WO2010075645A1 - A method and device for improving the linearity of a radio frequency power amplifier - Google Patents

A method and device for improving the linearity of a radio frequency power amplifier Download PDF

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Publication number
WO2010075645A1
WO2010075645A1 PCT/CN2008/002164 CN2008002164W WO2010075645A1 WO 2010075645 A1 WO2010075645 A1 WO 2010075645A1 CN 2008002164 W CN2008002164 W CN 2008002164W WO 2010075645 A1 WO2010075645 A1 WO 2010075645A1
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Prior art keywords
power amplifier
signal
radio frequency
input
final stage
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PCT/CN2008/002164
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French (fr)
Chinese (zh)
Inventor
朱国斌
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中兴通讯股份有限公司
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Priority to PCT/CN2008/002164 priority Critical patent/WO2010075645A1/en
Publication of WO2010075645A1 publication Critical patent/WO2010075645A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/36—Modulator circuits; Transmitter circuits
    • H04L27/366—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator
    • H04L27/367—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator using predistortion
    • H04L27/368—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator using predistortion adaptive predistortion
    • 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
    • H03F1/3276—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits using the nonlinearity inherent to components, e.g. a diode
    • 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

Definitions

  • the present invention relates to the field of communications, and in particular, to a method and apparatus for improving the linearity of a high power final stage power amplifier circuit and a high power user terminal equipment (CPE) RF power amplifier of a communication base station.
  • CPE user terminal equipment
  • WiMAX CPE combines the latest 3G technology to provide user voice and data services using Voice over Internet Protocol (VoIP).
  • VoIP Voice over Internet Protocol
  • the WiMAX signal amplification of the transmit channel generally uses a high-gain integrated power amplifier, or uses a multi-stage power amplifier link and the final stage power amplifier uses power back-off technology to improve the RF output linearity.
  • the integrated power amplifier is the preferred solution, but the integrated power amplifier has high cost, few equipment suppliers or even the problem of exclusive supply (currently only Mitsubishi Semiconductor has related devices), and the device characteristics are affected by the product application range. Limited and poorly flexible. Power backoff technology is currently the solution of most equipment providers, but this solution requires higher power capacity of the final stage power amplifier (because WiMAX signals have higher peak-to-average ratio and large dynamic range), thus causing device linearity. Low degree, small dynamic range, high price, low efficiency, large size and increased design difficulty.
  • the technical problem to be solved by the present invention is to provide an apparatus and method for improving the linearity of a radio frequency power amplifier to compensate and improve the linearity of the final stage power amplifier.
  • the present invention provides an apparatus for improving the linearity of a radio frequency power amplifier, including a final stage power amplifier, wherein:
  • a predistortion circuit including an output of the predistortion circuit and the final stage power amplifier
  • the input terminals are connected for phase shifting the input signal according to the input signal amplitude of the final stage power amplifier - the nonlinear distortion of the output signal phase to compensate for the nonlinear distortion.
  • the above device may also have the following features, and the predistortion circuit is a diode pre-distortion circuit.
  • the above device may also have the following features.
  • the diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shifting circuit, or a circulator and a varactor, or a circulator and a PIN diode.
  • the above device may also have the following features.
  • the diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shifting circuit, wherein the 3dB quadrature coupler includes an input port, an output port, and two internals connected to the varactor phase shifting circuit Port, the varactor phase shifting circuit comprises two varactor diodes, the negative poles of which are connected to ground, the positive poles are connected to a DC voltage, and respectively pass through a capacitor and an internal of the 3dB quadrature coupler The ports are connected.
  • the above device may further have the following features, the device further comprising a driving power amplifier, the output of the driving power amplifier being connected to the input end of the predistortion circuit.
  • the above device may also have the following features.
  • the device is a radio frequency signal transmitting device, and further comprises a fixed attenuator whose output is connected to the input end of the driving power amplifier, a balun filter connected to the fixed attenuator input, an input terminal and the final stage power amplifier A low pass filter connected to the output, and an RF switch connected to the low pass filter at the input end.
  • the above device may further have the following features: the device is a radio frequency signal transmitting device in a base station or a user terminal device, and the predistortion circuit is configured to phase shift the input radio frequency signal.
  • the present invention also provides a method for improving the linearity of a radio frequency power amplifier, including:
  • the signal Before the signal is input to the final stage RF power amplifier, the signal is phase-shifted according to the input signal amplitude of the final stage power amplifier - the nonlinear distortion of the output signal phase to compensate for the nonlinear distortion. Further, the above method may also have the following features.
  • the diode pre-distortion circuit is used to phase shift the RF signal.
  • the diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shift circuit.
  • the above method may also have the following features.
  • the final stage radio frequency power amplifier is located in a radio frequency signal transmitting device in a base station or a user terminal device, and the signal is a radio frequency signal.
