Author Affiliations
Abstract
1 National Mobile Communication Research Laboratory, Southeast University, Nanjing 211189, China
2 Purple Mountain Laboratories, Nanjing 211111, China
3 Chengdu Xphased Technology Company Ltd., Chengdu 610041, China
This article presents an 8-element dual-polarized phased-array transceiver (TRX) front-end IC for millimeter-wave (mm-Wave) 5G new radio (NR). Power enhancement technologies for power amplifiers (PA) in mm-Wave 5G phased-array TRX are discussed. A four-stage wideband high-power class-AB PA with distributed-active-transformer (DAT) power combining and multi-stage second-harmonic traps is proposed, ensuring the mitigated amplitude-to-phase (AM-PM) distortions across wide carrier frequencies without degrading transmitting (TX) power, gain and efficiency. TX and receiving (RX) switching is achieved by a matching network co-designed on-chip T/R switch. In each TRX element, 6-bit 360° phase shifting and 6-bit 31.5-dB gain tuning are respectively achieved by the digital-controlled vector-modulated phase shifter (VMPS) and differential attenuator (ATT). Fabricated in 65-nm bulk complementary metal oxide semiconductor (CMOS), the proposed TRX demonstrates the measured peak TX/RX gains of 25.5/21.3 dB, covering the 24?29.5 GHz band. The measured peak TX OP1dB and power-added efficiency (PAE) are 20.8 dBm and 21.1%, respectively. The measured minimum RX NF is 4.1 dB. The TRX achieves an output power of 11.0?12.4 dBm and error vector magnitude (EVM) of 5% with 400-MHz 5G NR FR2 OFDM 64-QAM signals across 24?29.5 GHz, covering 3GPP 5G NR FR2 operating bands of n257, n258, and n261.
fifth-generation (5G) power amplifier millimeter-wave transceiver phased-array Journal of Semiconductors
2024, 45(1): 012201
1 南京邮电大学 集成电路科学与工程学院, 南京 210003
2 南京邮电大学 射频集成与微组装技术国家地方联合工程实验室, 南京 210003
随着制造工艺的不断演进、电路规模的不断增大, 集成电路逐渐进入后摩尔时代。如何准确快速地进行寄生电容参数提取, 对于保证设计质量、减少成本和缩短设计周期变得越来越重要。文章提出了一种基于分段预留法的二维电容提取技术, 该技术基于改进的有限差分法, 采用非均匀网格划分和求解不对称系数矩阵方程, 模拟互连结构横截面, 可以高效计算出主导体的单位长度总电容以及主导体和相邻导体之间的单位长度耦和电容。为了验证提出方法的准确性和有效性, 进行了一系列验证实验。实验结果表明, 提出的互连线二维电容提取技术在寄生电容计算精度上平均提高了140倍, 运行时间平均缩了10%。
有限差分法 不对称系数矩阵 分段预留 寄生电容 FDM asymmetric coefficient matrix segment reservation parasitic capacitance
1 北京大学地球与空间科学学院，北京100871
2 眉山博雅新材料股份有限公司，眉山620000
3 眉山天乐半导体材料有限公司，眉山620000
作为第三代半导体材料的典型代表，碳化硅因具备宽的带隙、高的热导率、高的击穿电场以及大的电子迁移速率等性能优势，被认为是制作高温、高频、高功率以及高压器件的理想材料之一，可有效突破传统硅基功率半导体器件的物理极限，并被誉为带动“新能源革命”的绿色能源器件。作为制造功率器件的核心材料，碳化硅单晶衬底的生长是关键，尤其是单一4HSiC晶型制备。各晶型体结构之间有着良好的结晶学相容性和接近的形成自由能，导致所生长的碳化硅晶体容易形成多型夹杂缺陷并严重影响器件性能。为此，本文首先概述了物理气相传输（PVT）法制备碳化硅晶体的基本原理、生长过程以及存在的问题，然后针对多型夹杂缺陷的产生给出了可能的诱导因素并对相关机理进行解释，进一步介绍了常见的碳化硅晶型结构鉴别方式，最后对碳化硅晶体研究作出展望。
碳化硅晶体 物理气相传输 堆垛次序 多型夹杂 缺陷抑制 晶型鉴别 SiC crystal physical vapor transport stacking sequence polytype inclusion defect suppression polytype identification
单晶光纤因其独特的结构特点以及优良的物理性能而被广泛应用于高功率激光器、辐射探测以及高温环境监测等领域。本文综述了单晶光纤的生长技术, 探讨了微下拉法(μ-PD)、激光加热基座法(LHPG)以及导模法(EFG)的生长特点, 并重点梳理了单晶光纤生长过程中存在的问题及解决方案。此外详细介绍了包层制备技术发展现状以及局限性。最后, 阐述了现阶段单晶光纤的主要分类以及应用场景并对未来发展作出展望。
