JP2005322988A - Distortion compensated amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hold an optimum distortion compensated condition independent of a gain variation due to a environment change such as ambient temperature change, etc. or a secular change, etc. <P>SOLUTION: This distortion compensated amplifier is composed of a first variable attenuator controlled according to levels of input signals and output signals, a distortion generator for generating a distortion canceling signal for canceling distortion appearing at signal amplification by an amplifier, and a second variable attenuator disposed between the distortion generator and the first variable attenuator. The second variable attenuator is controlled according to the output level when the gain of the input signal is changed by the first variable attenuator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a distortion compensation amplifying apparatus that compensates for distortion generated during amplification by a predistortion (PD) method. Moreover, the amplification device according to the present invention can be applied to, for example, a base station device or a relay amplification device provided in a wireless communication system such as a mobile communication system.

Here, as the wireless communication system, for example, various systems such as a mobile phone system and a simple mobile phone system (PHS: Personal Handy Phone System) may be used.

As communication methods, for example, CDMA (Code Division Multiple Access) method, W (Wide band) -CDMA method, TDMA (Time Division Multiple Access) method, FDM, etc.
Various methods such as an A (Frequency Division Multiple Access) method may be used.

  Here, the configuration of the amplification device and the like according to the present invention is not necessarily limited to the above-described configuration, and various configurations may be used. The present invention can also be provided as, for example, a method or method for executing processing according to the present invention, a program for realizing such a method or method, and the like.

  The application field of the present invention is not necessarily limited to the above-described fields, and can be applied to various fields.

As a conventional distortion compensation amplifying apparatus, a distortion compensation amplifying apparatus using a PD method has been proposed (for example, see Patent Document 1).
Here, a conventional distortion compensation amplifying apparatus using the PD method will be described. FIG. 6 is a block diagram showing an example of a configuration of a conventional distortion compensation amplifying apparatus. 1 is an input terminal, 2 is a variable attenuator, 3 is a preamplifier, 4, 6, 7, 8, and 11 are directional couplers, 5 is a delay unit including, for example, a delay line, 9 is a distortion generating element, and 10 is An amplifying unit that amplifies the input signal, 12 is a control unit that controls each component, and 13 is an output terminal. Here, the directional couplers 7 and 8 and the distortion generating element 9 are referred to as a distortion canceling signal generating unit that generates a distortion canceling signal that cancels the distortion generated when amplified by the amplifying unit.

Next, the operation will be described.
The signal a input from the input terminal 1 is input to the directional coupler 4 via the variable attenuator 2 and the preamplifier 3. A signal is distributed by the directional coupler 4, one of which is input as a signal b to the delay unit 5 and the other as a signal c to the directional coupler 7. A signal is distributed by the directional coupler 7, one is directly input as a signal d to the directional coupler 8, and the other signal e is input to the distortion generating element 9, where the distortion components of the distortion generating element 9 are synthesized, Signal f. The distortion component is a signal having the same level as the distortion generated when the signal is amplified by an amplification unit described later. The signal d and the signal f are combined by the directional coupler 8. At this time, the signals d and f are in reverse phase. After being synthesized by the directional coupler 8, the signal g has only a distortion component. This is a distortion cancellation signal.

The signal b and the signal g are combined by the directional coupler 6, the signal h is output from the directional coupler 6, and the output signal h is amplified by the amplifying unit 10. As a result of amplification, the component of the signal g, which is a distortion cancellation signal, is canceled, and an amplified signal without distortion is output as the signal i. The signal j is obtained by detecting a part of the amplified signal i, and detects the output level and the like. The signal k is obtained by detecting a part of the input signal, whereby the input level can be detected. The input / output level is detected based on the detection value of the signal j and the detection value of the signal k, and the control unit 12 reads it. The control unit 12 sets the difference between the read input level and output level as the amplification gain of the amplification unit 10. Here, the difference between the input level k and the output level j is called an amplification gain value. When the amplification gain value is less than the specified value, the variable attenuator 2 is controlled so as to correct it to the specified value, and the gain of the input signal a is adjusted. As a result, a signal having an optimum output level is always output.

  The strain generating element 9 is composed of individual devices, and the devices may be provided in parallel or in series. Further, a combination of series and parallel may be used.

