JP2008160299A - Distortion compensation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distortion compensation device capable of reducing the influence of high order intermodulation distortion with a simple device configuration, obtaining a sufficient distortion compensation amount, and facilitating control. <P>SOLUTION: The distortion compensation device is provided with third order and fifth order distortion generators 18 of an analog circuit for generating third order distorted components and fifth order distorted components, a variable phase shifter 142 for controlling the phase of distortion generated in the distortion generator 18, and a variable attenuator 152 for controlling the amplitude of the distortion. The third order and the fifth order distortion generator 18 is provided with a distortion adjustment circuit for adjusting the phase and amplitude of the generated third order distorted component and fifth order distorted component so that the relation of the phase and the amplitude of the generated third order distorted component and fifth order distorted component is equal to the relation of the phase and the amplitude of the third order distorted component and the fifth order distorted component generated in an amplifier. In the variable phase shifter 142 and the variable attenuator 152, the phase or the amplitude of the third order distorted component and the fifth order distorted component can be adjusted altogether. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a distortion compensation apparatus that reduces distortion generated in an amplifier, and more particularly to a distortion compensation apparatus that has excellent distortion compensation characteristics with a simple configuration and can be easily controlled.

As represented by mobile phones, systems using radio waves have become widespread in recent years. Many of these wireless systems employ a linear modulation method, and linearity is required for an amplifier circuit that amplifies the signal.
Further, as represented by multicarrier amplification, cost reduction and improvement in amplification efficiency are required by performing common amplification.
In order to meet these demands, there is an amplifying apparatus (distortion compensating amplifying apparatus) that employs a distortion compensating method, and various distortion compensating methods are used.

Distortion compensation is realized by canceling distortion generated in the amplifier. As a distortion compensation method, a method using the distortion itself generated by the amplifier (feed forward, feedback) and a method using a distortion generated using an element different from the amplifier to be compensated (predistortion compensation, pre-distortion). Distortion).
Further, predistortion compensation includes an analog method using an analog element and a digital method using a digital signal processing device such as a DSP (Digital Signal Processor).

The digital predistortion compensation method has the advantages of realizing a high distortion compensation amount, good power efficiency, and good productivity, but has the disadvantage that the circuit scale is large and the device cost is high.
Although the analog predistortion compensation method has the disadvantage that the amount of distortion compensation is small compared to other distortion compensation methods, it has recently been reviewed due to its small circuit scale and excellent economy.

Here, a conventional analog predistortion compensation apparatus will be described with reference to FIG. FIG. 11A is a schematic block diagram of an amplification device with a predistortion device, and FIG. 11B is a block diagram of a conventional analog predistortion compensation circuit.
As shown in FIG. 11A, the amplifying apparatus with a predistortion device includes a predistortion circuit 1 in the previous stage of the main amplifier 2, and has distortion that is the reverse characteristic of the nonlinear distortion generated in the main amplifier 2. By adding in advance by the predistortion circuit 1, the distortion generated in the main amplifier 2 is compensated.

  As shown in FIG. 11B, a conventional analog predistortion compensation circuit (hereinafter referred to as “analog PD (Pre Distorter)”) includes a distributor 11, a delay line 12, and a third-order distortion generator 13. And a variable phase shifter 14, a variable attenuator 15, and a combiner 17.

The distributor 11 distributes an input signal.
The delay line 12 delays the distributed input signal for a predetermined time.
The third-order distortion generator 13 is adjusted in advance according to the third-order distortion generated by the amplifier 2 and generates third-order distortion.
The variable phase shifter 14 controls the phase of the third-order distortion generated by the third-order distortion generator 13.
The variable attenuator 15 controls the amplitude of the third-order distortion whose phase is adjusted. The variable phase shifter 14 and variable attenuator 15 perform vector adjustment.

The operation of the analog PD having the above configuration will be briefly described.
The input signal is distributed by the distributor 11, one being input to the delay line 12 and the other being input to the third-order distortion generator 13.
The third-order distortion generator 13 generates third-order distortion in accordance with the input signal so that the third-order distortion signal has an equal amplitude opposite phase to the distortion component to be compensated by the variable phase shifter 14 and the variable attenuator 15. The phase and amplitude are controlled and input to the synthesizer 17 as a distortion compensation signal.

The signal input to the delay line 12 is delayed for a certain time and input to the synthesizer 17, and is combined with the distortion compensation signal in the synthesizer 17 and input to the amplifier 2 as an input signal. The distortion generated when the amplifier 2 amplifies and the distortion compensation signal synthesized in advance with the input signal are canceled out to obtain an amplified output including no distortion.
In this way, in the conventional analog PD, the third-order distortion that appears at the largest level in the vicinity of the signal component is compensated.

