JP2000022454A - Power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power amplifier that decreases a delay of a delay line for an adjustment purpose limitlessly that is required in the case of synthesizing signals of two systems with different delays. SOLUTION: The power amplifier is provided with a power distributor 113 that consists of a combination of a band rejection filter(BRF) which leads an output signal (b) of a main amplifier 412 to a line of a difference detector 418 as a distribution signal and a band pass filter(BPF) which leads the output signal (b) to a delay line 414 as a distribution signal, and with a power combiner 215 consisting of a combination of a BRF that receives a signal (i) from a sub-amplifier 420 and a BPF that receives a signal from the delay line 414 so that a delay in the delay line 414 is reduced by synthesizing the signal with a time lead characteristic by the BRF in combination with the signal with a time lag characteristic by the BPF.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power amplifier provided at the last stage of a communication device or the like, and more particularly to a power amplifier having a distortion compensation function.

[0002]

2. Description of the Related Art FIG. 6 shows an example of the configuration of a conventional power amplifier having a distortion compensation function. This kind of power amplifying device 4
The pilot signal oscillator 410 generates a pilot signal of an empty channel of the main amplifier 412 or a pilot signal p of an out-of-band frequency, and outputs this to the synchronization detector 421 and the directional coupler 411. The directional coupler 411 combines the pilot signal p and the input signal, and inputs the combined signal a to the main amplifier 412. A directional coupler 413 is connected to the output side of the main amplifier 412, from which a part of the signal f of the amplifier output signal b (c) is extracted and output to the difference detector 418.

An input signal delayed by a delay line 417 is input to a difference detector 418, and a difference between this input signal and a signal f from a directional coupler 413, that is, a distortion component g is determined by a phase gain adjuster. 419. The phase / gain adjuster 419 adjusts the phase and gain of the distortion component g based on the control signal k, and
Output to 0. The sub-amplifier 420 amplifies the phase- and gain-adjusted signal h to generate a compensation signal i, which is output to the directional coupler 415.

The directional coupler 415 combines the compensation signal i with the output d of the directional coupler 413 delayed by the delay line 414, and outputs an amplified signal e with the distortion component compensated. The amplified signal e is output to the subsequent circuit through the directional coupler 416. Further, a part of the amplified signal j is input to the synchronization detector 421, where the control signal k is generated.

[0005]

A conventional power amplifying device 4
Is the difference detector 418 from the directional coupler 413,
Since the time delay between the gain adjuster 419 and the sub-amplifier 420 is large, the delay line 414 having a time delay equal to this time is used.
Has to be inserted between the two directional couplers 413 and 415. The insertion loss of the delay line 414 increases as the delay time increases, and the linearity range of the output signal decreases accordingly. This means that in order to secure an output signal of a required power level, it is necessary to increase the output power of the main amplifier 412 by the insertion loss of the delay line 414, which is disadvantageous in cost. I do.

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost power amplifier capable of minimizing the time lag and expanding the linearity range of an output signal.

[0007]

According to the present invention, there is provided a power amplifying apparatus for distributing an output signal of a main amplifier for amplifying an input signal to two lines, a distributed signal on one line and the input signal. A power synthesizing means for synthesizing a compensation signal based on a difference from the signal with a distribution signal on the other line, and a power amplifying device for compensating for a distortion component of the output signal by the synthesizing. A band rejection filter (hereinafter referred to as BRF) for guiding a distribution signal to the one line.
And a band-pass filter (hereinafter referred to as BPF) for guiding the distribution signal to the other line.

In another power amplifier of the present invention, the power combining means includes a BRF receiving the compensation signal as input and a BPF receiving a distribution signal on the other line as input and passing through the BRF. And a distributed signal that has passed through the BPF.

In another power amplifying apparatus according to the present invention, the power distribution means includes a BRF for guiding a distribution signal to the one line,
The power combining means includes a BRF receiving the compensation signal as an input, and a BPF receiving a distribution signal on the other line as an input. The compensation signal that has passed through the BRF and the distribution signal that has passed through the BPF are combined.

