JP2697618B2 - Feedforward amplifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedforward amplifier, and more particularly, to a feedforward amplifier requiring a high saturation output power.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional feedforward amplifier has a divider 2 for dividing a signal inputted from an input 1 into two parts, and a vector adjuster for adjusting the amplitude and phase of one output of the divider 2. Combiner 27, divider 22 for dividing the output of vector adjuster 27 into four, main amplifiers 6a, 6b, 6c and 6d for amplifying the output of divider 22, and outputs of main amplifiers 6a, 6b, 6c and 6d. Combiner 2
3, a divider 24 for dividing the output of the combiner 23 into two, and a delay line 25 for delaying one output signal of the divider 24
And a delay line 1 for delaying the other output signal of the distributor 2
3, the signal delayed by the delay line 13 and the distributor 24
, A vector adjuster 28 for adjusting the amplitude and phase of the signal output from the combiner 14, an auxiliary amplifier 15 for amplifying the output of the vector adjuster 28, and an auxiliary amplifier. 15 is provided with a synthesizer 9 for synthesizing the output of the signal 15 and the signal delayed by the delay line 25.

In FIG. 7, a signal path g and a signal path h have a vector adjuster 2 so that gains are equal and phases are opposite.
7 and the delay line 13. The signal path i and the signal path j are also adjusted by the vector adjuster 28 and the delay line 25 so that the gains are equal and the phases are opposite.

[0004] A signal input from an input 1 is distributed to a signal path g and a signal path h by a distributor 2, and
Synthesized by

[0005] The signal path g and the signal path h have the same gain,
Since the phases are adjusted to be opposite phases, the combiner 14
Outputs the difference between the signal path g and the signal path h. Here, the signal path h is the undistorted delay line 13.
Through the main amplifier 6 from the combiner 14.
Only the distortion components a, 6b, 6c and 6d are output.

Accordingly, a loop composed of the signal path g and the signal path i is called a distortion detection loop.

The signal containing the distortion component output from the combiner 23 is distributed to a signal path i and a signal path j by a distributor 24. Since the signal path i is a distortion-free delay line, a signal including a distortion component is directly input to the combiner 9. In the signal path j, after only the distortion component is extracted by the above-described distortion detection loop, the vector adjuster 2
8. The signal is input to the synthesizer 9 through the auxiliary amplifier 15. Here, since the signal path i and the signal path j are adjusted so that the gains are equal and the phases are opposite to each other, the difference from the signal path i and the signal path j from the output of the combiner 9, that is, the distortion is included. Only the distortion component is subtracted from the signal and output from the output 10.

Next, a calculation example of the saturation output power will be described.

FIG. 8 shows the main amplifier 26 of FIG. In FIG. 8, the saturation output power (Psat) of the main amplifiers 6a, 6b, 6c and 6d is 40 dBm (10 W), and the delay line 25
Assuming that the loss of the main amplifier 26 is -2 dB and the loss of the combiner 23 and the distributor 24 can be neglected, the saturation output power of the main amplifier 26 is 4 dB.
4.0 dBm (25.1 W), and the maximum power passing through the delay line 25 is 44.0 dBm (25.1 W).

As a reference publication, Japanese Patent Application Laid-Open No. 61-16620
In Japanese Patent Application Publication No. 6-36, a band rejection filter for blocking a monitor signal is inserted on the delay circuit side of an error detection loop, and the level of the monitor signal is monitored on the output side of the field forward amplifier to detect a failure of the error amplifier. A fault detection method for an error amplifier is disclosed.

In Japanese Patent Application Laid-Open No. 61-164307, an automatic gain adjustment circuit is provided on the error amplifier side of the error injection loop, and a pilot extracted from the output side of the delay circuit of the error injection loop and the output side of the error amplifier. A feedforward amplifier that obtains a signal with small distortion by automatically adjusting the gain so as to suppress the signal difference is disclosed.

