JPH0590844A - Distortion compensator - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to make it possible to easily and easily realize setting of a large distortion compensation amount with high efficiency. A coupling degree of a fourth directional coupler is U, a ratio between an intermodulation distortion component of an output signal of a first amplifier and a main signal is U, and the first is
_Let η _{M be} the efficiency of the amplifying means and η _{S be} the efficiency of the second amplifying means, and α ^1/2 / (1 + α ^1/2 ) Around (however, α =
U · η _M / η _S ) is set to achieve the intended purpose.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called feedforward type distortion compensator used in, for example, a high frequency amplifier.

[0002]

2. Description of the Related Art Generally, in this type of distortion compensator, an input signal input to an input terminal 1 is divided into a main signal and an auxiliary signal by a first directional coupler 2 as shown in FIG. The signal is amplified by the first amplifier 3. Then, a part of the main signal amplified by the first amplifier 3 and the intermodulation distortion component generated by the first amplifier 3 is taken out by the second directional coupler to be the third directional coupler. At 5, the signal is combined in antiphase with the auxiliary signal, and only the intermodulation distortion component generated in the first amplifier 3 is taken out. Then, this intermodulation distortion component is amplified by the second amplifier 6, is coupled to the opposite phase at the output side of the first amplifier 3 by the fourth directional coupler 7, and is generated in the first amplifier 3. The intermodulation distortion component that has been cancelled. The main signal from which this intermodulation distortion component is canceled is the output terminal 8
Will be output.

By the way, in such a distortion compensator, the coupling degree of the first to fourth directional couplers 2, 4, 5, 7 and the output level of the second amplifier 6 are selected. The distortion compensation efficiency and compensation amount are determined depending on the method. Therefore, the degree of coupling of the fourth directional coupler 7 and the output level of the second amplifier 6 are the efficiency η _T as an amplifier including the second amplifier 6 and the efficiency η _M of the second amplifier 6. Ratio η _T / η _M
Is set to be maximum.

However, in the above distortion compensator, the ratio η _T / η _M between the efficiency η _T as an amplifier including the second amplifier 6 and the efficiency η _M of the second amplifier is set to be maximum. For this reason, for example, if the degree of coupling of the fourth directional coupler 7 is increased, the output level of the second amplifier 6 may be set low, but this causes a problem that the loss of the main signal increases. Then, depending on the output capability (non-linearity) of the second amplifier 6, the intermodulation distortion component itself taken out may be distorted to deteriorate the distortion compensation degree. On the contrary, when the degree of coupling of the fourth directional coupler 7 is reduced, the loss of the main signal is small, but when the level of the intermodulation distortion component generated in the first amplifier 3 is large, Originally, there occurs a problem that the output level of the second amplifier 6 which is not related to the amplification of the main signal has to be increased. Therefore, it is very difficult to set the distortion compensation efficiency and the compensation amount with high accuracy.

[0005]

As described above, the conventional distortion compensator has a problem that setting the distortion compensation efficiency and the compensation amount with high precision is very troublesome.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a distortion compensator that is simple, easy, and highly efficient, and is capable of setting a large distortion compensation amount. To do.

[0007]

SUMMARY OF THE INVENTION The present invention is a high frequency input.
A first directional coupler for dividing a signal into a main signal and an auxiliary signal
A stage, first amplification means for amplifying the main signal, and
The main signal and the first amplification amplified by one amplification means
A part of the intermodulation distortion component generated by the means
The two directional coupling means and the second directional coupling means
The extracted signal is coupled to the auxiliary signal in reverse phase and
The intermodulation distortion component generated by the first amplification means is removed.
The third directional coupling means to be issued and the third directional coupling means
A second amplifier that amplifies the intermodulation products extracted by the stage.
The width means and the intermodulation distortion component amplified by the second amplifying means.
Component of the intermodulation distortion generated by the first amplifying means
A distortion compensator having a fourth directional coupling means for canceling the minute
The degree of coupling of the fourth directional coupling means is set to the first degree.
The intermodulation distortion component of the output signal of the amplifying means and the main signal
Signal ratio U, and the efficiency of the first amplification means η_M, The above
2 the efficiency of the amplification means η_SAs α^1/2 / (1 + α
^1/2 ) Near (however, α = U ・ η_M/ Η_S)
It is configured as follows.

[0008]

According to the above configuration, the distortion compensation efficiency and the distortion compensation amount are α ^1/2 / (1 + α ^1/2 ) Around (however, α = U ・ η _M
/ Η _S ), the coupling degree of the fourth directional coupling means is optimally set, and the efficiency is set to a large value.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. That is, the distortion compensator according to the embodiment of the present invention is configured, for example, as shown in FIG. _Assuming that the ratio of the distortion component and the main signal is U, the efficiency of the first amplifier 3 is η _M , and the efficiency of the second amplifier 6 is η _S , α ^1/2 / (1 + α ^1/2 ) Around (however, α
= U · η _M / η _S ) and the distortion compensation efficiency and the amount of distortion compensation are set.