  • the method of the invention minimizes the cost of the corresponding device such as WiMAX CPE and the design difficulty of the CPE product, and improves the overall launch performance of the corresponding device such as WiMAX CPE, such as improving the linearity of the whole machine of the WiMAX CPE and Dynamic range, reduced power consumption and low heat generation;
  • this design scheme reduces the volume of corresponding products in CPE or base station, is not limited by exclusive supply, can make full use of selectable general-purpose devices, and increase the usable frequency band. Selectivity thus limits the frequency band. ⁇ Use a power amplifier with a smaller power rating to reduce costs and improve cost performance.
  • FIG. 1 is a schematic structural diagram of a prior art WiMAX signal processing module
  • FIG. 2 is a schematic structural diagram of a WiMAX radio frequency signal transmission channel according to an embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of a diode predistortion circuit according to an embodiment of the present invention.
  • the present invention provides a predistortion process prior to the final stage general purpose power amplifier to phase shift the input RF signal of the final stage power amplifier to compensate for and improve the linearity and dynamic range of the final stage power amplifier.
  • the schematic diagram of the WiMAX signal processing module is shown in FIG. 1 , and includes a baseband processor 101 , a radio frequency processor 102 , a WiMAX radio frequency signal receiving channel 103 , and a WiMAX radio frequency signal transmission channel .
  • a baseband processor and a radio frequency processor of BECEEM are used, wherein:
  • the baseband processor 101 When transmitting, the baseband processor 101 modulates the baseband digital signal into a WiMAX modulated analog low frequency signal output to the RF processor 102.
  • the RF processor 102 converts the WiMAX modulated analog low frequency signal to the desired RF operating frequency band to generate a WiMAX modulated RF.
  • the signal is sent to the WiMAX radio frequency signal transmission channel 104, and the WiMAX radio frequency signal transmission channel 104 is responsible for processing the WiMAX modulated radio frequency signal and radiating it to the free space through the antenna;
  • the WiMAX RF signal receiving channel 103 Upon receiving, the WiMAX RF signal receiving channel 103 is responsible for receiving and filtering the WiMAX RF receiving signal, and transmitting the filtered WiMAX RF receiving signal to the RF processor 102.
  • the RF processor 102 converts the WiMAX RF receiving signal to an analog low frequency signal and outputs To the baseband processor 101, the baseband processor 101 demodulates the analog low frequency signal to a baseband digital signal.
  • the structure diagram of the WiMAX radio frequency signal transmission channel 104 is as shown in FIG. 2, and includes a balun filter 201 (BALU FILTER), a fixed attenuator 202, a driving power amplifier 203, a diode predistortion circuit 204, and a final stage power.
  • the stage power amplifier can be a general-purpose low-gain power amplifier; the RF switch can be a combined single-Pole Double-Throw (SPDT) RF switch.
  • the diode predistortion circuit 204 therein is added in this embodiment.
  • the diode predistortion circuit 204 includes a 3dB quadrature coupler and a varactor phase shift circuit, as shown in FIG.
  • the 3dB quadrature coupler has four ports.
  • the varactor phase shifting circuit consists of two varactor diodes. The negative poles of the two varactor diodes are connected to ground. The positive poles are connected to the DC voltage and pass through a capacitor and 3dB positive respectively. Port 3 of the AC coupler is connected to Port 4.
  • the RF signal is input through the 3dB quadrature coupler port 1, it is divided into two channels and transmitted to two varactor diodes connected through the capacitor.
  • the phase shift of the varactor diode the phase of the RF signal changes, and finally the reflected signal after the phase change.
  • the port 2 of the 3dB coupler is remixed and output together.
  • a diode predistortion circuit including a 3dB quadrature coupler and a varactor phase shifting circuit indirectly adjusts the PN junction capacitance of the diode by adjusting a bias DC voltage external to the varactor to indirectly shift the RF signal to compensate for the end.
  • Amplitude and phase distortion (AM-PM) of a stage power amplifier Linearity and dynamic range of high final power amplifier devices.
  • the diode predistortion circuit can also use a circulator plus a varactor diode, or a circulator plus
  • the balun filter 201 After the WiMAX radio frequency signal transmitting channel 104 receives the WiMAX modulated radio frequency signal transmitted by the radio frequency processor 102, the balun filter 201 generates a radio frequency transmitting signal that is balanced to unbalanced and filtered to remove out-of-band clutter, and Transmission to the fixed attenuator 202, in order to prevent the input port mismatch of the driving power amplifier 203 from affecting the passband characteristics of the balun filter 201, the fixed attenuator 202 is used to fixedly attenuate the radio frequency transmitting signal to improve the preamplifier.
  • the input of the driver stage is matched, and the attenuated RF transmission signal is transmitted to a driving power amplifier 203, which may be a medium power high gain power amplifier, and the driving power amplifier 203 amplifies the RF emission signal to a desired level and linearity.
  • the second stage is transmitted to the diode predistortion circuit 204.
  • the diode predistortion circuit 204 indirectly shifts the RF signal by adjusting the bias DC voltage outside the varactor to change the PN junction capacitance of the diode and transmits it to the final stage power amplifier 205.