JP 2000-261252 A (page 3-4, FIG. 1)

The gain of an amplifying element that amplifies a signal may change due to environmental changes, secular changes, and the like. In such a case, as described above, there is a method in which the output level of the amplified signal is detected by the signal j, the input level is further detected by the signal k, and the gain is adjusted by controlling the variable attenuator 2 based on them. is there. However, by adjusting the variable attenuator 2, the level of the input signal e to the distortion generating element 9 also changes, whereby the distortion component output from the distortion generating element 9 becomes the distortion component generated by the amplifying unit 10. Not equal, which may deviate from the optimal distortion compensation point.

  The present invention has been made to solve the above-described problems. In order to maintain an optimal distortion compensation state regardless of gain fluctuation, the input level to the distortion generating element is kept constant without using a complicated control function. There is provided a distortion compensation amplifying apparatus having the circuit as described above.

  In order to solve the above-described problem, a first variable attenuator that is controlled according to the levels of an input signal and an output signal, and a distortion generation unit that generates a distortion cancellation signal that cancels distortion generated when the amplification unit amplifies the signal. A distortion compensation amplifying apparatus comprising a second variable attenuator provided between the distortion generator and the first variable attenuator, wherein the gain of the input signal is changed by the first variable attenuator. Then, a distortion compensation amplifying apparatus is provided that controls the second variable attenuator according to the output level.

  Furthermore, in order to solve the above-described problem, a first variable attenuator controlled according to the levels of the input signal and the output signal, and a distortion that generates a distortion canceling signal that cancels the distortion generated when the signal is amplified by the amplifying unit. A distortion compensation amplifying apparatus comprising: a generation unit; and a second variable attenuator provided between the distortion generation unit and the first variable attenuator, wherein a gain of an input signal is obtained by the first variable attenuator. And a second variable attenuator is controlled in accordance with the level of the distortion component included in the output signal and the level of the distortion cancellation signal.

  According to the present invention, there is an effect of maintaining an optimal distortion compensation state regardless of environmental changes such as ambient temperature changes and gain fluctuations such as aging.

The distortion compensation amplifying apparatus of the present invention relates to a distortion compensation amplifying apparatus that provides stable distortion compensation that maintains an optimal distortion compensation state regardless of environmental changes such as changes in ambient temperature and gain fluctuations such as aging. Is. Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram illustrating an example of a configuration of a distortion compensation amplification apparatus according to the present embodiment. 1, the same reference numerals as those in FIG. 6 denote the same or corresponding parts as those in FIG. 6, and a description thereof will be omitted here. In this embodiment, a variable attenuator 101 is provided between the directional coupler 4 and the directional coupler 7, and a control unit 102 is provided instead of the control unit 12. The control unit 102 detects an input signal, an output signal, and a distortion level after output. Further, the variable attenuators 2 and 101 are controlled according to those values.

Hereinafter, the operation of the distortion compensation amplifying apparatus in the present embodiment will be described.
The signal a1 input from the input terminal 1 is input to the directional coupler 4 via the variable attenuator 2 and the preamplifier 3. A signal is distributed by the directional coupler 4, and one is input to the delay unit 5 as the signal b1 and the other is input to the variable attenuator 101 as the signal c1. The output c1 ′ of the variable attenuator 101 is input to the directional coupler 7. The signal is further distributed by the directional coupler 7, one is directly input to the directional coupler 8 as the signal d 1, and the other signal e 1 is input to the distortion generating element 9, where the distortion components of the distortion generating element are synthesized, Signal f1. The signal d1 and the signal f1 are combined by a directional coupler. At this time, the signals d1 and f1 are set to have opposite phases. In the signal g1 synthesized by the directional coupler 8, only the distortion component is output.

The signals b1 and g1 are combined by the directional coupler 6 to generate a signal h1. The signal h1 is a combination of the distortion component and the signal b, and is amplified by the amplification unit 10. By the amplification, the predistorted component, that is, the component of the signal g1 is canceled, and only the amplified signal component without distortion is output from the signal i1. The signal j1 is obtained by detecting a part of the amplified signal i1, and the output level is detected here. The signal k1 detects a part of the input signal and can detect the input level. The input / output level is detected based on the detection value of the signal j1 and the detection value of the signal k1, and the control unit 102 reads it. The control unit 102 sets the difference between the read input level and output level as the amplification gain of the amplification unit 10.

