LDPC-CM-UEP在数字图像水印技术的应用

数字图像水印技术是一种信息隐藏技术。针对信息隐藏对于秘密信息隐匿性和可靠性传输的高要求,采用LDPC编码调制的不等差错保护（LDPC-CM-UEP）方案应用于数字图像水印技术中,将水印信息经过LDPC编码后的码字分为两部分,分别利用两种QAM高效调制方式,使水印信息作为重要比特得到很好的保护。仿真结果表明该方案在保证水印鲁棒性和隐匿性的前提下,提高了系统的频带利用率,从而改善了数字图像水印系统的传输质量。     

大功率半导体激光器用电流源设计

半导体激光器是一种电流注入式发光器件,驱动电流源的性能优劣对其工作特性和使用寿命有着很大的影响。本文利用芯片LT3755设计了一种大功率LD电流源,电流在3.3~5.6 A连续可调。当输出电流为4.5 A时,连续工作3 h内电流变化量小于2 mA,电流稳定度达到4×10-4。此外,该电源还具有欠压保护、过压保护、过流保护和缓启动等多种功能。     

nBn型InAs/GaSb Ⅱ类超晶格红外探测器光电特性研究

设计了nBn结构的InAs/GaSb II类超晶格红外探测器,从理论和实验两方面对nBn器件的暗电流特性进行了研究,研究结果表明:理论计算的暗电流和实际测试结果趋势一致。另外,研制了p-i-n结构器件并与nBn器件进行了比较,测试结果显示:在77 K温度下,nBn器件的暗电流要比p-i-n器件暗电流小2个量级。温度升高到150 K时,nBn器件暗电流变大2个量级,而p-i-n器件暗电流变大4个量级;nBn器件峰值探测率下降到1/5,p-i-n器件峰值探测率下降2个量级。可见nBn器件适合高温工作,适合高性能红外焦平面探测器的研制。     

物联网风险评估和等级保护浅析

从信息系统等级保护和风险评估的基本概念出发,结合物联网技术的特点,分析物联网面临的安全问题,并探讨适用于物联网安全的风险评估和等级保护方法。     

牵引变电所电弧光保护方案在海外项目的应用实践

介绍了电弧光的危害,简述国内牵引变电所母线保护的现状,详述电弧光保护在白俄罗斯工程应用方案,展望方案推广的前景。     

Parameter variation aware hybrid TFET-CMOS based power gating technique with a temperature variation tolerant sleep mode

In this work, we discuss the origin and temperature dependence of various mechanisms behind the flow of leakage current in two topologies of TFET – basic TFET and pocket doped TFET. It is shown that the leakage current of pocket doped TFET shows relatively less variations with change in temperature when compared with MOSFET and basic TFET, and hence they can be deployed in low voltage temperature variation prone applications. But, this advantage of pocket-doped TFET is overshadowed by the huge sensitivity of its ON-state current towards variations in doping concentration at the tunnel junction. Hence, the fabrication of the TFET based circuits requires a negotiation with the yield and cost of the fabrication process. In order to mitigate this issue, we propose a hybrid TFET-CMOS based power gating technique. The hybrid technique utilizes a minimum number of TFETs to reduce the sleep mode leakage current, while enabling a temperature variation tolerant sleep mode at a supply voltage of 0.6 V.     

Highly linear micropower class AB current mirrors using Quasi-Floating Gate transistors

A design approach to achieve low-voltage micropower class AB CMOS cascode current mirrors is presented. Both class AB operation and dynamic cascode biasing are based on the use of Quasi-Floating Gate transistors. They allow high linearity for large signal currents and accurately set quiescent currents without requiring extra power consumption or supply voltage requirements. Measurement results show that dynamic cascode biasing allows a wider input range and a linearity improvement of more than 23 dB with respect to the use of conventional biasing. A THD value better than −35 dB is measured for input amplitudes up to 100 times the bias currents. Two class AB current mirror topologies are proposed, with slightly different ways to achieve class AB operation and dynamic biasing. The proposed current mirrors, fabricated in a 0.5 µm CMOS technology, are able to operate with a supply voltage of 1.2 V and a quiescent power consumption of only 36 µW, using a silicon area <0.025 mm².     

Ultra-fine pitch palladium-coated copper wire bonding: Effect of bonding parameters

Copper (Cu) wire bonding has become a mainstream IC assembly solution due to its significant cost savings over gold wire. However, concerns on corrosion susceptibility and package reliability have driven the industry to develop alternative materials. In recent years, palladium-coated copper (PdCu) wire has become widely used as it is believed to improve reliability. In this paper, we experimented with 0.6 ml PdCu and bare Cu wires. Palladium distribution and grain structure of the PdCu Free Air Ball (FAB) were investigated. It was observed that Electronic Flame Off (EFO) current and the cover gas type have a significant effect on palladium distribution in the FAB. The FAB hardness was measured and correlated to palladium distribution and grain structure. First bond process responses were characterized. The impact of palladium on wire bondability and wire bond intermetallic using a high temperature storage test was studied.     

Off-state breakdown and leakage current transport analysis of AlGaN/GaN high electron mobility transistors

Off-state breakdown characteristics of AlGaN/GaN high-electron-mobility transistors have been studied based on drain current injection method. It is found that at low drain current injection level, the observed premature breakdown is caused by excess gate-to-drain leakage current. Nevertheless, at high drain injection current level, buffer-leakage-dominated breakdown proceeds gate-leakage-dominated breakdown as the gate bias increases from pinch-off voltage to deep-depletion voltage. In both breakdown regions, the breakdown voltages show negative temperature coefficients. The buffer-leakage-induced breakdown should be defect-related, which is confirmed by temperature-dependent buffer leakage measurements.     

移动电话机通用锂离子电池解决方案探讨

2010年11月ITU-T SG5在日内瓦召开的会议中,讨论了工信部电信研究院泰尔实验室（CTTL）提出的移动电话机和其他ICT设备通用锂离子电池解决方案。本文从移动电话机用锂离子电池的使用现状及遇到的问题入手,阐述了电池通用化的目标,提出了我们的解决方案,并着重对标准化工作中各国关心的问题给出了建设性意见。