Next, the principle of distortion compensation will be briefly described with reference to FIG. FIG. 12 is a schematic explanatory diagram illustrating the principle of distortion compensation.
As shown in FIG. 12, if there are a third-order distortion component and a fifth-order distortion component as distortion components generated by the amplifier separately from the linear component, their signal vectors have the same magnitude (equal amplitude). It is only necessary to synthesize a signal vector (in the figure, “third-order distortion signal included in the amplifier input” and “fifth-order distortion signal included in the amplifier input”) in the opposite direction (reverse phase) into the input signal in advance. .
As a result, the distortion component generated in the amplifier and the distortion signal synthesized in advance cancel each other, and a linear component not including distortion can be obtained.

Here, the spectrum of the amplifier output will be described with reference to FIG. FIG. 13 is an explanatory diagram showing an output spectrum of the amplifier 2.
As shown in FIG. 13, when the amplifier output is close to the saturation output level, the output of the amplifier 2 has intermodulation distortion on the low frequency side and high frequency side of the signal component in addition to the fundamental wave component (signal component). included. From a position close to the signal component, third-order distortion, fifth-order distortion,...
In the example shown in FIG. 13, when the fundamental wave components are ω1 and ω2, 2ω1−ω2, 3rd order distortion components of 2ω2−ω1, 3ω1−2ω2, and 5th order distortion components of 3ω2−2ω1 are generated. In addition, the distortion component of each order also affects the low-order distortion and the fundamental wave component located inside (the fundamental wave component side).

In addition, as a prior art regarding a predistorter, there exists Unexamined-Japanese-Patent No. 2005-333353 "Predistorter" (applicant: Hitachi Kokusai Electric, Inc., inventor: Naoki Moe) published on December 2, 2005.
In this prior art, an amplifier replica means having input / output characteristics that are the same as or approximate to the input / output characteristics of the amplifier to be compensated for distortion is inputted and outputted, and the difference detection means is an input signal to the predistorter. And the amplifier replica signal changing means change the signal input to the amplifier replica means so that the difference detected by the difference detecting means is reduced, and this signal is This is output to the amplifier and can compensate for distortion generated in the amplifier.

JP 2005-333353 A

  However, if the amplifier is used in a higher output state, not only third-order distortion but also higher-order intermodulation distortion (5th order, 7th order,...) Is generated. This has an effect on low-order distortion, and the conventional predistortion device has a problem that the amount of distortion compensation is reduced.

  For example, the fifth-order distortion affects the third-order distortion, and the characteristics of the third-order distortion change because of the fifth-order distortion. Therefore, the pre-distortion compensation has a characteristic that cancels the original third-order distortion. In the apparatus, the characteristics are shifted and a sufficient amount of distortion compensation cannot be obtained.

Accordingly, a predistortion device shown in FIG. 14 has been proposed as a configuration for solving the problems of the conventional predistortion device. FIG. 14 is a block diagram showing the configuration of the proposed distortion compensation apparatus.
As shown in FIG. 14, the proposed distortion compensation apparatus includes distributors 110 and 111, a delay line 12, a third-order distortion compensation signal generation circuit 3, a fifth-order distortion compensation signal generation circuit 5, and a combiner. 170 and 171 and the main amplifier 2.

  Further, the third-order distortion compensation signal generation circuit 3 includes a third-order distortion generator 13, a variable phase shifter 140, and a variable attenuator 150. Similarly, the fifth-order distortion compensation signal generation circuit 5 includes 5 The second distortion generator 16, the variable phase shifter 141, and the variable attenuator 151 are included.

The distributor 110 distributes the input signal to the delay line 12 and the distributor 111.
The distributor 111 distributes the input signal to the third-order distortion compensation signal generation circuit 3 and the fifth-order distortion compensation signal generation circuit 5.
The third-order distortion compensation signal generation circuit 3 is the same as that shown in FIG. 11 and is a circuit that generates a third-order distortion compensation signal having the same amplitude and opposite phase as the third-order distortion generated by the amplifier 2.
The third-order distortion generator 13 generates a third-order distortion component.
The variable phase shifter 140 controls the phase of the third-order distortion component independently, and the variable attenuator 150 controls the amplitude of the third-order distortion component independently.

  Similarly, the fifth-order distortion compensation signal generation circuit 5 is a circuit that generates a fifth-order distortion compensation signal having the same amplitude and opposite phase as the fifth-order distortion generated in the amplifier 2, and the fifth-order distortion generator 16 is a third-order distortion component. The variable phase shifter 141 adjusts the phase of the fifth-order distortion component, and the variable attenuator 151 adjusts the amplitude of the fifth-order distortion component.

