EP2022179A1 - Amplificateur de puissance de linéarisation à haute efficacité pour une communication sans fil - Google Patents

Amplificateur de puissance de linéarisation à haute efficacité pour une communication sans fil

Info

Publication number
EP2022179A1
EP2022179A1 EP07861302A EP07861302A EP2022179A1 EP 2022179 A1 EP2022179 A1 EP 2022179A1 EP 07861302 A EP07861302 A EP 07861302A EP 07861302 A EP07861302 A EP 07861302A EP 2022179 A1 EP2022179 A1 EP 2022179A1
Authority
EP
European Patent Office
Prior art keywords
signal
predistortion
power amplifier
output
input
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07861302A
Other languages
German (de)
English (en)
Other versions
EP2022179A4 (fr
Inventor
Dali Yang
Jia Yang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dali Systems Co Ltd
Original Assignee
Dali Systems Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dali Systems Co Ltd filed Critical Dali Systems Co Ltd
Publication of EP2022179A1 publication Critical patent/EP2022179A1/fr
Publication of EP2022179A4 publication Critical patent/EP2022179A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • H03F1/3247—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits using feedback acting on predistortion circuits
    • 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
    • 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
    • H03F1/3294—Acting on the real and imaginary components of the input signal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/57—Separate feedback of real and complex signals being present
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2201/00—Indexing scheme relating to details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements covered by H03F1/00
    • H03F2201/32—Indexing scheme relating to modifications of amplifiers to reduce non-linear distortion
    • H03F2201/3233—Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion

