JP2000295048A - Feed forward amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure distortion compensation ability with respect to high peak power signal input by synthesizing a distortion component amplified by an auxiliary amplifier to a main amplifier output signal and removing the distortion component from the main amplifier output signal. SOLUTION: An amplifier with high P1dB is used for the power amplifying part of an auxiliary amplifier 2 and compensation quantity is raised to a value which is lower than a main amplifier 1 by about 2-3dB. The operation point of a feed forward amplifier is assumed to be 40dB and the signal of high peak power which is higher than average power by 6dB, for example, distortion cancel quantity can be secured to 20dB if P1dB of the auxiliary amplifier 2 is 42dBm lower than P1dB of the main amplifier 1 by 8dB and to 28dB if P1db of the auxiliary amplifier 2 is 48dBm lower than P1dB of the main amplifier 1 by 2dB. Distortion compensation ability can be secured with respect to the input signal of high peak power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedforward amplifier mainly used as a transmission power amplifier (T-PA) in a mobile communication base station such as a portable telephone.

[0002]

2. Description of the Related Art When a distortion occurs in an output signal of a transmission power amplifier in a mobile radio communication system or the like, the distortion component becomes leakage power to an adjacent channel, which causes a disturbance in communication on the adjacent channel. Therefore, in such a transmission power amplifier, it is necessary to suppress the generation of distortion. Therefore, in general, the operating point is set in a linear region (linear region) in the amplifier input / output characteristics, and the operation is performed in the linear region. The occurrence of is suppressed. However, generally, setting the operating point in the linear region in this way results in an amplifier with low power efficiency.

Improve power efficiency (reduce power consumption)
For this purpose, it is necessary to bring the operating region of the amplifier close to the saturation power. However, near the saturation power, the input / output characteristics of the amplifier become non-linear, and the generation of distortion cannot be avoided due to the non-linearity.

[0004] As one method of compensating (removing) this distortion, a feedforward amplifier is known. The distortion is caused by the non-linearity of the amplifier.
A feedforward amplifier is an amplifier that compensates for distortion caused by nonlinearity, in other words, an amplifier that improves the linearity of the entire amplifier by distortion compensation. The configuration and the principle of the linear operation will be described below.

[Basic Configuration] FIG. 7 is a diagram showing a basic configuration of a feedforward amplifier, and FIG. 8 is a diagram showing a signal path (signal path) of the feedforward amplifier.

In FIG. 1, 1 is a main amplifier (M-AMP) for amplifying an input signal to a predetermined level, 2 is an auxiliary amplifier (error amplifier: S-AMP) for amplifying a distortion component,
3 to 6 are directional couplers for distributing and combining signals;
Is a delay line for adjusting the amount of delay, and 9 and 10 are vector adjusters (amplitude and phase adjusters) for finely adjusting the amplitude and phase.

The signal path in the feedforward amplifier will be described with reference to FIG. Path is input 1
1 is an original signal path for amplifying a signal which is amplified by the main amplifier 1 and output to the output terminal 12 via the delay line 8. The path is amplified by the directional coupler 4 after the signal input to the input terminal 11 is amplified by the main amplifier 1, guided to the auxiliary amplifier 2 via the directional coupler 5 and amplified, and then amplified by the directional coupler 6. This is a signal path to be combined with the signal of the original path. In the path, a signal input to the input terminal 11 is partially branched by the directional coupler 3, delayed by the delay line 7, guided to the auxiliary amplifier 2 via the directional coupler 5, and amplified. 6 is a signal path to be combined with the signal of the original path.

Here, the directional coupler 5 has a function of extracting a distortion component generated in the output signal by the main amplifier 1 by combining the signals of the paths, and the auxiliary amplifier 2 has a function of extracting the extracted distortion component. Has a function of amplifying the distortion component to an appropriate size for distortion compensation, and the directional coupler 6 removes the distortion component in the output signal by combining the amplified distortion component with the main amplifier output signal of the path. Has functions. The delay lines 7 and 8 are for setting in-phase and out-of-phase of signals to be synthesized in order to fulfill these functions, and the vector adjusters 9 and 10 finely adjust the amplitude and phase of the signals for that purpose. Things.