The combiner 171 combines the fifth-order distortion compensation signal generated by the fifth-order distortion compensation signal generation circuit 5 and vector-adjusted with the third-order distortion compensation signal generated by the third-order distortion compensation signal generation circuit 3 and vector-adjusted. To do.
The synthesizer 170 synthesizes the (3rd order + 5th order) distortion compensation signal from the synthesizer 171 and the input signal from the delay line 12 and outputs them to the amplifier 2.
The amplifier 2 amplifies the input signal.

  In other words, the proposed distortion compensator includes a distortion generator that generates distortion corresponding to each order of nonlinear distortion, and a vector adjuster that independently controls the phase and amplitude of distortion generated in each distortion generator. A plurality of distortion compensation signal generation circuits provided in parallel with the delay line 12 are configured so that vector adjustment of distortion components generated for each order is performed independently, and accuracy is provided for each distortion compensation signal generation circuit of each order. It is possible to perform high vector adjustment.

  However, in the above distortion compensation device, the distortion signal for each order is generated independently, and the phase and amplitude of the distortion signal of each order are controlled independently. It could not be said that the consideration for doing was sufficient.

  The present invention has been made in view of the above circumstances, and can reduce the influence of high-order intermodulation distortion with a simple device configuration, obtain a sufficient distortion compensation amount, and facilitate control. It is an object of the present invention to provide a distortion compensation device capable of achieving the above.

  The present invention for improving the above conventional example includes a distortion generator that generates nonlinear distortion, and a vector adjuster that adjusts the phase and amplitude of distortion output from the distortion generator. A distortion compensation device that compensates for nonlinear distortion generated in an amplifier by synthesizing it with an input signal of the amplifier, wherein the distortion generator is composed of an analog circuit and generates a plurality of distortion components having different orders. And the phase shift and amplitude ratio of distortion components of different orders generated in each distortion generation circuit are equal to the phase shift and amplitude ratio of distortion components of different orders included in the nonlinear distortion generated in the amplifier. Thus, the distortion generator includes a distortion adjustment circuit that adjusts the phase and amplitude of the distortion component generated in each distortion generation circuit.

  According to the present invention, in the distortion compensation apparatus, a distortion generator generates a third-order distortion component from a distributed input signal, and a third-order distortion component generated by the third-order distortion generation circuit. A first distortion adjustment circuit that adjusts the phase and amplitude; a fifth-order distortion generation circuit that generates a fifth-order distortion component from the distributed input signal; and the phase and amplitude of the fifth-order distortion component generated by the fifth-order distortion generation circuit A second distortion adjustment circuit for adjusting the frequency, a fundamental wave cancellation circuit for reflecting a linear component generated together with the third-order distortion component or the fifth-order distortion component in each distortion generation circuit, and 3 adjusted by the first distortion adjustment circuit. The third-order distortion component adjusted by combining the signal including the fifth-order distortion component and the linear component adjusted by the second-order distortion adjustment circuit and the linear component reflected by the fundamental wave cancellation circuit. And a combiner that outputs the adjusted fifth-order distortion component. It is set to.

  According to the present invention, the distortion generator is composed of an analog circuit having a simple configuration, and a plurality of distortion generation circuits that generate distortion components having different orders, and phases of distortion components having different orders generated in the respective distortion generation circuits. The phase and amplitude of the distortion component generated in each distortion generating circuit is equal to the phase deviation and amplitude ratio of distortion components of different orders included in the nonlinear distortion generated in the amplifier. Since the distortion compensation device includes a distortion adjustment circuit to be adjusted, the vector adjustment amount to be adjusted in the vector adjuster is the same for any order of distortion components, and a plurality of distortion components of different orders are collectively The distortion generated by the amplifier can be compensated for, and a sufficient distortion compensation amount considering high-order distortion can be obtained with a simple device configuration, and the distortion compensation control can be facilitated. it can There is a result.

  According to the present invention, in the distortion compensation apparatus, the distortion generator generates a third-order distortion component, and a first distortion adjustment circuit adjusts the phase and amplitude of the third-order distortion component. A fifth-order distortion generation circuit that generates a fifth-order distortion component, a second distortion adjustment circuit that adjusts the phase and amplitude of the fifth-order distortion component, and a third-order distortion component or a fifth-order distortion component in each distortion generation circuit Combining a fundamental wave cancellation circuit that reflects a generated linear component, a signal that includes the adjusted third-order distortion component, a fifth-order distortion component, and a linear component, and a linear component reflected by the fundamental wave cancellation circuit; Since the distortion compensation apparatus includes a coupler that outputs the adjusted third-order distortion component and fifth-order distortion component, the relationship between the phase and amplitude of the third-order distortion component and the fifth-order distortion component generated in the amplifier, and the distortion The phase and amplitude relationship between the third-order distortion and the fifth-order distortion output from the generator are made equal to each other. The third-order distortion component and the fifth-order distortion component have the same vector adjustment amount to be adjusted in the torque adjuster, and the third-order distortion component and the fifth-order distortion component can be vector-adjusted collectively, thereby controlling distortion compensation There is an effect that can be facilitated.

