JP2013223227A - Distortion compensation circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distortion compensation circuit that sufficiently reduces a distortion component caused in a power amplifier.SOLUTION: An amplitude difference detector 7 detects an amplitude difference between an input signal delayed by a delay element 5 and an output signal of an attenuator 6 to detect a distortion component caused by a gain deviation of a nonlinear characteristic in a power amplifier 3, and outputs a control signal indicating a gain which solves the distortion component. A delay compensation circuit 8 performs a delay compensation process of advancing the phase of the control signal output from the amplitude difference detector 7, and outputs the delay-compensated control signal to a variable gain amplifier 2.

Description

  The present invention relates to a distortion compensation circuit that improves distortion components generated in a power amplifier.

FIG. 9 is a block diagram showing a conventional distortion compensation circuit disclosed in Patent Document 1 below.
Hereinafter, the operation of the distortion compensation circuit of FIG. 9 will be described. Here, for simplification of description, it is assumed that no phase deviation due to nonlinear characteristics occurs in the power amplifier 104.
A signal (for example, a modulated wave signal) input from the input terminal 101 is input to the variable gain amplifier 102 and the delay element 106.
A control signal output from an amplitude difference detector 108 described later is input to the control terminal of the variable gain amplifier 102, and a control signal output from a phase difference detector 109 described later is input to the control terminal of the phase shifter 103. Is entered.

The variable gain amplifier 102 amplifies the input signal with the gain indicated by the control signal output from the amplitude difference detector 108 (the gain of the variable gain amplifier 102 dynamically changes according to the control signal), and the amplified signal Is output to the phase shifter 103.
Upon receiving the amplified signal from the variable gain amplifier 102, the phase shifter 103 changes the phase of the input signal by the amount of phase shift indicated by the control signal output from the phase difference detector 109 (the passing phase of the phase shifter 103). Changes dynamically according to the control signal).
However, since it is assumed that a phase deviation due to nonlinear characteristics does not occur, the control signal for the phase shifter 103 does not change as will be described later. For this reason, since the passing phase of the phase shifter 103 does not change, the phase of the input signal and the output signal of the phase shifter 103 is the same.

The power amplifier 104 amplifies the output signal of the phase shifter 103, and outputs the amplified signal to the output terminal 105. Since the distortion component is generated by the gain deviation of the nonlinear characteristic in the power amplifier 104, the signal including the distortion component Is output to the output terminal 105.
The attenuator 107 attenuates the signal amplified by the power amplifier 104 by a predetermined level, and outputs the attenuated signal to the amplitude difference detector 108 and the phase difference detector 109.

The delay element 106 delays the signal input from the input terminal 101 by a predetermined time, and then outputs the input signal to the amplitude difference detector 108 and the phase difference detector 109.
The delay time in the delay element 106 is set to be a total value of delay times generated in the variable gain amplifier 102, the phase shifter 103, the power amplifier 104, and the attenuator 107.

The phase difference detector 109 detects the distortion component generated by the phase deviation of the nonlinear characteristic in the power amplifier 104 by detecting the phase difference between the input signal delayed by the delay element 106 and the output signal of the attenuator 107. Then, a control signal indicating the phase shift amount for eliminating the distortion component is output to the phase shifter 103.
However, since it is assumed here that the phase deviation of the nonlinear characteristic in the power amplifier 104 does not occur, the phase difference detected by the phase difference detector 109 is zero.
For this reason, the amount of phase shift indicated by the control signal output from the phase difference detector 109 is a constant value, and the phase of the input signal and the output signal of the phase shifter 103 is the same.

The amplitude difference detector 108 detects the distortion component generated by the gain deviation of the nonlinear characteristic in the power amplifier 104 by detecting the amplitude difference between the input signal delayed by the delay element 106 and the output signal of the attenuator 107. Then, a control signal indicating a gain for eliminating the distortion component is output to the variable gain amplifier 102.
As a result, the variable gain amplifier 102 operates so as to compensate for the gain deviation of the non-linear characteristic in the power amplifier 104, so that a distortion suppression effect that reduces the distortion component generated in the power amplifier 104 can be obtained.