Here, for example, a case where the gain of the amplifying unit 10 changes due to a change in environmental temperature will be described below.
At this time, the difference between the input level detected by the signal k1 and the output level detected by the signal j1 changes. Here, this level difference is called an amplification gain value.
The control unit 102 calculates a control value of the variable attenuator 2 that corrects the gain from the detected amplification gain value, and applies a control voltage. As a result, the signal whose signal level has changed is newly input to the directional coupler 4 and becomes a signal b1 and a signal c1. The control value of the variable attenuator 2 is calculated from the table in which the control unit 102 associates the control value of the variable attenuator 2 with the amplification gain value that the control unit 102 has.

The signal c1 is input to the variable attenuator 101, the signal level is adjusted and output as c1 ', and distortion compensation is performed. The variable attenuator 101 is controlled based on the value of the signal j1, and for example, the control unit 102 has a table of control values of the signal j1 and the variable attenuator 101, and the variable attenuator 101 is based on the table. Control is in progress.

FIG. 2A shows an example of the distortion generation amount of the amplification unit 10 and the distortion generation element 9. The horizontal axis is the output level of each element, and the vertical axis is the magnitude of the strain generation amount. The distortion of the amplifying unit 10 is represented by a solid line, and the distortion of the strain generating element is represented by a broken line.
As described above, there are cases where the distortion characteristics, that is, the distortion generation amount with respect to the output level are different. At this time, the part where the lines overlap each other, here, the part marked with ◯ is set as the output level so that the amount of distortion generation becomes the same level. Even if the input level to the element fluctuates and the output level slightly fluctuates, input / output to each amplification element is adjusted within a range where the amount of distortion does not change, and distortion compensation is performed.

When the variable attenuator 2 is controlled and gain correction is performed in the state where the magnitude of the distortion generation amount described in FIG. 2A is the same level, the input level to the distortion generation element 9 changes, and FIG. It deviates from the optimal distortion compensation point in (a). At this time, the variable attenuator 101 is controlled in accordance with the variation of the variable attenuator 2 to search for the optimum amount of distortion by the distortion generating element 9 and to follow the distortion compensation.

Next, a method for tracking distortion compensation will be described below.
Here, the variable attenuator 101 is controlled so that the detection voltage of the signal j1 is minimized.
In FIG. 5B, the solid line represents the relationship between the input level of the amplifying unit 10 and the amount of distortion, and the broken line represents the input level of the distortion generating element 9 and the amount of distortion. The horizontal axis represents the input level of each element, and the vertical axis represents the amount of distortion generated.
For example, when the input level of the amplifying unit 10 is a point A under the control of the variable attenuator 2, the input level of the amplifying unit at the point A is Amin and the amount of distortion is Amd. The input level is changed by the variable attenuator 101 so that the distortion amount Amd and the distortion amount Add generated in the distortion generating element 8 are at the same level, and the input level is set to Adin so that the distortion amount becomes Add.
At point B, the input of the amplifying unit is Bmin and the amount of distortion is Bmd. The input level is changed by the variable attenuator 101 so that the strain amount Bmd and the strain amount Bdd generated by the strain generating element 8 are the same level, and the input level is set to Bdin so that the strain amount becomes Bdd.
Similarly to points A and B at point C, when the input of the amplifying unit is Cmin and the distortion amount is Cmd, the distortion amount Cmd and the distortion amount Cdd generated at the distortion generating element 8 are variable so that they are at the same level. The input level is changed by the attenuator 101, and the input level is set to Cdin so that the distortion amount becomes Cdd.

In this way, the variable attenuator 101 is changed according to the amount of distortion generated by the input level to the amplifying unit 10, and the distortion amount of the same level as the amount of distortion generated by the input level to the amplifying unit 10 is distorted. It is generated from the generating element 9.
Here, the input level is changed from the normal input level by the variable attenuator. However, the input level is not limited to this, and may be further changed from the level changed from the normal input level.

Next, a second embodiment will be described with reference to FIG.
FIG. 3 is a block diagram showing an example of the configuration of the distortion compensation amplifying apparatus in the present embodiment. 3, the same reference numerals as those in FIGS. 1 and 6 denote the same or corresponding parts as those in FIGS. 1 and 6, and a description thereof is omitted here. In this embodiment, a variable attenuator 201 is provided between the directional coupler 4 and the directional coupler 7 instead of the variable attenuator 101 in FIG. 1, and a control unit 202 is provided instead of the control unit 102 in FIG. I have. The control unit 202 detects an input signal, an output signal, a distortion level after output, and a distortion level generated in the distortion generating element. Further, the variable attenuator 201 is controlled according to these values.