Embodiments of the present invention will be described with reference to the drawings.
The distortion compensator according to the present invention provides a phase shift and amplitude ratio between the third-order distortion and the fifth-order distortion generated by the distortion generator, and a ratio between the phase shift and amplitude between the third-order distortion and the fifth-order distortion generated by the amplifier. A distortion adjustment circuit that adjusts so that the phase and amplitude of the third-order distortion and fifth-order distortion generated by the distortion generator are adjusted at a time and synthesized with the input signal of the amplifier. Adjustment of the phase and amplitude of the distortion generated by the distortion generator can be performed in a lump, and the apparatus configuration can be simplified and distortion compensation control can be simplified.

FIG. 1 is a block diagram showing the configuration of a distortion compensation apparatus according to the first embodiment of the present invention.
As shown in FIG. 1, the distortion compensation apparatus (first distortion compensation apparatus) according to the first embodiment of the present invention includes a distributor 112, a delay line 12, and a third-order and fifth-order distortion generator 18. And a variable phase shifter 142, a variable attenuator 152, a combiner 172, and a main amplifier 2.
Among the components described above, the configuration and operation of the distributor 112, the delay line 12, the combiner 172, and the main amplifier 2 are the same as those in the prior art, and thus description thereof is omitted.

A characteristic part of the first distortion compensation device will be described.
The third-order / fifth-order distortion generator 18, which is a characteristic part of the first distortion compensator, is a composite signal (third-order / fifth-order) of a third-order distortion component and a fifth-order distortion component which are nonlinear distortions generated in the main amplifier 2. This is an analog circuit that generates distortion. Here, as a feature of the first distortion compensation device, in the third-order / fifth-order distortion generator 18, the relationship between the phase and amplitude in the third-order distortion component and the fifth-order distortion component generated in the main amplifier 2 is equalized. A third-order distortion component and a fifth-order distortion component whose phase and amplitude are adjusted are generated, and a signal obtained by synthesizing them is output.

  The “relationship between phase and amplitude” means “phase shift” and “ratio of amplitude”, and represents the third-order distortion component and fifth-order distortion component generated by the third-order / fifth-order distortion generator 18. The above adjustment is performed so that the “phase shift” and the “amplitude ratio” are equal to the “phase shift” and the “amplitude ratio” of the third-order distortion component and the fifth-order distortion component generated in the main amplifier 2. is there.

The variable phase shifter 142 adjusts the phase of the third-order and fifth-order distortions from the third-order and fifth-order distortion generator 18, and the third-order distortion component and the fifth-order distortion component generated in the main amplifier 2 are opposite in phase to each other. To do.
The variable attenuator 152 adjusts the amplitude of the third-order and fifth-order distortions that have undergone phase adjustment, and reverses the same amplitude as the combined distortion of the third-order distortion component and the fifth-order distortion component generated in the main amplifier 2. A phase distortion compensation signal is output.
Note that the variable phase shifter 142 and the variable attenuator 152 perform vector adjustment, and the order may be reversed.

  Here, the phase shift and amplitude ratio between the third-order distortion component and the fifth-order distortion component included in the third-order / fifth-order distortion are the phase shift between the third-order distortion component and the fifth-order distortion component generated in the main amplifier 2. And the third order distortion component and the fifth order included in the output signal from the third order / fifth order distortion generator 18 in order to compensate for the distortion generated in the main amplifier 2. The phase adjustment amount and the amplitude adjustment amount required for the distortion component are equal to each other, and the phase can be adjusted by the single variable phase shifter 142 and the amplitude can be adjusted by the single variable attenuator 152. It is.

The operation of the first distortion compensation device will be described.
One of the signals distributed by the distributor 112 is input to the third-order / fifth-order distortion generator 18, and a third-order distortion component and a fifth-order distortion component are generated based on the input signal and are generated by the main amplifier 2. The phase and amplitude are adjusted so as to be equal to the relationship between the phase and amplitude in the second-order distortion component and the fifth-order distortion component, and the resultant is combined and output as third-order and fifth-order distortion.

  The third and fifth order distortions are adjusted in phase and amplitude by the variable phase shifter 142 and the variable attenuator, and have the same amplitude and the same amplitude as the combined distortion of the third and fifth order distortion components generated in the main amplifier 2. It becomes a distortion compensation signal.

  The combiner 172 combines the signal from the delay line 12 and the distortion-compensated signal is input to the main amplifier 2 and is amplified. The distortion generated here and the distortion-compensation signal cancel each other to compensate for distortion. To be done.

