JP2001358539A - Distortion compensator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve miniaturization or the like of a device in the distortion compensator compensating tertiary distortion generated in an amplifier. SOLUTION: The distortion compensator is composed of a 3 dB coupler Q1 with four terminals, the first terminal P1 inputs a signal input to the amplifier or output from the amplifier, the second terminal P2 has a tertiary distortion generator Z1 generating tertiary distortion in which phase difference with the input signal reaches phase difference offsetting tertiary distortion generated by the amplifier in response to the input signal, the third terminal P3 has an amplitude regulator Z2 using an amplitude ratio of the input signal to tertiary distortion generated by a tertiary distortion generator as an amplitude ratio offsetting tertiary distortion generated by the amplifier by adjusting the amplitude of the input signal, and the fourth terminal P4 compensates tertiary distortion generated by the amplifier by synthesizing generated tertiary distortion and the input signal in which amplitude is adjusted, and outputting the synthesized distortion and signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion compensator for compensating for a third-order distortion generated by an amplifier, and more particularly, to a distortion compensator comprising a four-terminal power divider provided with a third-order distortion generator and an amplitude adjuster. The present invention relates to a distortion compensating device that realizes miniaturization of the device.

[0002]

2. Description of the Related Art It is known that, for example, when a signal is amplified by an amplifier, higher-order distortion is generated. In particular, it is known that third-order distortion generated by the amplifier has a large adverse effect on signal processing. I have. Here, assuming that a signal of a certain frequency input to the amplifier is a basic signal, the amplifier has a frequency of 3 different from the basic signal in accordance with the basic signal.
The next distortion occurs.

As a method of compensating for the third-order distortion in such an amplifier, for example, a third-order distortion for distortion compensation is generated at a stage preceding the amplifier, and the third-order distortion cancels out the third-order distortion generated in the amplifier. There is a way. As a configuration of a distortion compensating apparatus for generating such third-order distortion for distortion compensation, for example, a third-order distortion generated by a phase modulator is combined with a linear signal in an appropriate phase relationship and output to a subsequent-stage amplifier. One that uses a third-order distortion generator, a wideband phase shifter, or the like has been considered.

[0004]

However, in the conventional distortion compensating apparatus, for example, a signal processing system for handling an input basic signal and a signal processing system for generating a third-order distortion are separately provided, and these two signal processing systems are provided. Since the synthesizer for synthesizing the output signal (basic signal and third-order distortion signal) from the system is further provided separately, the device becomes large-scale, which is not suitable for miniaturization. Was.

In a conventional distortion compensator, for example, 3
Since a signal loss at the time of generating the second-order distortion is large, a wideband LNA (Low Noise Amplifier) that amplifies the third-order distortion is used.
ier), and a complicated external control circuit or a storage circuit that stores control information because high-precision control is required to generate a third-order distortion suitable for distortion compensation, for example. Had to be provided.

[0006] In view of the above, it has been desired to develop a distortion compensator suitable for miniaturization as described above, and also to realize, for example, reduction in power consumption. SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and has as its object to provide a distortion compensating apparatus suitable for miniaturization in a distortion compensating apparatus for compensating for third-order distortion generated in an amplifier. I do. Further, the distortion compensating device of the present invention can also realize, for example, reduction of power consumption.

[0007]

In order to achieve the above object, a distortion compensator according to the present invention compensates for third-order distortion generated in an amplifier by the following configuration. That is, the distortion compensating apparatus according to the present invention includes a power divider having four terminals, a first terminal for inputting a signal to be input to or output from the amplifier, and a second terminal for receiving an input signal. A third-order distortion generator having an amplitude that cancels out the third-order distortion generated by the amplifier and generating a third-order distortion whose phase difference with the input signal is a phase difference that cancels out the third-order distortion is provided. 3 generated by a third-order distortion generator
The secondary distortion is combined with the input signal input from the first terminal and output.

Accordingly, in the present invention, since the distortion compensating device is constituted by the four-terminal power distributor provided with the third-order distortion generator as described above, for example, the distortion compensating device is constituted by such a coupler unit using one coupler. The device can be configured and is very suitable for miniaturization of the device. A specific example of a method of setting the amplitude of the third-order distortion generated by the third-order distortion generator and a method of setting the phase of the third-order distortion will be described later in an embodiment.

