JPH0793538B2 - Amplifier - Google Patents

Description

The present invention relates to an amplifying device used for output amplification and relay amplification in digital wireless communication, for example.

[Conventional technology]

In general, as a method of amplifying a modulated wave used for communication, there are a method of amplifying the modulated wave by emphasizing the linearity of the amplifier and a method of ignoring the power efficiency.

When importance is attached to the linearity of the amplitude characteristic of the signal, the output of the amplifier is lowered to some extent to amplify the modulated wave in a region where the amplitude characteristic of the amplifier maintains the linearity. In this case, the out-of-band spectrum characteristic of the signal can be maintained and amplified. In this way, operating the amplifier with the output lowered is called output backoff.

On the other hand, the signal can be amplified with high power efficiency by amplifying the modulated wave using the saturation region (non-linear region) of the amplifier.

[Problems to be Solved by the Invention]

By the way, the present applicant has already proposed Japanese Patent Application No. Sho 63-114098 "Amplifier" as a device for amplifying a band-limited linearly modulated wave without deteriorating the out-of-band spectrum and power efficiency. . This is a technique in which a linearly modulated wave is decomposed into two systems of constant envelope modulated waves, and the two systems of constant envelope modulated waves are respectively amplified and then combined.

FIG. 4 shows a specific example of an amplification device using this technique.

In the figure, an input signal wave S (t) is decomposed by a quadrature detector 41 into two quadrature modulation signal components I (t) and Q (t).

Based on the two quadrature modulation signal components I (t) and Q (t), the waveform generation arithmetic circuit 42 uses two systems of constant envelope modulation signals I ₁ (t), Q ₁ (t) and I ₂ (T), Q ₂ (t) are generated. Here, two systems of constant envelope modulated signals I ₁ (t), Q
₁ (t) and I ₂ (t), Q ₂ (t) are generated so that the input signal wave S (t) is reproduced by combining these.

The quadrature modulators 43 and 44 have constant envelope modulation signals I
_The carrier wave is modulated by ₁ (t), Q ₁ (t) and I ₂ (t), Q ₂ (t), and two systems of constant envelope modulated waves S ₁ (t) and S ₂ (t) are output. To do.

The amplifiers 45 and 46 are operated in a saturation region (non-linear region) where high power efficiency is obtained, and the two constant envelope modulated waves S ₁ (t) and S ₂ (t) are amplified. Then, the combiner 47 combines the outputs of the amplifiers 45 and 46,
Obtain the output signal wave S ₀ (t).

However, in the technique described above, it is assumed that the amplitudes of the two systems of constant envelope modulated waves that are combined by the combiner 47 are the same, and the waveform generation arithmetic circuit 42 generates the two systems of constant envelope modulated signals. To be done. Therefore, the amplifier 45,46
If the amplitudes of the output signals are not the same, the input signal cannot be restored, which has the drawback of degrading the out-of-band spectrum.

By the way, when constructing an actual circuit, the characteristics of the two amplifiers 45 and 46 often do not completely match each other, so that in general, two systems of constant envelope modulated waves synthesized by the synthesizer 47 are used. The amplitudes do not match. Further, even when the characteristics of the two amplifiers 45 and 46 are adjusted so as to match in the initial stage, it is expected that a difference in characteristics will occur due to an external temperature change during use and a secular change in the characteristics.

The present invention has been made in view of such a point, and an object of the present invention is to provide an amplifying device capable of amplifying a signal having an envelope variation with good power efficiency without deteriorating an out-of-band spectrum. I am trying.

[Means for Solving the Problems]

 FIG. 1 is a block diagram of an amplifier device according to the present invention.