[0012]

In this conventional feedforward amplifier, since the outputs of the main amplifiers 6a, 6b, 6c are all output through the delay line 25, the saturation output is reduced by the loss of the delay line 25. The power is the main amplifier 6a, 6
There is a problem that it is lower than the sum of b, 6c and 6d.

The main amplifiers 6a, 6b, 6c and 6d
Are all passed through the delay line 25, so that the delay line 25 needs a line having a large power capacity.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a feedforward amplifier which can make the saturation output power higher than that of a conventional feedforward amplifier and can use a delay line having a passing power capacity of the delay line.

[0015]

According to the present invention, in a feedforward amplifier having two or more main amplifiers having the same characteristics, a first divider for dividing an input signal into two, and the first divider. A first vector adjuster for adjusting the amplitude and phase of one of the output signals of the device, a second divider for dividing the signal adjusted by the first vector adjuster into two, A first delaying one output signal of the distributor;
, A first main amplifier for amplifying a signal delayed by the first delay line, a second main amplifier for amplifying the other output signal of the second distributor, and a second main amplifier. A third splitter for splitting the output signal of the main amplifier into two, a second delay line for delaying one output signal of the third splitter, and a signal delayed by the second delay line. A first combiner for combining a signal with an output of the first main amplifier, a third delay line for delaying the other output signal of the first distributor, and a delay by the third delay line A second combiner for combining the output signal and the other output signal of the third divider, a second vector adjuster for adjusting the amplitude and phase of the output signal of the second combiner, An auxiliary amplifier for amplifying the signal adjusted by the second vector adjuster; an output of the auxiliary amplifier; Third for combining the output of one of the combiner
And a combiner of (1).

Further, according to the present invention, there is provided a feedforward amplifier, wherein a large number of the first main amplifiers are connected in parallel.

Further, according to the present invention, in a feedforward amplifier having two or more main amplifiers having the same characteristics, a first divider for dividing an input signal into two,
Adjusts the amplitude and phase of one output signal of the first divider.
, A second divider that distributes the signal adjusted by the first vector adjuster into N (N is a natural number), and N outputs (N− 1) first to (N-1) th delay lines for respectively delaying the output signals, and first to (N-th) delay lines for amplifying the signals delayed by the first to (N-1) th delay lines, respectively. 1) a main amplifier, an Nth main amplifier for amplifying the remaining one output signal of the second splitter, and a third splitter for splitting the output signal of the Nth main amplifier into two An N-th delay line for delaying one output signal of the third divider; a signal delayed by the N-th delay line;
1) a first combiner for combining the output signal of the main amplifier, a (N + 1) th delay line for delaying the other output signal of the first distributor, and a (N + 1) th delay line A second combiner for combining the delayed signal and the other output signal of the third divider, a second vector adjuster for adjusting the amplitude and phase of the output signal of the second combiner, , The second
And a third combiner for combining an output signal of the auxiliary amplifier with an output signal of the first combiner. An amplifier is obtained.

[0018]

The first and second main amplifiers are the same amplifier and have the same distortion characteristics. Therefore, a main amplifier is used for distortion detection, and the distortion is detected by a distortion detection loop composed of a signal path. In other main amplifiers, the amount of delay is adjusted by a delay line so that an output having the same phase as the signal amplified by the main amplifier is obtained when the signals are combined by the combiner.

Therefore, since the output of the combiner has the same distortion component as the main amplifier, it can be canceled by the distortion component detected by the distortion detection loop. With this configuration, the main amplifier does not require a delay line on the output side, and the saturation output power is increased by the loss of the delay line.

[0020]

Next, a feedforward amplifier according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the feedforward amplifier of the present invention. In the first embodiment described below and the second embodiment described later, the same parts as those in FIG. 7 are denoted by the same reference numerals.