Further, the distortion compensating apparatus according to the present invention compensates for the third-order distortion generated in the amplifier by the following configuration. That is, the distortion compensating apparatus according to the present invention includes a power divider having four terminals, a first terminal for inputting a signal to be input to or output from the amplifier, and a second terminal for receiving an input signal. A third-order distortion generator that generates a third-order distortion whose phase difference with the input signal cancels out the third-order distortion generated by the amplifier; a third terminal adjusts the amplitude of the input signal to adjust the input signal; An amplitude adjuster is provided for setting the amplitude ratio between the signal and the third-order distortion generated by the third-order distortion generator to an amplitude ratio that cancels out the third-order distortion generated by the amplifier, and the fourth terminal is generated by the third-order distortion generator. The third-order distortion and the input signal adjusted by the amplitude adjuster are combined and output.

Accordingly, in the present invention, since the distortion compensating device is constituted by the four-terminal power divider provided with the third-order distortion generator and the amplitude adjuster, for example, the distortion compensation is performed by the coupler unit using one such coupler. The device can be configured and is very suitable for miniaturization of the device. A specific example of how to set the phase of the tertiary distortion generated by the tertiary distortion generator and how to set the amplitude ratio to be adjusted by the amplitude adjuster will be described later in embodiments.

Further, in the distortion compensator according to the present invention, as an example of a preferred embodiment, the amplitude adjuster provided at the third terminal includes a fixed resistor provided between the third terminal and a ground terminal. As another example, the amplitude adjuster provided at the third terminal is constituted by a variable resistor provided between the third terminal and the ground terminal. When an amplitude adjuster is formed from such a resistor, the amplitude of the input signal and the third-order distortion are changed by utilizing the fact that the amplitude of the input signal changes according to the magnitude of the resistance value of the resistor. Adjust the ratio.

Here, "the first terminal is to be inputted to the amplifier or inputted to the signal outputted from the amplifier" means that the distortion compensating apparatus according to the present invention is provided at the preceding stage of the amplifier and the signal inputted to the amplifier is inputted to the amplifier. This indicates that the signal may be input from one terminal, or a signal output from the amplifier provided at the subsequent stage of the amplifier may be input from the first terminal. In any case, the third-order distortion generated in the amplifier can be compensated for by the distortion compensator generating the third-order distortion that cancels out the third-order distortion generated in the amplifier.

Further, the number of amplifiers to be subjected to distortion compensation is not necessarily limited to one. For example, a distortion compensator generated by a plurality of amplifiers provided in a preceding stage thereof may be used.
A second-order distortion compensating device, a third-order distortion generated by a plurality of amplifiers provided in a subsequent stage, or a first-order distortion compensating device provided in a preceding stage. It is also possible to adopt a configuration that compensates for third-order distortion generated by one or more amplifiers and one or more amplifiers provided at the subsequent stage.

As described above, when the distortion compensator compensates for the third-order distortion generated by the plurality of amplifiers, the distortion compensator can compensate for the total sum of the third-order distortion generated by the plurality of amplifiers. Generate third order distortion. In the present invention, “to cancel the third-order distortion generated by the amplifier” means not only the mode of canceling the third-order distortion generated by one amplifier but also the three-dimensional distortion generated by a plurality of amplifiers as described above.
This is a concept including a mode for canceling the sum of the secondary distortions.

The degree of offset referred to in the present invention is as follows:
For example, it is most preferable that the third-order distortion generated by the amplifier and the third-order distortion generated by the distortion compensator according to the present invention be summed to zero. However, the present invention is not necessarily limited to such an aspect. The mode in which the third-order distortion generated in the amplifier can be reduced to a practically effective level is also included in the cancellation according to the present invention.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A distortion compensator according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a circuit configuration of a distortion compensation device according to the present example. As shown in the figure, the distortion compensator of the present example has an input terminal (IN).
P1 and output terminal (ISO) P4 and 90 ° terminal P2 and 0 °
3 dB coupler Q1 having four terminals such as terminal P3
The 90 ° terminal P2 is connected to a third-order distortion generator Z1 that generates third-order distortion using, for example, a semiconductor active element, and the 0 ° terminal P3 is connected to the input terminal P1. An amplitude adjuster Z2 for adjusting the amplitude of the input signal is connected.

Here, in the present embodiment, as an example, a case is shown in which the distortion compensating apparatus of the present embodiment is applied to a mobile phone base station apparatus, a mobile phone terminal apparatus, or the like provided in a communication system. A case will be described in which the third-order distortion generated by the amplifier provided in the device or the mobile phone terminal device is compensated by the distortion compensating device of the present embodiment. Further, in this example, the distortion compensating device is provided before the amplifier to be subjected to distortion compensation, and a basic signal (in this example, a high-frequency signal communicated by, for example, a mobile phone terminal device) input to the amplifier is applied to the above-described input. The configuration and the like of the distortion compensator will be described by taking as an example the case where the signal is input from the terminal P1. An example in which the distortion compensator is provided at a stage subsequent to the amplifier will be described later with reference to FIG.