In the figure, an amplification unit receives a modulation signal, and inputs a waveform generation arithmetic means for outputting a first modulation signal and a second modulation signal corresponding to two constant envelope modulated waves, and a first modulation signal. As a first modulation wave for outputting a first modulation wave corresponding thereto, a second modulation means for receiving a second modulation signal as an input and outputting a second modulation wave corresponding thereto, a first modulation wave,
It has two amplifying means for amplifying each of the second modulated waves in the saturation region and a combining means for adding the two modulated waves amplified by both amplifying means.

The amplitude difference detection means detects the amplitude difference between the two modulated waves amplified by the two amplification means of the amplification section based on the output of the combination means of the amplification section.

The amplitude difference correction unit controls the amplification unit based on the amplitude difference detected by the amplitude difference detection unit so that the amplitudes of the two modulated waves added by the combining unit of the amplification unit match and the amplitude difference is corrected. To do.

[Work]

The waveform generating calculation means to which the modulation signal is input outputs the first modulation signal and the second modulation signal. Here, the first modulated signal and the second modulated signal are generated by synthesizing them so that the input modulated signal is reproduced.

The two modulators modulate the carrier wave by the corresponding modulation signals and output two systems of constant envelope modulated waves. The constant envelope modulated waves of these two systems are amplified by the amplifying means operating in the saturation region where the power efficiency is high, and then added by the combining means to become an output signal.

Based on this output signal, the amplitude difference detection means detects the amplitude difference between the two systems of constant envelope modulated waves. Based on this amplitude difference, the amplitude difference correction means controls the amplifier so that the amplitudes of the two systems of constant envelope modulated waves match.

According to the present invention, a carrier wave is input by generating two systems of constant envelope modulated waves based on the input modulation signal, amplifying the two systems of envelope modulated waves, and then combining the amplified signals. The same waveform as when the signal modulated by the modulation signal is linearly amplified is obtained.

Further, the amplitude difference correction means corrects the amplitude difference between the two constant envelope modulation waves based on the amplitude difference between the two constant envelope modulation waves detected by the amplitude difference detection means. The signal is accurately recovered by the means.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows the configuration of an amplifier device according to an embodiment of the present invention.

In the figure, a quadrature detector 11 quadrature-detects an input signal wave S _i (t) and extracts quadrature-modulated signals I (t) and Q (t).

The waveform generation arithmetic circuit 12 uses the quadrature modulation signal I (t), Q
By using (t), two systems of quadrature modulation signals I ₁ (t), Q
Generate ₁ (t) and I ₂ (t), Q ₂ (t).

Here, two systems of quadrature modulation signals I ₁ (t), Q ₁ (t) and I ₂ (t), Q ₂ (t) are generated by synthesizing them so that the input signal is reproduced. .

The quadrature modulator 13 is a quadrature modulation signal thus obtained.
The carrier is modulated by I ₁ (t), Q ₁ (t) to generate a constant envelope modulated wave S ₁ (t), and the quadrature modulator 14 similarly similarly quadrature modulated signal I ₂ (t), Q. _A constant envelope modulated wave S ₂ (t) is generated based on ₂ (t).

The amplifiers 15 and 16 amplify the constant envelope modulated waves S ₁ (t) and S ₂ (t), respectively, in a saturation region where high power efficiency is obtained.

Here, the amplifier 15 has, for example, an input signal voltage and a reference voltage Va.
Is amplified, and the amplifier 16 amplifies the difference between the input signal voltage and the reference voltage Vb. Also the amplifier 1
The constant envelope modulated wave S _a1 (t), S
_{Call it a2} (t).

In the hybrid 17, the constant envelope modulated wave S _a2 (t)
By adding 90 ° to the constant envelope modulated wave S _a1 (t) to synthesize an output signal wave S ₀ (t),
Further, the constant envelope modulated wave S _a1 (t) phase-shifted by 90 degrees and the constant envelope modulated wave S _a2 (t) are added to synthesize the second combined wave S _m (t). Output signal wave S
₀ (t) and the second combined wave S _m (t) are output, respectively.

