WO2001056147A1 - Systeme de reaction de transmission - Google Patents
Systeme de reaction de transmission Download PDFInfo
- Publication number
- WO2001056147A1 WO2001056147A1 PCT/GB2001/000307 GB0100307W WO0156147A1 WO 2001056147 A1 WO2001056147 A1 WO 2001056147A1 GB 0100307 W GB0100307 W GB 0100307W WO 0156147 A1 WO0156147 A1 WO 0156147A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- output
- amplitude
- signal
- power amplifier
- modulation
- Prior art date
Links
- 230000005540 biological transmission Effects 0.000 title description 3
- 238000005070 sampling Methods 0.000 claims abstract description 15
- 238000001914 filtration Methods 0.000 claims description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000000284 extract Substances 0.000 description 2
- 230000001934 delay Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002040 relaxant effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3036—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers
- H03G3/3042—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers in modulators, frequency-changers, transmitters or power amplifiers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/32—Modifications of amplifiers to reduce non-linear distortion
- H03F1/3241—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits
Definitions
- This invention relates to feedback control systems for employment in the generation of amplitude and phase modulated radio frequency carrier waves of high power.
- Some known systems use modulation feedback to control a power amplifier but suffer from a number of disadvantages and are therefore not widely used.
- Cartesian feedback the wide band noise floor that is produced by any vector modulator which is employed results in a requirement for complex filtering to ensure duplex operation.
- polar feedback the amplitude and phase components suffer from differential delays if the loops associated with each are not matched, which can result in inaccurate modulation and can create spectral distortion.
- the present invention seeks to overcome some of the above problems.
- a modulation feedback system for use with a transmitter power amplifier, the system comprising: means for sampling, in use, the output of a power amplifier; vector modulator means for receiving the output from the sampling means and applying a Cartesian representation of the desired modulation thereto; and means for receiving the output of the vector modulator means and means for employing the output to modulate, both in phase and amplitude terms, the input to the power amplifier in use.
- the system may further comprise a frequency convertor for mixing the output of a reference frequency oscillator with the signal from the sampling means.
- the system may further comprise a variable gain amplifier for scaling the output of the sampling means.
- the phase modulation may be performed by provision of a limiter for limiting a signal from the vector modulator; a frequency mixer for mixing a reference with the output of the limiter; and a phase loop filter for filtering the output of the frequency mixer and applying an input to a frequency controlled oscillator.
- the amplitude modulation may be performed by provision of an envelope detector; a comparator for comparing the output of the envelope detect with a reference amplitude; and a amplitude loop filter.
- Figure 1 is a schematic diagram of a first example of the present invention
- Figure 2 is a schematic diagram of a second example of the present invention.
- Figure 3 is a schematic diagram of a third example of the present invention.
- Figure 4 is a schematic diagram of a further example of the present invention.
- a power amplifier 1 provides an amplified signal to an antenna 21 at a level sufficient to ensure that the transmitted RF power from the transmitter is sufficient for the application for which the antenna 21 is being employed.
- Sampling means 2 samples the output of the power amplifier 1 and provides it to a vector modulator 3, which is used to provide an error signal based upon the sampled output and a reference quadrature representation of the modulation that it is desired for the output of the power amplifier 1 to have .
- a filter 4 is provided to remove harmonics from the output from the vector modulator means 3.
- a splitter 5 is provided to split the output from the filter 4 and provide it to two feedback paths A and B.
- Path A comprises an envelope detector 6 which extracts amplitude information from the signal from the filter 4. It further comprises an amplitude reference generator and a comparator 7 for comparing the output of the envelope detector 6 with the generated referenced amplitude. The output from the comparator 7 is filtered by a further filter 8 and provided to an amplitude modulator 9.
- Path B comprises a limiter 10 which extracts phase information from the output of the filter 4 and a phase comparator 11 which compares the output of the limiter 10 with a reference frequency.
- a filter 12 is provided to filter the output of the phase comparator 11 and the output of the filter 12 is then forwarded to a voltage controlled oscillator 13. The output of the voltage controlled oscillator 13 is then forwarded to the amplitude modulator 9, the output of which is provided to the amplifier 1 in order to close the feedback loops.
- Signal path A has a baseband representation of the amplitude of the signal generated by the envelope detector 6 in a manner which is independent of any phase modulation. After comparison with a reference amplitude by the comparator 7 the resulting signal represents an error in amplitude between ideal modulation and the modulation present at the output of the power amplifier 1. After further filtering this signal is applied to the amplitude modulator 9.
