A W-band source module using MMIC's

A W-band source module providing 4-GHz tuning bandwidth (92.5-96.5 GHz) has been developed. This module consists of three MMIC chips: a 23.5 GHz HBT VCO, a 23.5-94 GHz HEMT frequency quadrupler and a W-band three-stage HEMT output amplifier, all fabricated in TRW production lines. It exhibits a measured output power of 3 dBm at 94-95 GHz and a 3-dB tuning bandwidth greater than 3 GHz, with a phase noise of -92 dBc/Hz at 1 MHz offset. This work demonstrates a new and efficient way to implement high performance W-band source. Its wide tuning bandwidth with good phase noise performance, as well as design simplicity, makes this approach attractive for many W-band system applications     

通信光纤偏振模色散的在线测试-干涉法及其应用

重点讨论了干涉法测试单模光纤偏振模色散 ( PMD)的原理、方法 ,并对长飞光纤光缆有限公司生产的 G.65 2、G.65 5单模光纤进行了在线测试 ,根据测试数据 ,分别计算出了这两种光纤 PMD的链路值 .结果表明 ,长飞光纤光缆有限公司生产的这两种光纤的 PMD值均在标准范围之内     

光纤偏振模色散自动测量仪的试制

讨论了固定分析器法测量光纤偏振模色散(PMD)的测量原理，提出一种基于固定分析器法的光纤PMD自动测量仪，井给出了用该仪器测出的测量结果。     

大尺寸TFT-LCD电视的彩色和图像增强

最近几年,薄膜晶体管液晶显示器(TFT-LCD)技术取得了快速而显著的进步,其性能超过了PDP、CRT以及投影显示。毫无疑问,TFT-LCD已经成为高清电视应用的最佳实现方案。本文将介绍进一步增强大尺寸LCD电视的彩色和图像性能的技术。     

某鱼雷空中姿态控制装置自动测试系统的设计

通过对某鱼雷空中姿态控制装置进行分析与研究,并对被测对象测试需求特征进行综合分析,优化测试项目,优化测试资源配置,设计出适用的空中姿态控制装置测试设备。测试仪硬件采用基于ISA总线结构的工控机,软件采用LabWindows/CVI开发平台。     

Nanostructure effect of V2O5 buffer layer on performance of polymer-fullerene devices

Nanostructure of solar cell materials is often essential for the device performance. V₂O₅ nanobelt structure is synthesized with a solution process and further used as an anode buffer layer in polymer solar cells, resulting insignificantly improved power conversion efficiency (PCE of 2.71%) much higher than that of devices without the buffer layer (PCE of 0.14%) or with V₂O₅ powder as the buffer layer (1.08%). X-ray diffraction (XRD) results indicate that the V₂O₅ nanobelt structure has better phase separation while providing higher surface area for the P3HT:PCBM active layer to enhance photocurrent. The measured impedance spectrums show that the V₂O₅ nanobelt structure has faster charge transport than the powder material. This work clearly demonstrates that V₂O₅ nanobelt has great potential as a substitute of the conventionally used PEDOT-PSS buffer layer for high performance devices.     

Detection of OFDM Signals in Fast-Varying Channels With Low-Density Pilot Symbols

In fast-varying channels, an orthogonal frequency-division multiplexing system needs to insert denser pilot symbols among transmitted symbols in tracking the variation of a channel. However, using denser pilot symbols reduces transmission throughput. In this paper, we propose a pseudopilot algorithm for data detection in fast-varying channels without increasing the pilot density. Our algorithm is based on a regressional model-based least-squares-fitting approach. Within a block of received symbols, we select some data symbols and regard them as pseudopilot symbols. The receiver considers all the possible patterns of the pseudopilots and associates each of them with a data sequence and a corresponding metric. The associated data sequence, whose metric is minimum, is selected as the detected data sequence. Our algorithm is not based on a decision-directed or decision-feedback architecture because the pseudopilots do not come from any detected symbols. The proposed algorithm needs to search all the possible patterns of the pseudopilots, and the complexity may increase with the number of pseudopilots and constellation size. To reduce the number of search, we further propose two modified approaches. The simulation results show that the performance of the proposed algorithms could approach a bit-error probability lower bound that is obtained by letting the receiver know the true values of the pseudopilots. Compared with the linear interpolation method, the proposed algorithm shows obvious improvement in fast-varying channels. The proposed modified approaches could also effectively reduce the number of search while maintaining the performance. We also give the complexity analysis of the proposed algorithm and an approach to determine the degree of the regression polynomial.     

Engineering of charge transport materials for universal low optimum doping concentration in phosphorescent organic light-emitting diodes

A universal low optimum doping concentration of below 5% was demonstrated in phosphorescent organic light-emitting diodes (PHOLEDs) by managing the energy levels of charge transport materials. The device performances of PHOLEDs could be optimized at a low doping concentration of 3% irrespective of the host material in the emitting layer. The suppression of charge trapping and hopping by the dopant through charge transport layer engineering optimized the device performance at low doping concentration. In addition, it was revealed that PHOLEDs with low optimum doping concentration show better quantum efficiency, low efficiency roll-off and low doping concentration dependency of the device performance.     

椭圆曲线密码体制数字签各卡的实现

数字签名是电子商务安全可靠的重要技术手段.在介绍了数字签名原理和椭圆曲线密码体制基础上,针对椭圆曲线算法具有密钥短、安全强度高、计算量小,智能卡具有体积小、便于携带、具备一定数据存储和数据处理能力等特点.采用Infineon公司的SLE66CL160S智能卡实现了基于椭圆曲线算法的数字签名卡设计,给出了设计中应用的文件结构、自定义指令、数据交换协议及签名、验证流程等,并通过合理选取参数验证了设计的可行性.     

A low-voltage, low-power CMOS delay element

A low-voltage, low-power CMOS delay element is proposed. With a unit CMOS inverter load, a delay from 2.6 ns to 76.3 ms is achieved in 0.8 μm CMOS technology. Based on a CMOS thyristor concept, the delay value of the proposed element can be varied over a wide range by a control current. The inherent advantage of a CMOS thyristor in low voltage domains enables this delay element to work down to the supply voltage of 1 V while the threshold voltage of the nMOS and pMOS transistors are 840 mV and -770 mV, respectively. The designed delay value is less sensitive to supply voltage and temperature variation than RC-based or CMOS inverter-based delay elements. Temperature compensation and jitter performance in a noisy environment are also discussed