In the distortion compensator shown in FIG. 1, the third-order distortion generator Z1 generates the third-order distortion in response to the input of the basic signal from the input terminal P1, and the amplitude adjuster Z2 receives the input. The amplitude of the basic signal is adjusted, the reflected wave of the third-order distortion generated by the 3 dB coupler Q1 and the amplitude-adjusted basic signal are combined, and output from the output terminal P4.

Here, in the above-mentioned 3 dB coupler Q1,
For example, when both the 90 ° terminal P2 and the 0 ° terminal P3 are short-circuited or opened, the signal wave is totally reflected, and the basic signal input to the input terminal P1 is output from the output terminal P4 with ideal efficiency. Can be. In this example, in order to reduce the amount of signal attenuation by utilizing the property of the 3 dB coupler Q1, the terminal of the third-order distortion generator Z1 shown in FIG. ) And the terminal of the amplitude adjuster Z2 (the terminal opposite to the 0 ° terminal P3) are in a short-circuit state or an open state.

Further, when the 3 dB coupler Q1 is used as in the present embodiment, even if, for example, even-order distortion is parasitically generated together with the third-order distortion in the third-order distortion generator Z1, the even-order distortion is generated. It is preferable because distortion can be removed, and unnecessary signal components such as a leakage wave of a local signal or another system (for example, a communication system) can be removed.

Further, the distortion compensator of this embodiment has a control voltage terminal (not shown) for controlling the amplitude of the basic signal by changing the resistance value of a variable resistor R5, which will be described later, constituting the amplitude adjuster Z2. ) Is provided,
In this example, a control voltage terminal P5 for controlling the amplitude of the third-order distortion generated by the third-order distortion generator Z1 is further provided, and the basic signal is controlled by the magnitude of the DC voltage applied to each control voltage terminal. And the amplitude ratio between the third order distortion and the third order distortion can be controlled. In addition, the variation of the pass voltage in the distortion compensator is small and stable even by changing the DC voltage.

Next, a more specific configuration example of the distortion compensating apparatus of the present embodiment will be described with reference to FIG. In this example, a power divider having four terminals according to the present invention is configured by the 3 dB coupler Q1, and a first terminal configured to input a signal input to the amplifier or a signal output from the amplifier is configured by the input terminal P1. , A second terminal including a third-order distortion generator Z1 that generates a third-order distortion according to the input signal by the 90 ° terminal P2, and an amplitude adjuster Z2 that adjusts the amplitude of the input signal by the 0 ° terminal P3. A third terminal is configured, and a fourth terminal configured to combine and output the third-order distortion generated by the third-order distortion generator Z1 and the input signal adjusted by the amplitude adjuster Z2 by the output terminal P4 is configured.

An example of the circuit configuration of the third-order distortion generator Z1 connected to the 90 ° terminal P2 will be described. The third-order distortion generator Z1 of this example includes a fixed resistor R1 connected to a 90 ° terminal P2,
The capacitor C1 connected in series with the fixed resistor R1
And diode units D1 and D2 connected in anti-parallel with the capacitor C1, two capacitors C2 and C3 connected in series with the diode units D1 and D2, and a fixed resistor R2 grounding these capacitors C2 and C3. , A fixed resistor R3 connected between one diode portion D1 and the capacitor C2, and a capacitor C3 grounding the fixed resistor R3.
4 and a fixed resistor R4 for grounding between the other diode portion D2 and the capacitor C3. A control voltage terminal P5 is connected to the one diode portion D1 via the fixed resistor R3. I have.

The above-mentioned fixed resistor R1 is a matching resistor for matching the impedance of the 90 ° terminal P2 and the third-order distortion generator Z1, and the three capacitors C1 to C3 block a DC voltage and short-circuit at a high frequency. The capacitor is a DC voltage blocking capacitor, and a resistor that terminates or opens at high frequency is used as the fixed resistor R2. Also,
The diode units D1 and D2 include a Schottky barrier diode or the like which is a distortion generating element connected in series,
For example, when a high frequency signal is input, the Schottky barrier diode or the like has a function of generating third-order distortion. Also, two resistors R which are high-frequency open resistors are used.
3, R4 and capacitor C which is a high frequency cutoff capacitor
4 constitutes a bias circuit for the diode sections D1 and D2, and this bias circuit realizes an open or short circuit at a high frequency.

Here, the above-described diode sections D1, D2
However, the two diode units do not necessarily have to be connected in anti-parallel. For example, only one diode unit may be provided. However, if two diode units are provided and connected in anti-parallel as in this example, the temperature change It is preferable because characteristic fluctuations due to the above can be reduced. Also, the diode section D
1, the number of diodes provided in D2 is not particularly limited, and is set based on, for example, input power or an amplitude ratio between a required output wave and third-order distortion.

