JP2001103100A - Linearizer type transmission amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly efficiently perform a lowly distorted base band processing at a low cost in AM/PM conversion, even in the case of digital modulation for which a difference between average power and peak power is large. SOLUTION: A phase shifter 3 and a detector 9 are added to a conventional linearizer type transmission amplifier. The detector 9 detects a part of output signals of a high output amplifier 4, converts the amplitude of modulated wave components to a voltage level and feeds back the voltage level to the phase shifter 3. Then, the phase shifter 3 performs phase correction, corresponding to the fed-back voltage level to RF signals sent from an orthogonal transformer 2 and transmits them to the high output amplifier 4. Thus, when the RF signals of low distortion are outputted from the orthogonal transformer 2 and inputted to the phase shifter 3, optimum phase correction is performed to the RF signals of the low distortion by the phase shifter 3, and optimum transmission signals (RF signals) are transmitted to a transmission antenna 5 by the high output amplifier 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission amplifier that performs distortion compensation by a linearizer, and more particularly to a linearizer type transmission amplifier that performs optimal phase correction on an RF signal supplied to a transmission antenna.

[0002]

2. Description of the Related Art A linearizer type transmission amplifier is preferably used as a transmission amplifier for performing final amplification and distortion compensation in a stage preceding an antenna combiner. FIG. 3 is a block diagram showing a configuration of a conventional linearizer type transmission amplifier. This linearizer type transmission amplifier includes a baseband signal processing unit 11, a quadrature modulator 12, a high-power amplifier 14, a transmission antenna 15, an amplifier 16, a variable attenuator 17, and a quadrature demodulator 18. In this linearizer type transmission amplifier, when the high power amplifier 14 supplies a transmission signal to the transmission antenna 15, the high power amplifier 1
4 is detected and supplied to the amplifier 16. Then, the gain is controlled by the amplifier 16 and the variable attenuator 17 so that the signal level becomes optimal, and the quadrature demodulator 1
8 is output as a baseband signal. The baseband signal is processed by the baseband signal processing unit 11 into an optimal baseband signal so as to be a low-distortion RF (Resonance Frequency) signal, and is input to the quadrature modulator 12. Then, feedback control is performed so that a low-distortion RF signal is output from the quadrature modulator 12 and input to the high-output amplifier 14.

[0003] Such an amplifier circuit is well known and will not be described in detail. The amplitude and phase of the self-oscillation signal of the baseband signal and the amplitude and phase of the transmission signal obtained via the high-power amplifier 14 are described. And corrects the self-oscillation signal of the baseband signal by adding the opposite phase and the opposite amplitude of the difference. That is, the high power amplifier 14
AM-AM (Amplitude Modulation-Amplitude Modu
lation) The amplitude distortion of the signal obtained by the conversion and the AM-PM
(Amplitude Modulation-Phase Modulation) Control is performed to correct the phase distortion of the signal obtained by the conversion. Further, the optimum processing of the RF signal can be performed by monitoring the waveform with, for example, a spectrum analyzer or the like.

[0004]

By the way, a high-output amplifier 14, which is a transmission amplifier used in such a linearizer type transmission amplifier, is required to have low cost and high efficiency. However, there is a trade-off relationship between a low distortion amplifier and low cost and high efficiency, and therefore, it is necessary to take measures such as performing distortion compensation on a circuit. In particular, in the case of digital modulation in which the difference between the average power and the peak power is large, the phase distortion in the AM-PM conversion involving the back-off of the average output power of the high-power amplifier 14 also greatly affects the deterioration of the overall distortion. are doing. That is, in FIG.
As shown in the power amplification characteristic diagram of the amplifier, when the peak power reaches the non-linear region A, the input power B is not linearly amplified,
The output power C is distorted and amplified, and the amplitude is distorted in the AM-AM conversion. Further, since the phase is rotated in this region, the phase in the AM-PM conversion is also distorted. To solve such a phenomenon, it is necessary to increase the back-off. However, since the efficiency of the amplifier is reduced, the back-off cannot be increased in reality. It should be noted that the power amplification characteristic diagram of FIG. 4 is publicly known, and a detailed description thereof is omitted. That is, conventionally,
Particularly, in the AM-PM conversion, depending on the magnitude of the conversion amount, there is a problem that the processing of the baseband signal with reduced distortion cannot be performed efficiently.