However, since a delay due to processing occurs in analog circuits such as the variable gain amplifier 102, the phase shifter 103, the power amplifier 104, the attenuator 107, and the amplitude difference detector 108, the input timing of the input signal to the variable gain amplifier 102 There is a deviation from the input timing of the control signal.
For this reason, an error occurs between the timing when the gain deviation occurs in the power amplifier 104 and the timing when the variable gain amplifier 102 is controlled.
FIG. 10 is an explanatory diagram showing the relationship between the input signal of the variable gain amplifier 102 and the control signal, and shows that there is a difference between the input timing of the input signal and the input timing of the control signal.

JP 2002-353744 A (paragraph number [0004])

  Since the conventional distortion compensation circuit is configured as described above, processing-related delay occurs in analog circuits such as the variable gain amplifier 102, the phase shifter 103, the power amplifier 104, the attenuator 107, and the amplitude difference detector 108. If it is an ideal circuit that does not, distortion components generated in the power amplifier 104 can be sufficiently reduced. However, when a delay due to processing occurs in the analog circuit, an error occurs between the timing when the gain deviation occurs in the power amplifier 104 and the timing when the variable gain amplifier 102 is controlled. There is a problem that the compensation cannot be made and the distortion suppression effect is reduced.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a distortion compensation circuit capable of sufficiently reducing distortion components generated in a power amplifier.

  A distortion compensation circuit according to the present invention includes a variable gain amplifier that amplifies an input signal with a gain indicated by a control signal, a power amplifier that amplifies a signal amplified by the variable gain amplifier, and a signal amplified by the input signal and the power amplifier. And a distortion component detecting means for detecting a distortion component generated by a gain deviation of the nonlinear characteristic in the power amplifier and outputting a control signal indicating a gain for eliminating the distortion component, and a delay compensation circuit, A delay compensation process for advancing the phase of the control signal output from the distortion component detection means is performed, and the control signal after the delay compensation process is output to the variable gain amplifier.

  According to the present invention, the control signal indicating the gain for detecting the distortion component caused by the gain deviation of the nonlinear characteristic in the power amplifier by comparing the input signal and the signal amplified by the power amplifier, and for eliminating the distortion component The delay compensation circuit performs a delay compensation process for advancing the phase of the control signal output from the distortion component detection means, and outputs the control signal after the delay compensation process to the variable gain amplifier. With this configuration, there is an effect that distortion components generated in the power amplifier can be sufficiently reduced.

1 is a configuration diagram illustrating a distortion compensation circuit according to a first embodiment of the present invention. It is a block diagram which shows the delay compensation circuit 8 of the distortion compensation circuit by Embodiment 1 of this invention. It is a block diagram which shows the delay compensation circuit 8 of the distortion compensation circuit by Embodiment 1 of this invention. 6 is an explanatory diagram illustrating an example of a phase characteristic of the delay compensation circuit 8. FIG. 6 is an explanatory diagram showing an example of input / output signal waveforms of a delay compensation circuit 8; FIG. 4 is an explanatory diagram showing a relationship between an input signal of a variable gain amplifier 2 and a control signal. FIG. It is a block diagram which shows the distortion compensation circuit by Embodiment 2 of this invention. It is a block diagram which shows the distortion compensation circuit by Embodiment 3 of this invention. It is a block diagram which shows the conventional distortion compensation circuit currently disclosed by patent document 1. FIG. 3 is an explanatory diagram showing a relationship between an input signal of a variable gain amplifier 102 and a control signal. FIG.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a distortion compensation circuit according to Embodiment 1 of the present invention.
In FIG. 1, an input terminal 1 is a terminal for inputting a signal such as a modulated wave signal.
The variable gain amplifier 2 amplifies the signal input from the input terminal 1 with the gain indicated by the control signal output from the delay compensation circuit 8 to be described later (the gain of the variable gain amplifier 2 dynamically changes according to the control signal). The amplified signal is output to the power amplifier 3.
The power amplifier 3 amplifies the signal amplified by the variable gain amplifier 2 and outputs the amplified signal to the output terminal 4.
The output terminal 4 is a terminal that outputs a signal amplified by the power amplifier 3.