  • a low-pass filter 206, low-pass filters 206 filter out the higher harmonics emitted after RF signal 207 by RF switch transmits a combined signal of the RF transceiver to the antenna, the antenna transmitting the radio frequency signal is radiated into free space.
  • a diode predistortion circuit is added between the driving power amplifier of the WiMAX radio frequency signal transmitting channel and the final stage power amplifier, and the diode predistortion circuit mainly plays a phase shifting effect on the input radio frequency signal.
  • the final stage power amplifier is a nonlinear device, there is very large nonlinear distortion in high power applications, including input signal amplitude-output signal amplitude (AM-AM) distortion and input signal amplitude-output signal phase (AM- PM) distortion (as shown in Figure 4).
  • the role of the diode predistortion circuit is to phase shift the input signal to reduce AM-PM distortion.
  • the input signal enters the 3dB coupler and is split into two.
  • the two ports of the coupler are connected to varactor diodes (assumed to be ideal reactance components, only phase shifting), which is changed by adjusting the reverse bias voltage of the varactor.
  • the PN junction capacitance causes the phase of the RF signal to change.
  • the reflected signal after the phase change is remixed and output at the output port.
  • the reflected signal arrives at the input port 180. Inverted, so they can cancel each other out.
  • the present invention can also be applied to a high-power final-stage power amplifier circuit of a communication base station, such as a repeater, Global System For Mobile Communication (GSM), and code division multiple access (Code-Division). Multiple Access, CDMA), Wideband-CDMA (WCDMA), WiMAX, Long Term Evolution (LTE) and other base station power amplifier circuits and high-power CPE terminal products of the above communication systems.
  • GSM Global System For Mobile Communication
  • Code-Division Code division multiple access
  • the present invention can improve the linearity of a high power final stage power amplifier circuit and a high power user terminal equipment (CPE) RF power amplifier of a communication base station.
  • CPE user terminal equipment

Abstract

A device for improving the linearity of a radio frequency power amplifier includes a final stage power amplifier and a pre-distortion circuit. The output end of the pre-distortion circuit is coupled to the input end of the final stage power amplifier for performing the phase-shifting to the input signal according to the nonlinear distortion of the input signal's amplitude–output signal's phase of the final stage power amplifier, to compensate the nonlinear distortion. Accordingly, a method for improving the linearity of a radio frequency power amplifier is provided by the present invention. Before the signal is input to the final stage radio frequency power amplifier, the phase-shifting is firstly performed to the signal to compensate the nonlinear distortion, according to the nonlinear distortion of the input signal's amplitude–output signal's phase of the final stage power amplifier. The method of the present invention reduces the cost and design difficulty of corresponding devices such as WiMAX CPE, improves the whole machine transmitting linearity and dynamic range, and reduces the power dissipation. Furthermore the calorific power is small.

Description

一种改善射频功率放大器线性度的方法与装置  Method and device for improving linearity of radio frequency power amplifier
技术领域 Technical field
本发明涉及通讯领域， 尤其涉及一种改善通信基站大功率末级功放电路 和大功率用户终端设备 ( Customer Premises Equipment, CPE )射频功率放大 器线性度的方法与装置。 背景技术  The present invention relates to the field of communications, and in particular, to a method and apparatus for improving the linearity of a high power final stage power amplifier circuit and a high power user terminal equipment (CPE) RF power amplifier of a communication base station. Background technique
随着微波存取全球互通 (Worldwide Interoperability for Microwave Access, WiMAX)技术的高速发展， IP 网络逐渐成为人们日常工作和生活中必不可少 的工具。 WiMAX CPE结合目前 3G最新技术， 釆用 VoIP ( Voice over Internet Protocol )方式提供用户语音和数据业务。  With the rapid development of Worldwide Interoperability for Microwave Access (WiMAX) technology, IP networks have become an indispensable tool in people's daily work and life. WiMAX CPE combines the latest 3G technology to provide user voice and data services using Voice over Internet Protocol (VoIP).
在目前的 CPE设计中发射通道的 WiMAX信号放大一般釆用高增益集成 功率放大器， 或釆用多级功率放大链路且末级功率放大器釆用功率回退技术 来提高射频输出线性度的指标要求。 在以上两种方案中， 集成功率放大器是 优选方案， 但是集成功率放大器成本高、 设备提供商少甚至面临独家供应的 问题（目前只有三菱半导体公司有相关器件） ， 而且器件特性受产品应用范 围的限制且灵活性差。 功率回退技术是目前大多数设备提供商的方案， 但是 此方案要求末级功率放大器有较高的功率容量（因为 WiMAX信号有较高的 峰均比及大的动态范围） ， 因此造成器件线性度低、 动态范围小， 以及价格 高、 效率低、 体积大并且设计难度增加等。  In the current CPE design, the WiMAX signal amplification of the transmit channel generally uses a high-gain integrated power amplifier, or uses a multi-stage power amplifier link and the final stage power amplifier uses power back-off technology to improve the RF output linearity. . In the above two schemes, the integrated power amplifier is the preferred solution, but the integrated power amplifier has high cost, few equipment suppliers or even the problem of exclusive supply (currently only Mitsubishi Semiconductor has related devices), and the device characteristics are affected by the product application range. Limited and poorly flexible. Power backoff technology is currently the solution of most equipment providers, but this solution requires higher power capacity of the final stage power amplifier (because WiMAX signals have higher peak-to-average ratio and large dynamic range), thus causing device linearity. Low degree, small dynamic range, high price, low efficiency, large size and increased design difficulty.