A BPF passes a signal with a time lag characteristic, while a BRF passes a signal with a time lag characteristic. Therefore, by combining the two, it is possible to reduce the delay amount of the delay line required when synthesizing two systems of signals with delay. Note that an adjustment circuit for adjusting the amplitude or phase of the compensation signal to the amplitude or phase of the distribution signal on the other line side is inserted and connected to the one line.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a power amplifying apparatus according to an embodiment of the present invention. (First Embodiment) FIG. 1 is a configuration diagram of a power amplifying device 1 according to a first embodiment of the present invention. Components having the same functions as those of the conventional device 4 shown in FIG. It is attached. This power amplifying device 1 is provided with a power distributor 113 instead of the directional coupler 413 in the conventional device 4 shown in FIG. This power distributor 113
Of the directional coupler 413
Is equal to or less than the coupling degree of

As shown in FIG. 2, for example, a power divider 113 includes a band rejection filter (BR) including an LC series resonance circuit.
F) and a band pass filter (BP) including an LC parallel resonance circuit
F). In this embodiment, the line from the main amplifier 412 is connected to the common terminal T1, and the BR
The line to the difference detector 418 is connected to the F-side terminal T3, and the line to the delay line 414 is connected to the BPF-side terminal T2. Thereby, the signal b amplified by the main amplifier 412
Is input via the shared terminal T1 and distributed to the delay line 414 with a BPF characteristic, that is, a time delay characteristic. The signal is also distributed to the difference detector 418 with the BRF characteristic, that is, the time advance characteristic.

In the power amplifying apparatus 1, the main amplifier 4
The distortion component g of the amplified signal b output from 12 is removed as follows. A signal f of a part of the amplified signal b is extracted by the BRF of the power divider 113, and the difference detector 418
Extracts a distortion component g by comparing with a part of the input signal. This distortion component g is converted into a signal h whose phase and gain have been adjusted by the phase / gain adjuster 419,
At 20, the amplified signal i is amplified, and the amplified signal i is combined with the output signal d of the delay line 414 by the directional coupler 415. At this time, the delay amount of the delay line 414 and the phase / gain adjuster 419 are set so that the distortion component g is canceled.
The amount of phase and the gain in are adjusted.

In order for the distortion component g to be sufficiently canceled,
The delay amount of the delay line 414 over the necessary band is determined by the sub-amplifier 42 after the signal f is distributed from the power distributor 113.
It is necessary that the delay time until the signal is amplified by 0 and reaches the directional coupler 415 is equal to the delay time. In the conventional device 4 shown in FIG. 6, since all elements have delay characteristics, the delay amount of the delay line 414 needs to be considerably large. However, in the power amplifying device 1 of the present embodiment, the delay line 414 side is used. In the line of the sub-amplifier 420, the signal is distributed with the time advance characteristic by the BPF, and the signal is distributed with the time advance characteristic by the BRF in the line on the side of the sub-amplifier 420. Therefore, the delay amount of the delay line 414 can be reduced accordingly. Therefore, the insertion loss due to the delay line 414 is significantly reduced, and even when the same main amplifier 412 and sub-amplifier 420 are used, the linearity range of the output signal can be expanded.

Next, the reason why the time advance characteristic and the time delay characteristic can be realized by the power divider 113 combining the BRF and the BPF will be described. Here, as the simplest example, an example of a BPF having an LC parallel resonance circuit will be described.

1. Assuming that the input amplitude of the signal source is E1 and the impedance is Zo, the output amplitude Eo is expressed by the following equation (1). Eo = E1 * (XL || XC) / (Zo + (XL || XC)) (1) where (XL || XC) is the parallel impedance of the inductive reactance XL and the capacitive reactance XC. Since the inductive reactance XL is jωL and the capacitive reactance XC is represented by 1 / jωC, the equation (1) is
Equation (2) is obtained. Eo = E1 / (Zo (jωC + 1 / (jωL)) + 1) (2) In the vicinity of ω = ωo = 1 / root (LC), “jωC +
1 / (jωL) "is almost a zero value, so that | Eo | and | E1 | are almost the same in amplitude, but the value of phase 値 is as shown in the following equation (3). Ф = ∠ (Eo / E1) = − ∠ (Zo (jωC + 1 / (jωL)) + 1) Here, if Zo = R and Im (Zo) = 0, Ф is as follows. Ф = −∠ (1 / R + jωC + 1 / (jωL)) = − atan (ωC−1 / (ωL)) / (1 / R) (3)