The delay element 5 delays the signal input from the input terminal 1 by a predetermined time, and then outputs the input signal to the amplitude difference detector 7.
The delay time in the delay element 5 is set to be a total value of delay times generated in the variable gain amplifier 2, the power amplifier 3, and the attenuator 6.
The attenuator 6 attenuates the signal amplified by the power amplifier 3 by a predetermined level, and outputs the attenuated signal to the amplitude difference detector 7.
The amplitude difference detector 7 detects the distortion component caused by the gain deviation of the nonlinear characteristic in the power amplifier 3 by detecting the amplitude difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6. The control signal indicating the gain for eliminating the distortion component is output to the delay compensation circuit 8.
The delay element 5, the attenuator 6, and the amplitude difference detector 7 constitute distortion component detection means.

  The delay compensation circuit 8 changes the phase of the control signal output from the amplitude difference detector 7 by the delay time associated with the processing of the variable gain amplifier 2, power amplifier 3, attenuator 6, amplitude difference detector 7 and delay compensation circuit 8. The advanced delay compensation process is performed, and the control signal after the delay compensation process is output to the control terminal of the variable gain amplifier 2.

FIG. 2 is a block diagram showing the delay compensation circuit 8 of the distortion compensation circuit according to the first embodiment of the present invention.
In FIG. 2, the differential amplifier 11 receives the control signal output from the amplitude difference detector 7 from the first input terminal, and amplifies the difference between the control signal and the signal input from the second input terminal. The amplified signal is output from the output terminal as a control signal after delay compensation processing.
One end of the resistor 12 is connected to the output terminal of the differential amplifier 11, and the other end is connected to the second input terminal of the differential amplifier 11.
The capacitor 13 has one end connected to the other end of the resistor 12 and the other end connected to a reference potential (ground).

Although FIG. 2 shows an example in which the delay compensation circuit 8 includes the differential amplifier 11, the resistor 12, and the capacitor 13, the delay compensation circuit 8 may be configured as shown in FIG.
That is, the differential amplifier 21 receives the control signal output from the amplitude difference detector 7 from the first input terminal, amplifies the difference between the control signal and the signal input from the second input terminal, and outputs the difference. The amplified signal is output from the terminal as a control signal after delay compensation processing.
The resistor 22 is a first resistor having one end connected to the output terminal of the differential amplifier 21.
The inductor 23 has one end connected to the other end of the resistor 22 and the other end connected to the second input terminal of the differential amplifier 21.
The resistor 24 is a second resistor having one end connected to the other end of the inductor 23 and the other end connected to a reference potential (ground).

Next, the operation will be described.
Here, for simplification of explanation, it is assumed that the power amplifier 3 does not generate a phase deviation due to the nonlinear characteristic, but only a gain deviation of the nonlinear characteristic.
A signal (for example, a modulated wave signal) input from the input terminal 1 is input to the variable gain amplifier 2 and the delay element 5.
A control signal after delay compensation processing output from a delay compensation circuit 8 described later is input to the control terminal of the variable gain amplifier 2.

The variable gain amplifier 2 amplifies the input signal with a gain indicated by the control signal after delay compensation processing output from the delay compensation circuit 8 (the gain of the variable gain amplifier 2 dynamically changes according to the control signal), The amplified signal is output to the power amplifier 3.
When the power amplifier 3 receives the signal amplified by the variable gain amplifier 2, the power amplifier 3 amplifies the signal and outputs the amplified signal to the output terminal 4, but the distortion component is caused by the gain deviation of the nonlinear characteristic in the power amplifier 3. Therefore, a signal including a distortion component is output to the output terminal 4.
The attenuator 6 attenuates the signal amplified by the power amplifier 3 by a predetermined level, and outputs the attenuated signal to the amplitude difference detector 7.

