable attenuators (ATT), 9 to
12 is a control voltage input terminal, and 13 to 15 are adders. The input terminal 1 is divided into two by a π divider 2 and is divided into a signal P4 of 0 rad and a signal P5 of π rad. Signal P4 is π / 2 divider 3
, And the signal P5 is provided to the π / 2 distributor 4. π / 2
The in-phase output (I0) of the distributor 3 is supplied to the variable attenuator 5 and the quadrature output (Q0) is supplied to the adder 13 via the variable attenuator 6. The in-phase output (Iπ) of the π / 2 distributor 4 is supplied to the variable attenuator 7,
The quadrature output (Qπ) is provided to the adder 14 via the variable attenuator 8. The control voltage input terminals 9 to 12 are connected to the variable attenuators 5 to 8, respectively, and the adders 13 and 14 are connected to the output terminal 16 via the adder 15.

In FIG. 1, a signal input from an input terminal 1 is converted by a π divider 2 into an in-phase signal P as shown in FIG.
4 (0 rad) and a negative-phase signal P5 (π rad). The distributed in-phase signal P4 and anti-phase signal P5 are
Each is input to the two dividers 4. The operation from the π / 2 distributor 3 to the adder 13 and the operation from the π / 2 distributor 4 to the adder 14 have been described in the above-described conventional example, and thus description thereof will be omitted. However, the signal input to the π / 2 distributor 4 is
Since the phase of the signal input from the input terminal 1 is opposite to that of the signal input from the input terminal 1, the phase angle of the signal distributed by the π / 2 distributor 4 is π r with respect to the phase of the input signal of the input terminal 1.
ad or 3π / 2 rad signal. Therefore, the control voltage V1 input from the control voltage input terminal 9 and the control voltage input terminal 10
Output signal of the adder 13 according to the control voltage V2 input from the
In P6, an arbitrary phase angle of 0 rad to π / 2 rad can be set. The control voltage V3 input from the control voltage input terminal 11 and the control voltage V3 input from the control voltage input terminal 12
Thus, in the output signal P7 of the adder 14, π rad to 3π / 2
Any phase angle of rad can be set. Adder 13
The signals P6 and P7 output at S14 and S14 are provided to an adder 15, and the adder 15 outputs an output signal P8 obtained by adding the input signals. The output signal P8 of the adder 15 is as shown in FIG. 3, and becomes a composite vector P8 of the two vectors P6 and P7.
Therefore, the phase angle of the output of the adder 15 can be set in the range of 0 rad to 2π rad, and the output terminal 16 can correspond the phase shift amount in all regions.

Next, another embodiment of the present invention will be described with reference to FIG.
8 and FIG. 8, two of the four control voltages used in FIG.
An example in which two control voltages are controlled and the outputs of two controlled variable attenuators are added to realize a 2π phase shifter will be described. FIG. 7 is a block diagram showing the configuration of one embodiment of the phase shifter of the present invention. FIG. 8 is a diagram illustrating a signal obtained by adding the in-phase signal and the quadrature signal by the phase shifter of FIG. Components having the same functions as those described above are denoted by the same reference numerals. In addition, 17 and 18 are control voltage input terminals, and 19 and 20 are switches.

In FIG. 7, a variable attenuator 5 is connected to an input terminal 1.
1 to 8 are the same as those in FIG. Variable attenuators 5-8 are connected to switch 20 and switches
20 is connected to the output terminal 16 via the adder 15. Also,
The variable attenuators 5 to 8 are also connected to a switch 19, and the switch 19 is connected to input terminals 17 and 18 for control voltages VI and V2. Output signals of the variable attenuators 5 to 8 are respectively P9 to P12
And First, a case where the phase shift amount in the first quadrant (0 rad to π / 2 rad) is set will be described. According to the vector diagram of FIG. 8, the output signal P11 = P12 = 0 and the output signal P9
And P10, the combined vector of the output signals P9 and P10 satisfies the angle from 0 rad to π / 2 rad. That is, for example, in FIG.
To the variable attenuator 5 to control the variable attenuator 5, and
The control voltage input terminal 18 is connected to the variable attenuator 6 to control the variable attenuator 6. Therefore, the variable attenuators 5 and 6 can be controlled by the control voltages V1 and V2. Further, only the outputs of the variable attenuators 5 and 6 are selected by the switch 20, and the signals are added by the adder 15, so that the phase angle of the output signal can be arbitrarily set in the range of 0 rad to π / 2 rad. Can be set to the value of

Next, a case where the amount of phase shift in the second quadrant (π / 2 rad to π rad) is set will be described. From the vector diagram of FIG. 8, by setting P9 = P12 = 0 and changing P10 and P11, the combined vector of P10 and P11 satisfies the angle of π / 2 rad to π rad.