When the fixed resistor R2 terminates at a high frequency, for example, a reflected wave can be generated at the connection point between the capacitor C1 and the diode portions D1 and D2, while the high frequency is terminated by the fixed resistor R2. In the case where the circuit is left open, for example, a reflected wave can be generated between the capacitors C2 and C3 and the fixed resistor R2, and a preferable configuration can be used depending on the amplifier to be subjected to distortion compensation. .

In the third-order distortion generator Z1 having the above-described configuration, in response to the input of the basic signal from the input terminal P1 to the 90 ° terminal P2, the diode units D1 and D2 generate the third-order distortion for the basic signal. The reflected wave including the generated third-order distortion can be output to the output terminal P4. In the third-order distortion generator Z1 of the present example,
For example, the phase of the third-order distortion generated by the third-order distortion generator Z1 is adjusted according to the values set for the capacitance values of the three capacitors C1 to C3 and the resistance value of the fixed resistor R2. Can be.

Specifically, in this example, the third-order distortion generator Z
The capacitance value and the resistance value are set such that the phase difference between the third-order distortion generated in step 1 and the basic signal becomes a phase difference that cancels out the third-order distortion generated in the amplifier to be subjected to distortion compensation. The third-order distortion generator Z1 of this example has a configuration in which the amplitude of only the third-order distortion generated by controlling the DC voltage from the control voltage terminal P5 can be variably controlled. When such control is not performed, for example, a 90 ° terminal P2 from the input terminal P1
Is constant, the amplitude level of the third-order distortion generated by the third-order distortion generator Z1 according to the basic signal has a constant value.

Here, as described above, the phase difference for canceling the third-order distortion generated in the amplifier to be compensated for distortion is set as described above. Theoretically, the phase difference between the basic signal output from the distortion compensator and the third-order distortion is equal to the phase difference between the basic signal input to the distortion-compensation target amplifier and the third-order distortion generated by the amplifier. Out of phase (180
By setting a relationship of (a shifted value), a requirement relating to a phase difference for canceling the third-order distortion generated in the amplifier can be satisfied.

Specifically, for example, if the phase difference of the third-order distortion with respect to the basic signal in the amplifier is α, the phase difference of the third-order distortion with respect to the basic signal in the distortion compensator is (α + 1).
80 °), and in the present example, the above-described relationship of the opposite phases refers to such a relationship. In an actual device, the third-order distortion generator Z1 is used in accordance with the required accuracy of distortion compensation and the like.
May be arbitrarily set for the phase difference between the third-order distortion generated in step (1) and the basic signal.

A circuit configuration example of the amplitude adjuster Z2 connected to the 0 ° terminal P3 will be described. The amplitude adjuster Z2 of this example
Is composed of a variable resistor R5 having one end connected to the 0 ° terminal P3 and the other end grounded. In such a configuration, as the resistance value of the variable resistor R5 connected to the 0 ° terminal P3 increases, the amplitude level of the basic signal output to the output terminal P4 via the amplitude adjuster Z2 increases. As a result, 3 generated by the third-order distortion generator Z1
The amplitude ratio of the basic signal to the next-order distortion increases. Conversely, as the resistance value of the variable resistor R5 connected to the 0 ° terminal P3 decreases, the output terminal P via the amplitude adjuster Z2 decreases.
The amplitude level of the basic signal output to the fourth signal becomes smaller, and as a result, the amplitude ratio of the basic signal to the third-order distortion generated by the third-order distortion generator Z1 becomes smaller.

In the amplitude adjuster Z2 having the above configuration,
As described above, the amplitude of only the basic signal can be adjusted according to the resistance value of the variable resistor R5. Specifically, in response to the input of the basic signal from the input terminal P1 to the 0 ° terminal P3, the amplitude of only the basic signal is adjusted to generate the basic signal and the third-order distortion generated by the third-order distortion generator Z1. The amplitude ratio with the distortion can be adjusted, and the reflected wave of the amplitude-adjusted basic signal can be output to the output terminal P4. Further, in the amplitude adjuster Z2 of this example, the amplitude ratio between the basic signal and the third-order distortion is variably controlled by controlling the resistance value of the variable resistor R5 with a DC voltage from a control voltage terminal (not shown). can do.