单晶光纤 微下拉法 激光加热基座法 导模法 化学溶蚀法 包层制备 光纤种类 single crystal fiber micro-pulling-down method laser heated pedestal growth edge-defined film-fed growth chemical dissolution method cladding preparation fiber type
1 眉山博雅新材料有限公司, 眉山 620000
2 西南石油大学南充校区, 南充 637000
铈掺杂硅酸钇镥(LYSO∶Ce)晶体显示出优异的闪烁性能, 并在核医学、高能物理及安全检查等领域具有广泛应用。本文综述了LYSO∶Ce闪烁晶体的晶体结构、发光机制、晶体生长存在的主要问题以及LYSO∶Ce晶体可能的发展方向。同时, 梳理了LYSO∶Ce晶体生长过程中常见问题及对应的解决方案, 并进一步讨论了Ce3+占位情况以及Ce4+与闪烁性能之间的关系。此外还展示了本团队在LYSO∶Ce晶体生长的最新研究成果, 使用中频感应提拉炉生长出尺寸为95.42 mm×200 mm的LYSO∶Ce闪烁晶体。
闪烁晶体 晶体结构 晶体生长 闪烁机制 氧空位 LYSO∶Ce LYSO∶Ce scintillation crystal crystal structure crystal growth scintillation mechanism oxygen vacancy
南京信息工程大学 电子与信息工程学院，江苏 南京 210044
针对同一目标不同焦点图像优势互补的需求和现有多焦点图像融合算法存在焦点不清晰、边缘模糊和重影等问题，引入一种基于参数自适应脉冲耦合神经网络(PAPCNN)和卷积稀疏表示(CSR)的多聚焦图像融合算法。在非下采样剪切波变换(NSST)分解高低频子带的基础上，采用CSR融合低频子带系数，其中的高频子带系数利用一种参数自适应PCNN算法(PAPCNN)进行融合，并且对PAPCNN中的隐函数β进行改进，达到更好的融合效果。仿真实验结果表明，该方法解决了传统PCNN算法在融合图像时参数设置困难和传统稀疏表示细节保存性能不佳的问题，在视觉效果和客观指标方面与现有主流融合算法相比均具有较大优势。
图像融合 多聚焦图像 非下采样剪切波变换 参数自适应PCNN 卷积稀疏表示 image fusion multi-focus image Nonsubsampled Shearlet Transform Parameter Adaptive PCNN Convolutional Sparse Representation 太赫兹科学与电子信息学报
2021, 19(3): 471
Author Affiliations
Abstract
Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China
We demonstrate a continuous-wave (CW) dual-wavelength Nd:YVO4 laser working at 1064 and 1066 nm simultaneously. The method of Nd:YVO4 crystal angle tuning is used to balance the ratio of the stimulated emission cross sections of the two wavelengths, leading to the realization of a simultaneous dual-wavelength operation from only one laser. The experimental results show that at a 2.85 W pump power, the maximum output powers at wavelengths of 1064 and 1066 nm are 0.55 and 0.54 W, respectively. The linear resonate cavity is as short as 10 mm, which gives the laser the advantages of a miniature configuration and low threshold. Such a dual-wavelength laser can be very attractive for the development of compact THz sources based on difference frequency generation.
140.3580 Lasers, solid-state Chinese Optics Letters
2017, 15(7): 071401
Author Affiliations
Abstract
Strong-field and Ultrafast Photonics Lab, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China
The films of few-layer graphene are formed through laser exfoliation of a highly ordered pyrolytic graphite (HOPG), without a catalytic layer for the growth process. The femtosecond (fs) laser exfoliation process is investigated at different laser fluences and substrate temperature. For fs laser exfoliation of HOPG, the few-layer graphene is obtained at 473 K under an optimal laser fluence. The formation of few-layer graphene is explained by removal of intact graphite sheets occurred by an optimal laser fluence ablation. The new insights may facilitate the controllable synthesis of large area few-layer graphene.
160.0160 Materials 310.0310 Thin films 350.0350 Other areas of optics Chinese Optics Letters
2015, 13(2): 021601