FIG. 3 is an explanatory diagram of the relationship between the constant envelope modulated waves S _a1 (t) and S _a2 (t) and the output signal wave S ₀ (t) and the second combined wave S _m (t).

Two constant envelope modulated waves S _a1 introduced in the hybrid 17
If the amplitudes of (t) and S _a2 (t) are the same, the phase difference α between the hybrid output signal wave S ₀ (t) and the second composite wave S _m (t) is 0 degree or 180 degrees. (The case where the phase difference is 0 is shown in FIG. 3A).

On the other hand, the two constant envelope modulated waves S _a1 (t), S _a2 that are introduced
When the amplitudes of (t) are not the same, the phase difference α is 0 degree, 180 degrees.
It is a value other than degrees.

Here, assuming that the counterclockwise direction is a positive direction from the output signal wave S ₀ (t), a constant envelope modulated wave is obtained as shown in FIG. 3B, for example.
When the amplitude of S _a1 (t) is larger than that of the constant envelope modulated wave S _a2 (t), the phase difference α <0. When the amplitude of the constant envelope modulated wave S _a2 (t) is larger as shown in FIG. 3C, the phase difference α> 0.

In FIG. 2, the electric power of the second combined wave S _m (t) is introduced into one input terminal of another hybrid 18 and one end of a resistor 22 whose other end is grounded.

Since the other input terminal of the hybrid 18 is terminated via the resistor 23, the hybrid 18 is connected to the second combined wave S
A signal in phase with _m (t) and a third combined wave S _mt (t) obtained by shifting the second combined wave S _m (t) by 90 degrees are output.

The third combined wave S _mt (t) is introduced into the multiplier 19,
The other output terminal of the hybrid 18 is terminated via a resistor 24.

The third synthesized wave S _mt (t) is output by the multiplier 19 to the output signal wave S _0.
It is multiplied by a part of the electric power of (t), and the high-pass component is removed from the multiplication result by the low-pass filter 20.

As a result, the output signal wave S ₀ (t) and the second combined wave S _m (t)
A baseband signal S having a value corresponding to the phase difference α between
_B (t) is introduced into the voltage controller 21.

Here, the third combined wave S _mt (t) is equal to the second combined wave S _m (t).
Since the phase is shifted by 0 degrees, the two constant envelope modulated waves S _a1
If the amplitudes of (t) and S _a2 (t) are the same, the output signal wave S ₀
The phase difference between (t) and the third combined wave S _mt (t) becomes 90 degrees, and the value of the baseband signal S _B (t) becomes 0.

On the other hand, when there is a difference in amplitude between the two constant envelope modulated waves S _a1 (t) and S _a2 (t), the output signal wave S ₀ (t) and the third composite wave
Since the phase difference from S _mt (t) is not 90 degrees, the value of the baseband signal S _B (t) is a value other than 0.

As shown in FIG. 3, depending on whether the phase difference α is positive or negative, the two constant envelope modulated waves S _a1 (t), S
Since it is possible to determine which of the amplitudes of _a2 (t) is larger, which of the two amplifiers 15 and 16 should be adjusted based on the sign of the value of the baseband signal S _B (t). It is possible to specify

Therefore, the voltage control unit 21, for example, the baseband signal S _B
When the value of (t) is positive, the reference voltage Va is controlled so that the amplitude of the constant envelope modulated wave S _a1 (t) of the output of the amplifier 15 becomes small. Control the voltage Vb.

Here, when amplifying the constant envelope modulated wave, the linearity is maintained even in the saturation region. In addition, as described above, the voltage control unit 21 causes the amplification factors of the amplifiers 15 and 16 to be input to the hybrid 17 to generate two constant envelope modulated waves S.
_Since the amplitudes of _a1 (t) and S _a2 (t) are controlled to match, the output signal wave S ₀ synthesized by the hybrid 17 is
The waveform of (t) is a waveform without distortion as in the case where the input signal wave S _i (t) is linearly amplified.