Hereinafter, the operation of the distortion compensation amplifying apparatus in the present embodiment will be described.
The signal a2 input from the input terminal 1 is input to the directional coupler 4 via the variable attenuator 2 and the preamplifier 3. A signal is distributed by the directional coupler 4, and one is input to the delay unit 5 as the signal b2 and the other is input to the variable attenuator 201 as the signal c2. The output c2 ′ of the variable attenuator 201 is input to the directional coupler 7. The signal is further distributed by the directional coupler 7, one is directly input to the directional coupler 8 as the signal d 2, and the other signal e 2 is input to the distortion generating element 9, where the distortion components of the distortion generating element 9 are synthesized. , Signal f2. The signal d2 and the signal f2 are combined by the directional coupler 8. At this time, the signals d2 and f2 are set to have opposite phases. In the signal g2 synthesized by the directional coupler 8, only the distortion component is output.

Signals b2 and g2 are combined by a directional coupler 6 to generate a signal h2. The signal h2 is a combination of the distortion component and the signal b2, and is amplified by the amplification unit 10. By the amplification, the predistorted component, that is, the component of the signal g2 is canceled, and only the amplified signal component without distortion is output from the signal i2. The signal j2 is obtained by detecting a part of the amplified signal i2, and the output level is detected here. The signal k2 is obtained by detecting a part of the input signal, and the input level can be detected. The input / output level is detected based on the detection value of the signal j2 and the detection value of the signal k2, and the control unit 202 reads it. The control unit 202 uses the difference between the read input level and output level as the amplification gain of the amplification unit 10.

Here, for example, a case where the gain of the amplifying unit 10 changes due to a change in environmental temperature will be described below.
At this time, the difference between the input level detected by the signal k2 and the output level detected by the signal j2 changes. Here, this level difference is called an amplification gain value.
The control unit 202 calculates a control value of the variable attenuator 2 that corrects the gain from the detected amplification gain value, and applies a control voltage. As a result, the signal whose signal level has changed is newly input to the directional coupler 4 to become a signal b2 and a signal c2. The control value of the variable attenuator 2 is calculated from the table in which the control unit 202 associates the control value of the variable attenuator 2 with the amplification gain value that the control unit 202 has.

Since it is necessary to adjust the level of the signal c2 so that the distortion generation amount of the amplification unit 10 and the distortion generation amount of the distortion generation element 9 are equal, the signals l2 and m2 are detected, and the signal l2 is generated in the amplification unit 10. The control unit 202 controls the variable attenuator 201 so that the level of the distortion component m 2 is reached. The signal l2 is obtained by detecting a part of the signal f2, and detects the level of distortion generated by the distortion generating element 9. m2 detects a part of the signal i2, and detects the distortion level of the signal i2. The variable attenuator 301 is controlled based on the values of the signals l 2 and m 2. For example, the control unit 302 has a table of the signal l 2, the signal m 2, and the control value of the variable attenuator 301, and based on the table. Control of the variable attenuator 301 is performed.

Next, a method for tracking distortion compensation will be described below.
Here, the detection voltages of the signals l2 and m2 are monitored, and the variable attenuator 202 is controlled so that the levels are equal to each other, thereby obtaining stable distortion compensation.
In FIG. 4, the solid line represents the relationship between the frequency of the amplifying unit 10 and the amount of distortion, and the broken line represents the relationship between the frequency of the strain generating element 9 and the amount of distortion generated. The horizontal axis is frequency, and the vertical axis is distortion. 4A is the distortion component at i2, that is, the amount of the signal level of m2, and B is the distortion component at f2, that is, the amount of the signal level of l2.

The control unit 202 detects the levels of m2 and l2, respectively, and controls the variable attenuator 202 so that the detected values are equal, that is, the solid line part and the broken line part in FIG. As described above, the variable attenuator 202 may be controlled in accordance with, for example, the signals j2 and l2 and the control value of the variable attenuator 202 which are tabled.