The delay element 5 delays the signal input from the input terminal 1 by a predetermined time, and then outputs the input signal to the amplitude difference detector 7.
The delay time in the delay element 5 is set to be a total value of delay times generated in the variable gain amplifier 2, the power amplifier 3, and the attenuator 6.
The amplitude difference detector 7 detects the distortion component generated by the gain deviation of the nonlinear characteristic in the power amplifier 3 by detecting the amplitude difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6. Then, a control signal indicating a gain for eliminating the distortion component is output to the delay compensation circuit 8.

The delay compensation circuit 8 compensates for the difference between the input timing of the input signal to the variable gain amplifier 2 and the input timing of the control signal, so that the variable gain amplifier 2, the power amplifier 3, the attenuator 6, and the amplitude difference detector 7 and a delay compensation process for advancing the phase of the control signal output from the amplitude difference detector 7 for the delay time associated with the process of the delay compensation circuit 8, and the control signal after the delay compensation process is controlled by the variable gain amplifier 2. Output to the terminal.
Here, FIG. 4 is an explanatory diagram showing an example of the phase characteristics of the delay compensation circuit 8.
In FIG. 4, the horizontal axis indicates the frequency, and the vertical axis indicates the passing phase.
As is clear from FIG. 4, the phase increases as the frequency increases, so that a phase advance effect is obtained.
FIG. 5 is an explanatory diagram showing an example of input / output signal waveforms of the delay compensation circuit 8. FIG. 5 shows that the output signal advances with respect to the input signal of the delay compensation circuit 8 due to the phase advance effect of the delay compensation circuit 8. It shows a state.

The control signal output from the amplitude difference detector 7 is input to the control terminal of the variable gain amplifier 2 after the timing is advanced by the delay compensation circuit 8.
FIG. 6 is an explanatory diagram showing the relationship between the input signal of the variable gain amplifier 2 and the control signal.
As is apparent from FIG. 6, the delay time associated with the processing of the variable gain amplifier 2, the power amplifier 3, the attenuator 6, the amplitude difference detector 7, and the delay compensation circuit 8 is shortened, and the timing error between the input signal and the control signal. Is getting smaller. For this reason, the control signal input to the control terminal of the variable gain amplifier 2 is an ideal control signal with almost no delay.

  As apparent from the above, according to the first embodiment, the gain of the nonlinear characteristic in the power amplifier 3 is detected by detecting the amplitude difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6. An amplitude difference detector 7 that detects a distortion component caused by the deviation and outputs a control signal indicating a gain for eliminating the distortion component is provided, and the delay compensation circuit 8 outputs a control signal output from the amplitude difference detector 7. Since the delay compensation process for advancing the phase is implemented and the control signal after the delay compensation process is output to the variable gain amplifier 2, the distortion component generated in the power amplifier 3 can be sufficiently reduced. There is an effect.

  In the first embodiment, it is assumed that the amplitude difference detector 7 is configured by an analog circuit. However, the amplitude difference detector 7 may be configured by a digital circuit, and the same effect can be obtained.

Embodiment 2. FIG.
FIG. 7 is a block diagram showing a distortion compensating circuit according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG.
The phase shifter 31 changes the phase of the signal input from the input terminal 1 by the amount of phase shift indicated by the control signal output from the delay compensation circuit 33 described later (the passing phase of the phase shifter 31 depends on the control signal). Change dynamically).