That is, for example, in FIG. 7, the switch 19 is switched, the control voltage input terminal 17 is connected to the variable attenuator 6 to control the variable attenuator 6, and the control voltage input terminal 18 is connected to the variable attenuator 7. Connect to control the variable attenuator 7. Therefore, the variable attenuators 6 and 7 can be controlled by the control voltages V1 and V2. Further, only the outputs of the variable attenuators 6 and 7 are selected by the switch 20, and the signals are added by the adder 15, so that the phase angle of the output signal becomes π / 2 rad to π
It can be set to any value in the range of rad.

Similarly, when setting the phase shift amount in the third quadrant (π rad to 3π / 2 rad), P9 = P10 = 0 and P11 and P12 are changed from the vector diagram of FIG. Thus, the combined vector of P11 and P12 satisfies the angle of π rad to 3π / 2 rad. That is, for example, in FIG.
19, the control voltage input terminal 17 is connected to the variable attenuator 7 to control the variable attenuator 7, and the control voltage input terminal 18
Is connected to the variable attenuator 8 to control the variable attenuator 8. Therefore, the variable attenuators 7 and 8 can be controlled by the control voltages V1 and V2. In addition, only the outputs of the variable attenuators 7 and 8 are selected by the switch 20, and the signals are added by the adder 15, so that the phase angle of the output signal becomes π rad to
It can be set to any value in the range 3π / 2 rad.

Further, the fourth quadrant (3π / 2 rad to 2π rad)
Similarly, when the phase shift amount is set, P10 = P11 = 0 according to the vector diagram of FIG. 8, and by changing P9 and P12, the combined vector of P9 and P12 becomes 3π / 2 rad to 2π ra
Satisfies the angle of d. That is, for example, in FIG. 7, the switch 19 is switched, the control voltage input terminal 17 is connected to the variable attenuator 5, the variable attenuator 5 is controlled, and the control voltage input terminal 18 is connected to the variable attenuator 8, The variable attenuator 8 is controlled.
Therefore, the variable attenuators 5 and 8 can be controlled by the control voltages V1 and V2. Further, only the outputs of the variable attenuators 57 and 8 are selected by the switch 20, and the signals are added by the adder 15, so that the phase angle of the output signal becomes 3
It can be set to any value in the range of π / 2 rad to 2π rad.

Next, an embodiment in which the phase shifter of the present invention is applied to linear compensation of a power amplifier will be described with reference to FIG. FIG.
FIG. 2 is a block diagram showing a configuration of a power amplifier using a feedforward linear compensation method. 39 is an input terminal, 40 is a first power divider, 41 is a first variable attenuator (ATT), 42
Is a first phase shifter, 43 is a power amplifier, 44 is a first delay unit,
45 is a second power divider, 46 is a first adder, 47 is a second delay, 48 is a second variable attenuator, 49 is a second phase shifter, 50
Is a linear amplifier, 51 is a second adder, and 52 is an output terminal.

The input terminal 39 is connected to a first variable attenuator 41 and a first delay unit 44 via a first power divider 40. The first variable attenuator 41 includes a first phase shifter 42 and a power amplifier.
The second power divider 45 is connected to the output terminal 52 via the second delay unit 47 and the second adder 51 via the 43. On the other hand, the second power distributor
45 is connected to a first adder 46. The first delay unit 44 is also connected to the first adder 46, and the first adder 46
It is connected to a second adder 51 via a second variable attenuator 48, a second phase shifter 49, and a linear amplifier 50.

Hereinafter, this operation will be described with reference to FIG. The signal input from the input terminal 39 is passed through a first power divider 40, one of which is a first variable attenuator 41 and a first
To the power amplifier 43 via the phase shifter 42 of FIG. On the other hand,
The signal input from the input terminal 39 is input to the first delay unit 44. In the power amplifier 43, the input signal is amplified to a desired power, but the output of the power amplifier 43 includes a distortion component other than the main signal component due to the non-linearity of the power amplifier. On the other hand, the distortionless output is supplied to the first delay unit 44 by the power amplifier.
The same delay amount as the delay generated in 43 is given. Further, when the amplitude level and the phase change due to a temperature change or the like, fine adjustment is performed by the first variable attenuator 41 and the first phase shifter 42, respectively. The two signals are phase-shifted to the first
Adder 46 adds only the distortion component generated by the power amplifier 43 to the output of the first adder 46.
The extracted distortion component is applied to the linear amplifier 50, amplified, and sent to the second adder 51. On the other hand, the output of the power amplifier 43 is given the same delay amount as the delay generated by the linear amplifier 50 in the second delay unit 47, and the second adder 51
Is input to Fine adjustment of signal level and phase
And a second phase shifter 49.
By taking the difference between the two signal components input to the second adder 51, as a result, only the distortion component is removed from the output of the power amplifier, thereby compensating for the nonlinear distortion.