- the other portion of the split signal from the vector modulator output is sent via path B and applied to a limiter 10 which produces a phase-modulated carrier wave independent of any amplitude modulation.
- the output of the limiter 10 is applied to a phase comparator 11, where it is compared with a stable phase/frequency reference 20.
- the resulting base band signal represents the error in phase between an ideal modulation and the modulation at the output of the power amplifier 1.
- phase error signal thus generated is filtered by a filter 12 and used to control the frequency of a variable frequency oscillator 13.
- the output of the variable frequency oscillator 13 is a phase-modulated carrier wave of constant amplitude. This output is then applied to the amplitude modulator 9 and amplitude modulated from the signal from path A such that the resulting signal carrier's complex modulation closely related to the ideal modulation represented by the quadrature baseband components applied to the vector modulator 3, but predistorted to compensate for the non- linearity of the power amplifier 1.
- the complex modulator signal is applied to the input of the nonlinear power amplifier 1, resulting in an undistorted, high power, complex modulated signal at its output. Thus, both the amplitude and phase modulation loops are closed.
- Fig. 2 shows a further example of the present invention in which there is further provided a frequency convertor 14 which mixes the output of the sampling means 2 with the output of a reference local oscillator 15.
- the spectrum output from the frequency convertor 14 will have a centre frequency equal to that of the stable phase frequency reference 20.
- the loop operates as per the example shown in Fig. 1, except that the output frequency and the reference frequency differ by the local oscillator frequency.
- the output from the local oscillator 15 is variable then the output frequency will also vary, but the vector modulator 3, together with all of the other signal processing opponents, may operate at a fixed frequency with narrow bandwidth by appropriate control of variations in the local oscillator frequency.
- Fig. 3 shows a further example of the present invention in which a variable gain amplifier 16 is provided in the sampling path in combination with the additional features of Fig. 2.
- the amplitude output signal from the power amplifier 1 is sampled by the sampling means 2, but is scaled by the variable gain amplifier 16 before it is applied to the vector modulator 3.
- the gain of the variable gain amplifier 16 it is possible to reduce the dynamic range of the remaining processing components. This provides particular benefits, in that it allows the invention to support shaped pulses in TDMA systems without increasing the resolution required in the quadrature base band representation.
- Figure 4 shows yet another example of the present invention, which is similar to example of Figure 3, although with a number of modifications.
- (I,-Q) signals contain both the amplitude and phase content of the modulation. They are mixed with a carrier that contains only the phase content of the feedback signal.
- the output signal of the complex modulator carries the amplitude content of the modulation and the phase difference between the modulation and the feedback signal. Therefore, in the example of Figure 4 the complex error signal is obtained by mixing I and -Q signals with a constant envelope version of the feedback signal.
- a limiter 19 is inserted into the feedback path before the modulator and removes the amplitude content of the feedback signal fed through the modulator.
- the feedback signal is also fed through an envelope detector (6a) corresponding to that used in previous examples, the output of which is fed to the comparator 7 , and compared to the output of the envelope detector (6b) already included in path A allowing a straightforward subtraction of amplitude to be performed in the feedback loop.
- example of Figure 4 provides a linear behaviour for the amplitude loop as long as the power amplifier operates in its linear region, rather than the non-linear comparison of inverses of the earlier examples.
- the linearity feature allows the amplitude loop bandwidth to be reduced as compared to the previous examples. This is a significant improvement as the amplitude loop bandwidth is the result of a compromise: the bandwidth must be made much wider than the modulation bandwidth in order to apply the linearisation effect properly but is restricted by the limitations of the electronic components. So an easier compromise may be found and better performance should be obtained.
- the limiter 19 removes the amplitude content of the feedback signal. Therefore the I and Q modulator operates with a constant envelope signal on its carrier input allowing the mixers associated with the I and Q signal to operate at a higher carrier input level, relaxing their operational requirements and the specification placed on the devices providing their function.