Here, the amplitude ratio to be adjusted by the amplitude adjuster Z2 is 3
An amplitude ratio that cancels the secondary distortion is set. Theoretically, the amplitude ratio between the basic signal input to the distortion compensating device and the third-order distortion generated by the distortion compensating device is determined by dividing the amplitude ratio between the basic signal input to the distortion compensation target amplifier and the amplitude generated by the amplifier.
By setting the same value as the amplitude ratio with the third-order distortion, it is possible to satisfy the requirement relating to the amplitude for canceling the third-order distortion generated in the amplifier. In an actual device, the amplitude ratio adjusted by the amplitude adjuster Z2 may be arbitrarily set according to the required accuracy of distortion compensation or the like.

In this embodiment, as a preferred embodiment, the above-mentioned amplitude adjuster Z2 is composed of a variable resistor R5 connected between the 0 ° terminal P3 and the ground terminal (earth), and has a resistance value of Is controllable, for example, 0 °
An amplitude adjuster can also be constituted by a fixed resistor provided between the terminal P3 and the ground terminal (earth). In this case, the amplitude of the basic signal is adjusted according to the resistance value of the fixed resistor. Can be adjusted.

As described above, in the distortion compensating apparatus of the present embodiment, the amplitude ratio and the phase difference between the basic signal and the third-order distortion can be set arbitrarily. Satisfies the requirement of the phase of the third-order distortion generated by the amplifier Z1 and the requirement of the amplitude ratio adjusted by the amplitude adjuster Z2, thereby canceling the third-order distortion generated by the amplifier to be subjected to distortion compensation. Can be generated.

As described above, in the distortion compensator of the present embodiment, the third-order distortion generator Z1 has a phase that cancels out the third-order distortion generated by the amplifier according to the input signal (in this example, the basic signal). In addition to generating the third-order distortion, the amplitude adjuster Z
Numeral 2 adjusts the amplitude of the input signal (in this example, the basic signal) and adjusts the amplitude ratio between the input signal and the third-order distortion generated by the third-order distortion generator Z1 to cancel the third-order distortion generated by the amplifier. By combining the generated third-order distortion and the input signal whose amplitude has been adjusted and outputting the resultant signal from the output terminal P4, it is possible to compensate for the third-order distortion generated in the amplifier.

As an example, generally, when the power consumption of the amplifier is reduced, the intercept point IP3 is reduced (that is, the proportion of the third-order distortion included in the output signal is increased). By applying the device to compensate for third-order distortion, the apparent intercept point IP3 can be increased (ie, the proportion of third-order distortion included in the output signal can be reduced), such that, for example, output saturation Even when an amplifier with a low level is used, a high-frequency amplifier with low distortion is realized, which can contribute to miniaturization, low power consumption, and low cost of these devices.

The extent to which the third-order distortion generated by the amplifier can be compensated (distortion improvement amount) varies by controlling the DC voltage applied to the control voltage terminals of the third-order distortion generator Z1 and the amplitude adjuster Z2. However, as in this example, 3
In the configuration using the dB coupler Q1, for example, even when the DC voltage is fixedly set, it is possible to always obtain a distortion improvement amount of about 6 dB, which corresponds to an increase in the intercept point IP3 by 3 dB. However, power consumption can be reduced to about half as compared with a case where distortion compensation is not performed.

Further, as described above, since the 3 dB coupler Q1 is used in this embodiment, for example, the diode units D1 and D
Even if the even-order distortion occurs in 2,
It is possible to remove (attenuate) a signal in a frequency band other than the fundamental signal and the third-order distortion, thereby removing even-order distortion generated. Also, with this,
In the configuration of the present example, the power consumption of the third-order distortion generator Z1 and the amplitude adjuster Z2 connected to the 90 ° terminal P2 and the 0 ° terminal P3 of the 3dB coupler Q1 is made very small (for example, almost zero). Since the input basic signal can be output with a small amount of attenuation, power consumption can be significantly reduced.

In the distortion compensator of this embodiment, the amplitude of the basic signal can be adjusted by the amplitude adjuster Z2, and the tertiary distortion generator Z1 has a control voltage terminal P5. Although the configuration is such that the amplitude of the third-order distortion can be adjusted, for example, when the amplitude ratio between the basic signal and the third-order distortion can be adjusted to the required amplitude ratio described above only by the amplitude adjuster Z2. However, the configuration for controlling the amplitude of the third-order distortion by the control voltage terminal P5 as in the present embodiment is not necessarily required.

