一种改进LC匹配电路的Class-F射频功率放大器

为了改善传统F类射频功放LC输出匹配电路二阶阻抗不为零而造成的效率损害,提出了一种更加理想的新型LC输出匹配电路.根据双极型功放的特点,提出的新型LC输入匹配电路可以进一步提高输出效率.通过在Jazz SiGe BiCMOS 0.35μm工艺上的电路仿真设计表明,效率可以由63%增加到73%.工作在2.4 GHz频段上的此F类功率放大器可以适用于采用非线性调制的射频发送端.

Novel approach to harmonic control for Class F power amplifier with high power added efficiency

This paper presents a new topology to implement Class F power amplifier for eliminating the on-resistance (R_(ON))effect.The time-domain and frequency-domain voltage and current waveforms for Class F amplifier are ana- lyzed using Fourier series analysis method.Considering the on-resistance effect,the formulas of the efficiency,output power,dc power dissipation,and fundamental load impedance are given from ideal current and voltage waveforms.For experimental verification,we designed and implemented a Class F power amplifier,which operates at 850 MHz using MGaAs/GaAs Heterostructure FET(HFET)device,and analyzed the measurement results.Test results show that the maximum PAE of 67% can be achieved at 28 dBm output power level.

Comparative Analysis of Rigid PVC Foam Reinforced with Class C and Class F Fly Ash

Fly ash particles are usually spherical and based on their chemical composition;they are categorized into two classes: C and F. This study compares the microstructural, mechanical and thermal properties of extruded rigid PVC foam composites reinforced with class C and class F fly ash. The mechanical properties: such as tensile and flexural strength of composites containing class C fly ash were superior to the composites containing class F fly ash particles. Composites containing 6 phr class C fly ash showed a 24% improvement in the tensile strength in comparison to a mere 0.5% increase in composites reinforced with class F fly ash. Similarly, the addition of 6 phr of class F fly ash to the PVC foam matrix resulted in a 5.74% decrease in the flexural strength, while incorporating the same amount of class C fly ash led to a 95% increase in flexural strength. The impact strength of the composites decreased as the amount of either type of fly ash increased in the composites indicating that fly ash particles improve the rigidity of the PVC foam composites. No significant changes were observed in the thermal properties of the composites containing either type of fly ash particles. However, the thermo-mechanical properties measured by DMA indicated a steep increase in the viscoelastic properties of composites reinforced with class C flyash. The microstructural properties studied by Scanning Electron Microscopy (SEM) confirmed that fly ash particles were mechanically interlocked in the PVC matrix with good interfacial interaction with the matrix. However, particle agglomeration and debonding was observed in composites reinforced with higher amounts of fly ash.

Using LDMOS Transistor in Class-F Power Amplifier For WCDMA Applications

The fundamental operating principle of a Class F power amplifier and the factors aiding or affecting Class F performance were explicated previously. A Class F power amplifier design which satisfies WCDMA specifications is explained in this paper. The Class F amplifier was designed by employing Motorola’s LDMOS (Laterally Diffused Metal Oxide Semiconductor) transistor models and we simulated its performance by means of ADS. A variety of procedures were applied in the process of designing Class F amplifier, namely, DC simulation, bias point selection, source-pull and load-pull characterization, input and output matching circuit design and the design of suitable harmonic traps, which are explained here.

Analysis of the third harmonic for class-F power amplifiers with an Ⅰ–Ⅴ knee effect

The appearance of third-generation semiconductors represented by gallium nitride （GaN） material greatly improves the output power of a power amplifier （PA）, but the efficiency of the PA needs to be further improved. The Class-F PA reduces the overlap of drain voltage and current by tuning harmonic impedance so that high efficiency is achieved. This paper begins with the principle of class-F PA, regards the third harmonic voltage as an independent variable, analyzes the influence of the third harmonic on fundamental, and points out how drain efficiency and output power vary with the third harmonic voltage with an I-V knee effect. Finally, the best third harmonic impedance is found mathematically. We compare our results with the Loadpull technique in advanced design system environment and conclude that an optimized third harmonic impedance is open in an ideal case, while it is not at an open point with the I-V knee effect, and the drain efficiency with optimized third harmonic impedance is 4% higher than that with the third harmonic open.