That is, in the feedforward amplifier, the gain and the phase shift amount of each signal path are set as follows. 1. The gain or the amount of coupling of the main amplifier 1, the auxiliary amplifier 2, and the directional couplers 3 to 6 is selected so that the path, the path, and the pass gain of the path are all the same. 2. The line lengths of the delay lines 7 and 8 are selected so that the path and the path and the phase after the passage of the path are opposite to each other. At the same time, in order to perform broadband synthesis, the line length is selected such that the paths, paths, and delay amounts of the paths are all the same. 3. The vector adjusters 9 and 10 finely adjust the amplitude and phase of each path.

[0010] These can be expressed by the following equations.
Hereinafter, a vector of a signal that passes through the path and appears at the output terminal 12 is referred to as a vector. The same applies to vectors and vectors, which are signal vectors of each path appearing at the output terminal 12. | Vector | = | vector | = | vector | ∠vector = ∠vector + 180 ° ∠vector = ∠vector + 180 ° FIG. 10 (1)
The vector of each path at the output terminal 12 shown in FIG.

The operation of the feedforward amplifier will first be described qualitatively. FIG. 9 is a diagram for this purpose, and shows the spectrums (a) to (d) of the signals at the main points a to d.
Is shown. 1. A signal to be amplified such as a modulated wave is input to the input terminal 11. This amplified signal is assumed to be two signal components shown in the spectrum (a). 2. It is assumed that the signal is distorted by the non-linearity of the main amplifier 1 by amplifying this to a predetermined level by the main amplifier 1. Here, the distortion component generated at this time is a signal component generated on both sides of the spectrum (b). 3. In the directional coupler 4, a signal after the distortion distorted by the main amplifier 1 is extracted. The post-distortion signal corresponds to spectrum (b). 4. The directional coupler 3 extracts a pre-distortion signal before amplification by the main amplifier 1. This pre-distortion signal corresponds to the spectrum (a). 5. Item 3. in the directional coupler 5. And item 4. Are combined with the same amplitude and opposite phase, and only the distortion component is extracted. The extracted distortion component is the spectrum (c), which corresponds to a combination of the spectrum (a) and the spectrum (b) with the same amplitude and opposite phase. 6. In the auxiliary amplifier 2, item 5. Is amplified to a predetermined level. 7. In the directional coupler 6, item 2. And Item 6. Are synthesized with the same amplitude and opposite phase, and Removes only the distortion component from the signal. The signal from which the distortion component has been removed is the spectrum (d), which corresponds to a combination of the spectrum (a) and the spectrum (c) with the same amplitude and opposite phase.

As described above, only the distortion component of the signal distorted by the main amplifier 1 is extracted by the directional coupler 5, and the directional coupler 6 combines these distortion components with the same amplitude and opposite phase. Thus, the distortion component is removed from the output signal of the main amplifier 1.

Next, the operation of the feedforward amplifier will be described based on the concept based on signal vectors. [During linear operation: when main amplifier 1 is not distorted] FIG. 10 shows output terminal 1 in the case of linear operation in which main amplifier 1 is not distorted.
2 shows the state of each vector in FIG. 2, and FIG. 10A shows the vector of each path when the main amplifier 1 is not distorted.
Here, since the vectors have the same amplitude and opposite phases, when they are combined by the directional coupler 5, they cancel each other out and become zero. Therefore, the vector of the output signal at the output terminal 12 is a vector that does not include distortion, as shown in FIG. That is, during the linear operation in which the main amplifier 1 is not distorted, the signal amplified by the main amplifier 1 to a predetermined output level is output as it is.

[During linear operation: when main amplifier 1 is distorted] Consider, for example, a case where the main amplifier 1 is distorted, the gain of the main amplifier 1 is reduced, and the phase is rotated. FIG. 11 shows the state of each vector at the output terminal 12 in the case of the nonlinear operation in which the main amplifier 1 is distorted. FIG.
0 (1) is a vector of each path when the main amplifier 1 is not distorted, and the vector has a smaller amplitude and a rotated phase as compared with FIG. 10 (1). The vector has the same amplitude and opposite phase as this vector. Since the vector does not pass through the main amplifier 1 and is not affected by distortion of the main amplifier 1, the vector is at the same position as the vector in FIG.

