SAW滤波器自动测试系统设计

针对声表面波(SAW)滤波器测试参数较多,仪器设置较复杂,且封装尺寸不断缩小,传统人工测试效率低,可靠性也不能满足要求等问题。该文利用国内定制的自动测试机,基于LabVIEW软件实现表面贴装器件(SMD)封装的SAW滤波器的自动测试系统。结果表明,该测试系统可实现SMD的自动上料、测试和记录数据,并自动分离不合格品,测试速度约1 000只/h,满足研发及小批量生产的需求。     

数字IC的射频电磁发射模型建模方法

针对传统方法无法直接得到芯片内核到外部引脚传输路径特性的问题,提出了一种简单有效的数字IC的电磁发射建模方法。该模型由内部活动模型和传输路径模型组成。利用嵌入式环形振荡器的直流响应和外源射频干扰效应,直接测量出芯片内核到外部引脚路径的电压传输率,有效抽取出传输模型结构。利用晶体管级Hspice仿真得到内部活动模型,获得了完整的电磁发射模型。在SMIC 130 nm 工艺的测试芯片上应用该模型,对比模型仿真结果与实物测量结果,验证了该模型建模方法的正确性。该方法可用于系统设计阶段,对数字IC的电磁发射进行预测,使系统能满足电磁发射的要求。     

Efficient Infrared Solar Cells Employing Quantum Dot Solids with Strong Inter-Dot Coupling and Efficient Passivation

Lead chalcogenide quantum dot (QD) infrared (IR) solar cells are promising devices for breaking through the theoretical efficiency limit of single-junction solar cells by harvesting the low-energy IR photons that cannot be utilized by common devices. However, the device performance of QD IR photovoltaic is limited by the restrictive relation between open-circuit voltages (V_OC) and short circuit current densities (J_SC), caused by the contradiction between surface passivation and electronic coupling of QD solids. Here, a strategy is developed to decouple this restriction via epitaxially coating a thin PbS shell over the PbSe QDs (PbSe/PbS QDs) combined with in situ halide passivation. The strong electronic coupling from the PbSe core gives rise to significant carrier delocalization, which guarantees effective carrier transport. Benefited from the protection of PbS shell and in situ halide passivation, excellent trap-state control of QDs is eventually achieved after the ligand exchange. By a fine control of the PbS shell thickness, outstanding IR J_SC of 6.38 mA cm⁻² and IR V_OC of 0.347 V are simultaneously achieved under the 1100 nm-filtered solar illumination, providing a new route to unfreeze the trade-off between V_OC and J_SC limited by the photoactive layer with a given bandgap.     

Humidity-Responsive Liquid Crystalline Network Actuator Showing Synergistic Fluorescence Color Change Enabled by Aggregation Induced Emission Luminogen

Imitating the structures and behaviors of natural creatures is of great significance to scientists to explore novel materials for practical applications. However, the design and fabrication of biomimetic devices with complex and outstanding performances is still on the way. A bilayer film composed of liquid crystalline networks (LCN) film and hydrochromic aggregation-induced-emission molecule-doped hydrophilic layer is prepared. Under different relative humidity, the composite film can deform and change fluorescence color simultaneously. The influence of the content of the hydrophilic matrix on the fluorescent property and humidity-responsive behaviors of the bilayer film is investigated. Thanks to the mechanical anisotropy provided by uniform-aligned LCN film, different modes of deformation of the bilayer film are achievable, like bending, curling, and twisting. More importantly, due to the independence of the LCN film and the non-mesogenic molecules brought by this bimorph strategy, complex alignment of the LCN film and modification by immiscible molecules are realized in a single LCN actuator. Based on the functional composite film, artificial flowers showing synergistic blooming and shape-changing is prepared. By regulating the molecular alignment of the LC mesogens of the LCN film, the artificial flowers can imitate various blooming behaviors of natural flowers like confederate jasmine and jade lotus.     

