逆F类功放数字预失真改进算法

针对逆F类射频功率放大器高效率实现带来的严重的非线性失真,提出基于幅度索引的查找表(LUT)模型数字预失真改进算法,以获得具有高线性和高效率的逆F类射频放大系统。由于逆F类功放复杂的特性曲线,传统LUT数字预失真算法已经不能很好地拟合功放模型,为此采用非均匀取点拟合,并且结合多项式、EWMA和平滑等曲线拟合方法。实验结果表明:运用该方法,使3载波WCDMA信号施加到中心频率为930 MHz的逆F类功率放大器后的非线性失真现象明显改善。     

广义改进型Hammerstein预失真器的实现方法及验证

射频功率放大器与生俱来的非线性是无线通信前端设计需要解决的核心问题之一。根据广义改进型Hammerstein功率放大器非线性模型,提出一种应用于射频功放线性化的新型数字预失真器——广义改进型Hammerstein(Generalized Augmented Hammerstein, GAH)预失真器,并给出了该预失真器的实现方法。另外,为了精确分析GAH 预失真器的性能,采用实际功放的输入输出数据进行仿真和实验。被测功放为中心频率1960 MHz,带宽40 MHz, 输出功率45 dBm的Doherty功放。仿真和实验证明：提出的数字预失真器不仅计算复杂度远低于记忆多项式（Memory Polynomial,MP）和分数阶记忆多项式（Fractional Memory Polynomial, FMP）预失真器,而且其线性化能力也强于AH、MP及FMP等预失真器。     

无线通信中有记忆功率放大器的一种预失真方法

在WCDMA等宽带通信系统中,射频功率放大器记忆效应明显,传统的无记忆预失真技术无法达到理想的线性化效果.分析功放的记忆效应,并提出一种适合于有记忆射频功率放大器的顸失真方法.该方法首先基于记忆多项式构造预失真器,然后采用间接学习结构设计预失真系统,并运用限定记忆递推最小二乘算法更新预失真器参数,以跟踪放大器特性的变化.仿真结果表明,该方法能较好地补偿射频功放的非线性失真和记忆效应.     

功率放大器数字预失真技术的研究

在宽带码分多址(WCDMA)等宽带通信系统中,射频功率放大器呈现出严重的电记忆效应和热记忆效应,产生频谱再生和邻道干扰,传统的无记忆预失真技术已经无法消除信号失真而达到理想的线性化效果.针对此类有记忆性的功放,文章提出一种新的记忆多项式预失真器,以跟踪射频功率放大器特性的变化, 并进行非线性补偿.     

逆F类高效氮化镓Doherty射频功率放大器设计*

逆F 类功放在接近饱和区工作时效率很高,将其与Doherty 功放结构相结合,可以实现一种在大功率回退的情况下仍然具有很高效率的射频功率放大器。本文设计了一款基于GaN HEMT 晶体管的高效率的逆F 类Doherty 功率放大器,工作频带为910MHz-950MHz。单音信号测试结果显示,在930MHz 处,功放回退7.5dB 后漏极效率仍高达64.2%。使用3 载波WCDMA信号作为测试信号,利用数字预失真技术进行线性化后,功放输出信号的上下边带邻信道功率比(ACPR)分别为-35.39dBc 和-35.9dBc。     

一种高效率E-1 / F 类GaN HEMT 射频功率放大器

使用GaN HEMT 功率器件,设计了一款5G 低频段的高效率E-1 / F 类射频功率放大器。为降低晶体管寄生参数及高次谐波对逆E 类(E-1 )功放开关特性和输出性能的不良影响,将具有寄生参数补偿的逆F 类(F-1 )谐波控制网络引入逆E 类功放输出匹配电路中,实现了对二次谐波和三次谐波分别进行开路和短路处理,从而获得逆E 类功放要求的良好开关特性。同时,得益于逆F 类功放优良的谐波控制效果,改善了功放漏极电压和电流波形,大大降低其漏极峰值电压和电流,进而提升了功放的输出性能。实测结果表明,该功放在3. 3 ~ 3. 6 GHz 的300MHz 有效工作带宽内的功率附加效率为59. 1% ~ 71. 4%,最大漏极效率高达75. 6%,输出功率在40. 2 ~ 41. 5dBm之间,增益平坦度在依1dB 以内。最后利用20 MHz 带宽的单载波LTE 信号作为测试信号,基于广义记忆多项式数字预失真器对该功放进行线性化后,功放输出的邻信道功率比改善了近15 dB。     

