E-PHEMT射频功率放大器的设计与仿真

针对实现功率放大器输出端获得最大输出功率,放大器设计主要保证能减小失真,增加线性度,就可以提高功率,为此提出了一种利用负载牵引法找出功率放大器的最大输出功率时的最佳外部负载阻抗ZL的方法.并通过实例对中心频率为3GHz,带宽为1GH:射频放大器的稳定性,输入输出负载阻抗圆,以及功率增益进行了仿真,并给出了仿真结果和最终设计电路.仿真结果表明,功率放大器设计完全满足设计指标.并对功率放大器设计提供了重要的参考依据.     

射频功率放大器输入阻抗测量方法的研究

射频功率放大器实际工作条件下的输入阻抗是匹配网络设计中一个重要参数。为了提高射频功率放大器输入阻抗的测量精度,详细分析了常用的负载拉移法影响测量精度的原因,在此基础上提出了一种新的测量方法,并给出了具体步骤。实验结果表明,该方法可对输入阻抗进行准确的测量。理论分析和实验结果均表明提出的方法是可行且准确的,它为放大器输入阻抗的精确测试提供了方便,同时也适用于在较高射频功率量级下工作的大型功率放大器件。     

基于GaN HEMT F类功率放大电路设计

本文基于一款商用GaN HEMT功率器件设计了一款工作在2.45GHz的高效F类功率放大器。该电路的设计利用负载牵引—源牵引仿真技术的方法,确定基波的最佳功率和最佳效率阻抗区域。输出匹配网络在功率器件电流源面对二次谐波短路,对三次谐波开路。另外,为该放大器设计了一款时序保护电路,可提供栅极电压-2.7V,漏极电压28V。仿真结果显示,在2.45GHz时,饱和输出功率为44.17dBm,功率附加效率为73.1%,增益14.1dB。可以应用于微波无线能量传输、微波加热等领域。     

TD-SCDMA射频功率放大器研究

对采用时分双工模式的TD-SCDMA移动通信系统中的射频功率放大器的EVM性能进行了分析。通过分析功率放大器瞬态响应,得到射频功率放大器在时分双工模式下的EVM指标比频分双工模式下的EVM指标有所恶化的原因,并对基于MW6IC2240的射频功率放大器电路建立了一个二阶R-C模型,进一步分析了功率放大器件和外围电路的参数对功率放大器瞬态响应的影响,得到功率放大器瞬态响应的开关上升时间大小会影响时分双工模式下射频功率放大器EVM性能。基于此,提出了改进TD-SCDMA系统中射频功率放大器EVM性能的方法。改进后的TD-SCDMA射频功率放大器在时分双工模式下的EVM性能与频分双工模式时接近。     

射频功率放大器模块的设计与实现

提出了功率放大器设计中的两个关键问题，结合GSM直放站功率放大器模块的工程实例，详细分析了该功率放大器模块的设计过程．最后给出该模块样机的实测结果，进一步验证了设计方法的有效性。     

射频宽带功率放大器设计

针对软件无线电台的特点与要求,研制了一款射频宽带功率放大器。首先,判别功率管的稳定性,基于S参数的设计方法,对功放的输入输出匹配电路进行设计和仿真优化。最终使该款功率放大器测试结果达到设计要求。     

高效率的Doherty功率放大器设计

本文采用Doherty技术对高效率的功率放大器进行设计。利用ADS2008对放大器直流偏置,源、负载网络匹配,功率分配器以及功率放大器整体进行设计。观察仿真结果,可以看出补偿线的引入可以极大地提高Doherty结构的功率放大器增益和效率。     

基于GaN的输入谐波控制射频功率放大器设计

定量地分析了输入谐波控制理论对功放效率的影响.同时,选用了南京电子器件研究所的0.25 μm GaN HEMT器件,并对该GaN HEMT器件进行了负载牵引仿真和大信号仿真.根据仿真结果发现,通过输入谐波控制可以提升射频功率放大器的效率,在频带内能获得3～10％的效率提升.以此设计了一款X波段单级MMIC功放.经测试,...     

超宽带高效率高功率放大器的研究与设计

文章介绍了一种频段范围在1800MHz~2200MHz,输出功率43.5dBm的超宽带高效率高功率放大器,该放大器采用NXP公司的GaN功放管A2G22S160,使用Doherty高效率架构.通过负载牵引技术得到该器件在各个频率的阻抗Smith圆图,主要利用ADS工具仿真完成超宽带设计.     

宽带GaN功率放大器的建模与预失真

对正交频分复用传输系统中宽带GaN功率放大器的建模与预失真线性化方法进行研究。应用一个带有记忆的多项式模型来建模GaN功率放大器及其逆特性,并通过递推最小二乘法(RLS)辨识模型参数,然后利用预失真间接结构实现了GaN功率放大器的预失真器。最后,仿真验证预失真方法的有效性,结果表明记忆多项式模型可以对GaN功率放大器进行建模并实现线性化。     

X波段GaN基微波功率放大器的设计

给出了一种X波段GaN基功率放大器的设计方法。研究了相关的偏置电路、匹配网络以及稳定性网络,实现了6个GaNHEMT器件的功率合成。该方法在偏置VGS=-3.2V,VDS=6V,IDS=200mA,频率为8GHz时,可以仿真得到的放大器增益为20.380dB,饱和输出功率可以达到35.268dBm(约为3.36W)。     

Semi-polar GaN LEDs on Si substrate

Growth of semi-polar (1-101)GaN has been attempted on a patterned (001) silicon substrate adopting selective area MOVPE. The growth was initiated on (111) facets of the Si,which had been prepared by anisotropy etching in a KOH solution. A uniform semi-polar layer was achieved by coalescence of stripes. Since the growth was performed on facets,the surface was atomically flat in AFM surface analyses. By using a high temperature grown AlN nucleation layer,we achieved low threading dislocation density at the to...     