In the present invention, for example, a variable capacitor or a variable resistor is used as the capacitor C1 to C3 or the resistor R2 provided in the third-order distortion generator Z1 to control the capacitance value of the variable capacitor or the resistance value of the variable resistor. With this configuration, it is possible to variably adjust the phase of the third-order distortion generated by the third-order distortion generator Z1. In such a configuration, for example, corresponding to the fact that the actual Schottky barrier diode and the amplifier for which distortion is to be compensated each have unique distortion characteristics, a slight phase error caused by such distortion characteristics can be varied. This is preferable because it is possible to realize ideal distortion compensation by adjusting to

Similarly, the amplitude can be variably controlled by adjusting the amplitude of the basic signal by the amplitude adjuster Z2 and the amplitude of the tertiary distortion generated by the tertiary distortion generator Z1. May not be used. That is, according to the present invention, the amplitude ratio between the amplitude of the third-order distortion generated by the third-order distortion generator Z1 and the fundamental signal can cancel out the third-order distortion generated by the amplifier to be subjected to distortion compensation. If it is set, the amplitude of the basic signal and the third-order distortion may be fixedly set.

As described above, the distortion compensating apparatus of this embodiment
Since it is composed of a coupler provided with a secondary distortion generator Z1 and an amplitude adjuster Z2, for example, a distortion compensator can be composed of a coupler unit using such a single coupler, which is very useful for downsizing the apparatus. Suitable for. In the case of this example, by realizing such a miniaturization of the distortion compensating device, it is possible to reduce the weight of the mobile phone terminal device or the like provided with the distortion compensating device, Carrying around can be convenient. Further, as described above, the distortion compensating apparatus of the present example can also reduce power consumption.

Next, a specific example of a configuration for compensating for the third-order distortion generated in the amplifier using the above-described distortion compensating apparatus of the present embodiment will be described. FIG. 2 illustrates an example of a signal processing unit of, for example, a mobile phone terminal device to which the distortion compensation device of the present example is applied.
The signal processing unit includes an amplifier (AMP) connected in series.
1, the distortion compensator 2, the amplifier 3, and the attenuator (AT
T) 4, an amplifier 5, an attenuator 6, and an amplifier 7. The amplifier 1 is, for example, a low distortion amplifier.
The amplifiers 3, 5, and 7 are, for example, power amplifiers.

In the above-described signal processing unit, for example, a frequency-converted modulated signal is input from the input terminal N1 to the amplifier 1, and the signal passes through the distortion compensator 2, the amplifier 3, etc., and is output from the output terminal N2. . In this example, a case is shown in which the third-order distortion generated in the four amplifiers 1, 3, 5, and 7 is collectively compensated by the distortion compensating device 2 described above. That is, the distortion compensator 2 generates and outputs a third-order distortion that cancels out the sum of the third-order distortions generated by the four amplifiers 1, 3, 5, and 7.

Here, (a) to (f) in FIG.
FIG. 3 conceptually shows an example of a spectrum of a basic signal (basic signal wave) and a third-order distortion when such distortion compensation is performed. The horizontal axis represents frequency, and the vertical axis represents signal strength. Is shown. In this example, for convenience of explanation, signals of two frequencies within the frequency band of the modulation signal input to the input terminal N1 are shown as basic signals.

FIG. 3A shows an example of a basic signal input to the input terminal N1. FIG. 3B shows an example of a signal output from the amplifier 1.
The third-order distortion generated by the amplifier 1 is output together with the basic signal. FIG. 3C shows an example of a signal output from the distortion compensator 2. The third-order distortion generated by the distortion compensator 2 is added to the third-order distortion generated by the amplifier 1. Has been output.

FIG. 3D shows an example of a signal output from the amplifier 3. The third-order distortion generated by the amplifier 3 is converted to the third-order distortion output from the distortion compensator 2. It is added and output. FIG. 5E shows an example of a signal output from the amplifier 5. The third-order distortion generated by the amplifier 5 is added to the third-order distortion output from the amplifier 3 and output. ing.

FIG. 3F shows an example of a signal output from the amplifier 7 to the output terminal N2.
It is output in addition to the secondary distortion. As shown in the drawing, the third-order distortion generated by the four amplifiers 1, 3, 5, and 7 is canceled by the third-order distortion generated by the distortion compensating device 2, whereby the third-order distortion is output from the output terminal N2. Can be prevented.

Further, in the distortion compensating apparatus of this embodiment, as described above, the variable resistor R5 (which
The amplitude ratio between the basic signal and the third-order distortion can be adjusted according to the resistance value of the above-described fixed resistance. A setting example of such a resistance value will be described. That is, as an example, when the distortion compensating apparatus of the present example is used for performing distortion compensation of a low distortion amplifying apparatus provided in a mobile phone base station apparatus or the like, the amplitude ratio between the basic signal and the third-order distortion ( It is necessary to make the resistance value relatively large, for example, 1 kΩ or more. As such an application example, there is a case where the distortion compensator of the present example is applied to, for example, a train radio booster or a common amplifier of, for example, a W-CDMA base station device.