Here, the vector + is a signal obtained by amplifying a signal leaking from the directional coupler 5 into the auxiliary amplifier 2 and appearing at the output terminal 12, and a signal distortion component generated only when the main amplifier 1 is distorted. (Distortion component extraction). The vector + which is the signal distortion component and the vector distorted by the main amplifier 1 are combined by the directional coupler 6 to cancel the distortion component contained in the vector. The vector shown in (2) is obtained. That is, the output signal output from the output terminal 12 is not affected by the distortion of the main amplifier 1 (distortion component compensation). From the above, it is understood that high linearity can be realized in the feedforward amplifier.

[Improvement of input / output characteristics] The manner in which the input / output characteristics are improved by the feedforward amplifier will be described below. Now, the main amplifier 1 has a gain of G = 35 dB, P
1 dB = 50 dBm Auxiliary amplifier 2 has a gain of G = 40 dB and P1dB = 40 dB
Assume a condition of m, 42 dBm, 44 dBm, 46 dBm, or 48 dBm. In addition, P1dB shown here is
When the actual input / output characteristic (the non-linear characteristic part) falls below the ideal linear characteristic (virtual linear characteristic) by 1 dB, the output power (dBm) corresponding to that point is shown.

FIG. 12 shows the result of simulating the input / output characteristics of the feedforward amplifier under these conditions.
Shows the input / output characteristics of the feedforward amplifier (with and without compensation). In the figure, the horizontal axis is the input power (dB
m), the vertical axis is the output power (dBm), the dashed line is the input / output characteristic when distortion compensation is not performed, the solid line is the input / output characteristic when distortion compensation is performed, and the latter is P
1dB is 40dBm, 42dBm, 44dBm, 46dBm, 48
Input / output characteristics are shown for each case of dBm. It can be seen from FIG. 12 that when distortion compensation is performed by the feedforward method, the linearity is improved and P1dB is increased by several decibels (dB) as compared with the case where no compensation is performed.

FIG. 13 shows the result of simulating the amount of cancellation of the distortion component under the same conditions as the above as characteristics of the amount of cancellation of the distortion component by the feedforward amplifier. In the figure, the horizontal axis is the input power (dB
m), the vertical axis is the distortion component cancellation amount (dBm), and P1dB is 40 dBm, 42 dBm, and 44 dB as the auxiliary amplifier 2.
The characteristics of the amount of cancellation are shown for each of m, 46 dBm, and 48 dBm.

For example, at an operating point of 43 dBm output (20 dBm input), the smaller the P1dB of the auxiliary amplifier 2 is, the more the distortion cancellation amount is deteriorated.
Is 10 dB lower than P1dB of the main amplifier 1, it can be seen that the distortion component cancellation amount is -30 dB or less.

For this reason, conventionally, the auxiliary amplifier 2 whose P1dB is about 6 to 7 dB lower than the P1dB of the main amplifier 1 is used, thereby securing a required canceling amount, that is, a distortion compensation ability.

In general, an A class amplifier (class A amplifier) is used for the main amplifier 1 and the auxiliary amplifier 2 with emphasis on the linearity of each amplifier. In particular, the auxiliary amplifier 2, as can be seen from its operation principle,
If the operation is performed in the non-linear region, distortion is further added when amplifying the extracted distortion component, and the distortion component in the output signal of the main amplifier cannot be completely removed, thereby deteriorating the distortion compensation ability. For this reason, conventionally, a class A amplifier having good linearity is always used as the auxiliary amplifier 2, and it has not been considered to use an amplifier having poor linearity such as a class AB amplifier.

[0022]

[Deterioration of Distortion Compensation Ability at Peak Power Input] Modulated waves such as CDMA (code division multiple access) signals which will be used in mobile communications and the like in the future
The power level has the property of fluctuating greatly over time. For example, in the case of a W-CDMA signal, instantaneous large power (peak power) occurs with respect to the average power,
The probability of occurrence is 10% in the case of average power + 3dB.
%, About 1% when the average power is +6 dB, and about 0.1% when the average power is +8 dB. Consider a case where such a modulated wave is distortion-compensated by the feedforward amplifier simulated earlier.