A High Power-Added-Efficiency 2.5-GHz Class-F Power Amplifier Using 0.5 μm GaN on SiC HEMT Technology

This paper proposed the high-frequency, multi-harmonic-controlled, Class-F power amplifier (PA) implemented with 0.5 μm GaN Hetrojunction Electron Mobility Transistor (HEMT). For PA design at high frequencies, parasitics of a transistor significantly increase the difficulty of harmonic manipulation, compared to low-frequency cases. To overcome this issue, we propose a novel design methodology based on a band-reject, low-pass, output matching network, which is realized with passive components. This network provides optimal fundamental impedance and allows harmonic control up to the third order to enable an efficient Class-F behavior. The implemented PA exhibits performance at 2.5 GHz with a 50% PAE, 14 dB gain, and 10 W output power.

Prediction of Geopolymer Concrete Compressive Strength Using Convolutional Neural Networks

Geopolymer concrete emerges as a promising avenue for sustainable development and offers an effective solution to environmental problems.Its attributes as a non-toxic,low-carbon,and economical substitute for conventional cement concrete,coupled with its elevated compressive strength and reduced shrinkage properties,position it as a pivotal material for diverse applications spanning from architectural structures to transportation infrastructure.In this context,this study sets out the task of using machine learning(ML)algorithms to increase the accuracy and interpretability of predicting the compressive strength of geopolymer concrete in the civil engineering field.To achieve this goal,a new approach using convolutional neural networks(CNNs)has been adopted.This study focuses on creating a comprehensive dataset consisting of compositional and strength parameters of 162 geopolymer concrete mixes,all containing Class F fly ash.The selection of optimal input parameters is guided by two distinct criteria.The first criterion leverages insights garnered from previous research on the influence of individual features on compressive strength.The second criterion scrutinizes the impact of these features within the model’s predictive framework.Key to enhancing the CNN model’s performance is the meticulous determination of the optimal hyperparameters.Through a systematic trial-and-error process,the study ascertains the ideal number of epochs for data division and the optimal value of k for k-fold cross-validation—a technique vital to the model’s robustness.The model’s predictive prowess is rigorously assessed via a suite of performance metrics and comprehensive score analyses.Furthermore,the model’s adaptability is gauged by integrating a secondary dataset into its predictive framework,facilitating a comparative evaluation against conventional prediction methods.To unravel the intricacies of the CNN model’s learning trajectory,a loss plot is deployed to elucidate its learning rate.The study culminates in compelling findings that underscore the CNN model’s accurate prediction of geopolymer concrete compressive strength.To maximize the dataset’s potential,the application of bivariate plots unveils nuanced trends and interactions among variables,fortifying the consistency with earlier research.Evidenced by promising prediction accuracy,the study’s outcomes hold significant promise in guiding the development of innovative geopolymer concrete formulations,thereby reinforcing its role as an eco-conscious and robust construction material.The findings prove that the CNN model accurately estimated geopolymer concrete’s compressive strength.The results show that the prediction accuracy is promising and can be used for the development of new geopolymer concrete mixes.The outcomes not only underscore the significance of leveraging technology for sustainable construction practices but also pave the way for innovation and efficiency in the field of civil engineering.

X-band inverse class-F GaN internally-matched power amplifier

An X-band inverse class-F power amplifier is realized by a 1-mm Al Ga N/Ga N high electron mobility transistor（HEMT）.The intrinsic and parasitic components inside the transistor,especially output capacitor Cds,influence the harmonic impedance heavily at the X-band,so compensation design is used for meeting the harmonic condition of inverse class-F on the current source plane.Experiment results show that,in the continuous-wave mode,the power amplifier achieves 61.7% power added efficiency（PAE）,which is 16.3% higher than the class-AB power amplifier realized by the same kind of HEMT.To the best of our knowledge,this is the first inverse class-F Ga N internally-matched power amplifier,and the PAE is quite high at the X-band.

