JPH11154828A - Feedforward distortion compensation amplifier circuit - Google Patents

Abstract

(57) [Problem] In a feed-forward type distortion compensation amplifier circuit, if it is known in advance that there is no signal component in the band of the signal to be amplified and the frequency of the distortion component, it is necessary to control the temperature and other conditions. Provided is a distortion amplification amplifier circuit that performs optimal distortion compensation in accordance with the above and can be applied to a high-quality, high-quality wireless communication device. In a feedforward distortion amplifier circuit, a power detector (17) for detecting the power of a distortion component of a predetermined frequency in an output signal, and automatically adjusting the phase and level of the distortion component so that the detected power is minimized. With the provision of the controller (16) that adjusts the frequency, optimal distortion compensation according to the situation can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a power amplifier used in a radio communication device or the like, and more particularly, to a feed-forward type distortion compensation amplifier circuit.

[0002]

2. Description of the Related Art In a relay amplifier used in an analog relay transmission line, thermal noise generated from the amplifier, A +
The B-type secondary coupled wave distortion and the A + BC-type tertiary coupled wave distortion are the dominant factors of the S / N degradation, and noise design is usually performed so that the sum of these three types of noise is minimized. By the way, since the A + BC-type tertiary combined wave distortion generated from each amplifier is added in accordance with the voltage addition rule, its cumulative effect is remarkable especially in a multi-relay transmission line, and the required standard for the amplifier becomes strict. As a method for compensating for such distortion, a feed-forward type distortion compensating amplifier circuit has been proposed.
No. 2.

FIG. 2 shows an example of a feedforward distortion compensation circuit. In FIG. 2, 1 is a pilot signal transmitter,
2 is a pilot signal generator 1 and an input signal combiner, 3 is a distributor for distributing the input signal to a main circuit and a distortion extraction circuit, 4 is a main amplifier, 5 is a distortion extraction circuit and a distortion compensation circuit for the amplified main signal. 6 is a phase adjuster for adjusting the phase in the distortion extraction circuit, 7 is an attenuator for adjusting the level in the distortion extraction circuit, 8 is the level adjustment of the main signal by the attenuator 7 and the phase adjustment by the phase shifter 6. A combiner 9 for extracting a distortion component by combining with a signal, 9 is a power detector for detecting the power level of the entire required band, and 10 is a phase shifter 6 and an attenuator 7 so as to minimize the level detected by the detector 9.
Is a controller that adjusts 11 is a phase shifter for adjusting the phase in the distortion compensation circuit, 12 is an attenuator for adjusting the level in the distortion compensation circuit, 13 is an amplifier for amplifying the distortion component, and 14 is for synthesizing the amplified main signal and the extracted distortion component. A synthesizer for removing distortion components from the main signal, a detector for detecting a pilot signal from an output, and a phaser and an amplifier for adjusting a level of the pilot signal detected by the detector. Shows the controller.

According to the configuration of the prior art, an input signal is combined with a pilot signal and then distributed to a main circuit and a distortion extraction circuit. The main circuit amplifies the signal, and the distortion extraction circuit amplifies the signal. The phase is inverted at 6, the amplified output of the main circuit is leveled down by the attenuator 7, and synthesized by the synthesizer 8 to extract the distortion component. The phase is adjusted by the phase shifter 6 and the attenuator 7 by the controller 10 so as to be minimum.
The phase of the distortion component obtained by these adjustments is inverted by the phase shifter 11 in the distortion compensation circuit, the level is adjusted by the attenuator 12, then amplified by the amplifier 13, and combined with the amplified output of the main signal. Make compensation. In addition, by detecting the component of the pilot signal in the output by the detector 15 and adjusting the level by a controller so that the level is minimized, optimal distortion compensation is performed according to the situation even during communication. According to this conventional method, distortion can be effectively improved regardless of changes in the temperature or other conditions during data transmission, but a pilot signal must be input and the pilot signal There is a problem that the distortion originally desired cannot be improved depending on the frequency position.