Definitions

  • the present invention relates generally to wireless communications systems, and more particularly relates to systems, apparatus and methods for correcting the nonlinearity of a Power Amplifier (PA) such as might be used in a wireless RF transmitter.
  • PA Power Amplifier
  • a fundamental component of wireless communications systems is the power amplifier (PA).
  • PA power amplifier
  • Such wireless communications systems include a variety of broadband and multimedia services.
  • the power amplifier is supported by a wireless RF transmitter.
  • the power efficiency of the PA is an important aspect of the operational efficiency of the system as a whole.
  • the linearity and efficiency of power amplifiers have been two of the most difficult issues faced by wireless system designers and users. These problems are closely related to both the power spectrum efficiency and the power efficiency of power amplifiers.
  • Prior art predistortion technologies used to linearize the PA in wireless communication systems mainly use analog predistortion approaches. Some have also used a digital adjustment component implemented by means of an analog feed-forward approach and a digital predistortion approach employing a base-band digital signal processing (DSP) technique.
  • DSP digital signal processing
  • the present invention includes methods and apparatus for improving power efficiency and linearity of a PA by pre-distorting the input signal to the PA.
  • the conversion characteristic of the normally nonlinear PA becomes substantially linear.
  • the PA uses power more efficiently and provides advanced performance characteristics suitable for wireless signal transmission.
  • the present invention can be applied to a broad array of wireless communication systems, regardless of modulation type, to yield high quality signal transmission and expanded network capacity. It will be appreciated by those skilled in the art that the power amplifiers described herein can also be regarded as high power amplifiers.
  • a predistortion controller comprises analog peripheral circuits and a predistortion core processor for RF signal predistortion processing in preparation for PA signal transmission from a wireless communication device.
  • the analog peripheral circuits in the predistortion controller comprise the analog down-converter circuits prior to the PA input and the output of the PA, respectively, to pick up and compare an idealized signal from the modulator in the wireless system to the distorted feedback signal from PA's output.
  • the predistortion core processor operates together with a look-up table, where the look-up table stores predistortion information that is obtained by mathematically calculating AM-AM and AM-PM distortion components.
  • the output of the predistortion processor provides a pre-correction signal for the input of the PA.
  • the pre- correction signal is combined with the signal from the RF modulator by a multiplication operation to generate a pre-distorted input signal that is provided as the input to the PA.
  • Figure 1 shows a block diagram of the PA module with a predistortion controller in accordance with an embodiment of the invention.
  • Figure 2 presents a simplified architecture of an embodiment of the predistortion controller of Figure 1.
  • Figure 3 illustrates in greater detail the embodiment of Figure 2.
  • Figure 4 shows the operation and arrangement of the lookup table in the predistortion controller shown in Figure 3.
  • the present invention provides a novel predistortion controller to linearize the power amplifier (PA) used in wireless base stations operating in wireless networks using a wide variety of signal types including CDMA, TDMA, GSM, GPRS, 3G systems (UMTS, W-CDMA, CDMA2000, TDS-CDMA, 3GPP and others), WLAN, WiFi, WiMax and the like, as well as other proposed and upcoming wireless systems (4G/5G) that transmit a complex modulated signal by using a high power amplifier. Because the high power amplifier in wireless RF transmitters typically distorts the RF output signal, the adaptive predistortion controller of the present invention is useful to correct that non-linearity.
  • PA power amplifier
  • Embodiments of the present invention are suitable for use with all wireless base stations, access points and other wireless communication systems such as microwave and satellite communications.
  • the predistortion controller of the present invention offers the additional advantage that it can be added to existing wireless RF transmitters without otherwise changing or modifying the base station structure while at the same time yielding significant performance improvements. Included in these improvements is a substantial increase in the efficiency of the base station, which yields a significant reduction in power usage because, in current systems, significant power is wasted due to the nonlinear characteristics of typical PA's.
  • the predistortion control operation is fast and dynamic, which permits it to track and correct for nonlinearities of the PA in a wider, and makes it particularly suitable for use in base stations, repeaters and handsets. 4. It can be integrated into the design of the PA for convenient installation and replacement of aging PA's already installed in a wireless system.
  • a predistortion controller 5 received as an input a modulated RF signal 6 and also receives a feedback signal 7 which correlates to the output signal of a power amplifier
  • the predistortion controller modifies the RF signal 6 in accordance with the nonlinear and distortion characteristics of the output signal of the power amplifier 12 as characterized by the feedback signal 7, such that the output of the predistortion controller 5 is supplied to the power amplifier 12 to yield a substantially linearized and improved out put signal of the power amplifier 12.
  • the illustrated embodiment includes an Analog Multiplier 1 1 which receives a modulated RF signal v ⁇ from the RF modulator portion 10 [Figure 3] of the base station, and also receives a predistortion correction signal v p from a predistortion processor 200, shown generally in Figure 2 and in greater detail in Figure 3, and discussed in greater detail below.
  • the output of the analog multiplier 1 1 is provided as the input V 1n to the power amplifier (PA) 12, which in turn transmits an output signal V 0 to an Antenna 13.