Next, the configuration of the third-order / fifth-order distortion generator 18 of the first distortion compensation apparatus will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the third and fifth order distortion generator 18 of the first distortion compensation apparatus.
As shown in FIG. 2, the third-order / fifth-order distortion generator 18 includes a coupler 19, a distortion generation circuit 25, and a fundamental wave cancellation circuit 24.
The distortion generation circuit 25 generates distortion, but at this time, a linear component is also generated.
The fundamental wave canceling circuit 24 reflects the linear component included in the combined signal of the distortion component generated by the distortion generating circuit 25 and the linear component and inputs it to the coupler 19, and is adjusted so that the linear components cancel each other. Yes.

  The combiner 19 distributes the signal distributed by the distributor 112 to the distortion generation circuit 25 and the fundamental wave cancellation circuit 24, and combines the distortion component and linear component generated by the distortion generation circuit 25 and the fundamental wave cancellation circuit. The linear component reflected from 24 is combined to cancel the linear component and extract only the distortion.

The distortion generation circuit 25 includes a distributor 20, a third-order distortion generation circuit 21, a fifth-order distortion generation circuit 22, and distortion adjustment circuits 23a and 23b.
The distributor 20 distributes the input signal to the third-order distortion generation circuit 21 and the fifth-order distortion generation circuit 22, and outputs the third-order distortion component and the fifth-order distortion component that are reflected and adjusted to the coupler 19.

  The third-order distortion generating circuit 21 generates a third-order distortion component, and the fifth-order distortion generating circuit 22 generates a fifth-order distortion component. These distortion generation circuits are configured by a non-linear circuit having a single diode configuration or an anti-parallel diode configuration, or an element having nonlinear characteristics such as a transistor or an FET.

  The distortion adjustment circuit 23a adjusts the phase and amplitude by reflecting the third-order distortion component from the third-order distortion generation circuit 21, and the distortion adjustment circuit 23b similarly applies the fifth-order distortion from the fifth-order distortion generation circuit 22. The phase and amplitude of the component are adjusted. The distortion adjustment circuits 23a and 23b are configured by a transmission line such as a microstrip line, a circuit element such as a capacitor or a coil, or a circuit combining these elements.

  Although not shown in FIG. 2, a phase shifter (for example, a fixed transmission line) is inserted between the distributor 20 and each of the distortion generators 21 and 22, and the distortion adjusting circuits 23a and 23b are connected. It may be easy to adjust.

The operation of the distortion generator shown in FIG. 2 will be described.
The signal distributed by the distributor 112 in FIG. 1 is further distributed through the coupler 19 and the distributor 20 and input to the third-order distortion generation circuit 21 and the fifth-order distortion generation circuit 22. The third-order distortion generation circuit 21 and the fifth-order distortion generation circuit 22 generate a third-order distortion component, a fifth-order distortion component, and a linear component, respectively.

  The third-order distortion component generated by the third-order distortion generation circuit 21 is adjusted in phase and amplitude by the distortion adjustment circuit 23a, and the fifth-order distortion component generated in the fifth-order distortion generation circuit 22 is adjusted in phase and amplitude by the distortion adjustment circuit 23b. And input to the coupler 19 through the distributor 20.

In the fundamental wave cancellation circuit 24, the signal including the third-order distortion component, the fifth-order distortion component, and the linear component input to the coupler 19 is input and the linear component is reflected.
The combiner 19 combines the signal including the third-order distortion component, the fifth-order distortion component, and the linear component with the linear component reflected by the fundamental wave cancellation circuit 24, and includes only the third-order distortion component and the fifth-order distortion component. Output a signal.
The output distortion is input to the variable phase shifter 142 in FIG. In this way, the operation of the distortion generator is performed.

Here, the influence of distortion on the output will be described with reference to FIG. FIG. 3 is an explanatory diagram showing the influence of distortion on the output.
As shown in FIG. 3, when nonlinear distortion is taken into consideration up to the fifth order, if the linear component vector is A1V1, a third-order distortion component vector (V3) having a distortion phase Φ3 and an amplitude | A1V1 ³ | A fifth-order distortion component vector (V5) having an amplitude | A1V1 ⁵ | is generated. Since these distortion component vectors affect the linear components, the output becomes a vector V0 in which they are synthesized, and the linearity is lost.

Next, a distortion compensation control method will be described by comparing a conventional apparatus and the apparatus of the present invention. FIG. 4 is an explanatory diagram showing a distortion compensation control method in the conventional distortion compensation device, and FIG. 5 is an explanatory diagram showing a distortion compensation control method in the first distortion compensation device of the present invention.
As shown in FIG. 4, in the conventional control method, the relationship between the phase and amplitude of the distortion components output from the distortion generators of the respective orders (third order and fifth order) is the third order distortion component generated by the amplifier and 5 Since the relationship between the phase and amplitude of the second-order distortion component does not match and is completely different for each order, for each order, the distortion component to be compensated has the same amplitude and anti-phase (vector of the same length in the opposite direction) and It is necessary to perform control independently. Therefore, the control is complicated.