12 and 13, it is assumed that the operating point of the main amplifier 1 is 40 dBm output (17 dBm input). At this time, when the peak power higher than the average power by 6 dB is input, it can be seen that the distortion compensation capability at the time of inputting the peak power greatly differs depending on P1dB of the auxiliary amplifier 2. Specifically, as shown in FIG. 13, when the operating point is 17 dBm input, the distortion component cancellation amount is -35 dB. However, for this high peak power (17 dBm + 6 dBm) input,
When P1dB of the auxiliary amplifier 2 is 48 dBm, the distortion component cancellation amount is about 28 dB, while P1dB is 4 dB.
At 0 dBm, the distortion component cancellation amount is degraded to about 16 dB.

That is, when the P1 dB of the auxiliary amplifier 2 is configured by a P1 dB amplifier that is about 6 to 7 dB lower than the P1 dB of the main amplifier 1 as in the conventional configuration, distortion compensation is performed when a high peak power is input. The ability cannot be secured.

[High Power Consumption] As described above, a class A amplifier has conventionally been used for the main amplifier 1 and the auxiliary amplifier 2 in consideration of their linearity. However, the class A amplifier has a disadvantage that its power consumption is large. Furthermore, if the auxiliary amplifier 2 having a large value of P1dB is used so that the distortion compensating ability can be ensured even for high peak power, the power consumption of the auxiliary amplifier 2 is further increased, which leads to an increase in power consumption. The A-class operation amplifier is
The power consumption is almost constant irrespective of the output power, and there is a problem from this point in terms of power consumption efficiency.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. In a feedforward amplifier used for a wireless communication power amplifier or the like, when amplifying a modulated wave such as a CDMA signal having a high peak power, Ensures distortion compensation capability even for high peak power signal inputs,
Another object is to reduce power consumption.

[0027]

In order to solve the above problems, a feedforward amplifier according to the present invention is a feedforward amplifier for amplifying an input signal having a high peak power (for example, a CDMA signal). hand,
A main amplifier composed of a class AB amplifier, extraction means for extracting a distortion component generated by the main amplifier, an auxiliary amplifier composed of a class AB amplifier for amplifying the extracted distortion component, and a distortion component amplified by the auxiliary amplifier. Removing means for removing distortion components from the main amplifier output signal by combining the output signal with the output signal of the main amplifier. The extraction means branches the output signal of the main amplifier, branches the input signal before amplification of the main amplifier, and sets the branched signals to have the same amplitude and amplitude.
By combining the signals in opposite phases, it is possible to extract a distortion component in the output signal generated by the main amplifier. Further, the removing means removes the distortion component amplified by the auxiliary amplifier,
By combining the output signal of the main amplifier with the same amplitude and opposite phase as the distortion component in the output signal, the distortion component in the output signal of the main amplifier can be removed. In addition, P1dB of the above-mentioned auxiliary amplifier is lower than P1dB of the above-mentioned main amplifier within a range in which distortion compensation power for a high peak power input signal can be ensured (for example, conventionally, 7 to 8 dB).
A value that is about low is reduced to a value that is 2-3 dB lower).

[0028]

[Operation] [Ensuring distortion compensation capability at peak power input] An amplifier having a high P1dB is used for the power amplifier of the auxiliary amplifier 2, and the P1dB of the auxiliary amplifier 2 is lower than that of the main amplifier 1 by about 2 to 3 dB, for example. Up to In this case, for example, the operating point of the amplifier is set to 40 dB in FIGS.
Assuming that m output (17 dBm input), at this time, if a peak power 6 dB higher than the average power is input, for example, P1dB of the auxiliary amplifier 2 becomes 40 dBm (P of the main amplifier 1).
(10 dB lower than 1 dB), the distortion cancellation amount is 1
6dB, P1dB of auxiliary amplifier 2 is 48dB
m (2 dB lower than P1 dB of the main amplifier 1), a distortion cancellation amount of 28 dB can be secured. Therefore, by using a power amplifier having a higher P1dB than the conventional one (for example, about 3 dB lower than the P1dB of the main amplifier 1) as the auxiliary amplifier 2, it is possible to secure a high distortion compensation capability even when instantaneous peak power is generated. You can see what you can do. As a result, a signal having a temporally high peak power, such as a modulated wave such as a CDMA signal, can be amplified with low distortion.