  • the RF modulator 10 is typically although not necessarily a quadrature modulator or an orthogonal modulator. It will be appreciated that multiplier 11 can be implemented as multiple multipliers, each associated with one or more quadrature signals.
  • An input down-converter circuit 20 receives an idealized reference signal V RF from modulator in base station, and is biased by a local oscillator 40, such that it provides an output V d to an analog-to-digital converter 21.
  • the ADC 21 converts the signal V d to digital form, whereupon it is provided as one input to a Digital Predistortion Processor 200.
  • a feedback down-converter circuit 26 also biased by a local oscillator 40, receives a raw feedback signal V 0 (t) from the output of the PA, and provides a feedback signal V f to an feedback ADC 25.
  • the digital output of the ADC 25 then provides a second input, i.e. feedback signal, to the Digital Predistortion Processor 200.
  • the Digital Predistortion Processor 200 discussed in greater detail below, provides a digital output signal Vr to a DAC 30, which converts the digit signal to an analog form, where it is combined with the modulated RF signal in the multiplier 11.
  • address data formers 32I-32Q receive inputs from the ADC 21I/Q, and are designed to generate the required signal format for a lookup table 33I/Q.
  • the data formers 32I/Q address memory units within the lookup tables 33I/Q, where the lookup table provides separate I and Q outputs to an adder 31.
  • the lookup table 33 can be implemented as one or more lookup tables.
  • the address provided by the address formers 32I-32Q can be considered a lookup-table key or address.
  • the predistortion controller lookup tables 33I-33Q are designed memory units to store the predistortion signal for high power amplifier linearization.
  • the predistortion signals in the tables are based on the error generated by a comparison of the ideal signal v d and the feedback signal v/and the presented adaptive algorithm.
  • the data stored in the tables 33I-Q can be updated by adaptive iteration as described hereinafter, and forms digitally indexed data reflecting the nonlinear characteristics of the power amplifier.
  • the Digital Predistortion Processor calculates the error in the amplitude and phase components of the output signal V 0 (t) caused by the non-linear transmission characteristics of the high power amplifier 12.
  • the predistortion processor calculates and generates adaptively a compensation signal that is of inverse characteristics with the transform function of the PA
  • the outputs v p of the predistortion lookup table 33I-33Q are fed to multiplier 11, after an adder 31 and a digit-to-analog converter 30, to modify the modulated RF signal from modulator 10.
  • the output of the multiplier is the required predistortion signal v m (k) that is of an inverse non-linearity with that of the power amplifier 12 to yield a pre-compensation to the input of high power amplifier.
  • the use of the look-up tables 33 permits a memory function to be introduced into at least some embodiments of the present invention.
  • the lookup table of the predistortion controller 5 is based on a stored compensation principle that maps a set of input data into a digital output, and updated adaptively. Based on the stored function, each output signal of lookup table is actually related to both the current and the previously transmitted signal, and therefore has a memory function which compensate not only for the non-linearity of the PA, but also avoids the need for a special time-delay compensation circuit such as typically used in the prior art. See particularly U.S. Prov. Pat. Appn. S.N. 60/898,312, filed January 29, 2007, entitled Power Amplifier Time-delay Invariant Predistortion Methods and Apparatus.
  • FIG. 4 The architecture of an embodiment of a lookup table which can implement the compensation principle discussed above is shown in Figure 4.
  • the data from ADC 21 is supplied to address former 32, which in turn forms an address and applies it to the look-up tables 33.
  • the feedback signal V feedba c k from ADC 25 and the ideal signal Vi dea i from ADC 21 are compared in the error generator 23 and the resulting error signal is multiplied by a numerical value ⁇ in multiplier 35.
  • the value of ⁇ is typically between 0 and 1, and represents a convergence factor that can be better understood from the teachings in
  • the lookup table of predistortion controller is based on a stored compensation principle that maps a set of input data into a digital output, and are updated adaptively. Based on the stored function, each output signal of lookup table is actually related to both the current and previous transmitted signal, and therefore has a memory function when compensate the non-linearity of PA [I].
  • the architecture of lookup table based on the compensation principle is shown in Fig 4.
  • the performance of the predistortion controller is, in some respects, related to the number of bits in the analog-to-digital converters in the original and feedback channels, whereby the bigger the number of bits in the ADC, the better the performance of the predistortion controller is.
  • the memory function of the predistortion controller is also related to the number of bits in the address-shifting register, such that, within reasonable sizes, the performance of the predistortion controller improves as the number of bits in the register increases.
  • the PA may be operated in any region, such that, for example, its bias or static operation point can be set either in the saturation region or the cut-off region, with appropriate adjustments for operation in each region.
  • the output signal of predistortion controller is a stochastic control signal rather than a modulated high-frequency signal, and the signal is of the inverse characteristic with the AM-AM and AM-PM distortion component of power amplifier.
  • the output signal of the predistortion controller is not a high-frequency signal, and its frequency typically match the bandwidth of the signal to be transmitted by a power amplifier in a wireless transmitter.
  • the addressing of the lookup table is implemented by a set of N-bit vector data that contains the current input signal and previous N input signal as well. Therefore, the address of the lookup table is a combination of series of input sequences with the length of N. The longer the address of the lookup table, the wider the time-delay information range that the system can accommodate (i.e. the longer duration of time-delay effects that the system can tolerate).

