Research on the Effect of High Power Microwave on Low Noise Amplifier and Limiter Based on the Injection Method

The reliability of electronic device is threatened in high power microwave (HPM) environment. In accordance with the situation that the emulation is ineffective in evaluating the accuracy and precision of the HPM effect to electronic device, the experimental method is used to resolve the problem. Low Noise Amplifier (LNA) and Limiter are selected as the objects for the experiments, the structural characteristic of the front-end of radar receiver is described, the phenomena and criterion are elaborated and analyzed using injection method due to its ability to get an accurate threshold avoiding the complex coupling, the basic principle of injection experiment is demonstrated, and the method and process of effect experiment about Low Noise Amplifier and Limiter are also explained. The experimental system is established, and the system is composed of low power microwave source such as TWT, test equipment for obtaining the effect parameters, and some of auxiliary equipments as camera, optical microscope or electron microscopy, attenuator, detector, and directional coupler etc. The microwave delivered from source is adjusted to the power infused by attenuator, and pour in the decanting point of effecter via directional coupler, then the couple signal created by directional coupler is input to the recording instrument after detecting by detector, finally the power of effecter is obtained. The value of power, which damages the effecter in the microwave pulse environment, is classified at the index of sensitivity, and the threshold is obtained by power diagnose and wave test. Some regular understandings of the HPM effect to electronic device are obtained based on the results of the experiments. It turns out that the index of electronic device is influenced significantly by the energy via front door coupling, the MOSFET made up of GaAs is the most wearing part to HPM in LNA, the damage threshold of LNA is about 40dBm under single pulse while in repetitive pulse the value is from 33.3dBm to 43.9dBm according to different wave band. The damage threshold of Limiter is about 56dBm to80dBm.

A C-band 55% PAE high gain two-stage power amplifier based on AlGaN/GaN HEMT

A C-band high efficiency and high gain two-stage power amplifier based on Al Ga N/Ga N high electron mobility transistor(HEMT) is designed and measured in this paper. The input and output impedances for the optimum power-added efficiency(PAE) are determined at the fundamental and 2nd harmonic frequency( f0 and 2 f0). The harmonic manipulation networks are designed both in the driver stage and the power stage which manipulate the second harmonic to a very low level within the operating frequency band. Then the inter-stage matching network and the output power combining network are calculated to achieve a low insertion loss. So the PAE and the power gain is greatly improved. In an operation frequency range of 5.4 GHz–5.8 GHz in CW mode, the amplifier delivers a maximum output power of 18.62 W, with a PAE of 55.15% and an associated power gain of 28.7 d B, which is an outstanding performance.

A 600W Broadband Doherty Power Amplifier with Improved Linearity for Wireless Communication System

An asymmetric Doherty architecture based on three identical transistors is proposed in this paper. This proposed three.way topology reduces the difficulty in designing matching networks brought by the low optimal impedance of high power transistors. And the inverted Doherty topology as well as carefully chosen value of load impedance makes it possible to extend the bandwidth of high power amplifiers. Besides, bias networks of this proposed three.way architecture are also carefully considered to improve the linearity. The proposed high power three.way Doherty power amplifier(3W.DPA) is designed and fabricated based on theoretic analysis. Its maximum output power is about 600 Watts and the drain efficiency is above 35.5% at 9d B back off output power level from 1.9GHz to 2.2 GHz and the saturated drain efficiency is above 47% across the whole frequency band. The measured concurrent two.tone results suggest that the linearity of DPA is improved by at least 5d B.

High-efficiency S-band harmonic tuning GaN amplifier

In this paper, we present a high-efficiency S-band gallium nitride(GaN) power amplifier(PA). This amplifier is fabricated based on a self-developed GaN high-electron-mobility transistor(HEMT) with 10 mm gate width on SiC substrate.Harmonic manipulation circuits are presented in the amplifier. The matching networks consist of microstrip lines and discrete components. Open-circuited stub lines in both input and output are used to tune the 2nd harmonic wave and match the GaN HEMT to the highest efficiency condition. The developed amplifier delivers an output power of 48.5 dBm(～70 W)with a power-added efficiency(PAE) of 72.2% at 2 GHz in pulse condition. When operating at 1.8–2.2 GHz(20% relative bandwidth), the amplifier provides an output power higher than 48 dBm(～ 65 W), with a PAE over 70% and a power gain above 15 dB. When operating in continuous-wave(CW) operating conditions, the amplifier gives an output power over46 dBm(40 W) with PAE beyond 60% over the whole operation frequency range.