[Reduction of Power Consumption] The power consumption can be reduced by operating the main amplifier 1 and the auxiliary amplifier 2 in the AB class operation. One of the features of the AB class operation is that when the output power is reduced, the power consumption is also reduced. Therefore, at the time of low output (that is, at the time of low traffic or low traffic).
Power consumption can be greatly reduced. This means that, in actual operation, for example, when this feedforward amplifier is used as a transmission power amplifier of a mobile communication base station, when the number of mobile communication terminals communicating with the base station is small, the transmission of the base station is difficult. Since the power is reduced, the power consumption at that time can be reduced. Generally, the base station operates at a lower output power more frequently than at the time of maximum output (when using the maximum communication capacity), so that the low output power is obtained. It is important and indispensable to reduce power consumption at the time. On the other hand, the power consumption of the A-class operation amplifier is almost constant regardless of the output power.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a feedforward amplifier according to one embodiment of the present invention. In the figure, 1 is a main amplifier, 2 is an auxiliary amplifier, 3 to 6 are directional couplers, 7, 8
Is a delay line, 9 and 10 are vector adjusters, and their functions are the same as those described in the section of the prior art. 1
Numeral 3 denotes an attenuator for adjusting the amplitude of the branch signal of the directional coupler 4, which is adjusted by the directional coupler 5 so as to combine with the signal from the delay line 7 to extract only the distortion component. It is. The gain in each of these circuits is shown in the figure.

FIG. 3 shows a configuration example of the main amplifier 1 of the feedforward amplifier. The main amplifier 1 has a gain G of +47 dB and a P1 dB of 50 dBm, and is composed of a total of five vertical stages connected by amplifying units 101 to 106. 10
4 to 106 are configured by class AB power amplifiers that operate in class AB. The first three stages comprise an amplifier used as a preamplifier. AB class power amplifier 105 at the last stage,
Reference numeral 106 denotes a parallel arrangement for increasing the amplification power.

FIG. 4 shows a configuration example of the auxiliary amplifier 2 of the feedforward amplifier. This auxiliary amplifier 2
Indicates that the gain G is +42 dB, P1dB is 47 dBm (that is, 3 dB lower than P1dB of the main amplifier 1),
In the same manner as described above, a total of five stages are vertically connected by amplifying units 201 to 205, and the rear two-stage power amplifying units 204 and 205 having the largest power consumption are configured by AB class power amplifiers that operate in AB class. The amplifying units 201 to 203 are configured by amplifiers serving as preamplifiers.

Hereinafter, the operation of the feedforward amplifier of this embodiment will be described based on the concept of a signal vector. In addition,
As described above, also in this embodiment, the vector of the signal that passes through the path and appears at the output end 12 is called a vector,
The same applies to vectors.

FIG. 2 explains the operation of the feedforward amplifier of this embodiment using signal vectors. FIG.
In (1), since the main amplifier 1 is distorted, the vector decreases in gain and phase rotation occurs, the amplitude decreases from the original reference position (the position of the vector in FIG. 10A), and the phase rotates. I have. The vector is adjusted by a directional coupler, a delay line, a vector adjuster, an auxiliary amplifier, and the like, and has the same amplitude and opposite phase as the vector. Since the vector does not pass through the main amplifier 1, it is not affected by distortion due to its non-linearity. That is, the reference position is set.

Here, in the operation at the time of the non-linear operation shown in FIG. 11, the vector + functions as a vector for removing the distortion of the vector. Since the component signal is further distorted by the distortion characteristic of the auxiliary amplifier 2, the component signal is shifted from the position of the vector + shown in FIG. 11A and becomes a vector (+) ′.

As shown in FIG. 2B, the vector (+) ′ distorted by the auxiliary amplifier 2 is finally combined with the vector, and as a result, FIG.
As shown in FIG. 10, the vector of the output signal from the output terminal 12 is = + (+) ′, which is not equal to the reference position (vector position) shown in FIG.

That is, in the feedforward amplifier of this embodiment, the distortion component generated in the main amplifier 1 cannot be completely compensated. For this reason, the linearity of the feedforward amplifier is slightly deteriorated, and as a result, the distortion compensation ability is slightly deteriorated. For example, in FIG. 13, the flooring level (distortion component cancellation amount in the linear region) of the distortion component cancellation amount (distortion compensation amount) is about -35 dB, but this value is -3 in the feedforward amplifier of this embodiment.
It is about 0 dB. However, this value is still sufficient for practical use. On the other hand, the feedforward amplifier of this embodiment can secure the distortion compensation capability even for a high peak power input signal.