To compensate for the distortion, the output power of the first amplifier 3 is P _M , the power consumption is P _disM , the output power of the second amplifier 6 is P _S , the power consumption is P _disS , and the fourth power is P _disS . The degree of coupling expressed by the power ratio of the directional coupler 7 of C (0 <C <1)
Then, at the output end, the level (1-C) · U · P _M of the intermodulation distortion component generated in the first amplifier 3 and the intermodulation component of the first amplifier 3 amplified by the second amplifier 6 It is necessary that the levels C · P _S are equal, that is, (1−C) · U · P _M = C · P _S (1). That is, P _M = η _{M
Substituting} P _disM and P _S = η _S · P _{disS results} in (1-C) · U · η _M · P _disM = C · η _S · P _disS (2). Here, α = U · η _M / η _S (3) is set as a parameter determined by the nonlinear states of the first and second amplifiers 3 and 6. This becomes α = (C · P _disS ) / {(1-C) · P disM} (4) from the equation (2). Further, the total output power P _OUT as an amplifier is P _OUT = (1-C) · η _M · P _disM (5) The total power consumption P _T is P _T = P _disM + P _disS = {from the formula (4). (C + α−α · C) / C} · P _disM (6) Therefore, the total efficiency η _T is η _T = P _OUT / P _T = [(C−C ² ) · C + α}] · η _M (7)

Here, α (dB) = − 3 dB, −9 d
B, -15 dB (α = 0.5, 0.13, 0.032)
At that time, C (dB) and η _T / η _M (dB) show the relationship shown in FIG. Therefore, in FIG. 2, since there is a maximum value, η _T / η _M is obtained from the equation (7), and differentiated by C to be 0, C = α ^1/2 / (1 + α ^1/2 ), And η _T
/ ΗM is the maximum.

On the other hand, C = α^1/2 / (1 + α^1/2 )When
(C at this time is C_oC) for α (dB)
_o(DB), P_disS/ P_disM(DB), P_OUT/ P
_M(DB), η_T/ Η_M(DB) has the relationship shown in FIG.
To do. This is because the first and second
The power consumption, output power and efficiency of each amplifier 3, 6
The first and second amplifier.
If α determined by the non-linear state of 3 and 6 is determined,
It shows that the performance is not exceeded.

Therefore, the coupling degree C of the fourth directional coupler 7 is
To α ^1/2 / (1 + α ^1/2 ), Η _T
/ Η _M is maximum, and distortion compensation with a large amount of distortion compensation is realized.

As described above, in the distortion compensator, the degree of coupling of the fourth directional coupler 7 is U, the ratio of the intermodulation distortion component of the output signal of the first amplifier 3 to the main signal is U, and the first amplifier. _Let η _{M be} the efficiency of 3 and η _{S be} the efficiency of the second amplifier 6, and α ^1/2 /
(1 + α ^1/2 ) (Where α = U · η _M / η _S ). According to this, α ^1/2 / (1+
α ^1/2 ) The degree of coupling of the fourth directional coupler 7 is set to an optimum value without exceeding the performance shown in FIG. 3 by a simple adjustment by simply setting it near (however, α = U · η _M / η _S ). As a result, distortion compensation with high efficiency and large distortion compensation amount is realized. The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0015]

As described above in detail, according to the present invention, it is possible to provide a distortion compensator which is simple, easy, and highly efficient and capable of setting a large distortion compensation amount. ..

[Brief description of drawings]

FIG. 1 is a diagram showing a distortion compensator applied to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the coupling degree of a directional coupler and the ratio of the efficiency of the entire amplifier and the efficiency of the first amplifier.

FIG. 3 C = α for α^1/2 / (1 + α^1/2 )When
Degree of coupling, power consumption ratio of the first and second amplifier, amplification
Between the output power of the entire unit and the output power of the first amplifier
Ratio, the efficiency of the amplifier as a whole and the efficiency of the first amplifier
The figure which showed the relationship of ratio.

[Explanation of symbols]

1 ... Input end, 2, 4, 5, 7 ... 1st-4th directional coupler, 3, 6 ... 1st and 2nd amplifier, 8 ... Output end.

Claims (1)

[Claims] 1. A first directional coupling means for distributing a high-frequency input signal into a main signal and an auxiliary signal, a first amplification means for amplifying the main signal, and the main signal amplified by the first amplification means. Signal and said first
Second directional coupling means for extracting a part of the intermodulation distortion component generated by the amplifying means, and a signal extracted by the second directional coupling means in antiphase for coupling to the auxiliary signal. Third directional coupling means for taking out the intermodulation distortion component generated by the first amplifying means, second amplifying means for amplifying the intermodulation component taken out by the third directional coupling means, and this second Distortion compensator amplified by the amplifying means, and a fourth directional coupling means for canceling the intermodulation distortion component generated by the first amplifying means, the fourth directional coupling The degree of coupling of the means is U, the ratio of the intermodulation distortion component of the output signal of the first amplifying means and the main signal is U, the efficiency of the first amplifying means is η _M , and the efficiency of the second amplifying means is As η _S , α ^1/2 / (1 + α ^1/2 ) Near (however, α = U · η _M / η _S ) is set.