Design of 35 GHz 1 Watt GaAs pHEMT Power Amplifier MMIC

By using 0.15 μm GaAs pHEMT (pseudomorphic high electron mobility transistor) technology,a design of millimeter wave power amplifier microwave monolithic integrated circuit (MMIC) is presented.With careful optimization on circuit structure,this two-stage power amplifier achieves a simulated gain of 15.5 dB with fluctuation of 1 dB from 33 GHz to 37 GHz.A simulated output power of more than 30 dBm in saturation can be drawn from 3 W DC supply with maximum power added efficiency (PAE) of 26%.Rigorous electromagnetic simulation is performed to make sure the simulation results are credible.The whole chip area is 3.99 mm2 including all bond pads.

Damage effect and mechanism of the GaAs high electron mobility transistor induced by high power microwave

In this paper, we present the damage effect and mechanism of high power microwave(HPM) on Al GaAs/GaAs pseudomorphic high-electron-mobility transistor(p HEMT) of low-noise amplifier(LNA). A detailed investigation is carried out by simulation and experiment study. A two-dimensional electro-thermal model of the typical GaAs p HEMT induced by HPM is established in this paper. The simulation result reveals that avalanche breakdown, intrinsic excitation, and thermal breakdown all contribute to damage process. Heat accumulation occurs during the positive half cycle and the cylinder under the gate near the source side is most susceptible to burn-out. Experiment is carried out by injecting high power microwave into GaAs p HEMT LNA samples. It is found that the damage to LNA is because of the burn-out at first stage p HEMT. The interiors of the damaged samples are observed by scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS). Experimental results accord well with the simulation of our model.

Evolution of modes in double-clad Raman fiber amplifier

Stimulated Raman scattering in a double cladding optical fiber is studied with a continuous wave laser used as a pump source.Under various launch conditions,pump modes are differently excited.Considering the mode coupling effect among the pump modes,the evolution of the power in the Stokes modes is studied.The results show that the scattered waves(the Stokes waves)in the fiber core with 9-μm diameter and 0.14 NA could propagate predominantly in the fundamental mode of the fiber by carefully adjusting the pump light launching conditions.

基于LUT的HPA数字基带预失真方法研究

该文深入研究了OFDM系统中基于查询表LUT方法的HPA数字预失真技术。针对传统LUT方法收敛速度非常慢的不足,有关文献提出了相应的改进措施。该文从误码率BER,功率谱密度PSD和算法收敛速度几个方面进行了算法性能的仿真比较分析,指出以上算法存在的不足,并提出了新的改进方法,仿真及分析结果表明了该文提出改进方法在性能上的优越性。

基于自适应扩展卡尔曼滤波与神经网络的HPA预失真算法

针对强记忆功放的非线性问题,提出一种基于自适应扩展卡尔曼滤波与神经网络的高功放(High power amplifier,HPA)预失真算法.采用实数固定延时神经网络(Real-valued focused time-delay neural network,RVFTDNN)对间接学习结构预失真系统中的预失真器和逆估计器进行建模,扩展卡尔曼滤波(Extended Kalman filter,EKF)算法训练神经网络,从理论上指出Levenberg-Marquardt(LM)算法是EKF算法的特殊情况,并用李亚普诺夫稳定性理论分析EKF算法的稳定收敛条件,推导出测量误差矩阵的自适应迭代公式.结果表明:自适应EKF算法的训练误差和泛化误差均比LM算法更低,预失真后的邻道功率比(Adjacent channel power ratio,ACPR)比LM算法改善了2 d B.