Further, assuming that ω = ωo + △ (△ is a deviation from the center frequency), ωC−1 / (ωL) = ((ωo +
Δ) squared × LC-1) / (ωL), which is 2 △
Since C can be approximated, Ф can be approximated by the following equation (4). Ф = -atan (2 △ CR) (4)

If 2 << CR << 1, the phase difference Ф is -2.
It is represented by ΔCR. That is, the phase difference Ф is proportional to the deviation 中心 from the center frequency, and the higher the frequency, the more the phase is delayed. FIG. 3A illustrates this.

2. Here, a case where a signal of the carrier frequency ωo modulated by the modulation signal f (t) is input to the BPF will be considered. The side band Es due to the modulation at this time is as follows:
Let it be given by equation (5). Es = Σ (Ai × sin (ωit + θi)) (5) where Σ represents the sum for i, and ωi represents the angular frequency deviation from ωo. For example, in the case of AM modulation, “Ai × s
in (ωit + θi) ”is given by Fourier expansion of f (t). The sideband Es becomes a signal Eso as shown in the following equation (6) by passing through the BPF. Eso = Σ (Ai * sin (ωit + θi−2CRωi)) (6) The phase (−2CRωi) is 2CR for all ωi.
, And the sum of them, Eso's E
The time delay τ with respect to s is “2CR” as shown in FIG.

3. As for the BRF, the polarity of the phase difference Ф is opposite to that of the above-described BPF, and the time difference characteristic is exhibited.

As described above, the time delay characteristic is obtained by the BPF, and the time advance characteristic is obtained by the BRF. By combining these, the delay time of the signal from distribution to synthesis can be adjusted. Can be reduced, and the power level of the output signal can be made higher than that of the conventional device 4. When a constant power level is required, it is possible to make up for it with the main amplifier 412 of lower power, so that an inexpensive power amplifying device can be configured, and the effect is great.

(Second Embodiment) FIG. 4 is a configuration diagram of a power amplifying device 1 according to a second embodiment of the present invention. The components having the same functions as those of the components of the conventional device 4 shown in FIG. The same reference numerals are given. This power amplifying device 2 is configured as shown in FIG.
1 is provided with a power combiner 215 instead of the directional coupler 415 in the conventional device 4 shown in FIG. The loss value due to the insertion and connection of the power combiner 215 is equal to or less than the coupling degree of the directional coupler 415.

The power combiner 215 has the above-mentioned BRF and BP
F. For example, in the configuration shown in FIG.
A terminal T2 and a line from the sub-amplifier 420
3. The common terminal T1 is connected to the line directed to the directional coupler 416. As a result, the signal i amplified by the sub-amplifier 420 is combined with the signal d from the delay line 414 with a BRF characteristic (time advance characteristic),
The delay time due to the line on the sub-amplifier 420 side can be reduced.

(Third Embodiment) The above-described power distributor 113
And the power combiner 215 may be used at the same time. FIG. 5 is a configuration diagram of the power amplification device 3 having such a configuration. This power amplifying device 3 is provided with a power distributor 113 and a power combiner 215 instead of the directional couplers 413 and 415 in the conventional device 4 shown in FIG. The connection relationship with the line is as described in the first and second embodiments. The time characteristics of the signal by the power amplifying device 3 are obtained by adding the effects of the above-described two forms of the power amplifying devices 1 and 2. Therefore, the delay amount of the delay line 414 can be further reduced, and a power amplifier with less loss can be obtained.