More specifically, in this embodiment, as described above, an amplifier having a high P1dB is used for the power amplifier of the auxiliary amplifier 2, and P1dB of the auxiliary amplifier 2 compared to the main amplifier 1 is calculated as follows.
The value is increased from the conventional low value of about 7 to 8 dB to a low value of about 2 to 3 dB. Now, the operating point of this feedforward amplifier is set to 40 dBm output (17 dBm
Input). At this time, assuming that a signal having a high peak power 6 dB higher than the average power is input, for example, P1dB of the auxiliary amplifier 2 is 42 dBm (P1 of the main amplifier 1).
8 dB lower than dB), the distortion cancellation amount is 20d
B, On the other hand, if the P1dB of the auxiliary amplifier 2 is 48 dBm (2 dB lower than the P1dB of the main amplifier 1), a distortion cancellation amount of 28 dB can be secured, and the distortion compensation ability is secured even for an input signal having a high peak power. You can see what you can do.

FIG. 5 shows the distortion compensation capability of the feedforward amplifier of this embodiment, and shows adjacent channel leakage power when a CDMA signal is amplified as an input signal. In detail, the actual CDMA signal (chip rate 4.069 MHz)
4.0 which is 5 MHz apart when amplifying z)
The adjacent channel leakage power (distortion power) leaked to a channel having a bandwidth of 96 MHz is shown. The horizontal axis indicates the output power (dBm) of the feedforward amplifier, and the vertical axis indicates the leakage power (dB) to the adjacent channel. In the figure, the characteristic indicated by the broken line in (a) indicates that the conventional feedforward amplifier (a class A amplifier is used as the auxiliary amplifier 2 and its P1dB is used as the main amplifier 1).
The characteristics of the adjacent channel leakage in the case of (6 dB lower than P1dB) and the characteristics of the solid line in (b) are based on the feedforward amplifier of the present invention (P1dB is used as the auxiliary amplifier 2 using a class AB amplifier and the P1dB is used as the main amplifier 1). 3dB than P1dB
2) adjacent channel leakage characteristics.

As can be seen from the characteristic diagram of FIG. 5, in the feedforward amplifier of the present invention, the adjacent channel leakage characteristic is significantly improved as compared with the conventional system, and the leakage to the adjacent channel in the conventional system is reduced. It is considered that the cause is mainly the distortion component generated by the high peak power input, and as a result, it is understood that the feedforward amplifier of the present invention secures the distortion compensation ability for the input signal with the high peak power.

FIG. 6 shows the relationship between the transmission power (W) and the power consumption (W) of the feedforward amplifier of the embodiment. In the feedforward amplifier of this embodiment,
Since the main amplifier 1 and the auxiliary amplifier 2 are AB class amplifiers (class AB amplifiers), their power conversion efficiency can be increased and their power consumption can be reduced. Also,
As a feature of the amplifier that performs the AB class operation, the power consumption is reduced when the output power is reduced. Therefore, even in the feedforward amplifier of this embodiment, when the transmission power is reduced, the power consumption is also reduced, thereby greatly reducing the power consumption at a low output. Can be reduced.

[0042]

As described above, according to the present invention, a CDM having a high peak power is provided in a feedforward amplifier used for a power amplifier for wireless communication and the like.
When amplifying a modulated wave such as the A signal, it is possible to secure the distortion compensation capability even for the input of a high peak power signal and reduce the power consumption.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a feedforward amplifier as one embodiment according to the present invention.

FIG. 2 is a diagram illustrating a state of each signal vector at an output terminal for describing an operation of the feedforward amplifier according to the embodiment.

FIG. 3 is a diagram illustrating a configuration example of a main amplifier in a feedforward amplifier according to an embodiment;

FIG. 4 is a diagram illustrating a configuration example of an auxiliary amplifier 2 in the feedforward amplifier according to the embodiment;

FIG. 5 illustrates a feedforward amplifier according to an embodiment.
FIG. 3 is a diagram for explaining adjacent channel leakage power when a CDMA signal is amplified.

