微电子器件测试技术(下)

(接上一期) 3.电压调整器测试技术 电压调整器(集成稳压器)由于其优良的性能和简捷的外围电路,而被广泛应用在模拟电源的稳压线路中.如何测准表现其调整能力和稳定性水平的调整率参数是电压调整器测试的技术难点.     

Radiation of millimeter waves from NRD leaky wave antennas withtapered transition and tuning aperture

The radiation of millimeter waves from the nonradiative dielectric (NRD) leaky wave antennas with the tapered transition and the tuning aperture is investigated. An accurate theory for the leakage constant and the phase constant of the antennas is presented, which is based on the generalized scattering parameters considering the higher-order mode interactions at the discontinuities. The associated transverse equivalent network involves the characterization of the mode couplings at two air-to-dielectric interfaces, the coupled mode analysis of the tapered transition, and the calculation of the radiation fields at the tuning aperture via the extended spectral domain approach. The interesting behavior of the present modified configuration of NRD leaky wave antennas is illustrated by typical examples. The validity of the theory is confirmed by the comparison of the theoretical results with experimental data for the limiting cases     

Magnetostatic wave propagation in YIG double layers

Calculations are presented for the magnetostatic surface wave propagation characteristics in single-crystal yttrium-iron-garnet (YIG) double layers with arbitrary direction of magnetization. The induced uniaxial magnetic anisotropy field is assumed to be different in the two layers; hence, the magnetization in one layer is aligned at an angle with respect to the magnetization direction in the other layer. The magnetostatic field interactions between layers depend on the angle between the two magnetization directions and on the separation between the two YIG layers. The wave propagation directions and time delays in each layer can be strongly affected by the use of an applied magnetic field and the magnetostatic coupling between the two layers, as well as by the uniaxial anisotropy energy in each layer     

龙滩碾压混凝土重力坝防渗结构研究--沥青混合料防渗结构

在调查分析国内外116座碾压混凝土坝基础上，论述碾压混凝土坝单独设置防渗结构的必要性。对调查的碾压混凝土坝的防渗结构归纳为三大类型，即：（1）刚性防渗结构；（2）柔性防渗结构；（3）联合防渗结构。在分析比较这三类防渗结构优缺点的基础上，首先推荐柔性防渗结构中的沥青混合料防渗结构作为龙滩碾压混凝土坝防渗结构。并对沥青混合料防渗结构的耐久性、环境污染、应用效果等进行充分论证；对防渗结构构造、防渗层的厚度和沥青混台料的类型作了分析和建议；对沥青混合料流变侧压力进行了计算；提出了沥青混合料防渗结构综合机械化施工方案和质量保证措施。     

无线宽带“最后一公里”接入技术--WiMAX

WiMAX作为一种“最后一公里”无线宽带接入的网络解决方案已得到很多认可。为了深入理解WIMAX（IEEE802．16）在解决“最后一公里”接入问题上的优势,将对现有的主流宽带接入技术进行分析比较,并展望了WiMAX未来所面临的问题。     

一种基于Deramp处理的空时自适应处理方法

在多通道合成孔径雷达动目标检测(SAR-GMTI)系统中,直接利用传统的后多普勒空时自适应处理(PD-STAP)技术进行杂波抑制会导致3个问题。第一,由于动目标径向速度引起的多普勒偏移会导致动目标出现谱卷绕,直接利用匹配滤波的方法对动目标聚焦会出现虚假目标。第二,在信号下采样的情况下,动目标聚焦位置会出现脉冲重复频率(PRF)的偏差,从而导致一个动目标可能出现在多个位置,使得动目标检测变得复杂。第三,利用传统的PD-STAP技术进行杂波抑制会导致很大的计算复杂性。基于此,该文提出一种基于Deramp处理的空时自适应处理方法进行杂波抑制处理,可以有效解决上述问题。该文最后通过仿真实验验证了该方法的有效性。     

移相120°单极倍频变换器研究

论述了移相120°单极倍频变换器研究的必要性,分析了移相120°单极倍频变换器的谐波、基波成分。分析及实验表明移相120°单极倍频电路有利于消除低次谐波、改善输出波形;并实现单/三相控制电路的通用。     

Room-temperature optically pumped InAs/GaAs quantum dots microdisk lasers on SiO2/Si chip

We report on room temperature continuous-wave optically pumped InAs/GaAs quantum dot whispering gallery mode microdisk lasers,heterogeneously integrated on silica/silicon chips.The microdisks are fabricated by photolithography and inductively coupled plasma etching.The lasing wavelength is approximately 1200 nm and the obtained lowest laser threshold is approximately 28μW.The experimental results show an approach of possible integrated Ⅲ-Ⅴ optical active materials on silica/silicon chip for low threshold WGM microdisk lasers.     

Novel Fault-Tolerant Decompression Method of Corrupted LZSS Files

Data compression and decompression have been widely applied in modern communication and data transmission fields. But how to decompress corrupted lossless compressed files is still a challenge. This paper presents an effective method to decompress corrupted LZSS files. It is achieved by utilizing source prior information and heuristic method. In this paper, we propose to use compression coding rules and grammar rules as the source prior information. Based on the prior information, we establish a mathematical model to detect error bits and estimate the rough range of the error bits. As for error correction, a heuristic method is developed to determine the accurate positions of error bits and correct the errors. The experimental results demonstrate that the proposed FTD method can achieve a correction rate of 96.45% for corrupted LZSS files when successfully decompressed. More importantly, the proposed method is a general model that can be applied to decompress various types of lossless compressed files of which the original files are natural language texts.