一种基于神经网络的非线性卫星HPA预失真器

卫星通信中放大器使用的行波管(TWT)会引起信号的非线性畸变,对通信质量造成较大影响。为解决这种不利影响,在放大器前端采用非线性预失真,能较理想地消除放大器的非线性。由于神经网络能够对非线性函数进行较好地拟合,可以将其引入预失真器的设计。为简化神经网络中的LM算法,提出了一种采用LMS算法的系统模型,并建立新的自适应预失真器的结构模型,大大降低计算复杂度,有利于系统性能的提高。仿真表明,采用含有一个隐层(9个神经元)的神经网络模型来设计预失真器,能够达到较好的预校正效果。

基于微通道散热的板条激光放大器热仿真分析

众所周知,热效应是限制大功率高能量激光器发展的一大瓶颈,在高能激光产生的过程中伴随着大量的废热产生,影响高能量激光器的光束质量甚至会影响其正常工作。为了保证高能量激光器的稳定运作并研究其工作物质的散热过程中的热分布状态,本文建立了一种用于高能Zig Zag板条激光放大器的双端入水微通道散热模型,利用CFD模拟仿真软件在额定工况下对微通道与空腔热沉进行散热对比,还研究了模型的可变参量:通道高度、翅片厚度,以及水流量对于散热性能的影响。模拟研究发现本文提出的微通道热沉冷却效果优于全腔水冷效果,微通道热沉将晶体表面最高温差控制在4℃以内,表面温度也降低了32;同时在压降允许范围内优化通道参数能再将冷却效果提升10,实现增益介质分布式高效散热。

0.2~2.0GHz100W超宽带GaN功率放大器

设计并实现了一款基于0.25μm GaN高电子迁移率晶体管(HEMT)工艺的100 W超宽带功率放大器。基于SiC无源工艺设计了集成无源器件(IPD)输入预匹配电路芯片;设计了基于陶瓷基片的T型集成输出预匹配电路;基于建立的传输线变压器(TLT)的精确模型,设计了宽带阻抗变换器,在超宽频带内将50Ω的端口阻抗变换至约12.5Ω,再通过多节微带电路与预匹配后的GaN HEMT芯片实现阻抗匹配。最终,以较小的电路尺寸实现了功率放大器的超宽带性能指标。测试结果表明,功率放大器在0.2~2.0 GHz频带内,在漏极电压36 V、输入功率9 W、连续波的工作条件下,输出功率大于103 W,漏极效率大于50%,输入电压驻波比(VSWR)≤2.5。

基于RBF神经网络的HPA自适应预失真算法

卫星通信中,高速数据传输系统要求使用频谱利用率高的高阶调制技术,但高阶调制对高功率放大器(HPA)的非线性非常敏感,会造成码间干扰和邻信道间干扰。提出一种基于RBF神经网络的自适应预失真算法,以实现HPA的线性化,同时推导了自适应算法的迭代公式。仿真结果表明,该算法能明显改善信号星座图,并能大大提高系统的误比特率性能。

基于BPNN的OFDM系统的HPA预失真

本文针对高功率放大器(HPA)的非线性失真导致OFDM(Orthogonal Frequency Division Multiplexing)系统传输性能下降问题,采用两个类似结构的单输入单输出BP神经网络串联后级联HPA实现其预失真,前一网络是HPA的AM-AM特性的逆模型,用来实现HPA的幅度预失真,后一网络是HPA的AM-PM特性模型,回避了其逆模型的建立,实现了HPA更高精度的相位预失真,提高了整体预失真效果。仿真结果显示了即使输入回退只有2.93dB,带外谱增长仍能降低约10dB,表明该方案能够方便高效地实现OFDM系统中HPA的自适应预失真,大大提高OFDM系统的传输性能。

基于HPA特性曲线拟合的自适应预失真技术

提出了一种用于正交频分复用(OFDM)系统中补偿由大功率放大器引起的非线性失真的基带自适应预失真方法。自适应预失真器是基于对大功率放大器的非线性特性进行分段估计,由曲线拟合逐段取逆变换来训练大功率放大器的预失真器的非线性参数,以达到预是真补偿的目的。计算机仿真结果表明,该方法具有收敛速度快、需要动态存储器(RAM)少、补偿效果好等特点。

