大功率GaN基LED的提取效率

影响GaN基LED效率的主要因素是内量子效率和提取效率. 蓝光GaN基的LED内量子效率可达70%以上， 紫外GaN基LED可达80%，进一步改善的空间较小. 而传统大面积结构GaN基LED由于全反射和吸收等原因，外提取效率只有百分之几，提高空间很大. 本文从几何和物理光学角度分析了影响GaN基LED外提取效率的因素，针对全反射、吸收、横向光波导等问题总结了现有的各种提高GaN基LED提取效率的手段及其优缺点.     

p型微氮直拉硅中氧施主的电学特性

研究了p型含氮以及不含氮直拉(CZ)硅中热施主(TD)以及氮氧(N-O)复合体的电学性质.硅片在350～850℃范围进行不同时间的退火后,利用四探针和通过室温傅里叶红外光谱(FTIR)分别测量其载流子浓度和间隙氧浓度的变化.实验结果表明:p型含氮直拉硅(NCZ)中热施主的电学特性基本与n型NCZ硅相同,但N-O复合体的消除温度明显低于n型NCZ硅,这是由于p型NCZ硅中硼促进了N-O复合体的消除.     

新型半导体清洗剂的清洗工艺

报道了利用红外吸收谱、X射线光电子谱和表面张力测试仪对新型半导体清洗工艺进行研究的结果.采用DGQ系列清洗剂清洗硅片时,首先需用HF稀溶液浸泡硅片,以利于将包埋于氧化层内的金属和有机污染物去除;溶液的配比浓度由临界胶束浓度和硅片表面的污染程度确定,要确保清洗过程中溶液内部有足够的胶束存在,一般DGQ -1、DGQ-2的配比浓度在90%到98%之间;当温度接近表面活性剂溶液的浊点温度时,增溶能力最强,因而清洗液的温度定在60℃.     

一种用局部非线性预测模式实现的语音编码算法

该文提出了一种基于局部非线性模式的语音信号预测模型(LNLP),并将其应用于语音编码中。在同样的算法条件下,LNLP提高了预测增益,改善了合成语音质量,而其算法复杂度与常规算法相比并无显著增加。     

Intelligent Handoff for Mobile Wireless Internet

This paper presents an intelligent mobility management scheme for Mobile Wireless InterNet – MWIN. MWIN is a wireless service networks wherein its core network consisting of Internet routers and its access network can be built from any Internet-capable radio network. Two major standards are currently available for MWIN, i.e., the mobile IP and wireless LAN. Mobile IP solves address mobility problem with the Internet protocol while wireless LAN provides a wireless Internet access in the local area. However, both schemes solve problems independently at different layers, thereby some additional problems occur, e.g., delayed handoff, packet loss, and inefficient routing. This paper identifies these new problems and performs analyses and some real measurements on the handoff within MWIN. Then, a new handoff architecture that extends the features of both mobile IP and wireless LAN handoff mechanism was proposed. This new architecture consists of mobile IP extensions and a modified wireless LAN handoff algorithm. The effect of this enhancement provides a linkage between different layers for preventing packet loss and reducing handoff latency. Finally, some optimization issues regarding network planning and routing are addressed.     

A unified algebraic transformation approach for parallel recursiveand adaptive filtering and SVD algorithms

In this paper, a unified algebraic transformation approach is presented for designing parallel recursive and adaptive digital filters and singular value decomposition (SVD) algorithms. The approach is based on the explorations of some algebraic properties of the target algorithms' representations. Several typical modern digital signal processing examples are presented to illustrate the applications of the technique. They include the cascaded orthogonal recursive digital filter, the Givens rotation-based adaptive inverse QR algorithm for channel equalization, and the QR decomposition-based SVD algorithms. All three examples exhibit similar throughput constraints. There exist long feedback loops in the algorithms' signal flow graph representation, and the critical path is proportional to the size of the problem. Applying the proposed algebraic transformation techniques, parallel architectures are obtained for all three examples. For cascade orthogonal recursive filter, retiming transformation and orthogonal matrix decompositions (or pseudo-commutativity) are applied to obtain parallel filter architectures with critical path of five Givens rotations. For adaptive inverse QR algorithm, the commutativity and associativity of the matrix multiplications are applied to obtain parallel architectures with critical path of either four Givens rotations or three Givens rotations plus two multiply-add operations, whichever turns out to be larger. For SVD algorithms, retiming and associativity of the matrix multiplications are applied to derive parallel architectures with critical path of eight Givens rotations. The critical paths of all parallel architectures are independent of the problem size as compared with being proportional to the problem size in the original sequential algorithms. Parallelism is achieved at the expense of slight increase (or the same for the SVD case) in the algorithms' computational complexity     

Method of high-level technology mapping based on knowledge(rule)

This paper studies the linkage problem between the result of high-level synthesis and back-end technology, presents a method of high-level technology mapping based on knowledge, and studies deeply all of its important links such as knowledge representation, knowledge utility and knowledge acquisition. It includes: (1) present a kind of expanded production about knowledge of circuit structure; (2) present a VHDL-based method to acquire knowledge of technology mapping; (3) provide solution control strategy and algorithm of knowledge utility; (4) present a half-automatic maintenance method, which can find redundance and contradiction of knowledge base; (5) present a practical method to embed the algorithm into knowledge system to decrease complexity of knowledge base. A system has been developed and linked with three kinds of technologies, so verified the work of this paper.     

A skeletonization algorithm based on euclidean distance maps and morphological operators

In this letter a new skeletonization algorithm is proposed. It combines techniques of fast construction of Euclidean Distance Maps(EDMs), ridge extraction, Hit-or-Miss Transformation (HMT) of structuring elements and the set operators. It first produces the EDM image with no more than 4 passes through an image of any kinds, and then the ridge image is extracted by applying a turn-on scheme and performing a rain-fall elimination to accelerate the processing. The one-pixel wide skeleton is finally acquired by carrying out the HMTs of two structure elements and the SUBTRACT and OR operations. Experimental results obtained by practical applications are also presented.     

利用集成光学调制器实现ICF固体激光驱动器中激光脉冲任意整形 Ⅱ.集成光学调制器

本文利用集成光学和光纤技术制作了集成光学调制器,驱动调制器的电压仅为４伏,配之以高稳定的、ＬＤ泵浦的单纵模振荡源和任意整形电脉冲源,大大提高了ＩＣＦ固体激光驱动器前级整形系统对激光脉冲整形的稳定性和灵活性．     

一种用于逐次逼近ADC的高能效高线性度开关电容时序

提出了一种用于逐次逼近模数转换器的高能效高线性度开关电容时序。相较于典型的基于V_CM的开关原理,该开关时序可减少37%的开关能量,并具有更高的线性度。该开关时序已应用于1V,10位300kS/s的SAR ADC,并在0.18μm标准CMOS工艺下成功流片。测试结果表明,在1V电源电压下,此SAR ADC的SNDR为55.48dB,SFDR为66.98dB,功耗为2.13μW,品质因数到达14.66fJ/c-s。DNL和INL分别为0.52/-0.47 LSB和0.72/-0.79 LSB,并且与静态非线性模型一致,最大INL出现在 V_FS/4处和3V_FS/4处。