[0005]

The above-mentioned conventional feed-forward distortion compensating amplification circuit controls the level of distortion by the pilot signal, and therefore requires a pilot signal generation circuit and the frequency position of the pilot signal. In some cases, there is a problem that optimal feedforward control cannot be performed. SUMMARY OF THE INVENTION An object of the present invention is to provide a feed-forward distortion compensation amplification circuit that can improve distortion that meets system requirements by configuring so as to detect distortion power itself without using a pilot signal. .

[0006]

In order to achieve the above object, the present invention provides a distortion frequency band detector, detects the power level of the distortion itself, and compensates for the distortion so as to minimize it. The circuit is controlled to perform distortion compensation.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a block diagram showing an embodiment of a feed-forward distortion compensation amplifier circuit of the present invention for detecting a carrier distortion and controlling a distortion compensation circuit. In FIG. 1, 3 is a distributor for distributing an input signal, 4 is a main amplifier, 5
Is a distributor for distributing the amplified output of the main amplifier, 6 is a phase shifter for adjusting the phase in the distortion extracting circuit, 7 is an attenuator for adjusting the level, 8 is a signal component containing distortion and a signal component without distortion. A power detector 9 detects only the power within the band, and a controller 10 adjusts the level and phase so that the power detected by the detector 9 is minimized. Reference numeral 11 denotes a phase shifter for adjusting the phase in the distortion compensation circuit; 12, an attenuator for adjusting the level; 13, an amplifier for amplifying the signal to the same level as the main signal; 14, a distortion component whose phase and level have been adjusted;
A combiner for compensating for a distortion component from the main signal by combining the output amplified by the above, a power detector 17 for detecting power of a preset frequency, and a power detector 16 for minimizing the power detected by the detector. Shows a controller for adjusting the phase shifter 12 and the amplifier 13.

The operation of this embodiment will be described below by taking as an example the case where two carriers are input. The input carriers A and B are amplified by the main amplifier. At this time, distortion components 2A-B and 2BA corresponding to the frequency difference between the input carriers appear. In the present invention, there is provided a power detector 17 for selecting a frequency band in which distortion is desired to be further improved and measuring the power at that frequency. As an example, the distortion power detector 17 of the distortion compensation circuit is adjusted to measure the power at the frequency of 2A-B. At this time, in the distortion compensating circuit, the input distortion is amplified by the amplifier 13 and combined with the main signal by the combiner 14 to output a signal whose distortion has been improved. −
The detection circuit at the frequency B is connected, and the measured power is sequentially input. The controller 16 adjusts the phase shifter 11 and the attenuator 12 in the distortion compensating circuit so as to minimize the power, and can perform the most effective distortion improvement at that time.

In the distortion compensation amplifier circuit according to the present embodiment, the frequency at which the distortion appears is known in advance, and when there is no other signal component at that frequency, the distortion itself is controlled so as to minimize the distortion itself. It is possible to perform a great distortion compensation. Also, the frequency of appearance of the distortion is known,
If there is no other signal component at that frequency, a circuit is provided to detect the power level of the distortion at multiple frequencies, and the controller is set so that the total value of the power is minimized. Can also be improved.

[0011]

As described above, according to the present invention, there is provided a feed-forward distortion compensation amplifier circuit which detects the power of distortion to be improved most without using a pilot signal and always performs optimal distortion compensation. You can do it.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a conventional feedforward distortion compensation amplification circuit.

[Explanation of symbols]

1: pilot signal generator, 2, 8, 14: synthesizer, 3, 5: distributor, 4: main amplifier, 6, 11: phase shifter, 7, 12: attenuator (ATT), 13: amplifier,
9: power detector, 10, 16: controller,
15: Power detector for pilot signal, 17: Power detector for specified frequency.

Claims (1)

[Claims] A broadband amplifier circuit for amplifying a plurality of carriers, comprising: a main circuit including a power amplifier for amplifying the plurality of carriers in common; A distortion extraction circuit that extracts a distortion component generated in the main circuit by combining the signal with the adjusted signal, and adjusts the level and phase of the distortion component obtained by the distortion extraction circuit and combines the signal with the signal amplified by the main circuit. A feed-forward distortion compensating amplifier circuit having a distortion compensating circuit that compensates for distortion by performing: a detector that detects power of a frequency component that generates only distortion corresponding to the carrier frequency; and a distortion that is detected by the detector. A control unit for adjusting the distortion compensation circuit so as to minimize the distortion.