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
- Transmitters (AREA)
Abstract
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU30337/01A AU3033701A (en) | 2000-01-27 | 2001-01-26 | Transmission feedback system |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP00300612.9 | 2000-01-27 | ||
EP00300612A EP1120903A1 (fr) | 2000-01-27 | 2000-01-27 | Système de rétroaction pour système de transmission |
GB0013680A GB0013680D0 (en) | 2000-06-05 | 2000-06-05 | Transmission feedback system |
GB0013680.4 | 2000-06-05 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001056147A1 true WO2001056147A1 (fr) | 2001-08-02 |
Family
ID=26072978
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2001/000307 WO2001056147A1 (fr) | 2000-01-27 | 2001-01-26 | Systeme de reaction de transmission |
Country Status (2)
Country | Link |
---|---|
AU (1) | AU3033701A (fr) |
WO (1) | WO2001056147A1 (fr) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7076698B2 (en) | 2003-05-21 | 2006-07-11 | Agere Systems, Inc. | Vector monitor, related method of controlling a transmitter and transmitter employing the same |
US7345531B2 (en) | 2003-05-21 | 2008-03-18 | Agere Systems Inc. | Comparator circuit, related method of comparing a vector to comparison boundaries and transmitter employing the same |
CN100477511C (zh) * | 2004-01-22 | 2009-04-08 | 美国博通公司 | 调整功率放大器输出功率的方法及*** |
US8290527B2 (en) | 2004-07-30 | 2012-10-16 | Airvana, Corp. | Power control in a local network node (LNN) |
US8503342B2 (en) | 2004-07-30 | 2013-08-06 | Airvana Llc | Signal transmission method from a local network node |
US9876670B2 (en) | 2004-07-30 | 2018-01-23 | Commscope Technologies Llc | Local network node |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2532491A1 (fr) * | 1982-08-24 | 1984-03-02 | Thomson Csf | Dispositif de linearisation pour amplificateur haute frequence |
US5101172A (en) * | 1989-12-26 | 1992-03-31 | Mitsubishi Denki Kabushiki Kaisha | Linear amplifier |
US5175879A (en) * | 1991-04-25 | 1992-12-29 | Motorola, Inc. | Linear amplifier with feedback path and phase error compensation |
US5182524A (en) * | 1992-03-10 | 1993-01-26 | The Regents Of The University Of Calif. | Method and apparatus for stabilizing pulsed microwave amplifiers |
US5420536A (en) * | 1993-03-16 | 1995-05-30 | Victoria University Of Technology | Linearized power amplifier |
US5675288A (en) * | 1994-07-08 | 1997-10-07 | Alcatel Espace | Method of linearizing a non-linear amplifier, linearization circuit and amplifier including a circuit of this kind |
-
2001
- 2001-01-26 WO PCT/GB2001/000307 patent/WO2001056147A1/fr active Application Filing
- 2001-01-26 AU AU30337/01A patent/AU3033701A/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2532491A1 (fr) * | 1982-08-24 | 1984-03-02 | Thomson Csf | Dispositif de linearisation pour amplificateur haute frequence |
US5101172A (en) * | 1989-12-26 | 1992-03-31 | Mitsubishi Denki Kabushiki Kaisha | Linear amplifier |
US5175879A (en) * | 1991-04-25 | 1992-12-29 | Motorola, Inc. | Linear amplifier with feedback path and phase error compensation |
US5182524A (en) * | 1992-03-10 | 1993-01-26 | The Regents Of The University Of Calif. | Method and apparatus for stabilizing pulsed microwave amplifiers |
US5420536A (en) * | 1993-03-16 | 1995-05-30 | Victoria University Of Technology | Linearized power amplifier |
US5675288A (en) * | 1994-07-08 | 1997-10-07 | Alcatel Espace | Method of linearizing a non-linear amplifier, linearization circuit and amplifier including a circuit of this kind |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7076698B2 (en) | 2003-05-21 | 2006-07-11 | Agere Systems, Inc. | Vector monitor, related method of controlling a transmitter and transmitter employing the same |
US7345531B2 (en) | 2003-05-21 | 2008-03-18 | Agere Systems Inc. | Comparator circuit, related method of comparing a vector to comparison boundaries and transmitter employing the same |
CN100477511C (zh) * | 2004-01-22 | 2009-04-08 | 美国博通公司 | 调整功率放大器输出功率的方法及*** |
US8290527B2 (en) | 2004-07-30 | 2012-10-16 | Airvana, Corp. | Power control in a local network node (LNN) |
US8311570B2 (en) | 2004-07-30 | 2012-11-13 | Airvana Llc | Method and system of setting transmitter power levels |
US8503342B2 (en) | 2004-07-30 | 2013-08-06 | Airvana Llc | Signal transmission method from a local network node |
US8886249B2 (en) | 2004-07-30 | 2014-11-11 | Airvana Lp | Method and system of setting transmitter power levels |
US9876670B2 (en) | 2004-07-30 | 2018-01-23 | Commscope Technologies Llc | Local network node |
Also Published As
Publication number | Publication date |
---|---|
AU3033701A (en) | 2001-08-07 |
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