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A novel topology with controllable wideband baseband impedance for power amplifiers

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Frontiers of Information Technology & Electronic Engineering 2024年第2期25卷 308-315页

作者： Yao YAO zhijiang dai Mingyu LI School of Intelligent Technology and Engineering Chongqing University of Science and TechnologyChongqing400065China School of Microelectronics and Communication Engineering Chongqing UniversityChongqing400065China

This paper presents a novel topology to control the baseband impedance of a power amplifier(PA)to avoid performance deterioration in concurrent dual-band *** topology can avoid pure resonance of capacitors and inductors LC,which leads to a high impedance at some frequency ***,it can be applied to transmitters that are excited by broadband *** particular,by adjusting the circuit parameters and increasing stages,the impedance of the key frequency bands can be flexibly controlled.A PA is designed to support this design *** saturated output power is around 46.7 dBm,and the drain efficiency is>68.2%(1.8-2.3 GHz).Under concurrent two-tone excitation,the drain efficiency reaches around 40%even under 5.5 dB back-off power with the tone spacing from 10 MHz to 500 *** results demonstrate that the proposed topology is capable of controlling wideband baseband impedance.

关键词： Baseband impedance Concurrent dual-band Power amplifier

A novel method for extending the output power back-off range of an asymmetrical Doherty power amplifier

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Frontiers of Information Technology & Electronic Engineering 2023年第3期24卷 470-479页

作者： Mingyu LI Xiaobing CHENG zhijiang dai Kang ZHONG Tianfu CAI Chaoyi HUANG School of Microelectronics and Communication Engineering Chongqing UniversityChongqing 400044China School of Optoelectronic Engineering Chongqing University of Posts and TelecommunicationsChongqing 400065China

A novel method is proposed to extend the output power back-off(OPBO)range of the Doherty power amplifier(DPA).This study reveals that the OPBO range of the DPA can be extended by tuning the output impedance of the peaking stage away from infinity and changing the phase delay of the output matching network of the carrier power *** on this theory,a large-OPBO-range high-efficiency asymmetrical DPA working band from 1.55 to 2.2 GHz(35%relative bandwidth)is designed to verify the proposed *** results show that the DPA operates from 1.6 to 2.1 *** range of the measured efficiency is 42.2%–52.1%in the OPBO state and 47%–62.7%in the saturation *** OPBO range is 11.1–13.2 dB.

关键词： Doherty power amplifier(DPA) Output power back-off(OPBO) Output impedance Network phase

Broadband and asymmetrical Doherty based on circuit parameter solution space

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Frontiers of Information Technology & Electronic Engineering 2024年第11期25卷 1552-1564页

作者： Cheng BI Haotian LI Shuai WANG zhijiang dai Jingzhou PANG Ruibin GAO Kang ZHONG Jingsong WANG School of Microelectronics and Communication Engineering Chongqing UniversityChongqing 400044China The 54th Research Institute of China Electronics Technology Group Corporation Shijiazhuang 050081China

The input impedance of the post-matching network(PMN)is configured as a complex *** parameter solution space is determined based on the fundamental principles of the Doherty power amplifier(DPA),enabling the DPA to achieve high efficiency at the output power back-off(OBO).The parameter solution space comprises three variables:the phase parameter of the output matching network for the carrier power amplifier(carrier PA),the phase parameter of the output matching network for the peaking power amplifier(peaking PA),and the input impedance of *** parameters are optimized to enable the DPA to achieve high efficiency at the *** this paper,a one-to-one mapping relationship is established between the frequency and the parameter solution space,allowing for a precise optimization of the DPA across a broad frequency *** this mapping relationship,an asymmetric DPA designed to operate over the 1.8–2.6 GHz frequency band is designed and fabricated,demonstrating the feasibility and effectiveness of the proposed *** continuous wave excitation,the test results show that the drain efficiency(DE)is 42.7%–56.4%at 9.5 dB OBO and the saturated DE is 45.8%–71.1%.The saturated output power of this DPA is 46.9–48.8 dBm with a gain of 5.5–8.0 dB at saturation.A 20-MHz long-term-evolution modulated signal with a peak-to-average power ratio of 8 dB is also applied to the fabricated DPA at 1.8,2.1,and 2.6 *** these conditions,at 8 dB OBO,the DPA shows an adjacent channel power ratio always lower than 48 dBc after digital pre-distortion linearization.