FIG. 10 is a diagram showing the spectrum of points A to D shown in FIG. 5 in the operation described above. FIG. 10 is a diagram for explaining the operation of the power amplifier of the present invention. The horizontal axis indicates frequency, and the vertical axis indicates signal power level.
FIG. 10A shows the output A of the power amplifier 43 in FIG.
(b) is the output B of the first delay unit 44 in FIG. 5, FIG. 10 (c)
Is the output C of the first adder 46 in FIG. 5, and FIG. 10D is the output D of the second adder 51 in FIG.

The distortion extraction and the distortion compensation realize wideband distortion compensation by using the above-described phase shifters for the phase shifters used in the respective systems. As a method of compensating the distortion of the power amplifier, there are a feedback method and a pre-distortion method in addition to the feed-forward described here.Both of them require a phase adjustment by a phase shifter to perform the distortion compensation. The 2π phase shifter described in the embodiment can be used.

[0025]

As described above, according to the present invention, the phase angle of 0 to 2π rad can be controlled with a smaller configuration than in the prior art, and the loss of the entire phase shifter can be reduced. In addition, a highly efficient and high quality communication device can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a phase shifter of the present invention.

FIG. 2 is a view for explaining an embodiment of the operation of the present invention.

FIG. 3 is a diagram illustrating an embodiment of the operation of the present invention.

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

FIG. 5 is a diagram showing a signal obtained by adding an in-phase signal and a quadrature signal.

FIG. 6 is a diagram showing a signal obtained by adding an in-phase signal and a quadrature signal.

FIG. 7 is a block diagram showing a configuration of an embodiment of a phase shifter of the present invention.

FIG. 8 is a diagram showing a signal obtained by adding an in-phase signal and a quadrature signal.

FIG. 9 is a block diagram showing a configuration of an embodiment of the power amplifier of the present invention.

FIG. 10 illustrates an operation of the power amplifier of the present invention.

[Explanation of symbols]

1: input terminal, 2: π distributor, 3, 4, 21, 25, 29, 3
3: π / 2 distributor, 6, 7, 8, 22, 23, 25, 26, 30, 31,
34, 35: Variable attenuator, 10, 11, 12, 17, 18, 37, 38:
Control voltage input terminal, 13, 14, 15: adder, 16: output terminal, 19, 20: switch, 39: input terminal, 40: first power divider, 41: first variable attenuator, 42: First
43: power amplifier, 44: first delay unit,
45: second power divider, 46: first adder, 47: second delayer, 48: second variable attenuator, 49: second phase shifter, 50: linear amplifier, 51: Second adder, 52:
Output terminal.

Claims (8)

[Claims] 1. A 2π phase shifter for changing a phase of an input signal from 0 rad to 2π rad, the first phase shifter distributing a phase of the input signal into a signal of 0 rad and a signal shifted by π rad. A splitter, and a signal of 0 rad and π rad distributed by the first splitter.
A second divider that further divides the phase of the phase-shifted signal into two signals that are shifted in phase by 0 rad and two signals that are shifted by π / 2 rad; A 2π phase shifter, comprising: four variable attenuators for changing levels, control means for controlling the four variable attenuators, and means for adding outputs of the four variable attenuators. 2. The 2π phase shifter according to claim 1, further comprising control voltage input means for inputting two arbitrary control voltages to each of the four variable attenuators, and A 2π phase shifter, wherein each of the four variable attenuators controls an amount of attenuation, thereby controlling a level of an output signal of the second divider and shifting a phase of the input signal. . 3. The phase shifter according to claim 2, further comprising control voltage switching means for applying the two control voltages to desired two of the four variable attenuators, respectively. 2π phase shifter characterized by phase shifting. 4. The 2π phase shifter according to claim 3, wherein the range in which the 2π phase shifter is shifted by arbitrarily changing the two control voltages is set to 0 rad by the control voltage switching means. ~ Π / 2 rad,
π / 2 rad to π rad, π rad to 3π / 2 rad, 3π / 2 rad to π
A 2π phase shifter characterized by switching to any one of four ranges of rad. 5. The 2π phase shifter according to claim 2, further comprising an output switching means for selecting and adding two outputs from the outputs of the four variable attenuators, A 2π phase shifter characterized by shifting the phase of an input signal. 6. A π rad phase shifter that shifts the phase of an input signal to 0 rad and π rad and outputs each of them,
Input two signals output by the phase shifter, and input 0 rad and π / 2 rad
Two π / 2 rad phase shifters for phase-shifting and outputting respectively, a variable attenuator for attenuating the output level of each of the two π / 2 rad phase shifters, and each output of the variable attenuator An adder for adding a signal to be applied to each of the variable attenuators, and by switching a control voltage to be input to each of the variable attenuators, thereby switching the amount of attenuation of each of the variable attenuators, thereby shifting the phase of the input signal. Characterized by 2
π phase shifter. 7. The 2π phase shifter according to claim 6, wherein a phase of said input signal is shifted by inputting said control voltage to two of said variable attenuators.
2π phase shifter. 8. A power amplifier comprising the 2π phase shifter according to claim 1 and using a linear compensation circuit to compensate for linear distortion.