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Amplifiers (AREA)

Abstract

Un mode de réalisation de l'invention utilise un signal de correction de prédistorsion pour une combinaison du signal RF modulé par un multiplicateur analogique pour une linéarisation des amplificateurs de puissance ayant des caractéristiques non linéaires telles que celles utilisées dans les émetteurs RF sans fil. Un contrôleur de prédistorsion comprend une pluralité de convertisseurs abaisseurs de fréquence pour récupérer à la fois les informations non déformées idéales et les informations de réaction déformées, avec les informations de prédistorsion indexées numériquement pré-stockées stockées, par exemple, dans une table de conversion. Les informations indexées numériquement modélisent les caractéristiques non linéaires de l'amplificateur à puissance élevée, et sont stockées avant le traitement de pré-compensation dans l'amplificateur de puissance. Lorsque les informations de prédistorsion sont combinées au signal RF modulé dans le multiplicateur analogique, le résultat est une transmission d'informations essentiellement linéaires à partir de l'amplificateur de puissance.
EP07861302A 2006-04-28 2007-04-30 Amplificateur de puissance de linéarisation à haute efficacité pour une communication sans fil Withdrawn EP2022179A4 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US79582006P 2006-04-28 2006-04-28
US87664006P 2006-12-22 2006-12-22
US89774607P 2007-01-26 2007-01-26
US89831207P 2007-01-29 2007-01-29
PCT/US2007/010566 WO2008105775A1 (fr) 2006-04-28 2007-04-30 Amplificateur de puissance de linéarisation à haute efficacité pour une communication sans fil

Publications (2)

Publication Number Publication Date
EP2022179A1 true EP2022179A1 (fr) 2009-02-11
EP2022179A4 EP2022179A4 (fr) 2009-12-23

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EP07861302A Withdrawn EP2022179A4 (fr) 2006-04-28 2007-04-30 Amplificateur de puissance de linéarisation à haute efficacité pour une communication sans fil

Country Status (2)

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EP (1) EP2022179A4 (fr)
WO (1) WO2008105775A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6985704B2 (en) 2002-05-01 2006-01-10 Dali Yang System and method for digital memorized predistortion for wireless communication
US8380143B2 (en) 2002-05-01 2013-02-19 Dali Systems Co. Ltd Power amplifier time-delay invariant predistortion methods and apparatus
US8811917B2 (en) 2002-05-01 2014-08-19 Dali Systems Co. Ltd. Digital hybrid mode power amplifier system
US8064850B2 (en) 2002-05-01 2011-11-22 Dali Systems Co., Ltd. High efficiency linearization power amplifier for wireless communication
KR20100014339A (ko) 2006-12-26 2010-02-10 달리 시스템즈 씨오. 엘티디. 다중 채널 광대역 통신 시스템에서의 기저 대역 전치 왜곡 선형화를 위한 방법 및 시스템
CN101908861B (zh) * 2009-06-08 2012-11-07 瑞昱半导体股份有限公司 传送器、输出信号失真降低方法及预失真参数产生方法
US8682338B2 (en) 2010-09-14 2014-03-25 Dali Systems Co., Ltd. Remotely reconfigurable distributed antenna system and methods

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6314142B1 (en) * 1996-06-19 2001-11-06 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Pre-distortion for a non-linear transmission path in the high frequency range

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6985704B2 (en) * 2002-05-01 2006-01-10 Dali Yang System and method for digital memorized predistortion for wireless communication

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6314142B1 (en) * 1996-06-19 2001-11-06 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Pre-distortion for a non-linear transmission path in the high frequency range

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO2008105775A1 *

Also Published As

Publication number Publication date
EP2022179A4 (fr) 2009-12-23
WO2008105775A1 (fr) 2008-09-04

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