The present invention has been made in view of such circumstances, and has as its object to perform digital modulation in which a difference between average power and peak power is large without performing distortion compensation on a circuit. However, it is an object of the present invention to provide a linearizer type transmission amplifier capable of performing low-distortion baseband processing with low cost and high efficiency, particularly in AM-PM conversion.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a linearizer type transmission amplifier for amplifying and correcting distortion of an RF signal by a linearizer.
Means for generating a voltage level corresponding to the amplitude of the modulated wave component of the F signal, and means for correcting the phase of the RF signal by the generated voltage level, and according to the amplitude of the modulated wave component of the RF signal, This is a linearizer-type transmission amplifier that performs optimal phase correction on an RF signal. That is, if a part of the RF signal is detected and the phase is corrected by a voltage corresponding to the amplitude of the modulated wave component included in the RF signal, phase distortion in the AM-PM conversion of the amplifier can be improved, A highly efficient and low-cost amplifier can be provided.

Further, the present invention relates to the above-mentioned invention, wherein R
A transmitting antenna for transmitting the radio wave of the F signal to another wireless device;
High-power amplifying means for supplying an RF signal to the transmitting antenna, gain control means for controlling a gain of a part of the RF signal output from the high-power amplifying means, and a baseband signal having the gain-controlled signal input thereto And a quadrature demodulation means for outputting the baseband signal, and a baseband signal, and distortion compensation for outputting a low-distortion RF signal from the high-output amplification means, and outputting an optimal baseband signal. Baseband signal processing means, a baseband signal is input to generate a low-distortion RF signal, quadrature modulation means for outputting the RF signal, and part of the RF signal output from the high-power amplification means are detected. Then, a voltage level corresponding to the amplitude of the modulated wave component included in the RF signal is generated, and a detection means for feeding back the voltage level and an RF signal transmitted from the orthogonal transformation means are input. And phase shifting means for performing an optimal phase correction on the RF signal based on the voltage level fed back from the detecting means, wherein the phase shifting means shifts in accordance with the amplitude of the modulated wave component of the RF signal detected by the detecting means. The phase means performs an optimal phase correction on the RF signal supplied to the transmission antenna.

That is, the present invention can be realized only by newly adding a detection means and a phase shift means between the quadrature modulation means and the high output amplification means of the existing linearizer type transmission amplifier. Thereby, the detecting means detects a part of the RF signal output from the high-power amplifying means,
A voltage level corresponding to the amplitude of the modulated wave component included in the RF signal is generated, and the phase shifter receives the RF signal transmitted from the orthogonal transformer and receives the RF signal based on the voltage level fed back from the detector. Then, feedback control is performed so as to perform an optimal phase correction on the RF signal. in this way,
Since the phase of the RF signal can be automatically corrected to the optimum value according to the amplitude of the modulated wave component of the RF signal, a highly efficient and low-cost amplifier can be easily realized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a linearizer type transmission amplifier according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a linearizer type transmission amplifier of the present invention. That is, the linearizer type transmission amplifier of the present invention performs phase correction according to the voltage level on the RF signal sent from the quadrature modulator 2 with respect to the conventional linearizer type transmission amplifier, and , And a part of the output signal of the high-power amplifier 4 is detected, the amplitude of the modulated wave component is converted into a voltage level, and this voltage level is fed back to the phase shifter 3. A detector 9 is added.

Therefore, the linearizer type transmission amplifier of the present invention comprises: a transmission antenna 5 for transmitting a radio wave of an RF signal to another radio; a high output amplifier 4 for supplying a transmission signal (RF signal) to the transmission antenna; This high power amplifier 4
6 that controls the gain of a part of the RF signal output from
And a variable attenuator 7, a gain-controlled signal is input to generate a baseband signal, and a quadrature demodulator 8 that outputs the baseband signal. A baseband signal processing unit 1 that performs distortion compensation so as to output a low distortion transmission signal (RF signal) and outputs an optimal baseband signal, and inputs an optimal baseband signal to generate a low distortion RF signal A quadrature modulator 2 for outputting the signal and a low-distortion RF signal sent from the quadrature modulator 2 based on a voltage level corresponding to the amplitude of the modulated wave component detected from the high-output amplifier 4. A phase shifter 3 for performing an optimum phase correction, and a part of the RF signal output from the high-power amplifier 4, and the amplitude of the modulated wave component is converted into a voltage and fed back to the phase shifter 3. And the detector 9 That.