高效率Class F功率放大器的设计

本文基于InGaP/GaAs HBT(HBT为异质结双极晶体管)工艺设计了一款高效率的Class F功率放大器。文中首先描述了F类功率放大器的特点和电路原理,然后对放大器的设计过程如匹配电路设计技术、谐波抑制对功率效率的影响,以及偏置电路的设计等问题做了详细的讨论。测试结果表明,设计的功率放大器在电源电压为5V,输出功率为37dBm时,效率达68%。

UHF波段功率放大器设计

为某UHF波段的发射机设计一款己类功率放大器,工作于频段430~455 MHz,介绍了谐波控制和匹配网络的设计。在放大器输出匹配网络前添加谐波控制电路,通过对晶体管漏极的谐波控制生成己类放大器的工作波形。同时,在输入、输出阻抗是复阻抗的情况下,使用简化实频技术对电路进行匹配,提高了匹配网络的效率。测试结果显示,该放大器输出功率达60 dBm,对应的增益为20 dB,PAE为79%,达到设计要求。

输入谐波相位控制的宽带高效率连续逆F类功率放大器

卫星通信与地面移动通信的互补融合已成为趋势,这意味着以功率放大器(功放)为核心的无线射频前端需要应对大带宽和高效率的双重挑战。该文提出的输入谐波相位控制方法可以有效突破功放带宽和效率相互制约的瓶颈,并以连续逆F类工作模式为基础,通过控制输入端二次谐波相位来重构晶体管漏极时域波形,在保证高效率的同时获得阻抗设计空间的大幅提升。利用这一拓展的阻抗设计空间,研制了一款1.7~3.0 GHz的连续逆F类功放,实测结果表明在该工作频段内可以实现40.62~42.78 dBm的输出功率和72.2%~78.6%的漏极效率,同时增益可达10.6~14.8 dB。

基于阻抗缓冲概念的连续逆F类功率放大器设计

为了满足移动通信系统中功率放大器宽频带和高效率的需求,介绍了一种高效率连续逆F类功率放大器设计方法,并基于CREE公司的CGH40010F高功率管设计了验证电路。在分析连续逆F类模式的基波和谐波阻抗基础上,提出了一款基于阻抗缓冲概念的新型谐波控制网络,设计并实现了一个1.2 GHz~2.3 GHz宽带的连续逆F类功率放大器。ADS版图联合仿真结果表明:在1.2 GHz~2.3 GHz工作频带内,漏极效率在58.9%~74.4%之间,输出功率为39.3 dBm~41.3 dBm,增益大于10.3 dB,增益平坦度小于±1 dB。本文的设计方法能为功放设计者提供一定的参考。

面向功放-整流一体化设计的逆F类功率放大器

针对微波无线功率传输对于高功率处理能力的高效整流器需求,提出一种基于高效率功率放大器的功放-整流一体化设计思路。文章首先使用型号为CG2H40010F的氮化镓高电子迁移率晶体管(GaN HEMT),通过谐波控制、负载牵引等方法,设计出一款工作在2.45GHz逆F类高效率功率放大器。在高效率功率放大器的基础上基于时间反转对偶理论,通过改变逆F类功率放大器电流方向,同时结合耦合器和移相器实现了高功率容量整流电路的设计。仿真结果表明,在2.45GHz工作频率下,功率放大器的输入功率为28dBm时,功率附加效率达到76%,输出功率40dBm;整流电路的输入功率为41dBm时,RF-DC转换效率可达到79%,整流最佳效率大于80%,显示了整流器的高功率处理能力。引入了两个单刀双掷开关实现功率放大器和整流器的功能切换,文章对核心电路功率放大器进行了实物测试,测试结果与仿真重合较好,验证了功放-整流一体化设计的可行性。

1.25GHz高效率F类射频功率放大器

传统F类射频功放由于功放管寄生参数影响造成LC输出匹配电路二阶阻抗不为零而导致效率下降,对此采用补偿功放管寄生参数和优化调节二次谐波阻抗的方法,设计了一款结构可调而稳定的输出回路单元,获得了较高的效率和带宽.经过ADS仿真验证后得知,功率放大器工作在1.25GHz时,该功率附加效率达到74.3%以上,输出功率为47.6dBm,带宽为240 MHz.