The phase difference detector 32 detects the distortion component generated by the phase deviation of the nonlinear characteristic in the power amplifier 3 by detecting the phase difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6. Then, a control signal indicating the phase shift amount for eliminating the distortion component is output to the delay compensation circuit 33.
The delay element 5, the attenuator 6 and the phase difference detector 32 constitute a distortion component detection means.

The delay compensation circuit 33 changes the phase of the control signal output from the phase difference detector 32 by the delay time associated with the processing of the phase shifter 31, power amplifier 3, attenuator 6, phase difference detector 32 and delay compensation circuit 33. The advanced delay compensation process is performed, and the control signal after the delay compensation process is output to the control terminal of the phase shifter 31.
Note that the delay compensation circuit 33 is configured as shown in FIG. 2 or FIG. 3, as with the delay compensation circuit 8 of FIG.

Next, the operation will be described.
Here, for simplification of explanation, it is assumed that the power amplifier 3 does not generate a gain deviation due to the non-linear characteristic but only a non-linear characteristic phase deviation.
A signal (for example, a modulated wave signal) input from the input terminal 1 is input to the phase shifter 31 and the delay element 5.
A control signal after delay compensation processing output from a delay compensation circuit 33 described later is input to the control terminal of the phase shifter 31.

The phase shifter 31 changes the phase of the signal input from the input terminal 1 by the amount of phase shift indicated by the control signal output from the delay compensation circuit 33 (the passing phase of the phase shifter 31 varies according to the control signal). Will change).
When the power amplifier 3 receives the output signal of the phase shifter 31, the power amplifier 3 amplifies the signal and outputs the amplified signal to the output terminal 4. However, a distortion component is generated due to the phase deviation of the nonlinear characteristic in the power amplifier 3. , A signal including a distortion component is output to the output terminal 4.
The attenuator 6 attenuates the signal amplified by the power amplifier 3 by a predetermined level, and outputs the attenuated signal to the phase difference detector 32.

The delay element 5 delays the signal input from the input terminal 1 by a predetermined time, and then outputs the input signal to the phase difference detector 32.
The delay time in the delay element 5 is set to be a total value of delay times generated in the phase shifter 31, the power amplifier 3 and the attenuator 6.
The phase difference detector 32 detects the phase difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6, thereby detecting distortion components generated by the phase deviation of the nonlinear characteristic in the power amplifier 3. Then, a control signal indicating a phase shift amount for eliminating the distortion component is output to the delay compensation circuit 33.

The delay compensation circuit 33 compensates for a shift between the input timing of the input signal to the phase shifter 31 and the input timing of the control signal, so that the phase shifter 31, the power amplifier 3, the attenuator 6, and the phase difference detector. 32 and the delay compensation circuit 33, a delay compensation process for advancing the phase of the control signal output from the phase difference detector 32 is performed for the delay time associated with the process of the delay compensation circuit 33, and the control signal after the delay compensation process is controlled by the phase shifter 31. Output to the terminal.
The phase advance effect by the delay compensation circuit 33 is the same as the phase advance effect by the delay compensation circuit 8 of FIG.

The control signal output from the phase difference detector 32 is input to the control terminal of the phase shifter 31 after the timing is advanced by the delay compensation circuit 33.
In the case of the second embodiment, similarly to the first embodiment, the delay time associated with the processing of the phase shifter 31, the power amplifier 3, the attenuator 6, the phase difference detector 32, and the delay compensation circuit 33 is shortened. Thus, the timing error between the input signal and the control signal is small (see FIG. 6).
For this reason, the control signal input to the control terminal of the phase shifter 31 is an ideal control signal with almost no delay.

  As apparent from the above, according to the second embodiment, the phase difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6 is detected, so that the phase of the nonlinear characteristic in the power amplifier 3 is detected. A phase difference detector 32 that detects a distortion component caused by the deviation and outputs a control signal indicating a phase shift amount that eliminates the distortion component is provided, and the delay compensation circuit 33 is output from the phase difference detector 32. Since the delay compensation process for advancing the phase of the control signal is performed and the control signal after the delay compensation process is output to the phase shifter 31, the distortion component generated in the power amplifier 3 can be sufficiently reduced. There is an effect that can.