As a result, even when the gain correction by the variable attenuator 1 is performed based on the amount of distortion generated by the distortion generating element 8 and the amount of distortion generated by the amplifying unit 10, stable distortion compensation is possible.

A third embodiment will be described with reference to FIG.
FIG. 5 is a block diagram showing an example of the configuration of the distortion compensation amplifying apparatus in the present embodiment. In FIG. 5, the same reference numerals as those in FIGS. 1 and 6 denote the same or corresponding parts as those in FIGS. 1 and 6, and the description thereof is omitted here.
In this embodiment, a variable attenuator 501 is provided between the directional coupler 4 and the directional coupler 7 in place of the variable attenuator 101 in FIG. 1, and a control unit 502 is provided in place of the control unit 102 in FIG. I have. As another configuration, a variable attenuator 503 and a variable phase shifter 504 are provided between the directional coupler 7 and the directional coupler 8. Further, a variable attenuator 505 and a variable phase shifter 506 are provided between the directional coupler 8 and the directional coupler 6, and a variable attenuator 507 is provided between the directional coupler 6 and the amplifying unit 10.

The variable attenuator 503 and the variable phase shifter 504 are the phase and amplitude of the signal d3 distributed by the directional coupler 7 and f3 which is also distributed by the directional coupler 7 and becomes an output signal from the distortion generating element 9. Is to adjust. By adjusting the phase and amplitude of d3 according to the signal f3, components other than the distortion component of f3 are canceled out by the component of d3, and in g3, only a signal equivalent to the distortion generated in the amplifying unit 10 can be extracted. it can.

The variable attenuator 505 and the variable phase shifter 506 adjust the amplitude and phase by matching the signal g3 with the signal b3. As a result, when the output signal h3 of the directional coupler 6 is amplified by the amplifying unit 10, a previously applied distortion component, here, the component of the signal g3 is canceled.

The variable attenuators 503 and 505 and the variable phase shifters 504 and 506 are controlled based on values such as k3 that detects the input signal level, output signal level j3, and l3 that detects a part of f3 that is the output of the distortion generating element. The unit 502 controls each attenuator and phase shifter.

As in the first embodiment, the gain value is detected from k3 and j3, and the variable attenuator 2 is controlled. Accordingly, the variable attenuator is controlled according to the value of j3, and appropriate distortion compensation is performed.

Similarly to the second embodiment, the gain value is detected from k3 and j3, the variable attenuator 2 is controlled, and accordingly, the variable attenuator is controlled according to the values of j3 and m3, and appropriate distortion compensation is performed. You may go.

1 is a block diagram illustrating an example of a configuration of a distortion compensation amplification device in Embodiment 1. FIG. FIG. 4 is a diagram illustrating a relationship between an amplification element and a distortion component in Example 1. FIG. 10 is a block diagram illustrating an example of a configuration of a distortion compensation amplifying apparatus according to a second embodiment. FIG. 10 is a diagram illustrating distortion components in Example 2. FIG. 10 is a block diagram illustrating an example of a configuration of a distortion compensation amplification device according to a third embodiment. It is a block diagram which shows an example of a structure of the conventional distortion compensation amplifier.

Explanation of symbols

2, 101, 301, 501... Variable attenuator 12, 102, 302, 502 ... Control unit 9 ... Strain generating element 10 ... Amplifying unit 4, 6, 7, 8 ... Directional coupler

Claims (2)

A first variable attenuator controlled according to the levels of the input signal and the output signal;
A distortion generation unit that generates a distortion cancellation signal that cancels distortion generated when the signal is amplified by the amplification unit;
A distortion compensation amplifying apparatus comprising a second variable attenuator provided between the distortion generator and the first variable attenuator;
A distortion compensation amplifying apparatus that controls a second variable attenuator according to an output level when a gain of an input signal is changed by the first variable attenuator. A first variable attenuator controlled according to the levels of the input signal and the output signal;
A distortion generation unit that generates a distortion cancellation signal that cancels distortion generated when the signal is amplified by the amplification unit;
A distortion compensation amplifying apparatus comprising a second variable attenuator provided between the distortion generator and the first variable attenuator;
When the gain of the input signal is changed by the first variable attenuator, the second variable attenuator is controlled according to the level of the distortion component included in the output signal and the level of the distortion cancellation signal. Distortion compensation amplifying device.

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