发明内容 Summary of the invention
本发明要解决的技术问题是提供一种改善射频功率放大器线性度的装置 与方法， 以补偿和提高末级功率放大器的线性度。  The technical problem to be solved by the present invention is to provide an apparatus and method for improving the linearity of a radio frequency power amplifier to compensate and improve the linearity of the final stage power amplifier.
为了解决上述问题， 本发明提供了一种改善射频功率放大器线性度的装 置， 包括末级功率放大器， 其中：  In order to solve the above problems, the present invention provides an apparatus for improving the linearity of a radio frequency power amplifier, including a final stage power amplifier, wherein:
还包括一个预失真电路， 该预失真电路的输出端与所述末级功率放大器 的输入端相连， 用于根据所述末级功率放大器的输入信号幅度-输出信号相位 的非线性失真对输入的信号移相， 以补偿该非线性失真。 A predistortion circuit including an output of the predistortion circuit and the final stage power amplifier The input terminals are connected for phase shifting the input signal according to the input signal amplitude of the final stage power amplifier - the nonlinear distortion of the output signal phase to compensate for the nonlinear distortion.
进一步地， 上述装置还可具有以下特点， 所述预失真电路为二极管预失 真电路。  Further, the above device may also have the following features, and the predistortion circuit is a diode pre-distortion circuit.
进一步地， 上述装置还可具有以下特点，  Further, the above device may also have the following features.
所述二极管预失真电路包含 3dB正交耦合器和变容二极管移相电路， 或 者环形器和变容二极管， 或者环形器和 PIN型二极管。  The diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shifting circuit, or a circulator and a varactor, or a circulator and a PIN diode.
进一步地， 上述装置还可具有以下特点，  Further, the above device may also have the following features.
所述二极管预失真电路包含 3dB正交耦合器和变容二极管移相电路， 其 中该 3dB正交耦合器包括一个输入端口、 一个输出端口和与所述变容二极管 移相电路连接的两个内部端口，该变容二极管移相电路包括两个变容二极管， 该两个变容二极管的负极均接到地， 正极均接到直流电压， 并分别通过一个 电容与 3dB正交耦合器的一个内部端口相连。  The diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shifting circuit, wherein the 3dB quadrature coupler includes an input port, an output port, and two internals connected to the varactor phase shifting circuit Port, the varactor phase shifting circuit comprises two varactor diodes, the negative poles of which are connected to ground, the positive poles are connected to a DC voltage, and respectively pass through a capacitor and an internal of the 3dB quadrature coupler The ports are connected.
进一步地， 上述装置还可具有以下特点， 该装置还包括驱动功率放大器， 该驱动功率放大器的输出端与所述预失真电路的输入端相连。  Further, the above device may further have the following features, the device further comprising a driving power amplifier, the output of the driving power amplifier being connected to the input end of the predistortion circuit.
进一步地， 上述装置还可具有以下特点，  Further, the above device may also have the following features.
该装置为一射频信号发射装置， 还包括输出端与所述驱动功率放大器输 入端连接的固定衰减器， 与该固定衰减器输入端连接的巴伦滤波器， 输入端 与所述末级功率放大器输出端连接的低通滤波器， 以及输入端与所述低通滤 波器连接的射频开关。  The device is a radio frequency signal transmitting device, and further comprises a fixed attenuator whose output is connected to the input end of the driving power amplifier, a balun filter connected to the fixed attenuator input, an input terminal and the final stage power amplifier A low pass filter connected to the output, and an RF switch connected to the low pass filter at the input end.
进一步地， 上述装置还可具有以下特点， 该装置为基站或用户终端设备 中的射频信号发射装置， 所述预失真电路用于对输入的射频信号移相。  Further, the above device may further have the following features: the device is a radio frequency signal transmitting device in a base station or a user terminal device, and the predistortion circuit is configured to phase shift the input radio frequency signal.
为了解决上述问题， 本发明还提供了一种改善射频功率放大器线性度的 方法， 包括： In order to solve the above problems, the present invention also provides a method for improving the linearity of a radio frequency power amplifier, including:
在将信号输入到末级射频功率放大器之前， 先根据所述末级功率放大器 的输入信号幅度-输出信号相位的非线性失真， 将该信号进行移相， 以补偿该 非线性失真。 进一步地， 上述方法还可具有以下特点， Before the signal is input to the final stage RF power amplifier, the signal is phase-shifted according to the input signal amplitude of the final stage power amplifier - the nonlinear distortion of the output signal phase to compensate for the nonlinear distortion. Further, the above method may also have the following features.