关键词： Doherty power amplifier Output matching network Parameter solution space

Broadband Sequential Load-Modulated Balanced Amplifier Using Coupler-PA Co-Design Approach

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ZTE Communications 2022年第4期20卷 62-68页

作者： RAN Xiongbo dai zhijiang ZHONG Kang PANG Jingzhou LI Mingyu School of Microelectronics and Communication Engineering Chongq-ing UniversityChongqing 400044China

The basic theory of the sequential load-modulated balanced amplifier(SLMBA)is introduced and the working principle of its active load modulation is analyzed in this *** order to further improve the performance of the SLMBA,a codesigned method of the coupler and power amplifier(PA)is proposed,which is different from the traditional design of *** to the back-off point and saturation point of the SLMBA,this coupler-PA codesign approach can make the working state of the coupler and three-way PA closer to the actual situation,which improves the overall performance of the *** maximum output power ratio of the control PA and the balance PA is then determined by the preset output power back-off(OBO)of 10 dB,and the phase compensation line is determined by the trace of the load modulation impedance of the balanced *** order to verify the proposed method,an SLMBA operating at 1.5–2.7 GHz(57%relative bandwidth)is *** layout simulation results show that its saturated output powers achieve 40.7–43.7 dBm and the small signal gains are 9.7–12.4 ***,the drain efficiencies at the saturated point and 10 dB OBO point are 52.7%–73.7%and 44.9%–59.2%respectively.

关键词： SLMBA broadband coupler co-design

基于改进的稀疏最小二乘双子支撑向量回归的数字预失真技术

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电子与信息学报 2023年第2期45卷 418-426页

作者：代志江孔淑曼李明玉蔡天赋靳一徐常志重庆大学微电子与通信工程学院重庆400044 中国空间技术研究院西安分院西安710100

为了补偿大容量卫星通信射频前端的功率放大器的非线性,传统的数字预失真(DPD)模型需要更多的系数和更高的阶次,严重影响预失真前馈路径的资源消耗。为了解决这一问题,该文提出一种基于改进的稀疏最小二乘双子支撑向量回归(ISLSTSVR)的... 详细信息

为了补偿大容量卫星通信射频前端的功率放大器的非线性,传统的数字预失真(DPD)模型需要更多的系数和更高的阶次,严重影响预失真前馈路径的资源消耗。为了解决这一问题,该文提出一种基于改进的稀疏最小二乘双子支撑向量回归(ISLSTSVR)的低复杂度DPD方法。首先通过构建原空间的决策函数解决最小二乘双子支撑向量回归(LSTSVR)模型解不稀疏的问题;同时引用截断最小二乘损失函数增加模型的鲁棒性;然后采用Nystrom逼近方法得到核矩阵的低秩近似,进一步采用Cholesky分解降低核矩阵的运算复杂度;最后由低秩的核矩阵求得模型稀疏解。实验选用基于单管氮化镓(GaN)器件的宽带AB类功率放大器,以40 MHz的32QAM信号进行激励。预失真实验表明,该方法能在保证模型精度的情况下大幅减少DPD模型系数和计算复杂度,为星载射频前端的预失真技术提供了有效的系数降维思路和方法。

关键词：数字预失真稀疏LSTSVR Cholesky分解功率放大器

Research status and prospects of the fractal analysis of metal material surfaces and interfaces

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 20-38页

作者： Qinjin dai Xuefeng Liu Xin Ma Shaojie Tian Qinghe Cui Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China Laboratory for Advanced Materials Processing of Ministry of Education University of Science and Technology BeijingBeijing 100083China School of Mechanical and Electrical Engineering Xinjiang Institute of EngineeringUrumqi 830023China

As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine *** analysis has been used to characterize the shapes of metal materials at various scales and *** methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and ***,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal *** the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear *** relationship between the fractal dimensions and properties of metal material surfaces and interfaces is *** from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be *** is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.