Thus, by the hybrid 18, the second synthetic S
_A third combined wave S _mt (t) obtained by moving _m (t) by 90 degrees is generated, and this and an output signal wave S ₀ (t) are applied to a multiplier 19, and a high frequency component is removed through a low pass filter 20. As a result, the output signal wave S ₀ that is the two outputs of the hybrid 17 is output.
A baseband signal S _B (t) having a value corresponding to the phase difference α between (t) and the second combined wave S _m (t) is obtained.

Based on whether the value of this baseband signal S _B (t) is positive or negative,
By adjusting the reference voltages Va and Vb of the amplifiers 15 and 16 by the voltage control unit 21, the constant envelope modulated wave S
It is possible to perform correction so that the amplitudes of _a1 (t) and S _a2 (t) match.

As a result, the two constant envelope modulated waves S ₁ (t), S
₂ (t) is amplified to have the same amplitude and then combined to produce an output signal wave having a waveform without distortion as in the case where the input signal wave S _i (t) is linearly amplified.
S ₀ (t) can be obtained.

Further, since the amplifiers 15 and 16 operate in the saturation region, it is possible to increase the power efficiency for amplification.

In the above-described embodiment of the present invention, a hybrid, a multiplier, and a low-pass filter are used as the amplitude difference detecting means, and two amplifying means are detected from the phase difference between the two outputs of the hybrid used as the combining means. Although the case of detecting the amplitude difference of the output is considered, the present invention is not limited to this, and any control that corrects the amplitude difference based on the amplitude difference of the constant envelope modulated waves of the two systems can be applied.

Further, although the amplifiers 15 and 16 amplify the difference between the input signal and the reference voltage, the present invention is not limited to this, and the amplification degree may be changed based on the control signal. The point is that the output signals of the amplifiers 15 and 16 can be variably controlled.

Furthermore, the present invention is not limited to the embodiments described above,
It will be readily apparent to those skilled in the art that the present invention has various modifications.

〔The invention's effect〕

As described above, according to the present invention, the signal wave having the envelope fluctuation is decomposed into two constant envelope modulated waves, and the amplitudes of the constant envelope modulated waves are corrected and then combined to obtain the envelope. It is possible to maintain the linearity of a signal wave having line fluctuation and to amplify the signal wave with high power efficiency.

[Brief description of drawings]

 FIG. 1 is a block diagram of an amplifier according to the present invention, FIG. 2 is a block diagram of an amplifier according to an embodiment of the present invention, FIG. 3 is an explanatory diagram of a relationship between a constant envelope modulated wave and a composite wave, and FIG. The figure is a block diagram of an amplifier. In the figure, 11,41 is a quadrature detector, 12,42 is a waveform generation arithmetic circuit, 13,14,43,44 are quadrature modulators, 15,16,45,56 are amplifiers, 17,18 are hybrids, 19 Is a multiplier, 20 is a low-pass filter, 21 is a voltage controller, and 47 is a combiner.

Claims (1)

[Claims] 1. A waveform generation arithmetic means for inputting a modulation signal and outputting a first modulation signal and a second modulation signal corresponding to two constant envelope modulated waves, and using the first modulation signal as an input. A first modulation means for outputting a first modulated wave corresponding thereto, a second modulation means for receiving the second modulated signal corresponding to the second modulated signal, and a second modulated wave corresponding thereto, the first modulated wave, the first modulated wave An amplifying section having two amplifying means for amplifying each of the two modulated waves in a saturation region and a synthesizing means for adding the two modulated waves amplified by the both amplifying means; Amplitude difference detecting means for detecting the amplitude difference between the two modulation signals, and the two modulated waves added by the synthesizing means on the basis of the amplitude difference detected by the amplitude difference detecting means are matched with each other. Amplifier section Controlled and amplifying apparatus characterized by comprising an amplitude difference correcting means for correcting the amplitude difference.