釆用二极管预失真电路来对所述射频信号进行移相， 该二极管预失真电 路包含 3dB正交耦合器和变容二极管移相电路。  The diode pre-distortion circuit is used to phase shift the RF signal. The diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shift circuit.
进一步地， 上述方法还可具有以下特点，  Further, the above method may also have the following features.
所述末级射频功率放大器位于基站或用户终端设备内的射频信号发射装 置中， 所述信号为射频信号。  The final stage radio frequency power amplifier is located in a radio frequency signal transmitting device in a base station or a user terminal device, and the signal is a radio frequency signal.
本发明所述的方法最大程度的降低了相应装置如 WiMAX CPE的成本和 CPE产品的设计难度， 提高了相应装置如 WiMAX CPE的整机发射性能， 如 提高了 WiMAX CPE的整机发射线性度及动态范围，降低了功耗且发热量小； 此外，本设计方案使 CPE或基站中相应产品体积减小、不受独家供应的限制， 可以充分利用可选择的通用器件， 增加了可使用频段的选择性从而使频段不 受限制。 釆用较小额定功率的功率放大器减低成本、 提高性价比。 附图概述 The method of the invention minimizes the cost of the corresponding device such as WiMAX CPE and the design difficulty of the CPE product, and improves the overall launch performance of the corresponding device such as WiMAX CPE, such as improving the linearity of the whole machine of the WiMAX CPE and Dynamic range, reduced power consumption and low heat generation; In addition, this design scheme reduces the volume of corresponding products in CPE or base station, is not limited by exclusive supply, can make full use of selectable general-purpose devices, and increase the usable frequency band. Selectivity thus limits the frequency band.功率 Use a power amplifier with a smaller power rating to reduce costs and improve cost performance. BRIEF abstract
图 1是现有技术的 WiMAX信号处理模块的结构示意图；  1 is a schematic structural diagram of a prior art WiMAX signal processing module;
图 2是本发明实施例的 WiMAX射频信号发射通道的结构示意图； 图 3是本发明实施例的二极管预失真电路的结构示意图。 本发明的较佳实施方式  2 is a schematic structural diagram of a WiMAX radio frequency signal transmission channel according to an embodiment of the present invention; and FIG. 3 is a schematic structural diagram of a diode predistortion circuit according to an embodiment of the present invention. Preferred embodiment of the invention
本发明提供一种在末级通用功率放大器前进行预失真处理， 使末级功率 放大器的输入的射频信号移相， 以补偿和提高末级功率放大器的线性度及动 态范围。  The present invention provides a predistortion process prior to the final stage general purpose power amplifier to phase shift the input RF signal of the final stage power amplifier to compensate for and improve the linearity and dynamic range of the final stage power amplifier.
下面以在 WiMAX CPE的应有为例， 结合附图对本发明的技术方案实施 例作进一步的详细说明：  In the following, the embodiment of the technical solution of the present invention will be further described in detail by taking the example of the WiMAX CPE as an example:
WiMAX信号处理模块的结构示意图如图 1所示， 包含基带处理器 101、 射频处理器 102、 WiMAX射频信号接收通道 103和 WiMAX射频信号发射通 道 104, 本发明实施例中釆用 BECEEM公司的基带处理器和射频处理器， 其 中： The schematic diagram of the WiMAX signal processing module is shown in FIG. 1 , and includes a baseband processor 101 , a radio frequency processor 102 , a WiMAX radio frequency signal receiving channel 103 , and a WiMAX radio frequency signal transmission channel . In the embodiment of the present invention, a baseband processor and a radio frequency processor of BECEEM are used, wherein:
发送时， 基带处理器 101将基带数字信号调制为 WiMAX已调制模拟低 频信号输出到射频处理器 102, 射频处理器 102将 WiMAX已调制模拟低频 信号变频到所需射频工作频段， 产生 WiMAX 已调制射频信号并发送给 WiMAX射频信号发射通道 104 , WiMAX射频信号发射通道 104 负责将 WiMAX已调制射频信号处理后经过天线辐射到自由空间；  When transmitting, the baseband processor 101 modulates the baseband digital signal into a WiMAX modulated analog low frequency signal output to the RF processor 102. The RF processor 102 converts the WiMAX modulated analog low frequency signal to the desired RF operating frequency band to generate a WiMAX modulated RF. The signal is sent to the WiMAX radio frequency signal transmission channel 104, and the WiMAX radio frequency signal transmission channel 104 is responsible for processing the WiMAX modulated radio frequency signal and radiating it to the free space through the antenna;
接收时， WiMAX射频信号接收通道 103 负责 WiMAX射频接收信号的 接收与滤波， 并将滤波后 WiMAX射频接收信号传输给射频处理器 102, 射 频处理器 102将 WiMAX射频接收信号变频到模拟低频信号并输出给基带处 理器 101 , 基带处理器 101将模拟低频信号解调恢复为基带数字信号。  Upon receiving, the WiMAX RF signal receiving channel 103 is responsible for receiving and filtering the WiMAX RF receiving signal, and transmitting the filtered WiMAX RF receiving signal to the RF processor 102. The RF processor 102 converts the WiMAX RF receiving signal to an analog low frequency signal and outputs To the baseband processor 101, the baseband processor 101 demodulates the analog low frequency signal to a baseband digital signal.