The signal input from the input 1 is divided by the splitter 2 into 2
One is adjusted in amplitude and phase by a vector adjuster 27, and is further split into two by a splitter 3. The other is delayed by delay line 13 and input to combiner 14. One of the two divided by the divider 3 is delayed by the delay line 4 and divided by the divider 5.
Is divided into three. The signals divided into three by the divider 5 are amplified by the main amplifiers 6a, 6b and 6c and are combined by the combiner 7. The other of the two divided by the distributor 3 is the main amplifier 6d.
And is divided into two by the distributor 11.

One of the two divided by the divider 11 is delayed by the delay line 12 and is combined with the output of the combiner 7 by the combiner 8. The other of the two divided by the distributor 11 is the delay line 1
The signal delayed by 3 is combined with the signal by the combiner 14, the amplitude and the phase are adjusted by the vector adjuster 28, amplified by the auxiliary amplifier 15, combined with the output of the combiner 8 and the combiner 9, and output by the combiner 9. Output.

Here, the signal path a and the signal path b are adjusted by the vector adjuster 27 and the delay line 13 so that the gains are equal and the phases are opposite. The signal path c and the signal path d are adjusted by the vector adjuster 28 and the delay line 12 so that the phases are opposite.

The signal path e and the signal path f are adjusted by the delay line 4 so as to have the same phase and the same delay amount.

When the signal shown in FIG. 5A is input from the input 1, the signal input from the input is distributed to the signal path a and the signal path b by the distributor 2. A signal containing a distortion component as shown in FIG. 5B is output from the output of the main amplifier 6d in the signal path a, and a signal containing the distortion component shown in FIG. Input to the device 14. Since the signal path b only passes through the undistorted delay line 13, an input signal having the same component as that of FIG.
4 is input. Here, since the signal path a and the signal path b are adjusted so that the gains are equal and opposite phases, the combiner 1
In FIG. 4, the input signal components cancel each other, and
As shown in (d), only the distortion component is output.

The output of the synthesizer 14 is adjusted in amplitude and phase by a vector adjuster 28 and amplified by the auxiliary amplifier 15 to obtain the output shown in FIG.

Next, FIG. 2 shows an example of a level diagram of the main amplifying section 16 of FIG. In FIG. 2, the main amplifiers 6a, 6
b, 6c and 6d are amplifiers having the same characteristics and a gain of 20 dB. The loss of the delay lines 4 and 12 is -2.
dB and the loss of the distributor and the combiner is ignored.

The input to the main amplifying section 16 is 20 dBm. When 20 dBm is input to the input, the distributor 3
19.2 dBm on the delay line 4 side, 1 on the main amplifier 6d side
This is a distributor that distributes to a level different from 2.4 dBm.
When 19.2 dBm is input from the divider 3 to the delay line 4, the output of the delay line 4 is 1 since the loss of the delay line 4 is -2 dB.
7.2 dBm. This is divided into three signals by the distributor 5, and 12.4 dBm is output from each terminal. The signal output from the distributor 5 is amplified by the main amplifiers 6a, 6b and 6c, and outputs 32.4 dBm. The output signal is synthesized by the synthesizer 7 into 37.2d.
The output of Bm is obtained.

The 12.4 on the main amplifier 6d side of the distributor 3
The dBm is amplified by the main amplifier 6d to output 32.4dBm. Since the loss of the distributor 11 is ignored, the delay line to which 32.4 dBm is input is -2d.
The output is 30.4 dBm due to the loss of B. Here, the output 37.2 dBm of the combiner 7 and the output 30.4 dBm of the delay line 12 are combined by the combiner 8 and the output is 38.0.
dBm is obtained. The combiner 8 is a combiner for combining different levels, and an example is shown in FIG.

In the case of FIG. 4, the combination of 37.2 dBm and 30.4 dBm is realized by using a λ / 4 impedance converter having a transmission line 17 of 55Ω and a transmission line 18 of 120Ω as the characteristic impedance of the transmission line. I have.

Therefore, in FIG. 1, the main amplifiers 6a, 6a
Since b, 6c and 6d operate at exactly the same level, the same distortion occurs in the main amplifiers 6a, 6b, 6c and 6d (but at different timings).