Design and analysis of low-insertion-loss G-band CMOS four-way Wilkinson power dividers and dual balun

We present the design and analysis of G-band CMOS Wilkinson power dividers and dual balun for G-band communication and imaging systems. Miniature spiral and U-shaped four-way Wilkinson power dividers, which are based on three two-way Wilkinson power dividers, are designed and implemented. Miniature spiral dual balun, which is equivalent to an upper balun and a lower balun in parallel, is also designed and implemented for comparison. These devices are planar and symmetrical, and their main structure is implemented by the 2.34-µm-thick topmost metal to minimize the resistive loss. This leads to low insertion loss, and small amplitude imbalance (AI) magnitude and phase difference (PD) deviation. For instance, the spiral four-way Wilkinson power divider occupies 0.033 mm² chip area and achieves S₁₁ of???11.4 dB, S₂₁ of???6.271 dB, S₃₁ of???6.445 dB, S₄₁ of???6.676 dB, and S₅₁ of???6.111 dB at 180 GHz, one of the smallest chip areas and lowest insertion losses for four-way power dividers with similar operation frequency. The corresponding AI magnitude and PD deviation are 0.565 dB and 3.2°, respectively. Moreover, the spiral dual balun occupies 0.026 mm² chip area and achieves S₁₁ of???10.6 dB, S₂₁ of???7.549 dB, S₃₁ of???7.1 dB, S₄₁ of???7.598 dB, and S₅₁ of???7.352 dB at 180 GHz. The corresponding AI magnitude and PD deviation are 0.498 dB and 5.7°, respectively. The prominent results of the spiral and U-shaped four-way Wilkinson power dividers, and the spiral dual balun indicate that they are suitable for power division/combination in G-band systems.

     

皮秒激光辐照硅基PIN光电二极管的瞬态响应信号分析

实验研究了超短脉冲皮秒激光辐照硅基PIN光电二极管的瞬态响应的规律特性,测量了在不同激光能量密度辐照下的脉冲响应信号.分析实验结果表明,随着激光能量密度的增大,器件出现了非线性饱和状态,半高宽从37.2μs到113μs,底宽从181μs到322 μs,脉冲响应信号出现展宽现象,信号的展宽意味着器件的瞬态响应发生了退化,同时对于饱和前后的信号特征量的半高宽和底宽进行了分析,发现无论是绝对增幅还是相对增幅,可以看出饱和后有更为显著的展宽现象,并且主要由于器件饱和后的下降沿出现速度的衰减所致.通过理论分析发现,由于注入的光生载流子浓度变化对双极输运过程造成影响,从而改变其载流子输运过程中的速度,导致器件响应出现退化现象.     

星载微脉冲光子计数激光雷达的探测性能仿真分析

星载微脉冲光子计数激光雷达能够实现对地面目标的高重频、多波束探测,有效提高了激光雷达在轨测量的采样密度和覆盖宽度,满足全球高效高精度测绘的需求。依据微脉冲光子计数激光雷达的工作原理,建立了基于多像元光电倍增管（PMT）的星载微脉冲光子计数激光雷达的探测仿真分析模型,并对典型探测过程进行了仿真分析。结果表明,多像元PMT像元数的增加能够明显降低激光雷达的首光子效应,提高测距精度;激光雷达的测距标准差随地形坡度增大而明显增大;对于复杂地形,增加像元数和回波光子数,光子计数点云能够更准确描述地形轮廓的分布特征。同时,机载飞行试验验证了在复杂地形条件下,多像元PMT能够显著增加有效回波光子计数点,准确有效地反映了被测地形的轮廓特征,实现复杂地形下的高精度光子计数测距,验证了仿真分析结果的正确性。     

"通信原理"差异化翻转教学探索与实践

本文面向理论性较强的专业课程,分析了传统教学方法在应对学生差异性时面临的问题和痛点,并以"通信原理"课程为例,提出了一种差异化翻转教学实践方案.实践结果表明,所设计方案能够兼顾不同层次学生,获得显著优于传统教学的授课效果.本文研究成果对其他相似课程具有借鉴作用.     

Low-thermal-budget Au-free ohmic contact to an ultrathin barrier AlGaN/GaN heterostructure utilizing a micro-patterned ohmic recess

A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB) AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56 Ω.mm at an alloy temperat-ure of 550 ℃.The sheet resistances increase with the temperature following a power law with the index of +2.58,while the spe-cific contact resistivity decreases with the temperature.The contact mechanism can be well described by thermionic field emis-sion (TFE).The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52 × 1018 cm-3,which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer.A good correlation between ohmic trans-fer length and the micro-pattern size is revealed,though in-depth investigation is needed.A preliminary CMOS-process-compat-ible metal-insulator-semiconductor high-mobility transistor (MIS-HEMT) was fabricated with the proposed Au-free ohmic con-tact technique.     

上转换激光晶体研究进展

本文综述近年来晶体材料的上转换过程研究进展，介绍了上转换发光晶体材料研究中的一些新动向以及在室温环境下，掺杂稀土离子的晶体上转换激光运转的成功经验，列举了几种室温上转换激光器的泵浦条件、发射波长、以及转换效率等参数，说明晶体材料的上转换激光技术已趋于实用化。