其中， WiMAX射频信号发射通道 104的结构示意图如图 2所示， 包含 依次连接的巴伦滤波器 201 ( BALU FILTER )、 固定衰减器 202、 驱动功率 放大器 203、 二极管预失真电路 204、 末级功率放大器 205、 低通滤波器 206 和射频开关 208 , 此外还包括供电和控制电路（图略） ； 其中如固定衰减器 可以为 3dB衰减器；驱动功率放大器可以为集成高增益功率驱动功率放大器； 末级功率放大器可以为通用低增益功率放大器； 射频开关可以为组合式单刀 双掷 ( Single-Pole Double-Throw, SPDT )射频开关。 其中的二极管预失真电 路 204是本实施例增加的。  The structure diagram of the WiMAX radio frequency signal transmission channel 104 is as shown in FIG. 2, and includes a balun filter 201 (BALU FILTER), a fixed attenuator 202, a driving power amplifier 203, a diode predistortion circuit 204, and a final stage power. Amplifier 205, low pass filter 206 and RF switch 208, in addition to power supply and control circuit (figure omitted); wherein the fixed attenuator can be a 3dB attenuator; the drive power amplifier can be an integrated high gain power drive power amplifier; The stage power amplifier can be a general-purpose low-gain power amplifier; the RF switch can be a combined single-Pole Double-Throw (SPDT) RF switch. The diode predistortion circuit 204 therein is added in this embodiment.
其中二极管预失真电路 204包含 3dB正交耦合器和变容二极管移相电路， 如图 3所示。 3dB正交耦合器有四个端口， 变容二极管移相电路包括两个变 容二极管， 两个变容二极管的负极均接到地， 正极均接到直流电压， 同时分 别通过一个电容与 3dB正交耦合器的端口 3和端口 4相连。射频信号通过 3dB 正交耦合器端口 1 输入后被分成两路传输到通过电容连接的两个变容二极 管， 经过变容二极管的移相， 使射频信号相位改变， 最后将相位改变后的反 射信号在 3dB耦合器的端口 2重新混合后一起输出。  The diode predistortion circuit 204 includes a 3dB quadrature coupler and a varactor phase shift circuit, as shown in FIG. The 3dB quadrature coupler has four ports. The varactor phase shifting circuit consists of two varactor diodes. The negative poles of the two varactor diodes are connected to ground. The positive poles are connected to the DC voltage and pass through a capacitor and 3dB positive respectively. Port 3 of the AC coupler is connected to Port 4. After the RF signal is input through the 3dB quadrature coupler port 1, it is divided into two channels and transmitted to two varactor diodes connected through the capacitor. After the phase shift of the varactor diode, the phase of the RF signal changes, and finally the reflected signal after the phase change. The port 2 of the 3dB coupler is remixed and output together.
包含 3dB正交耦合器和变容二极管移相电路的二极管预失真电路通过调 节变容二极管外部的偏置直流电压来改变二极管的 PN结电容从而间接的对 射频信号进行移相， 用以补偿末级功率放大器的幅相失真（AM-PM )从而提 高末级功率放大器器件的线性度和动态范围。 A diode predistortion circuit including a 3dB quadrature coupler and a varactor phase shifting circuit indirectly adjusts the PN junction capacitance of the diode by adjusting a bias DC voltage external to the varactor to indirectly shift the RF signal to compensate for the end. Amplitude and phase distortion (AM-PM) of a stage power amplifier Linearity and dynamic range of high final power amplifier devices.
此外， 二极管预失真电路还可以釆用环形器加变容二极管， 或环形器加 In addition, the diode predistortion circuit can also use a circulator plus a varactor diode, or a circulator plus
PIN ( P-I-N )型二极管的形式等。 The form of a PIN (P-I-N) type diode, etc.