基于认知无线电的NC-OFDM系统HPA非线性的研究

研究了高功率放大器(HPA)非线性对非连续OFDM(NC-OFDM)信号的影响,给出了基于认知无线电的NC-OFDM系统模型,并仿真分析了主用户(PU)频带干扰温度与NC-OFDM系统HPA参数、频带占用率、子信道间隔、保护载波数量等系统参数的关系,结果表明,HPA的IBO参数和PU频带占用率是决定PU频带干扰的主要因素,而且单纯依靠增加保护载波和子信道间隔对PU频带干扰温度的改善是有限的。所得结论可为NC-OFDM系统中预失真、旁瓣抑制及功率分配等算法的研究提供参考。

考虑HPA非线性的NC-OFDM系统最优参数设计

给出了计算非连续OFDM(NC-OFDM)系统带外功率泄漏和主用户(PU)频带干扰功率的数学模型,在此基础上,把NC-OFDM系统参数设计问题转化为次用户(SU)频谱开销和主用户(PU)干扰温度限制下的非线性规划问题的优化求解.给出了NC-OFDM系统最优参数与高功率放大器(HPA)的输入回退(IBO)参数、PU频带占用率和PU干扰温度容限之间的关系.仿真结果表明,当PU频带占用率和干扰容限给定的条件下,求解所建立的优化问题可以为SU设计最佳的系统参数:最少的保护载波数及系统对功率放大器IBO参数的要求.

改进磷虾群与NBN联合优化神经网络的HPA预失真方法

为克服现有神经网络预失真方法复杂度高、易陷入局域最小等缺陷,提出一种正交差分进化磷虾群(ODEKH)与neuron-by-neuron(NBN)算法联合优化实数固定延时全连接级联神经网络(RVFTDFCCNN)的高功率放大器预失真方法。采用RVFTDFCCNN对预失真系统中的预失真器和逆估计器进行建模,通过ODEKH算法进行全局搜索获得RVFTDFCCNN的初始化参数,再用NBN算法对RVFTDFCCNN进行训练,同时根据复合函数求偏导数的链式规则,从2个层次对NBN算法中的Jacobian矩阵元素计算进行优化。采用宽带DTMB信号作为输入信号,对预失真系统进行仿真。结果表明:当训练误差和泛化误差均在同一数量级时,RVFTDFCCNN的NBN算法计算量比单隐层(SHL)神经网络明显降低;ODEKH算法比传统磷虾群算法具有更快的收敛速度,ODEKH-NBN联合算法的训练精度比Levenberg-Marquardt(LM)算法提高一个数量级,预失真后的邻道功率比(ACPR)比LM算法改善了2 d B。说明本文的预失真方法具有较低的复杂度和良好的预失真性能。

一种V波段高效率5W GaN功率放大器MMIC

基于0.13μm SiC基GaN高电子迁移率晶体管(HEMT)工艺,设计了一款V波段GaN功率放大器单片微波集成电路(MMIC)。该功率放大器MMIC采用三级放大拓扑结构以满足增益需求;使用高低阻抗微带传输线进行阻抗匹配,通过威尔金森功分器/合成器完成功率放大器的末端功率合成;通过对晶体管宽长比的设计与多胞晶体管的合成,实现了功率放大器的高功率稳定工作和高效率输出。经过测试,在59~61 GHz频率范围内,在占空比为20%、脉宽为100μs时,该功率放大器MMIC的饱和输出功率达到37 dBm以上,功率附加效率(PAE)大于21.1%,功率增益大于17 dB;连续波测试条件下输出功率大于36.8 dBm, PAE大于21%。该设计在输出功率和PAE上具有一定的优势。

高压大电流磁轴承功率放大器的系统研究与应用

针对三相三线制交流电网输入、高压大电流隔离输出、交流掉电不间断供电10 min,以及较大频率响应范围、稳态特性和动态特性良好的要求,提出一种N+1冗余不间断的稳压电源和三态PWM调制的功率放大器。阐述了磁悬浮轴承控制系统的工作原理,设计并制造了600 V/60 A的高压大电流功率放大器系统。实验结果表明,稳压电源能够实现10 min左右的不间断供电且变换器具有冗余功能,磁轴承功率放大器具有较小的输出电流纹波,同时具有较好的跟随特性、稳态特性、动态特性和较大频率响应范围。样机实验结果表明,所设计系统能够满足要求,对磁悬浮轴承控制系统的商业化生产制造具有一定的指导意义。