The signal paths e and f have the same phase and the same delay amount, so that the distortion generated in the main amplifiers 6a, 6b and 6c is
The distortion generated in 6d becomes the same phase in the combiner 8 and is combined.
Further, since the signal path c and the signal path d are in opposite phases, the auxiliary amplifier 15 outputs a component having a phase opposite to the distortion component of the main amplifier 6d. Since the distortion components of the main amplifiers 6a to 6c are in phase with the distortion component of the main amplifier 6d in the combiner 8, the output of the auxiliary amplifier 15 is output from the main amplifiers 6a, 6b, 6c
, And 6d. Therefore,
By adjusting the amplitude of the vector adjuster 28 and appropriately adjusting the output of the auxiliary amplifier 15, the main amplifiers 6a, 6b, 6
By canceling the distortion components of c and 6d, an output without distortion as shown in FIG. 5F can be obtained.

Next, a calculation example of the saturation output power will be described. FIG.
1 shows the main amplifying unit 16 of FIG. In FIG. 3, the main amplifier 6
The saturated output power (Psat) from 6a to 6d is 40 dBm,
It is assumed that the loss of the delay line 12 is -2 dB, and the loss of the combiner 7, the distributor 8, and the distributor 11 can be ignored. Since the delay line 4 is on the input side of the main amplifiers 6a, 6b and 6c, it does not affect the saturation output power. The saturation output power at the output of the combiner 7 is 44.8 dBm (30.0 W), and the main amplifier 6 d has a loss of −2 dB due to the delay line 12.
3W). This is synthesized by the synthesizer 8 to obtain 4
A saturated output power of 5.6 dBm (36.3 W) is obtained. Further, the passing power of the delay line 12 is 38.0 dB at the maximum.
m (6.3 W).

Next, a second embodiment of the feedforward amplifier according to the present invention will be described with reference to the drawings. FIG. 6 is a block diagram showing a second embodiment of the present invention.

The signal input from the input 1 is divided by the splitter 2 into 2
One of them is adjusted in amplitude and phase by a vector adjuster 27, and further divided into four by a distributor 19. The other is delayed by delay line 13 and input to combiner 14. Distributor 1
One of the outputs divided into four by 9 is amplified by the main amplifier 6d and is divided into two by the distributor 11. The remaining three outputs of the distributor 19 are delayed by delay lines 20a to 20c and amplified by the main amplifiers 6a, 6b and 6c. One of the two divided by the divider 11 is delayed by the delay line 12, and the main amplifier 6
The outputs of a, 6b and 6c are combined with the combiner 21. The other is synthesized with the signal delayed by the delay line 13 by the synthesizer 14 and the amplitude and the phase are adjusted by the vector adjuster 28.
The output of the combiner 21 amplified by the auxiliary amplifier 15 and the combiner 9
And output from the output 10. Where the signal path k
And the signal path l are adjusted by the vector adjuster 27 and the delay line 13 so that the gains are equal and the phases are opposite.

The signal path m and the signal path n are adjusted by the vector adjuster 28 and the delay line 12 so that the phases are opposite.

The four systems from the output of the distributor 19 to the input of the synthesizer 21 are all adjusted by the delay lines 20a to 20c so that they have the same phase and the same delay amount.

In the above configuration, the operation of FIG. 6 is the same as that of the first embodiment, and the main amplifiers 6a and 6b are controlled by varying the amplitude of the vector adjuster 28 and appropriately adjusting the output of the auxiliary amplifier 15. , 6c and 6d can be canceled to obtain an output without distortion as shown in FIG. Also, the saturation output power is the same as in the first embodiment.

[0039]

As described above, according to the present invention, when there are two or more main amplifiers having the same characteristic, only one of the two or more main amplifiers is used for detecting distortion, and the other main amplifiers are used for the other main amplifiers. Since the configuration is such that a delay line is provided on the input side, there is an effect that the saturation output power can be made higher than that of a conventional feedforward amplifier.