F类与逆F类功率放大器的效率研究

为了对F类与逆F类功率放大器的效率进行研究,首先从理论方面对两种放大器工作模式各自的效率进行了计算。通过计算可以看出,在相同的输出功率下,因为晶体管导通内阻的存在,逆F类功率放大器的效率优于F类功率放大器。再通过软件仿真设计F类和逆F类功率放大器,在相同的输出功率下,逆F类功率放大器的最高漏极效率为91.8%,F类功率放大器的最高漏极效率为89.3%。

基于F类和逆F类的双模式双频带功率放大器

应用氮化镓高电子迁移率晶体管设计并实现了一种基于F类和逆F类工作模式的双频段功率放大器。首先,分别讨论了F类和逆F类工作模式在理想晶体管和实际晶体管中的差异,结合动态负载线和电压电流波形,对实际晶体管功率和效率下降的原因作了深入分析。在此基础上,提出一种在双频段分别实现F类和逆F类工作模式的输出匹配电路。基于该匹配电路,仿真设计了一款双模式、双频带功率放大器,并进行了实物加工和性能测试。实测结果表明,在L和S频段200 MHz带宽范围内,功放输出功率分别大于41.3 dBm和41.2 dBm,漏极效率分别高于72%和69%,其峰值功率和效率在L频段为41.7 dBm和75.5%,在S频段为41.3 dBm和69.5%。实测和仿真结果吻合度高,证明了提出的设计方法的正确性和有效性。

采用寄生补偿的高效率逆F类GaN HEMT功率放大器

为了提高无线通信系统的工作效率,提出了一种基于逆F类结构的新型高效率功率放大器。结合功率晶体管的寄生参数,设计了一种添加了寄生补偿电路的输出端谐波控制网络,对2到5次谐波阻抗进行了处理。针对电路中寄生反馈元件的存在,在输入端对2次和3次谐波阻抗也分别进行了开路和短路处理。该功率放大器选用GaN工艺的HEMT器件作为功率晶体管,当工作在940MHz频率时,经测试所获得的最大漏极效率为87.4%,最大功率附加效率为78.6%,饱和输出功率为39.8dBm。

一种连续F类/逆F类模式转换功率放大器

传统的F类和逆F类功率放大器的带宽不宽,且对于功放输出信号的谐波控制比较严格。在连续类功放理论的基础上,设计了一款在工作带宽内连续F类和连续逆F类模式转换的功率放大器。设计的功放采用了Cree公司的CGH40010F GaN HEMT晶体管。通过调整功放管输出端的谐波控制网络,控制谐波阻抗在Smith圆图中位置分布,从而在带宽内同时实现连续F类和连续逆F类的工作模式。制作了测试板,结果表明在2.4～4.2 GHz的带宽内,增益在11 dB以上,漏极效率为55%～82%,输出功率在39.5～41.9 dBm。采用了10 MHz的LTE单载波信号进行功放的数字预失真测试,功放的输出ACPR改善了6 dB以上。

GaN逆F类高效率功率放大器及线性化研究

效率和线性度是功率放大器的重要指标,也是设计的技术难点。该文设计了2.5-2.6 GHz高效率GaN逆F类功率放大器,其输入输出谐波匹配网络由解析的方法设计得到。单音测试结果表明,在2.55 GHz处,功放的漏极效率超过75%。为了建立逆F类功放的行为模型进行数字预失真,对传统的Hammerstein模型进行了改进,提升了模型拟合精度,对20 MHz带宽、峰均功率比为9.6 dB的16-QAM OFDM调制信号,结合峰值因子降低技术和数字预失真技术对逆F类功放进行线性化后,功放的相邻信道功率比(ACPR)优于-48 dBc。

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Ga N 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7.5d B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-35.39d Bc和-35.9d Bc。