Growth and characterization of 0.8-μm gate length AlGaN/GaN HEMTs on sapphire substrates

AlGaN/GaN high electron mobility transistor (HEMT) structures were grown on 2 inch sapphire substrates by MOCVD, and 0.8-μm gate length devices were fabricated and measured. It is shown by resistance mapping that the HEMT structures have an average sheet resistance of approximately 380 Θ/sq with a uniformity of more than 96%. The 1-mm gate width devices using the materials yielded a pulsed drain current of 784 mA/mm atV _gs=0.5 V andV _ds=7 V with an extrinsic transconductance of 200 mS/mm. A 20-GHz unity current gain cutoff frequency (f _T) and a 28-GHz maximum oscillation frequency (f _max) were obtained. The device with a 0.6-mm gate width yielded a total output power of 2.0 W/mm (power density of 3.33 W/mm) with 41% power added efficiency (PAE) at 4 GHz.     

Investigation on harmonic spur characteristics of hybrid integrated LDMOS and AlGaN/GaN power amplifiers at different temperatures

The harmonic spur characteristics of a hybrid integrated S‐band power amplifier (PA), consisting of both stages of LDMOSFET and AlGaN/GaN HEMT, are studied at different temperatures. The PA offers a peak output power of 50 dBm (100 W) with power added efficiency higher than 50%, and adjacent channel power ratio performance is less than ?30 dBc. A temperature test chamber is employed for measuring the harmonic spur of PA from 233 to 393 K, and its linear response to temperature is captured at high output power level.     

Hydrogen sensing of N-polar and Ga-polar GaN Schottky diodes

N-polar and Ga-polar GaN grown on c-plane sapphire were used to fabricate platinum deposited Schottky contacts for hydrogen sensing at room temperature. After exposure to hydrogen, Ga-polar GaN Schottky barrier reduced by 3–4 meV, while the N-polar GaN Schottky contacts became fully Ohmic. The N-polar GaN Schottky diodes showed stronger and faster response to 4% hydrogen than that of Ga-polar Schottky diodes. The abrupt current increase from N-polar GaN Schottky exposure to hydrogen was attributed to the high reactivity of the N-face surface termination. The surface termination dominates the sensitivity and response time of the hydrogen sensors made of GaN Schottky diodes.     

2–6 GHz GaN distributed power amplifier MMIC with tapered gate‐series/drain‐shunt capacitors

In this article, using a 0.25 μm GaN HEMT process, we present a 2–6 GHz GaN two‐stage distributed power amplifier MMIC that utilizes tapered gate series capacitors and nonuniform drain transmission lines with tapered shunt capacitors to simultaneously obtain a linear gain enhancement and optimum load line for each transistor. By using well‐derived equations to provide each transistor with the optimum load impedance and to tune the phase delay between the input and output transmission lines, the nonuniform distributed power amplifier is designed for second‐stage amplification, and satisfactory performance is demonstrated. The phase balance and tapering of the gate series capacitors have a role in improving the linear gain of the two‐stage amplifier. The measured data show a linear gain of 22 ± 1 dB, an input/output return loss of more than 15 dB, saturated output power of 41.2–43.1 dBm under a continuous‐wave mode, and a power‐added efficiency of 18–22% from 2 to 6 GHz which are very competitive values compared with previous works. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:456–465, 2016.     

基于ICP刻蚀GaN选择比的研究

在干法刻蚀GaN时使用AZ-4620作为掩膜层,为了在较快的GaN刻蚀速率下获得良好的GaN/AZ-4620刻蚀选择比,使用电感耦合等离子刻蚀机(ICP),运用Cl2和BCl3作为刻蚀气体,改变气体总流量、直流自偏压、ICP功率、气体组分等工艺条件,并讨论了这些因素对GaN/AZ-4620刻蚀选择比以及对GaN刻蚀速率的影响.实验结果获得了GaN在刻蚀速率为225nm/min时的GaN/AZ-4620选择比为0.92,可以应用于实际生产.     

Ka频段GaN功放的预失真线性化器设计

基于满足目前高效复杂的调制技术对功率放大器线性化度越来越高的需求的目的,采用模拟预失真技术设计了一种线性化器,用来改善Ka频段氮化镓(GaN)固态功放的非线性化失真。通过改进传统的并联式二极管预失真电路,采用开环技术,将两个肖特基二极管并联。改变二极管的偏置状态,得到不同的改善程度的预失真信号。结合使用专用电磁仿真软件ADS2013做电路仿真,通过参数扫描得到二极管偏置状态的初始值,为实物调试提供理论基础。通过对已加工的实物测试,结果表明：增益幅度补偿达到6.4dB,相位补偿达到28°。     

Charge density and bare surface barrier height in GaN/AlGaN/GaN heterostructures: A modeling and simulation study

In this article, we present a physics‐based model to explain the effect of the GaN cap layers on the 2D electron gas density and the bare surface barrier height in AlGaN/GaN heterostructures. We consider that the 2DEG originates from the surface donor states present on the GaN cap top surface. The influence of a 2D hole gas, formed when the valence band crosses the Fermi energy level, has also been considered. This model agrees well with the published experimental results and TCAD simulations, and can easily be incorporated into the modeling of GaN/AlGaN/GaN‐based HEMT devices.