本发明的实施例如下所述： The implementation of the invention is as follows:
当 WiMAX射频信号发射通道 104接收到射频处理器 102 发射来的 WiMAX 已调制射频信号后， 经过巴伦滤波器 201后产生经过平衡到不平衡 变换和滤除带外杂波的射频发射信号， 并传输到固定衰减器 202, 为防止驱 动功率放大器 203的输入端口不匹配而影响巴伦滤波器 201的通带特性， 因 此釆用固定衰减器 202对所述射频发射信号进行固定衰减以提高前级驱动级 的输入匹配， 将衰减后的射频发射信号传输到驱动功率放大器 203 , 该驱动 功率放大器 203可以为中功率高增益功率放大器， 驱动功率放大器 203将射 频发射信号放大到所需的电平和线性度后传输到二极管预失真电路 204, 二 极管预失真电路 204通过调节变容二极管外部的偏置直流电压来改变二极管 的 PN结电容从而间接的对射频信号进行移相并传输到末级功率放大器 205, 通过末级功率放大器 205放大并传输到低通滤波器 206, 低通滤波器 206滤 除射频发射信号的高次谐波后通过一个组合式射频收发的射频开关 207将信 号传输给天线， 由天线将射频发射信号辐射到自由空间。  After the WiMAX radio frequency signal transmitting channel 104 receives the WiMAX modulated radio frequency signal transmitted by the radio frequency processor 102, the balun filter 201 generates a radio frequency transmitting signal that is balanced to unbalanced and filtered to remove out-of-band clutter, and Transmission to the fixed attenuator 202, in order to prevent the input port mismatch of the driving power amplifier 203 from affecting the passband characteristics of the balun filter 201, the fixed attenuator 202 is used to fixedly attenuate the radio frequency transmitting signal to improve the preamplifier. The input of the driver stage is matched, and the attenuated RF transmission signal is transmitted to a driving power amplifier 203, which may be a medium power high gain power amplifier, and the driving power amplifier 203 amplifies the RF emission signal to a desired level and linearity. The second stage is transmitted to the diode predistortion circuit 204. The diode predistortion circuit 204 indirectly shifts the RF signal by adjusting the bias DC voltage outside the varactor to change the PN junction capacitance of the diode and transmits it to the final stage power amplifier 205. , amplified and transmitted by the final stage power amplifier 205 A low-pass filter 206, low-pass filters 206 filter out the higher harmonics emitted after RF signal 207 by RF switch transmits a combined signal of the RF transceiver to the antenna, the antenna transmitting the radio frequency signal is radiated into free space.
本实施例在 WiMAX射频信号发射通道的驱动功率放大器和末级功率放 大器之间增加了二极管预失真电路， 二级管预失真电路主要对输入射频信号 起移相作用。 因为末级功率放大器是一个非线性器件， 在大功率应用时存在 非常大的非线性失真， 主要包括输入信号幅度-输出信号幅度（AM-AM ) 失 真和输入信号幅度-输出信号相位（ AM-PM )失真（如图 4所示 ) 。 二极管预 失真电路的作用就是对输入信号进行移相减小 AM-PM失真。 输入信号进入 3dB耦合器后被分成两路，耦合器的两个端口分别接了变容二极管（假定是理 想电抗元件， 只有移相作用） ， 通过调节变容二极管的反向偏置电压来改变 PN结电容，从而使射频信号的相位得到了改变。相位改变后的反射信号在输 出端口重新混合在一起输出。 而反射信号到达输入端口时 180。反相， 所以可 以相互抵消。 本发明除可用于 WiMAX用户终端设备外， 还可以应用于通信基站大功 率末级功放电路， 如直放站、 全球移动通信 ( Global System For Mobile Communication, GSM ) 、 码分多址 (Code-Division Multiple Access, CDMA), 宽带码分多址（ Wideband-CDMA, WCDMA )、 WiMAX,长期演进（ Long Term Evolution, LTE )等基站的末级功率放大电路和以上通信制式的大功率 CPE 终端产品。 In this embodiment, a diode predistortion circuit is added between the driving power amplifier of the WiMAX radio frequency signal transmitting channel and the final stage power amplifier, and the diode predistortion circuit mainly plays a phase shifting effect on the input radio frequency signal. Because the final stage power amplifier is a nonlinear device, there is very large nonlinear distortion in high power applications, including input signal amplitude-output signal amplitude (AM-AM) distortion and input signal amplitude-output signal phase (AM- PM) distortion (as shown in Figure 4). The role of the diode predistortion circuit is to phase shift the input signal to reduce AM-PM distortion. The input signal enters the 3dB coupler and is split into two. The two ports of the coupler are connected to varactor diodes (assumed to be ideal reactance components, only phase shifting), which is changed by adjusting the reverse bias voltage of the varactor. The PN junction capacitance causes the phase of the RF signal to change. The reflected signal after the phase change is remixed and output at the output port. The reflected signal arrives at the input port 180. Inverted, so they can cancel each other out. In addition to being applicable to WiMAX user terminal equipment, the present invention can also be applied to a high-power final-stage power amplifier circuit of a communication base station, such as a repeater, Global System For Mobile Communication (GSM), and code division multiple access (Code-Division). Multiple Access, CDMA), Wideband-CDMA (WCDMA), WiMAX, Long Term Evolution (LTE) and other base station power amplifier circuits and high-power CPE terminal products of the above communication systems.
工业实用性 本发明可以改善通信基站大功率末级功放电路和大功率用户终端设备 ( Customer Premises Equipment, CPE )射频功率放大器线性度。 Industrial Applicability The present invention can improve the linearity of a high power final stage power amplifier circuit and a high power user terminal equipment (CPE) RF power amplifier of a communication base station.