  Therefore, in the present invention, as shown in FIG. 5, paying attention to the fact that the relationship between the distortion phase and the amplitude between the distortions of different orders generated in the amplifier does not basically change, and the third-order distortion component generated in the amplifier and 5 The phase relationship (phase shift) and amplitude relationship (amplitude ratio) in the second-order distortion component are measured in advance, and the third-order distortion component output from the distortion generator and 5 so that the same phase and amplitude relationship are obtained. The phase and amplitude of the next distortion component are adjusted.

In the example of FIG. 5, if the phase relationship (phase shift) between the third-order distortion component and the fifth-order distortion component generated in the amplifier is θ, the phase of the third-order distortion component and the fifth-order distortion component output from the distortion generator. Is also adjusted so that θ is shifted.
Similarly, the amplitudes of the third-order distortion component and the fifth-order distortion component output from the distortion generator are set so that the amplitude relationship (ratio of amplitudes) between the third-order distortion component and the fifth-order distortion component generated by the amplifier is the same. adjust.

  Accordingly, the relationship between the phase and amplitude of the third-order distortion component generated by the amplifier and the third-order distortion component output from the distortion generator, and the fifth-order distortion component generated by the amplifier and the fifth-order distortion output from the distortion generator. The phase and amplitude relationships of the components are equal.

  For this reason, the phase adjustment amount and the amplitude adjustment amount performed on the third-order distortion component and the fifth-order distortion component output from the distortion generator in order to obtain a vector having the same amplitude opposite phase as the distortion component to be compensated are equal to each other. The phase and amplitude of the third-order distortion component and the fifth-order distortion component output from the distortion generator can be collectively adjusted. Thereby, control in distortion compensation can be facilitated.

Next, another configuration example of the first distortion compensation apparatus will be described with reference to FIG. FIG. 6 is a block diagram showing another configuration example of the distortion generator of the first distortion compensation apparatus.
In the first distortion compensation apparatus shown in FIG. 1, the third-order and fifth-order distortion generator 18 is provided as a distortion generator to compensate for the third-order distortion component and the fifth-order distortion component. In the example, the principle configuration of a distortion generator in the first distortion compensation apparatus is shown, and higher-order distortion components are also compensated.

  As shown in FIG. 6, another distortion generator is used instead of the third-order / fifth-order distortion generator 18 shown in FIG. 1, and as a part similar to FIG. A fundamental wave cancellation circuit 24, a distributor 20, a third-order distortion generation circuit 21, a distortion adjustment circuit 23a, a fifth-order distortion generation circuit 22, and a distortion adjustment circuit 23b are provided. Next, a 9th-order distortion generation circuit and a distortion adjustment circuit corresponding thereto, and a higher-order distortion generation circuit and a distortion adjustment circuit corresponding thereto are connected in parallel.

  Even in the above configuration, the distortion and adjustment circuit adjusts the phase and amplitude so that the distortion components of the respective orders generated by the distortion generation circuit have the same phase and amplitude relationship as the distortion components generated by the amplifier. In the variable phase shifter 142 and the variable attenuator 152 shown in FIG. 1, phase adjustment and amplitude adjustment can be performed for a plurality of order distortion components at once, and distortion compensation control can be facilitated. It is.

Further, as another configuration, a configuration in which a distributor is not used is also possible. FIG. 7 is a configuration block diagram of a distortion generator with a reduced number of distributors.
As shown in FIG. 7, a distortion generator that does not use a distributor includes a coupler 19, a fundamental wave cancellation circuit 24, a third-order distortion generation circuit 21, and a distortion adjustment circuit 23a as in FIG. A fifth-order distortion generation circuit 22 and a distortion adjustment circuit 23b are provided. As a characteristic part of this configuration, a distribution circuit 26 is provided instead of the distributor 20 in FIG.
The distribution circuit 26 is realized by a board-like pattern or wiring, thereby reducing the number of distributors and reducing the size.

FIG. 8 is a block diagram showing another configuration of the distortion generator with a reduced number of distributors.
As shown in FIG. 8, in the distortion generator having a reduced number of distributors, a combination of higher-order distortion generation circuits such as the seventh order and the ninth order and a distortion adjustment circuit are provided in the same manner as the distortion generator shown in FIG. Corresponding so that the phase and amplitude relationship between the distortion components generated in the distortion generating circuit of each order is the same as the phase and amplitude relationship between the distortion components of each order generated in the main amplifier. Since the output is adjusted and output by a distortion adjustment circuit, the variable phase shifter 142 and variable attenuator 152 shown in FIG. 1 can collectively adjust the phase and amplitude of a plurality of orders of distortion components. This makes it possible to easily control distortion compensation.