  In the first embodiment, it is assumed that the phase difference detector 32 is configured by an analog circuit. However, the phase difference detector 32 may be configured by a digital circuit, and similar effects can be obtained.

Embodiment 3 FIG.
In the first embodiment, the gain deviation of the nonlinear characteristic in the power amplifier 3 is compensated. In the second embodiment, the phase deviation of the nonlinear characteristic in the power amplifier 3 is compensated. Now, what compensates for both the gain deviation and the phase deviation of the nonlinear characteristic in the power amplifier 3 will be described.
FIG. 8 is a block diagram showing a distortion compensation circuit according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIGS.
However, in the third embodiment, the amplitude difference detector 7 constitutes first distortion component detection means, and the phase difference detector 32 constitutes second distortion component detection means.
The delay compensation circuit 8 constitutes a first delay compensation circuit, and the delay compensation circuit 33 constitutes a second delay compensation circuit.

Next, the operation will be described.
A signal (for example, a modulated wave signal) input from the input terminal 1 is input to the variable gain amplifier 2 and the delay element 5.
A control signal after delay compensation processing output from the delay compensation circuit 8 is input to the control terminal of the variable gain amplifier 2, and delay compensation processing output from the delay compensation circuit 33 is input to the control terminal of the phase shifter 31. Later control signals are input.

The variable gain amplifier 2 amplifies the input signal with a gain indicated by the control signal after delay compensation processing output from the delay compensation circuit 8, and outputs the amplified signal to the phase shifter 31.
The phase shifter 31 changes the phase of the signal amplified by the variable gain amplifier 2 by the amount of phase shift indicated by the control signal output from the delay compensation circuit 33.
When the power amplifier 3 receives the output signal of the phase shifter 31, the power amplifier 3 amplifies the signal and outputs the amplified signal to the output terminal 4, but the distortion component is caused by the gain deviation and phase deviation of the nonlinear characteristic in the power amplifier 3. Therefore, a signal including a gain deviation distortion component and a phase deviation distortion component is output to the output terminal 4.
The attenuator 6 attenuates the signal amplified by the power amplifier 3 by a predetermined level, and outputs the attenuated signal to the amplitude difference detector 7 and the phase difference detector 32.

The delay element 5 delays the signal input from the input terminal 1 by a predetermined time, and then outputs the input signal to the amplitude difference detector 7 and the phase difference detector 32.
The delay time in the delay element 5 is set to be a total value of delay times generated in the variable gain amplifier 2, the phase shifter 31, the power amplifier 3 and the attenuator 6.

The amplitude difference detector 7 detects the distortion component generated by the gain deviation of the nonlinear characteristic in the power amplifier 3 by detecting the amplitude difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6. Then, a control signal (first control signal) indicating a gain for eliminating the distortion component is output to the delay compensation circuit 8.
The phase difference detector 32 detects the phase difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6, thereby detecting distortion components generated by the phase deviation of the nonlinear characteristic in the power amplifier 3. Then, a control signal (second control signal) indicating a phase shift amount for eliminating the distortion component is output to the delay compensation circuit 33.

  The delay compensation circuit 8 compensates for a shift between the input timing of the input signal to the variable gain amplifier 2 and the input timing of the control signal, so that the variable gain amplifier 2, the phase shifter 31, the power amplifier 3, and the attenuator 6 are compensated. The delay compensation process for advancing the phase of the control signal output from the amplitude difference detector 7 is performed only for the delay time associated with the processes of the amplitude difference detector 7 and the delay compensation circuit 8, and the control signal after the delay compensation process is variable. Output to the control terminal of the gain amplifier 2.