As another example, the distortion compensator of this example uses a final stage PA (final stage power amplifier) with a low back-off, such as a portable terminal device, a pulse amplifier, a radar amplifier, or a TV broadcasting station. When used to perform distortion compensation of such a device, it is necessary to make the amplitude ratio between the basic signal and the third-order distortion relatively small, and correspondingly set the resistance value to a small value. . Examples of such applications include, for example, digital mobile phone terminals and W-CDs.
The distortion compensator of the present example may be applied to an MA terminal device or, for example, the amplifier as described above.

Next, a distortion compensating apparatus according to a second embodiment of the present invention will be described with reference to FIG. The figure shows an example of a circuit configuration of the distortion compensating apparatus according to the present example. The configuration of the distortion compensating apparatus according to the present example is such that the 0 ° terminal P3 does not have an amplitude adjuster, Except that the terminal P3 is grounded, it is the same as that shown in FIG. 1 of the first embodiment. For this reason, in this figure and this example, the same components are denoted by the same reference numerals as those shown in FIG. 1 of the first embodiment, and detailed description of these similar components is omitted. .

In the distortion compensator of the present embodiment, a third-order distortion generator Z1 provided at a 90 ° terminal P2 has a third-order distortion having an amplitude and a phase that cancels out the third-order distortion generated in the amplifier to be compensated for distortion. 3 generated in this way
The second distortion is combined with the basic signal input from the input terminal P1 and output from the output terminal P4. Specifically, in this example, the third-order distortion generator Z1 is adjusted by adjusting the capacitance values of the three capacitors C1 to C3 and the resistance value of the fixed resistor R2. The phase difference between the third-order distortion generated in Z1 and the basic signal is set to the required phase difference described above, and the third-order distortion generator Z
The amplitude ratio between the third-order distortion and the basic signal is set to the above-mentioned required amplitude ratio by the control using the control voltage terminal P5 provided in 1.

In this example, a power divider having four terminals according to the present invention is constituted by the 3 dB coupler Q1, and a first terminal for inputting to an amplifier or for inputting a signal output from the amplifier by an input terminal P1. Is composed of 90
A second terminal including a third-order distortion generator Z1 that generates third-order distortion according to an input signal is configured by the terminal P2, and the third-order distortion generated by the third-order distortion generator Z1 and the first terminal are configured by the output terminal P4. A fourth terminal is configured to combine and output an input signal input from a terminal (the input terminal P1 in this example).

As described above, the distortion compensating apparatus of this embodiment is also constituted by a coupler having a third-order distortion generator Z1, for example, like the distortion compensating apparatus shown in the first embodiment. For example, a distortion compensator can be configured from a coupler unit using such one coupler,
Very suitable for miniaturization of the device. Further, for example, similarly to the case of the first embodiment, the distortion compensating apparatus of this embodiment can also reduce power consumption.

Here, in the distortion compensator shown in the above embodiment, the third-order distortion generator Z1 is connected to the 90 ° terminal P2 of the 3dB coupler Q1, while the amplitude adjuster Z2 is connected to the 0 ° terminal P3. Although the same configuration is shown, for example, a configuration in which the third-order distortion generator Z1 is connected to the 0 ° terminal P3 and the amplitude adjuster Z2 is connected to the 90 ° terminal P2 can be used. In the same manner as in the above embodiment, it is possible to generate and output third-order distortion for compensating for third-order distortion generated in the amplifier.

Further, the configuration of the distortion compensating apparatus of the present invention is not necessarily limited to the configuration shown in the above embodiment, and various configurations may be used. As an example, for example, an FET or the like can be used as an element for generating the third-order distortion.

The number of amplifiers for which distortion is compensated by the distortion compensator may be, for example, one.
For example, there may be a plurality. Further, in practical use, for example, an amplifier positioned at the last stage among amplifiers to be compensated for distortion (the amplifier to be compensated for distortion is one).
In this case, it is preferable that the distortion compensation device is provided before the amplifier). However, in the present invention, even when the distortion compensation device is provided, for example, after the amplifier, distortion compensation can be realized. .

Further, in the above embodiment, as an example, the case where the distortion compensating device according to the present invention is applied to a mobile phone terminal device or the like provided in a communication system is shown.
The present invention can be applied to various fields in which the third-order distortion generated in the amplifier is compensated. In addition, for example, WC
In a device in which a signal in a wide frequency band is amplified by an amplifier, such as a mobile phone terminal device used for communication in DMA, it is particularly important to compensate for the third-order distortion generated in the amplifier. The present invention is very effective.