Further, a delay line is provided on the output side of the main amplifier used for distortion detection, and a delay line is provided on the input side of the other main amplifiers having a low level. It has the effect of being able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a feedforward amplifier according to the present invention.

FIG. 2 is a block diagram showing a level diagram of a main amplifier in FIG. 1;

FIG. 3 is a block diagram showing a saturation output power of a main amplifier of FIG. 1;

FIG. 4 is a circuit diagram of a synthesizer when input levels are different.

5A and 5B are graphs showing the spectrum of each part in FIG. 1, wherein FIG. 5A shows an input signal, FIG. 5B shows a main amplifier output, and FIG. 5C shows a part of the main amplifier extracted by a distributor. , (D) shows a diagram in which only the distortion component is extracted, (e) shows the output of the auxiliary amplifier, and (f) shows an output signal from which the distortion component has been canceled.

FIG. 6 is a block diagram showing a second embodiment of the feedforward amplifier according to the present invention.

FIG. 7 is a block diagram showing an example of a conventional feedforward amplifier.

FIG. 8 is a block diagram showing the saturation output power of the main amplifier of FIG. 7;

[Explanation of symbols]

1 input 2, 3, 5, 11, 19, 22, 24 distributor 4 delay line 6a, 6b, 6c, 6d, 16, 26 main amplifier 7, 8, 9, 14, 21, 23 combiner 10 output 12, 13, 20a, 20b, 20c, 25 Delay line 15 Auxiliary amplifier 17, 18 Transmission line 27, 28 Vector adjuster a, b, c, d, e, f, g, h, i, j, k, l,
m, n, signal path

Claims (3)

(57) [Claims] 1. A feedforward amplifier having two or more main amplifiers having the same characteristic, a first divider for dividing an input signal into two, and an amplitude and a phase of one output signal of the first divider. , A second divider that divides the signal adjusted by the first vector adjuster into two, and delays one output signal of the second divider. A first delay line;
A first amplifying signal delayed by the first delay line;
A second main amplifier for amplifying the other output signal of the second divider, a third divider for dividing the output signal of the second main amplifier into two, A second delay line for delaying one output signal of the three dividers, a first combiner for combining the signal delayed by the second delay line and the output of the first main amplifier, A third delay line for delaying the other output signal of the first distributor;
A second combiner for combining the signal delayed by the delay line of the third and the other output signal of the third divider, and a second combiner for adjusting the amplitude and phase of the output signal of the second combiner. A vector adjuster; an auxiliary amplifier for amplifying the signal adjusted by the second vector adjuster; and a third combiner for combining an output of the auxiliary amplifier and an output of the first combiner. A feed-forward amplifier, characterized in that: 2. The feedforward amplifier according to claim 1, wherein a plurality of said first main amplifiers are connected in parallel. 3. A feedforward amplifier having two or more main amplifiers having the same characteristics, a first divider for dividing an input signal into two, and an amplitude and a phase of one output signal of the first divider. And a second divider that distributes the signal adjusted by the first vector adjuster to N (N is a natural number),
First to (N-1) th delay lines for delaying (N-1) output signals of the N outputs of the second distributor, and first to (N-1) th delay lines A first to (N-1) -th main amplifier for amplifying the signal delayed by the second splitter, an N-th main amplifier for amplifying the remaining one output signal of the second distributor, and the N-th main amplifier. Output signal of main amplifier is 2
A third divider, an N-th delay line for delaying one output signal of the third divider, a signal delayed by the N-th delay line, and the first to ( N-
1) a first combiner for combining the output signal of the main amplifier, a (N + 1) th delay line for delaying the other output signal of the first distributor, and a (N + 1) th delay line A second combiner for combining the delayed signal and the other output signal of the third divider, a second vector adjuster for adjusting the amplitude and phase of the output signal of the second combiner, , The second
And a third combiner for combining an output signal of the auxiliary amplifier with an output signal of the first combiner. amplifier.