Claims

权 利 要 求 书 Claim
1、 一种改善射频功率放大器线性度的装置， 包括末级功率放大器，其特 征在于： 1. A device for improving the linearity of a radio frequency power amplifier, including a final stage power amplifier, characterized by:
还包括一个预失真电路， 该预失真电路的输出端与所述末级功率放大器 的输入端相连， 用于根据所述末级功率放大器的输入信号幅度-输出信号相位 的非线性失真对输入的信号移相， 以补偿该非线性失真。  Also included is a predistortion circuit having an output coupled to the input of the final stage power amplifier for inputting a signal based on the input signal amplitude of the final stage power amplifier - a nonlinear distortion of the output signal phase The signal is phase shifted to compensate for this nonlinear distortion.
2、 如权利要求 1所述的装置，其特征在于， 所述预失真电路为二极管预 失真电路。 2. Apparatus according to claim 1 wherein said predistortion circuit is a diode predistortion circuit.
3、 如权利要求 2所述的装置， 其特征在于： 3. Apparatus according to claim 2 wherein:
所述二极管预失真电路包含 3dB正交耦合器和变容二极管移相电路， 或 者环形器和变容二极管， 或者环形器和 PIN型二极管。  The diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shifting circuit, or a circulator and a varactor, or a circulator and a PIN diode.
4、 如权利要求 2所述的装置， 其特征在于： 4. Apparatus according to claim 2 wherein:
所述二极管预失真电路包含 3dB正交耦合器和变容二极管移相电路， 其 中该 3dB正交耦合器包括一个输入端口、 一个输出端口和与所述变容二极管 移相电路连接的两个内部端口，该变容二极管移相电路包括两个变容二极管， 该两个变容二极管的负极均接到地， 正极均接到直流电压， 并分别通过一个 电容与 3dB正交耦合器的一个内部端口相连。  The diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shifting circuit, wherein the 3dB quadrature coupler includes an input port, an output port, and two internals connected to the varactor phase shifting circuit Port, the varactor phase shifting circuit comprises two varactor diodes, the negative poles of which are connected to ground, the positive poles are connected to a DC voltage, and respectively pass through a capacitor and an internal of the 3dB quadrature coupler The ports are connected.
5、 如权利要求 1或 2或 3或 4所述的装置， 其特征在于： 5. Apparatus according to claim 1 or 2 or 3 or 4, characterized by:
该装置还包括驱动功率放大器， 该驱动功率放大器的输出端与所述预失 真电路的输入端相连。  The apparatus also includes a drive power amplifier having an output coupled to the input of the pre-distortion circuit.
6、 如权利要求 5所述的装置， 其特征在于： 6. Apparatus according to claim 5 wherein:
该装置为一射频信号发射装置， 还包括输出端与所述驱动功率放大器输 入端连接的固定衰减器， 与该固定衰减器输入端连接的巴伦滤波器， 输入端 与所述末级功率放大器输出端连接的低通滤波器， 以及输入端与所述低通滤 波器连接的射频开关。 The device is a radio frequency signal transmitting device, and further comprises a fixed attenuator whose output is connected to the input end of the driving power amplifier, a balun filter connected to the fixed attenuator input, an input terminal and the final stage power amplifier A low pass filter connected to the output, and an RF switch connected to the low pass filter at the input end.
7、 如权利要求 5所述的装置，其特征在于，该装置为基站或用户终端设 备中的射频信号发射装置， 所述预失真电路用于对输入的射频信号移相。 7. The apparatus of claim 5, wherein the apparatus is a radio frequency signal transmitting apparatus in a base station or a user terminal device, and the predistortion circuit is configured to phase shift the input radio frequency signal.
8、 一种改善射频功率放大器线性度的方法， 包括： 8. A method of improving the linearity of a radio frequency power amplifier, comprising:
在将信号输入到末级射频功率放大器之前， 先根据所述末级功率放大器 的输入信号幅度-输出信号相位的非线性失真， 将该信号进行移相， 以补偿该 非线性失真。  Before the signal is input to the final stage RF power amplifier, the signal is phase-shifted according to the input signal amplitude of the final stage power amplifier - the nonlinear distortion of the output signal phase to compensate for the nonlinear distortion.
9、 如权利要求 8所述的方法， 其特征在于： 9. The method of claim 8 wherein:
釆用二极管预失真电路来对所述射频信号进行移相， 该二极管预失真电 路包含 3dB正交耦合器和变容二极管移相电路。  The diode pre-distortion circuit is used to phase shift the RF signal. The diode predistortion circuit includes a 3dB quadrature coupler and a varactor phase shift circuit.
10、 如权利要求 8或 9所述的方法， 其特征在于： 10. The method of claim 8 or 9, wherein:
所述末级射频功率放大器位于基站或用户终端设备内的射频信号发射装 置中， 所述信号为射频信号。  The final stage radio frequency power amplifier is located in a radio frequency signal transmitting device in a base station or a user terminal device, and the signal is a radio frequency signal.
PCT/CN2008/002164 2008-12-31 2008-12-31 A method and device for improving the linearity of a radio frequency power amplifier WO2010075645A1 (en)

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