CMOS集成时钟恢复电路设计

该文设计了一个集成时钟恢复电路,恢复时钟的频率为125MHz。通过采用电流相减技术等补偿措施,很大程度上降低了振荡器的压控增益,从而在不影响电路性能的前提下大大地降低了芯片面积。本设计采用0.25m标准CMOS工艺实现,有效芯片面积小于0.2mm2,功耗仅10mW。在各种工艺角、温度以及供电电源条件下的仿真结果均表明,该电路相位偏差小于200ps,时钟抖动的峰峰值小于150ps。该文对一个采用本时钟恢复电路的100MHz PHY系统进行流片、测试,验证了时钟恢复电路能够正常工作。     

High-frequency MnZn soft magnetic ferrite by engineering grain boundaries with multiple-ion doping

MnZn soft magnetic ferrites have been widely utilized in power electronics,owing to the combined merits of high permeability and low energy loss.However,their deployment would result in a drastic increase in power dissipation at ＞3 MHz,thus limiting the scope extent of miniaturization,together with their efficiency.Here,we report a high-performance MnZn ferrite by doping multiple ions (La,Ti,Si,Ca) at grain boundaries,achieving the most optimized power loss of 267 kW/m3 at 5 MHz (10 m T,100 ℃) and initial permeability of 644,which is much better than the previously reported results and commercial products.Such an improvement is attributed to weakened magnetic exchange coupling at grain-boundary regions,associated with a significant transition from the multi-to mono-domain structures,originating physi-cally from large crystallographic mis-orientations (＞25°).The present study bears important significance in understanding the intrinsic correlation between the crystallographic mis-orientation and magnetic domain structure,and provides an alternative way for optimizing high-frequency soft magnetic ferrites.     

基于700MHz频段TD-LTE网络的村通宽带建设方案

本文首先分析了引入700 MHz频段TD-LTE进行乡镇农村宽带网络建设的优势和迫切性、700 MHz频段的频率规划方案,然后研究了无线宽带网络的端到端组网方案、700 MHz频段TD-LTE作为无线回程网络的规划建设方案,并对基于700 MHz频段TD-LTE网络的村通宽带业务发展提供了建议。经研究表明,基于700 MHz频段TD-LTE网络的村通宽带建设方案具有良好的社会和经济效益。     

Functionalization of carbon nanomaterials for advanced polymer nanocomposites: A comparison study between CNT and graphene

The allotropes of carbon nanomaterials (carbon nanotubes, graphene) are the most unique and promising substances of the last decade. Due to their nanoscale diameter and high aspect ratio, a small amount of these nanomaterials can produce a dramatic improvement in the properties of their composite materials. Although carbon nanotubes (CNTs) and graphene exhibit numerous extraordinary properties, their reported commercialization is still limited due to their bundle and layer forming behavior. Functionalization of CNTs and graphene is essential for achieving their outstanding mechanical, electrical and biological functions and enhancing their dispersion in polymer matrices. A considerable portion of the recent publications on CNTs and graphene have focused on enhancing their dispersion and solubilization using covalent and non-covalent functionalization methods. This review article collectively introduces a variety of reactions (e.g. click chemistry, radical polymerization, electrochemical polymerization, dendritic polymers, block copolymers, etc.) for functionalization of CNTs and graphene and fabrication of their polymer nanocomposites. A critical comparison between CNTs and graphene has focused on the significance of different functionalization approaches on their composite properties. In particular, the mechanical, electrical, and thermal behaviors of functionalized nanomaterials as well as their importance in the preparation of advanced hybrid materials for structures, solar cells, fuel cells, supercapacitors, drug delivery, etc. have been discussed thoroughly.     

1030/1090 MHz频谱的共享与干扰问题综述

1 030/1 090MHz频率广泛应用于民用和军用航空电子系统中,随着飞行器和机场地面设备的快速增加,1 030/1 090MHz频谱的共享越来越复杂,由此带来的干扰问题日趋严重。研究了使用1 030/1 090MHz频率的各种电子系统的工作原理和机制,包括二次监视雷达、自动广播相关监视系统、多点定位系统、空中防撞系统、敌我识别器系统、测距仪和交通信息广播服务系统等,重点分析了各系统对该频点的使用频度,讨论了可能出现的各种干扰形式,指出了对1 030/1 090MHz频谱现状进行监测,对未来的干扰环境和应用系统的性能进行评估的重要意义。     

基于光无线融合的用电信息采集通信系统

提出了一种基于射频拉远光无线融合技术的LTE230M无线通信方案,构建用电信息采集通信系统.利用射频拉远技术将传统的基站拆分为基站单元与射频单元,设计了基带单元与射频单元的模块结构,研究了系统的组网结构与特点,总结了基带单元与射频单元安装选址的原则.     

高含泥地层25MHz介电常数解释模型

通过对大量２５ＭＨｚ下岩石介电常数与其影响因素关系的分析，提出了一种新的２５ＭＨｚ介电常数解释模型———ＳＶ模型，通过与通用的ＴＰＯ模型对比，新的ＳＶ模型具有更适合于高含泥地层的定量解释的特点。     

868MHz频段微功率设备研究

随着无线通信技术的演进,微功率短距离无线电发射设备作为物联网不可或缺的终端设备倍受关注。本文首先介绍868MHz频段在国际上的规划情况,同时讨论了该频段微功率设备的主要技术体制,最后研究了868MHz频段微功率设备的型号核准情况和主要应用场景。     

关于700 MHz频段用于LTE网络的研究与探讨

700 MHz频段具有优质的传播特性,有利于IMT系统实现快速部署。通过分析国内频谱分配现状及全球运营商的LTE商用网络频段使用策略,指出国内现有LTE网络部署缺乏低频谱资源,不利于LTE网络实现低成本快速部署。700 MHz已成为国际应用LTE主流频段之一,而我国尚未明确700 MHz频谱的应用规划。随着广电行业地面电视模数转换进程的推进,建议政府相关部门主导,区域性推动700 MHz频段广电清频,并明确相关规划。     

350MHz集群微波拉远系统的开发与应用

简述了350 MHz集群微波拉远系统的原理及技术特点,为提高350 MHz集群网络在复杂地形地段覆盖的深度和广度,提供了一种很好的解决方案。