Furthermore, the distortion adjustment circuit of the third-order / fifth-order distortion generator 18 shown in FIG. 2 can be configured with a variable phase shifter and a variable attenuator. FIG. 9 is a block diagram showing a third-order / fifth-order distortion generator in which the distortion adjustment circuit includes a variable phase shifter and a variable attenuator.
As shown in FIG. 9, another third-order / fifth-order distortion generator includes a coupler 19, a fundamental wave cancellation circuit 24, a distributor 20, a third-order distortion generation circuit 21, and a fifth-order distortion generation circuit 22. 2 is the same part as FIG. 2, and a variable phase shifter 143 and a variable attenuator 153 are provided as a configuration corresponding to the distortion adjustment circuit 23a of FIG. 2, and a configuration corresponding to the distortion adjustment circuit 23b of FIG. As shown, a variable phase shifter 144 and a variable attenuator 154 are provided.

  In the configuration of FIG. 9, the variable phase shifters 143 and 144 and the variable attenuators 153 and 154 generate the third order distortion generated by the third order distortion generation circuit 21 and the fifth order distortion generated by the fifth order distortion generator 22. The phase and amplitude are adjusted to be equal to the relationship between the phase and amplitude of the third-order distortion and fifth-order distortion generated in the main amplifier 2 and output to the variable phase shifter 142 and variable attenuator 152 in FIG. Therefore, the variable phase shifter 142 and the variable attenuator 152 can collectively adjust the phase and amplitude of a plurality of orders of distortion components, and can easily control distortion compensation.

Furthermore, as an application example of the third-order / fifth-order distortion generator shown in FIG. 9, another distortion compensation apparatus will be described with reference to FIG. FIG. 10 is a block diagram showing the configuration of another distortion compensation apparatus that is an application example of the third-order and fifth-order distortion generator shown in FIG.
As shown in FIG. 10, another distortion compensation apparatus includes a distributor 113, a delay line 12, a synthesizer 173, a main amplifier, and a third and fifth order distortion generator 27. The variable phase shifter 142 and the variable attenuator 152 provided in 1 are not provided.

The third-order / fifth-order distortion generator 27 in FIG. 10 has the same configuration as the distortion generator shown in FIG. 9, but the control is different.
In the third-order / fifth-order distortion generator 18 shown in FIG. 10, the variable phase shifter 143 and the variable attenuator 153 generate the phase and amplitude of the third-order distortion component generated by the third-order distortion generation circuit with an amplifier 3 The fifth-order distortion is adjusted such that the phase and amplitude of the fifth-order distortion component generated by the variable-order phase shifter 144 and the variable attenuator 154 are generated by the amplifier. It is adjusted so as to have an equiamplitude reverse phase with the component.

  As a result, the third-order and fifth-order distortions output from the third-order and fifth-order distortion generator 27 are output in a state where vector adjustment has been made so as to compensate for the third-order distortion and fifth-order distortion generated in the main amplifier. Therefore, the variable phase shifter 142 and variable attenuator 152 provided in FIG. 1 can be dispensed with.

  According to the distortion compensator according to the first embodiment, in the distortion compensator that compensates for the nonlinear distortion generated in the amplifier, the third-order and fifth-order distortion generators of the analog circuit that generate the third-order distortion and the fifth-order distortion. 18, a variable phase shifter 142 that controls the phase of the distortion generated by the distortion generator 18, and a variable attenuator 152 that controls the amplitude of the distortion. The phase and amplitude of the third-order distortion component generated by the third-order distortion generation circuit 21, the fifth-order distortion generation circuit 22 that generates the fifth-order distortion component, and the third-order distortion generation circuit 21 are adjusted. A distortion adjustment circuit 23a, and a distortion adjustment circuit 23b that adjusts the phase and amplitude of the fifth-order distortion component generated by the fifth-order distortion generation circuit 22. The distortion adjustment circuits 23a and 23b generate third-order distortion components generated by the amplifier. And distortion to be equal to the relationship between the phase and amplitude of the fifth-order distortion component. Since the phase and amplitude of the third-order distortion component and fifth-order distortion component generated in the circuits 21 and 22 are adjusted, the third-order distortion component and the fifth-order distortion are adjusted in the variable phase shifter 142 and the variable attenuator 152. The phase or amplitude of the components can be collectively adjusted so that the third-order distortion component and the fifth-order distortion component to be compensated have the same amplitude opposite phase, and the control in distortion compensation can be facilitated. .