[0060]

As described above, according to the distortion compensating apparatus according to the present invention, the distortion compensating apparatus is constituted by a four-terminal power divider, and the first terminal receives a signal input to the amplifier or the like. A third-order distortion generator having a second terminal having an amplitude that cancels out the third-order distortion generated in the amplifier and generating a third-order distortion whose phase difference with the input signal is a phase difference that cancels out the third-order distortion; Since the third-order distortion generated by the fourth terminal is combined with the input signal and output, the third-order distortion generated in the amplifier is compensated. For example, a coupler unit using one such coupler is provided. Thus, a distortion compensating device can be configured, and the size of the device can be reduced.

Further, according to the distortion compensating apparatus according to the present invention, the distortion compensating apparatus is composed of a four-terminal power divider, and the first terminal inputs a signal to be input to the amplifier and the second terminal 3 The third-order distortion generator generates third-order distortion in which the phase difference between the input signal and the third-order distortion generated in the amplifier cancels out. The amplitude adjuster at the third terminal uses the input signal and the third-order distortion generator to generate a third-order distortion. The amplitude ratio of the generated third-order distortion to the third-order distortion generated by the amplifier is set as an amplitude ratio, and the third-order distortion generated by the fourth terminal and the amplitude-adjusted input signal are synthesized and output. Since the third-order distortion generated in the above is compensated, for example, a distortion compensator can be configured from a coupler unit using such a single coupler, and the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a circuit configuration of a distortion compensation device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a signal processing unit including a distortion compensation device.

FIG. 3 is a diagram illustrating a circuit configuration example of a distortion compensation device according to a second embodiment of the present invention.

[Explanation of symbols]

Q1 ·· 3dB coupler, P1 ··· Input terminal, P2 ·
· 90 ° terminal, P3 · · · 0 ° terminal, P4 · · · output terminal, P5 · · · control voltage terminal, Z1 · · · third-order distortion generator, Z2 · · · amplitude adjuster, R1 ~ R4 · · · resistor, R5 ·・ Variable resistance, C1-C4 ・ ・ Capacitor,
D1, D2, diode section, N1, input terminal, N
2 ··· Output end, 1, 3, 5, 7 ··· Amplifier, 2 ··· Distortion compensator, 4, 6 ··· Attenuator,

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaki Sudo 3-14-20 Higashinakano, Nakano-ku, Tokyo Kokusai Electric Co., Ltd. (72) Inventor Shoji Fujimoto 3-14-20 Higashinakano, Nakano-ku, Tokyo Kokusai Electric (72) Inventor Hidefumi Ito 43-224 Tsunonumadai, Tenno-cho, Tenno-cho, Minamiakita-gun, Akita F-term (reference) 5J090 AA01 AA41 CA27 CA36 CA92 FA01 FA19 GN02 GN04 HA19 HA25 HA26 HA29 KA00 KA23 TA01 TA03 5J091 AA01 AA41 CA27 CA36 CA92 FA01 FA19 HA19 HA25 HA26 HA29 KA00 KA23 TA01 TA03

Claims (4)

[Claims] 1. A distortion compensator for compensating for third-order distortion generated in an amplifier, comprising a power divider having four terminals, a first terminal for inputting a signal input to the amplifier or for inputting a signal output from the amplifier. The second terminal has an amplitude that cancels the third-order distortion generated by the amplifier according to the input signal, and generates a third-order distortion whose phase difference with the input signal becomes a phase difference that cancels the third-order distortion. A fourth terminal connected to the third-order distortion generated by the third-order distortion generator;
A distortion compensator, which combines and outputs an input signal input from a terminal. 2. A distortion compensator for compensating a third-order distortion generated in an amplifier, comprising a power divider having four terminals, a first terminal for inputting a signal input to the amplifier or for inputting a signal output from the amplifier. The second terminal includes a third-order distortion generator that generates a third-order distortion whose phase difference with the input signal is a phase difference that cancels out the third-order distortion generated by the amplifier in accordance with the input signal. By adjusting the amplitude of the input signal,
An amplitude adjuster that sets an amplitude ratio with the third-order distortion generated by the third-order distortion generator to an amplitude ratio that cancels out the third-order distortion generated by the amplifier, and a fourth terminal connected to the third-order distortion generated by the third-order distortion generator A distortion compensator that combines distortion and an input signal adjusted by an amplitude adjuster and outputs the combined signal. 3. The distortion compensator according to claim 2, wherein the amplitude adjuster provided at the third terminal is constituted by a fixed resistor provided between the third terminal and the ground terminal. Distortion compensating device. 4. The distortion compensator according to claim 2, wherein the amplitude adjuster provided at the third terminal is constituted by a variable resistor provided between the third terminal and the ground terminal. Distortion compensating device.