Next, the operation of the linearizer type transmission amplifier of this embodiment will be described. That is, the transmission signal (R
When the transmission of the radio wave is performed by supplying the F signal, a part of the output signal (RF signal) of the high power amplifier 4 is detected by the detector 9 and supplied to the amplifier 6. Then, the gain is controlled by the amplifier 6 and the variable attenuator 7 to obtain an optimum signal level, and the signal is output from the quadrature demodulator 8 as a baseband signal. Then, the baseband signal is processed by the baseband signal processing unit 1 to generate a low-distortion R signal.
An optimal baseband signal is processed so as to become an F signal and input to the quadrature modulator 2. And the quadrature modulator 2
Output a low-distortion RF signal and input it to the phase shifter 3. Further, the phase shifter 3 performs an optimal phase correction on the low-distortion RF signal, and an optimal transmission signal (RF signal) is transmitted from the high-output amplifier 4 to the transmission antenna 5.

At this time, a part of the output power of the high-power amplifier 4 is detected by the detector 9 and fed back to the phase shifter 3. In the detector 9, the RF output from the high power amplifier 4
The amplitude of the modulated wave component of the signal is converted into a voltage and fed back to the phase shifter 3. Then, the phase shifter 3 performs control so as to perform optimal phase correction in accordance with the amplitude of the voltage-converted modulated wave component. For example, when the amplitude of the modulated wave component increases in the phase when the average power is output by the high-output amplifier 4 by the AM-PM conversion, the phase also changes according to the magnitude of the amplitude. At this time, the voltage level based on the amplitude of the modulated wave component detected by the detector 9 is fed back to the phase shifter 3 so as to cancel the change in phase.
As a result, the phase shifter 3 controls the phase according to the magnitude of the amplitude of the modulated wave component of the RF signal (that is, the magnitude of the voltage level). The change is automatically controlled, and as a result, the phase distortion can be improved.

The state in which the detector 9 detects the RF signal and optimally corrects the phase will be specifically described with reference to waveform diagrams. 2A and 2B are waveform diagrams of a detector and a phase shifter for a phase shifter performing phase correction in the circuit of FIG. 1, wherein FIG. 2A is an RF signal detected by the detector, and FIG. FIG. 3C is a phase correction diagram in which a phase shifter performs a phase correction according to a voltage level, in which the amplitude component of the modulated wave is voltage-converted by the phase shifter. The figure shows a state in which the detector 9 responds at a high speed, and the detector 9 outputs the signal R from the output of the high-power amplifier 4 as shown in FIG.
When the F signal is detected, the detector 9 detects the detected RF signal.
Based on the signal, as shown in FIG.
The amplitude of the modulated wave component of the signal is converted to a voltage level.

The detector 9 inputs a voltage level based on the amplitude of the modulated wave component to an inverting input terminal or a non-inverting input terminal of a built-in operational amplifier, so that a voltage of a level corresponding to the amplitude is obtained. And outputs this voltage level to the phase shifter 3. Then, the phase shifter 3 corrects the phase of the RF signal according to the voltage level input from the detector 9. That is, as shown in FIG. 9C, the phase of the RF signal is corrected so that the phase of the RF signal changes to φ0, φ1, φ2, φ3,... Depending on the voltage levels V0, V1, V2, V3,. In the figure, the phase is φ0 when the voltage level is V0, and when the phase rotation is positive, the phase changes to φ1 and φ2 according to the voltage levels V1 and V2,
When the phase rotation is negative, the phase changes to φ3, φ4 according to the voltage levels V3, V4. Thus, the phase shifter 3
Is controlled so that the amount of phase shift of the RF signal is changed according to the voltage level fed back. That is, if the amplitude of the modulated wave component of the RF signal changes, the phase correction is performed so as to cancel the change in the amplitude. Therefore, when a signal having a large power is input in advance, if the sign of the rotation direction of the phase is determined, the phase can be moved in a predetermined direction at the moment when the signal having a large power is input, and optimally. A phase-corrected RF signal can be obtained.