When the degree of coupling between the power divider 113 and the power combiner 215 used in the power amplifiers 1, 2, 3 has a temperature characteristic, the main amplifier 412 and the sub-amplifier 42
There is a concern that it may affect the gain of 0 or the like. Therefore,
As a result of examining the degree of this effect, the following conclusions were obtained. Sub-amplifier 42 with insertion of power divider 113
A change in the coupling degree toward the zero side does not affect the output signal. However, depending on the magnitude of the signal component appearing on the output side of the difference detector 418, another distortion component is generated unless the linearity range of the output signal of the sub-amplifier 420 is widened. Need some extra time. However, this is not so problematic in the power amplifier as a whole. On the other hand, changes in the gain of the sub-amplifier 420 and the coupling degree due to the insertion of the power combiner 215 are as follows.
Since it directly affects the gain of the entire power amplifying device, it is necessary to individually or collectively perform temperature compensation. However, such a problem can be solved by using a component or element having a flat temperature characteristic.

[0026]

As is apparent from the above description, according to the power amplifier of the present invention, the delay amount of the delay line for adjustment, which is necessary when two signals having different delay amounts are combined, is reduced. Since it can be made as small as possible, there is a specific effect that the insertion loss is reduced and the linearity range of the output signal is expanded.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a power amplification device according to a first embodiment of the present invention.

FIG. 2 shows a band rejection filter (B) including an LC parallel resonance circuit.
RF) and a bandpass filter (B) including an LC series resonance circuit.
FIG. 2 is a configuration diagram of a power distributor that combines the power distribution method (PF).

FIG. 3A is a diagram showing that a phase difference 信号 of a signal passing through a BPF is proportional to a deviation 中心 from a center frequency, and the phase is delayed as the frequency increases, and FIG. FIG. 6 is a diagram showing that the signal is delayed by −2CR (C is a capacitance, and R is a resistance).

FIG. 4 is a configuration diagram of a power amplification device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a power amplification device according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional power amplifying device.

[Explanation of symbols]

 1, 2, 3, 4 Power amplification device having distortion compensation function 113 Power divider 215 Power combiner 410 Pilot signal oscillator 411, 413, 415, 416 Directional coupler 412 Main amplifier 414, 417 Delay line 418 Difference detector 419 Phase / gain adjuster 421 Synchronous detector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J090 AA01 AA41 CA21 GN02 GN05 HA25 HA29 HA33 HN16 KA15 KA16 KA23 KA32 KA44 KA45 TA01 TA02

Claims (4)

[Claims] 1. A power distribution means for distributing an output signal of a main amplifier for amplifying an input signal to two lines, and a compensation signal based on a difference between a distribution signal on one line and the input signal on the other line. A power amplifying device for compensating for a distortion component of the output signal by the combining, wherein the power distributing unit is configured to guide the distributed signal to the one line. And a band-pass filter for guiding a distribution signal to the other line. 2. A power distribution means for distributing an output signal of a main amplifier for amplifying an input signal to two lines, and a compensation signal based on a difference between a distribution signal on one line and the input signal on the other line. A power amplifying device having power combining means for combining with the above distributed signal, wherein the power combining means compensates for a distortion component of the output signal by the combining; A band-pass filter having a distributed signal on the other line as an input, wherein the compensating signal passing through the band-stop filter and the distributed signal passing through the band-pass filter are combined. Characteristic power amplifying device. 3. A power distribution means for distributing an output signal of a main amplifier for amplifying an input signal to two lines, and a compensation signal based on a difference between a distribution signal on one line and the input signal on the other line. A power amplifying device for compensating for a distortion component of the output signal by the combining, wherein the power distributing unit is configured to guide the distributed signal to the one line. And a band-pass filter for guiding a distribution signal to the other line, wherein the power combining means includes a band-stop filter having the compensation signal as an input, and a distribution signal on the other line as an input. And a compensating signal passed through the band rejection filter and a distribution signal passed through the band pass filter. Power amplifier. 4. An adjustment circuit for adjusting the amplitude or phase of the compensation signal to the amplitude or phase of the distribution signal on the other line side is inserted and connected to the one line. Item 4. The power amplifying device according to item 1, 2 or 3.