一种模拟预失真自适应线性化方法

针对射频功率放大器的非线性问题,提出一种基于两个复量多项式的模拟预失真电路,并根据射频功率放大器的响应用LMS(最小均方)算法自适应优化多项式的系数,从而使功率放大器的线性性能达到最佳。该预失真器的优点是电路简单,运算量少,适用于宽带通信。基于双频信号和WCDMA(宽带码分多址)信号对该预失真器进行了仿真测试。实验结果表明,该预失真线性化方法对交调失真分量抑制效果明显,ACPR(邻信道功率比)可改善至56.1dB,对功率放大器的非线性具有良好的补偿效果。     

一种用于TETRA系统的数字子带滤波预失真器

本文提出一种适用于TETRA数字集群系统的基于子带滤波技术的数字自适应预失真器。数字子带滤波预失真器将发射信号分为若干子带进行功放线性化处理,降低了预失真过程中运算速率的要求,增加自适应收敛速度。子带滤波技术同时解决了功放宽带化所带来的记忆性问题,扩展了数字预失真器的工作带宽。TETRA多载波发射信号的仿真结果说明,数字子带滤波预失真器对无记忆功放和有记忆功放均具有良好的线性化效果,明显扩大了功放的线性工作范围。      

一种新的用于有记忆功放的查找表预失真器

 针对有记忆非线性功放提出了一种新的基于查找表的记忆型预失真器.该记忆型预失真器采用无记忆预失真器的级联扩展,其横向滤波器结构相比记忆多项式方法降低了复杂度,却能够得到与其相近的线性化效果.并且针对查找表固有的量化误差大和自适应收敛速度慢的缺点,分别采用线性内插和加权窗迭代更新的方法加以改进.在非线性功放的记忆多项式模型下,通过多载波WCDMA宽带信号和OFDM宽带信号验证了基于查找表的记忆型预失真器的良好线性化效果和改进方法的有效性.     

一种模拟预失真技术的宽带功率放大器的研究

介绍了一种新的应用于WGDMA的射频高线性功放系统,采用模拟预失真技术,预失真信号由肖特基二极管的非线性产生,通过该预失真信号抵消主功放的互调成分(IMD),可以大幅度提高射频功率放大器的线性度.将此预失真器应用于WCDMA 16W射频系统中,可以使AGPR改善16dB左右.     

S波段高效GaN逆E类功率放大器

介绍一种高效逆E类功率放大器的设计方法,并选用GaN器件设计了工作于2.3GHz的逆E类功率放大器。当供电26V,输入功率26dBm时,放大器输出功率40.2dBm,工作效率76.1%,PAE为73.3%。提供了详尽的仿真与实测数据并对放大器性能进行分析。用数字预失真技术对逆E类功率放大器进行线性化校正并取得了良好的效果。     

Analysis and design of continuous class-E power amplifier at sub-nominal condition

The continuous class-E power amplifier at sub-nominal condition is proposed in this paper. The class-E power amplifier at continuous mode means it can be high efficient on a series matching networks while at sub-nominal condition means it only requires the zero-voltage-switching condition. Comparing with the classical class-E power amplifier, the proposed design method releases two additional design freedoms, which increase the class-E power amplifier’s design flexibility. Also, the proposed continuous class-E power amplifier at sub-nominal condition can perform high efficiency over a broad bandwidth. The performance study of the continuous class-E power amplifier at sub-nominal condition is derived and the design procedure is summarised. The normalised switch voltage and current waveforms are investigated. Furthermore, the influences of different sub-nominal conditions on the power losses of the switch-on resistor and the output power capability are also discussed. A broadband continuous class-E power amplifier based on a Gallium Nitride (GaN) transistor is designed and testified to verify the proposed design methodology. The measurement results show, it can deliver 10–15 W output power with 64–73% power-added efficiency over 1.4–2.8 GHz.     