  The delay compensation circuit 33 compensates for a shift between the input timing of the input signal to the phase shifter 31 and the input timing of the control signal, so that the phase shifter 31, the power amplifier 3, the attenuator 6, and the phase difference detector. 32 and the delay compensation circuit 33, a delay compensation process for advancing the phase of the control signal output from the phase difference detector 32 is performed for the delay time associated with the process of the delay compensation circuit 33, and the control signal after the delay compensation process is controlled by the phase shifter 31. Output to the terminal.

The control signal output from the amplitude difference detector 7 is input to the control terminal of the variable gain amplifier 2 after the timing is advanced by the delay compensation circuit 8.
As a result, similarly to the first embodiment, the delay time associated with the processing of the variable gain amplifier 2, the phase shifter 31, the power amplifier 3, the attenuator 6, the amplitude difference detector 7, and the delay compensation circuit 8 is shortened. The timing error between the input signal and the control signal is small. For this reason, the control signal input to the control terminal of the variable gain amplifier 2 is an ideal control signal with almost no delay.

The control signal output from the phase difference detector 32 is input to the control terminal of the phase shifter 31 after the timing is advanced by the delay compensation circuit 33.
As a result, as in the second embodiment, the delay time associated with the processing of the phase shifter 31, the power amplifier 3, the attenuator 6, the phase difference detector 32, and the delay compensation circuit 33 is shortened, and the input signal and the control are controlled. The signal timing error is small.
For this reason, the control signal input to the control terminal of the phase shifter 31 is an ideal control signal with almost no delay.

  As apparent from the above, according to the third embodiment, the gain of the nonlinear characteristic in the power amplifier 3 is detected by detecting the amplitude difference between the input signal delayed by the delay element 5 and the output signal of the attenuator 6. An amplitude difference detector 7 for detecting a distortion component caused by the deviation and outputting a control signal indicating a gain for eliminating the distortion component; an input signal delayed by the delay element 5 and an output signal of the attenuator 6; By detecting the phase difference, the distortion component generated by the phase deviation of the nonlinear characteristic in the power amplifier 3 is detected, and the phase difference detector 32 that outputs a control signal indicating the phase shift amount for eliminating the distortion component is provided. The delay compensation circuit 8 performs a delay compensation process for advancing the phase of the control signal output from the amplitude difference detector 7, outputs the control signal after the delay compensation process to the variable gain amplifier 2, and the delay compensation circuit 33. Is the phase difference detector 3 Since the delay compensation process for advancing the phase of the control signal output from the control signal is implemented and the control signal after the delay compensation process is output to the phase shifter 31, the distortion component generated in the power amplifier 3 is sufficiently eliminated. There is an effect that can be reduced.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  1 input terminal, 2 variable gain amplifier, 3 power amplifier, 4 output terminal, 5 delay element (distortion component detection means), 6 attenuator (distortion component detection means), 7 amplitude difference detector (distortion component detection means), 8 Delay compensation circuit, 11 differential amplifier, 12 resistor, 13 capacitor, 21 differential amplifier, 22 resistor (first resistor), 23 inductor, 24 resistor (second resistor), 31 phase shifter, 32 phase difference detection (Distortion component detection means), 33 delay compensation circuit, 101 input terminal, 102 variable gain amplifier, 103 phase shifter, 104 power amplifier, 105 output terminal, 106 delay element, 107 attenuator, 108 amplitude difference detector, 109 Phase difference detector.

Claims (8)