关键词： metal material surfaces and interfaces fractal analysis fractal dimension homogeneity

A Multi-Objective Particle Swarm Optimization Algorithm Based on Decomposition and Multi-Selection Strategy

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Computers, Materials & Continua 2025年第1期82卷 997-1026页

作者： Li Ma Cai dai Xingsi Xue Cheng Peng School of Computer Science Shaanxi Normal UniversityXi’an710119China Fujian Provincial Key Laboratory of Big Data Mining and Applications Fujian University of TechnologyFuzhou350118China Information Construction and Management Center and Institute of Artificial Intelligence and Educational New Productivity Ningxia Normal UniversityGuyuan756099China

The multi-objective particle swarm optimization algorithm(MOPSO)is widely used to solve multi-objective optimization *** the article,amulti-objective particle swarm optimization algorithmbased on decomposition and multi-selection strategy is proposed to improve the search ***,two update strategies based on decomposition are used to update the evolving population and external archive,***,a multiselection strategy is *** first strategy is for the subspace without a non-dominated *** the neighbor particles,the particle with the smallest penalty-based boundary intersection value is selected as the global optimal solution and the particle far away fromthe search particle and the global optimal solution is selected as the personal optimal solution to enhance global *** second strategy is for the subspace with a non-dominated *** the neighbor particles,two particles are randomly selected,one as the global optimal solution and the other as the personal optimal solution,to enhance local *** third strategy is for Pareto optimal front(PF)discontinuity,which is identified by the cumulative number of iterations of the subspace without non-dominated *** the subsequent iteration,a new probability distribution is used to select from the remaining subspaces to ***,an adaptive inertia weight update strategy based on the dominated degree is designed to further improve the search ***,the proposed algorithmis compared with fivemulti-objective particle swarm optimization algorithms and five multi-objective evolutionary algorithms on 22 test *** results show that the proposed algorithm has better performance.

关键词： Multi-objective optimization multi-objective particle swarm optimization decomposition multi-selection strategy

Oxidation Resistance of Form-stable Hightemperature Phase Change Thermal Energy Storage Materials Doped by Impregnated Graphite

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 1-12页

作者： LI Baorang dai Jianhuan ZHANG Wei LIU Xiangchen YANG Liu School of Energy Power and Mechanical Engineering North China Electric Power UniversityBeijing 102206China School of Ener-gy and Environment Southeast UniversityNanjing 210096China

We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite *** mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 *** typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable *** investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat *** on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation *** investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.

关键词： phase change materials graphite impregnation method oxidation,sintering thermal analysis

Peripheral blood RNA biomarkers can predict lesion severity in degenerative cervical myelopathy

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Neural Regeneration Research 2025年第6期20卷 1764-1775页

作者： Zhenzhong Zheng Jialin Chen Jinghong Xu Bin Jiang Lei Li Yawei Li Yuliang dai Bing Wang Department of Spine Surgery The Second Xiangya Hospital of Central South UniversityChangshaHunan ProvinceChina

Degenerative cervical myelopathy is a common cause of spinal cord injury,with longer symptom duration and higher myelopathy severity indicating a worse *** numerous studies have investigated serological biomarkers for acute spinal cord injury,few studies have explored such biomarkers for diagnosing degenerative cervical *** study involved 30 patients with degenerative cervical myelopathy(51.3±7.3 years old,12 women and 18 men),seven healthy controls(25.7±1.7 years old,one woman and six men),and nine patients with cervical spondylotic radiculopathy(51.9±8.6 years old,three women and six men).Analysis of blood samples from the three groups showed clear differences in transcriptomic *** analysis identified 128 differentially expressed genes that were enriched in patients with neurological *** least absolute shrinkage and selection operator analysis,we constructed a five-gene model(TBCD,TPM2,PNKD,EIF4G2,and AP5Z1)to diagnose degenerative cervical myelopathy with an accuracy of 93.5%.One-gene models(TCAP and SDHA)identified mild and severe degenerative cervical myelopathy with accuracies of 83.3%and 76.7%,*** of two immune cell types(memory B cells and memory-activated CD4^(+)T cells)predicted levels of lesions in degenerative cervical myelopathy with 80%*** results suggest that peripheral blood RNA biomarkers could be used to predict lesion severity in degenerative cervical myelopathy.

关键词： biomarkers candidate genes degenerative cervical myelopathy gene expression analysis immune cell types neurological disabilities peripheral blood RNA profiles spinal cord injury