Design of inverse class-E amplifier with finite D.C. feed inductance

This paper reports on a design of inverse class-E amplifier with finite D.C. feed inductance. The finite D.C. feed inductance is resonated by the parallel capacitance at the fundamental frequency. The direct design equations required to determine the optimum operations are derived in detail. Comparing with the classic inverse class-E amplifier, numerical results show that improvements in minimizing size, cost, and complexity of the circuit can be obtained by the inverse class-E topology with finite D.C. feed inductance. Comparing with the sub-harmonic and parallel-circuit class-E amplifiers, the inverse class-E topology with finite D.C. feed offers advantages for MMIC realization. Theoretical analysis is validated by numerical simulation and measurement. Excellent agreement between theory and simulation results is achieved. Comparison between simulations and measurements of an experimental circuit validate the feasibility of the design. A measured output power of 40.01 dBm, with a drain efficiency of 80.16% and power-added efficiency of 78.93% were obtained at 250 MHz with a 22-dBm input power.     

Off-Nominal Operation of Class-E Amplifier at Any Duty Ratio

Design equations for satisfying the suboptimum operating condition, i.e., only the zero-voltage switching (ZVS) condition, of a class-E amplifier with a linear shunt capacitance at any duty ratio are derived. By exploiting the suboptimum class-E operation, various amplifier parameters such as operating frequency, output power, load resistance, and component values can vary, while the ZVS operation and high efficiency can be achieved. An example of a design procedure of the class-E amplifier is given. The theoretical results were verified with PSpice simulation and an experiment.     

A fully integrated UHF RFID reader SoC for handheld applications in the 0.18 μm CMOS process

A low cost fully integrated single-chip UHF radio frequency identification(RFID) reader SoC for short distance handheld applications is presented.The SoC integrates all building blocks—including an RF transceiver,a PLL frequency synthesizer,a digital baseband and an MCU—in a 0.18μm CMOS process.A high-linearity RX frontend is designed to handle the large self-interferer.A class-E power amplifier with high power efficiency is also integrated to fulfill the function of a UHF passive RFID reader.The measure...     

Broadband circularly polarised high efficiency active antenna

A broadband circularly polarised (CP) high efficiency active antenna is presented, where the antenna is integrated directly with a high efficiency class-E power amplifier (PA). The printed antenna is employed not only as a broadband CP radiator but also as a harmonics-termination load network for the class-E PA. Measured results demonstrate broadband CP radiation and high efficiency.     

Reliability evaluation of class-E and class-a power amplifiers with nanoscaled CMOS technology

Circuit reliability of class-E and class-A power amplifiers is investigated based on a newly developed degradation subcircuit model. Measured degradation characteristics on the fabricated circuits agree well with the simulation predictions. Using this model, we have found that the class-E amplifier degrades faster than a class-A amplifier, due to a much higher stress level during switching. With a drastic decrease of PAE, a shorter lifetime is expected for a class-E amplifier.     

一种宽禁带器件的高效E类功率放大器设计

E类功率放大器是一种新型高效率放大器,属于开关模式功率放大器,其理论效率可以达到100%。可用于雷达、通信和电子对抗等领域的末级功率放大器,是系统高效率、高功率和小型化功率放大器的重要途径。通过分析其工作原理,设计了一款L波段高效E类功率放大器,输出功率大于10 W,实际漏极效率达到74.8%。     

A common-gate switched 0.9-W class-E power amplifier with 41% PAEin 0.25-μm CMOS

A power amplifier for wireless applications has been implemented in a standard 0.25-μm CMOS technology. The power amplifier employs class-E topology to exploit its soft-switching property for high efficiency. The finite dc-feed inductance in the class-E load network allows the load resistance to be larger for the same output power and supply voltage than that for an RF choke. The common-gate switching scheme increases the maximum allowable supply voltage by almost twice from the value for a simple switching scheme. By employing these design techniques, the power amplifier can deliver 0.9-W output power to 50-Ω load at 900 MHz with 41% power-added efficiency (PAE) from a 1.8-V supply without stressing the active devices     

微带线E类功率放大器的设计与实现

E类功率放大器作为开关模式放大器一种,其理想效率为100%。一种简单微带线拓扑网络的E类功率放大器被提出,这种微带线负载网络不仅满足E类功率放大器工作模式的特殊要求,而且对高次谐波有很好的抑制性,同时通过增加合适的偏置微带线可以拓宽放大器的工作带宽。采用ADS软件仿真电路,并在1GHz频率点电路实现了输出功率为4W,漏极效率为73.4%,其中漏极效率效率在63%以上的电路带宽为200MHz。