A variable gain amplifier that amplifies the input signal with the gain indicated by the control signal;
A power amplifier for amplifying the signal amplified by the variable gain amplifier;
The input signal and the signal amplified by the power amplifier are compared, a distortion component generated by a gain deviation of the nonlinear characteristic in the power amplifier is detected, and a control signal indicating a gain for eliminating the distortion component is output. Distortion component detection means;
A distortion compensation circuit comprising: a delay compensation circuit that performs a delay compensation process for advancing the phase of the control signal output from the distortion component detection means and outputs the control signal after the delay compensation process to the variable gain amplifier.   The delay compensation circuit performs a delay compensation process for advancing the phase of the control signal output from the distortion component detection unit by a delay time generated by the variable gain amplifier, the power amplifier, the distortion component detection unit, and the delay compensation circuit. The distortion compensation circuit according to claim 1, wherein: A phase shifter that changes the phase of the input signal by the phase shift amount indicated by the control signal;
A power amplifier for amplifying the output signal of the phase shifter;
The input signal and the signal amplified by the power amplifier are compared to detect a distortion component caused by the phase deviation of the nonlinear characteristic in the power amplifier, and a control signal indicating a phase shift amount that eliminates the distortion component Distortion component detection means for outputting;
A distortion compensation circuit comprising: a delay compensation circuit that performs a delay compensation process for advancing the phase of the control signal output from the distortion component detection means, and outputs the control signal after the delay compensation process to the phase shifter.   The delay compensation circuit performs a delay compensation process for advancing the phase of the control signal output from the distortion component detection unit by a delay time generated by the phase shifter, the power amplifier, the distortion component detection unit, and the delay compensation circuit. 4. The distortion compensation circuit according to claim 3, wherein A variable gain amplifier that amplifies the input signal with a gain indicated by the first control signal;
A phase shifter that changes the phase of the signal amplified by the variable gain amplifier by the amount of phase shift indicated by the second control signal;
A power amplifier for amplifying the output signal of the phase shifter;
A first control signal indicating a gain that eliminates the distortion component by comparing the input signal and the signal amplified by the power amplifier to detect a distortion component caused by a gain deviation of a nonlinear characteristic in the power amplifier First distortion component detection means for outputting
Comparing the input signal and the signal amplified by the power amplifier to detect a distortion component caused by the phase deviation of the nonlinear characteristic in the power amplifier, and to display a second phase shift amount that eliminates the distortion component; Second distortion component detection means for outputting a control signal;
A first delay for performing a delay compensation process for advancing the phase of the first control signal output from the first distortion component detection means and outputting the first control signal after the delay compensation process to the variable gain amplifier A compensation circuit;
A second delay for performing a delay compensation process for advancing the phase of the second control signal output from the second distortion component detection means and outputting the second control signal after the delay compensation process to the phase shifter; A distortion compensation circuit comprising: a compensation circuit. The first delay compensation circuit outputs from the first distortion component detection means only the delay time generated by the variable gain amplifier, the phase shifter, the power amplifier, the first distortion component detection means and the first delay compensation circuit. A delay compensation process for advancing the phase of the first control signal generated,
The second delay compensation circuit is output from the second distortion component detection means for the delay time generated in the phase shifter, the power amplifier, the second distortion component detection means, and the second delay compensation circuit. The distortion compensation circuit according to claim 5, wherein a delay compensation process for advancing the phase of the second control signal is performed. Delay compensation circuit
The control signal output from the distortion component detection means is input from the first input terminal, the difference between the control signal and the signal input from the second input terminal is amplified, and the amplified signal is delayed from the output terminal A differential amplifier that outputs as a control signal after compensation processing;
A resistor having one end connected to the output terminal of the differential amplifier and the other end connected to the second input terminal of the differential amplifier;
The distortion according to any one of claims 1 to 6, wherein one end is connected to the other end of the resistor and the other end is connected to a reference potential. Compensation circuit. Delay compensation circuit
The control signal output from the distortion component detection means is input from the first input terminal, the difference between the control signal and the signal input from the second input terminal is amplified, and the amplified signal is delayed from the output terminal A differential amplifier that outputs as a control signal after compensation processing;
A first resistor having one end connected to the output terminal of the differential amplifier;
An inductor having one end connected to the other end of the first resistor and the other end connected to a second input terminal of the differential amplifier;
7. The device according to claim 1, further comprising: a second resistor having one end connected to the other end of the inductor and the other end connected to a reference potential. The distortion compensation circuit described.

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