The embodiment described above is an example for describing the present invention, and the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention. is there. For example, the phase correction is not limited to being performed at the position of this embodiment, but may be performed at any position where the amplitude of the modulated wave component of the RF signal can be converted into a voltage level and feedback controlled. It may be performed at any position in the amplifier system.

[0016]

As described above, the linearizer type transmission amplifier of the present invention can be realized only by adding the detection means and the phase shift means to the conventional linearizer type transmission amplifier. Thereby, the detecting means detects a part of the RF signal output from the high-power amplifying means, generates a voltage level corresponding to the amplitude of the modulated wave component included in the RF signal, and the phase shifting means, Feedback control is performed so that the RF signal transmitted from the orthogonal transform means is input, and based on the voltage level fed back from the detection means, the RF signal is optimally phase-corrected. In this manner, R is automatically adjusted according to the amplitude of the modulated wave component of the RF signal.
The phase of the F signal can be corrected to an optimum value, and in particular, the phase distortion in the AM-PM conversion of the amplifier can be improved. Therefore, a high-efficiency and low-cost amplifier can be easily realized without causing a reduction in the distortion improvement efficiency of the linearizer distortion compensation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a linearizer type transmission amplifier of the present invention.

FIGS. 2A and 2B are waveform diagrams of a detector and a phase shifter for performing phase correction by the phase shifter in the circuit of FIG. 1, wherein FIG. 2A is an RF signal detected by the detector, and FIG. FIG. 3C is a phase correction diagram in which a phase shifter performs a phase correction according to a voltage level, in which the amplitude component of the modulated wave is voltage-converted by the phase shifter.

FIG. 3 is a block diagram showing a configuration of a conventional linearizer type transmission amplifier.

FIG. 4 shows power amplification characteristics of an amplifier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Baseband signal processing part 2 Quadrature modulator 3 Phase shifter 4 High power amplifier 5 Transmission antenna 6 Amplifier 7 Variable attenuator 8 Quadrature demodulator 9 Detector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 27/36 H04L 27/00 FF Term (Reference) 5J090 AA01 AA41 CA21 CA36 DN02 FA17 FA19 GN06 KA00 KA16 KA23 KA53 KA55 MA11 SA14 TA01 TA06 5J091 AA01 AA41 CA21 CA36 FA17 FA19 KA00 KA16 KA23 KA53 KA55 MA11 SA14 TA01 TA06 5K004 AA08 JF04 5K060 BB07 CC04 FF06 HH06 HH09 JJ06 LL24 LL30

Claims (2)

[Claims] 1. A linearizer type transmission amplifier for performing amplification and distortion correction of an RF signal by a linearizer, wherein: a means for generating a voltage level corresponding to the amplitude of a modulated wave component of the RF signal; Means for correcting the phase of the RF signal, and performing an optimal phase correction on the RF signal in accordance with the amplitude of the modulated wave component of the RF signal. 2. A transmitting antenna for transmitting a radio wave of the RF signal to another wireless device, a high-power amplifier for supplying the RF signal to the transmitting antenna, and the RF signal output from the high-power amplifier. Gain control means for controlling the gain of a part of the signal; quadrature demodulation means for generating a baseband signal by inputting the signal subjected to the gain control and outputting the baseband signal; and inputting the baseband signal, Baseband signal processing means for performing distortion compensation so as to output a low-distortion RF signal from the high-output amplification means and outputting an optimal baseband signal; and inputting the baseband signal to generate the low-distortion RF signal A quadrature modulation unit that outputs the RF signal; and a part of the RF signal output from the high-power amplification unit is detected, and an electric power corresponding to the amplitude of a modulated wave component included in the RF signal is detected. Detecting means for generating a pressure level and feeding back the voltage level; and inputting the RF signal transmitted from the orthogonal transforming means, based on the voltage level fed back from the detecting means, Phase shift means for performing an optimal phase correction on the RF signal supplied to the transmission antenna according to the amplitude of the modulated wave component of the RF signal detected by the detection means. 2. The linearizer-type transmission amplifier according to claim 1, wherein a phase correction is performed.