  In addition, according to the distortion compensation apparatus according to the first embodiment, the distortion generator that compensates for the nonlinear distortion generated in the amplifier includes a distortion generation circuit that generates a distortion component of a specific order, and the distortion generation circuit. A plurality of sets of distortion adjustment circuits for adjusting the phase and amplitude of the generated distortion component are provided, and the phase and amplitude of the distortion component generated by the distortion generation circuit of each order are set to the phase and amplitude of the distortion component of each order generated by the amplifier. Therefore, the variable phase shifter 142 and the variable attenuator 152 collectively adjust the phase or amplitude of distortion components of different orders to adjust the vector to be compensated. The distortion and the opposite phase and the same amplitude can be obtained, and there is an effect that the vector adjustment can be easily controlled.

  In addition, according to the first distortion compensation apparatus, since the distortion generator is configured by an analog circuit, there is an effect that the apparatus can be realized simply and at low cost.

  The present invention is suitable for a distortion compensation apparatus that has an excellent distortion compensation characteristic with a simple configuration and can be easily controlled.

1 is a configuration block diagram of a distortion compensation apparatus according to a first embodiment of the present invention. It is a block diagram which shows the structure of the 3rd * 5th distortion generator 18 of a 1st distortion compensation apparatus. It is explanatory drawing which shows the influence on the output by distortion. It is explanatory drawing which shows the distortion compensation control method in the conventional distortion compensation apparatus. It is explanatory drawing which shows the distortion compensation control method in the 1st distortion compensation apparatus of this invention. It is a block diagram which shows another structural example of the distortion generator of a 1st distortion compensation apparatus. It is a block diagram of a distortion generator with a reduced number of distributors. It is a block diagram showing another configuration of a distortion generator with a reduced number of distributors. It is a block diagram showing a third-order / fifth-order distortion generator in which a distortion adjustment circuit includes a variable phase shifter and a variable attenuator. FIG. 10 is a configuration block diagram of another distortion compensation apparatus that is an application example of the third-order / fifth-order distortion generator shown in FIG. 9. (A) is a schematic block diagram of an amplifier with a predistortion device, and (b) is a block diagram of a conventional analog predistortion compensation circuit. It is a schematic explanatory drawing which shows the principle of distortion compensation. 3 is an explanatory diagram showing an output spectrum of an amplifier 2. FIG. It is a block diagram which shows the structure of the said distortion compensation apparatus proposed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Predistortion compensation circuit, 2 ... Main amplifier, 3 ... Third order distortion compensation signal generation circuit, 5 ... Fifth order distortion compensation signal generation circuit, 11, 112, 113 ... Distributor, 12 ... Delay line, 13 ... 3 Order distortion generator, 14, 142, 143, 144,... Variable phase shifter, 15, 152, 153, 154,... Variable attenuator, 16 ... fifth order distortion generator, 17, 172, 173 ... synthesizer, 18 3rd and 5th order distortion generators, 19 ... 4th order distortion generators, 19 ... Couplers, 20 ... Distributors, 21 ... 3rd order distortion generation circuits, 22 ... 5th order distortion generation circuits, 23 ... Distortion adjustment circuits, 24 ... Fundamental wave cancellation circuit, 26 ... Distribution circuit, 27 ... Third and fifth order distortion generator

Claims (2)

A strain generator that generates nonlinear distortion;
A vector adjuster for adjusting the phase and amplitude of the distortion output from the distortion generator;
A distortion compensation apparatus that compensates for nonlinear distortion generated in an amplifier by combining vector-adjusted distortion with an input signal of the amplifier,
The distortion generator is composed of an analog circuit;
A plurality of distortion generating circuits that generate distortion components of different orders;
The ratio of phase shift and amplitude between distortion components of different orders generated in each distortion generating circuit is equal to the ratio of phase shift and amplitude of distortion components of different orders included in the nonlinear distortion generated in the amplifier. A distortion compensation apparatus comprising: a distortion adjustment circuit that adjusts a phase and an amplitude of a distortion component generated in each distortion generation circuit. A distortion generator that generates a third-order distortion from the distributed input signal; and a first distortion adjustment circuit that adjusts the phase and amplitude of the third-order distortion generated by the third-order distortion generation circuit; ,
A fifth-order distortion generation circuit that generates a fifth-order distortion component from the distributed input signal; a second distortion adjustment circuit that adjusts the phase and amplitude of the fifth-order distortion component generated by the fifth-order distortion generation circuit;
A fundamental wave cancellation circuit that reflects a linear component generated together with a third-order distortion component or a fifth-order distortion component in each distortion generation circuit;
A signal including a third-order distortion component adjusted by the first distortion adjustment circuit, a fifth-order distortion component adjusted by the second distortion adjustment circuit, and a linear component, and the linear reflected by the fundamental wave cancellation circuit 2. The distortion compensator according to claim 1, wherein the distortion compensator comprises a combiner that combines the components and outputs an adjusted third-order distortion component and an adjusted fifth-order distortion component.

Images