FIG. 6 is a diagram illustrating a relationship between transmission power and power consumption in the feedforward amplifier according to the embodiment.

FIG. 7 is a diagram illustrating a basic configuration of a feedforward amplifier.

FIG. 8 is a diagram illustrating a signal path of a feedforward amplifier.

FIG. 9 is a diagram showing spectra at respective main points for explaining a qualitative operation of the feedforward amplifier.

FIG. 10 is a diagram for explaining an operation based on a signal vector of the feedforward amplifier, and is a diagram illustrating a state of each vector at an output terminal during a linear operation.

FIG. 11 is a diagram for explaining an operation based on a signal vector of the feedforward amplifier, and is a diagram illustrating a state of each vector at an output terminal during a nonlinear operation.

FIG. 12 is a diagram showing input / output characteristics (with and without compensation) of a feedforward amplifier.

FIG. 13 is a diagram illustrating the characteristic of canceling a distortion component by a feedforward amplifier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main amplifier 2 Auxiliary amplifier 3-6 Directional coupler 7,8 Delay line 9,10 Vector adjuster 11 Input terminal (IN) 12 Output terminal (OUT) 13 Attenuator 101-103,201-203 Amplifier part 104- 106, 204, 205 AB class power amplifier

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J090 AA04 AA21 AA41 AA63 CA21 CA25 CA27 CA36 FA08 FA20 GN02 GN05 GN07 GN11 HN16 KA15 KA16 KA23 KA44 MA08 MA14 MA20 SA14 TA01 TA02 TA03 5J092 AA04 AA21 CA20 CA27 GR09 KA15 KA16 KA23 KA44 MA08 MA14 MA20 SA14 TA01 TA02 TA03 VL08

Claims (5)

[Claims] 1. A feedforward amplifier for amplifying an input signal having a high peak power, comprising: a main amplifier comprising a class AB amplifier; and extraction means for extracting a distortion component generated by the main amplifier. An auxiliary amplifier comprising a class AB amplifier for amplifying the extracted distortion component; and a removing means for combining the distortion component amplified by the auxiliary amplifier with the output signal of the main amplifier and removing the distortion component from the output signal of the main amplifier. Feed forward amplifier. 2. A feed-forward amplifier for amplifying an input signal having a high peak power, comprising: a main amplifier comprising a class AB amplifier; a branch signal for an output signal of the main amplifier; Extracting means for extracting a distortion component in the output signal generated by the main amplifier by branching the previous input signal and synthesizing those branch signals with the same amplitude and opposite phase; A feedforward amplifier comprising: an auxiliary amplifier including a class AB amplifier to be amplified; and a removing unit configured to combine a distortion component amplified by the auxiliary amplifier with an output signal of the main amplifier and remove a distortion component from an output signal of the main amplifier. 3. A feed-forward amplifier for amplifying an input signal having a high peak power, comprising: a main amplifier comprising a class AB amplifier; and extraction means for extracting a distortion component generated by the main amplifier. An auxiliary amplifier composed of a class AB amplifier for amplifying the extracted distortion component; and combining the distortion component amplified by the auxiliary amplifier with the output signal of the main amplifier with the same amplitude and opposite phase as the distortion component in the output signal. And a removing means for removing a distortion component in the output signal of the main amplifier. 4. A feed-forward amplifier for amplifying an input signal having a high peak power, comprising: a main amplifier comprising a class AB amplifier; a branch signal for an output signal of the main amplifier; Extracting means for extracting a distortion component in the output signal generated by the main amplifier by branching the previous input signal and synthesizing those branch signals with the same amplitude and opposite phase; An auxiliary amplifier composed of a class AB amplifier to be amplified; and a distortion component amplified by the auxiliary amplifier is combined with an output signal of the main amplifier at the same amplitude and opposite phase as a distortion component in the output signal, thereby obtaining the main amplifier. Removing means for removing distortion components in the output signal of the feedforward amplifier. 5. The apparatus according to claim 1, wherein P1dB of said auxiliary amplifier is lower than P1dB of said main amplifier within a range in which distortion compensation power for a high peak power input signal can be ensured. Feed-forward amplifier.