超深亚微米LDD nMOSFET中的非幸运电子模型效应

通过对采用0.18μm CMOS工艺制造的两组不同沟道长度和栅氧厚度的LDD器件电应力退化实验发现,短沟薄栅氧LDD nMOSFET(Lg=0.18μm,Tox=3.2nm)在沟道热载流子(CHC)应力下的器件寿命比在漏雪崩热载流子(DAHC)应力下的器件寿命要短,这与通常认为的DAHC应力(最大衬底电流应力)下器件退化最严重的理论不一致.因此,这种热载流子应力导致的器件退化机理不能用幸运电子模型(LEM)的框架理论来解释.认为这种"非幸运电子模型效应"是由于最大碰撞电离区附近具有高能量的沟道热电子,在Si-SiO2界面产生界面陷阱(界面态)的区域,由Si-SiO2界面的栅和漏的重叠区移至沟道与LDD区的交界处以及更趋于沟道界面的运动引起的.     

一种采用开关阶跃电容的压控振荡器(下): 电路设计和实现

为了验证阶跃可变电容压控振荡器调谐特性理论分析的正确性,提出了一种采用开关阶跃电容的新型压控振荡器电路,该压控振荡器电路采用0.25μm 1P5M CMOS工艺实现.一种新型开关阶跃电容实现了频率调谐功能,该电容的调谐电容是传统反型MOS管可变电容的146%.在1/f3区域,差分调谐振荡器的相位噪声比单端调谐振荡器低7dB.在载波频率偏差10kHz,100kHz和1MHz处测得差分调谐时的相位噪声分别是-83,-107和-130dBc/Hz,功耗为8.6mW.     

低电场应力下闪速存储器的退化特性

基于负栅源边擦除的闪速存储器存储单元,研究了形成应力诱生漏电流的三种导电机制,同时采用新的实验方法对引起瞬态和稳态电流的电压漂移量进行了测量.并利用电容耦合效应模型对闪速存储器存储单元的可靠性进行了研究,结果表明,在低电场应力下,其可靠性问题主要由载流子在氧化层里充放电引起.     

超长跨距光传输技术研究

超长跨距光传输系统具有结构简单,无需建立有源中继站,维护成本低等特点,因此具有高性价比,是长站距之间通信和特殊场合建网的有效解决方案.文章介绍了超长跨距光传输系统,总结了主要几类传输方案,并对系统涉及的关键技术及其研究进展予以分析,探讨了超长跨距系统的应用前景.     

Optimal base-station locations in two-tiered wireless sensor networks

We consider generic two-tiered wireless sensor networks (WSNs) consisting of sensor clusters deployed around strategic locations, and base-stations (BSs) whose locations are relatively flexible. Within a sensor cluster, there are many small sensor nodes (SNs) that capture, encode, and transmit relevant information from a designated area, and there is at least one application node (AN) that receives raw data from these SNs, creates a comprehensive local-view, and forwards the composite bit-stream toward a BS. This paper focuses on the topology control process for ANs and BSs, which constitute the upper tier of two-tiered WSNs. Since heterogeneous ANs are battery-powered and energy-constrained, their node lifetime directly affects the network lifetime of WSNs. By proposing algorithmic approaches to locate BSs optimally, we can maximize the topological network lifetime of WSNs deterministically, even when the initial energy provisioning for ANs is no longer always proportional to their average bit-stream rate. The obtained optimal BS locations are under different lifetime definitions according to the mission criticality of WSNs. By studying intrinsic properties of WSNs, we establish the upper and lower bounds of maximal topological lifetime, which enable a quick assessment of energy provisioning feasibility and topology control necessity. Numerical results are given to demonstrate the efficacy and optimality of the proposed topology control approaches designed for maximizing network lifetime of WSNs.     

Rotatable Aggregation‐Induced‐Emission/Aggregation‐Caused‐Quenching Ratio Strategy for Real‐Time Tracking Nanoparticle Dynamics

Real‐time tracking of the dynamics change of self‐assembled nanostructures in physiological environments is crucial to improving their delivery efficiency and therapeutic effects. However, such tracking is impeded by the complex biological microenvironment leading to inhomogeneous distribution. A rotatable fluorescent ratio strategy is introduced that integrates aggregation‐induced emission (AIE) and aggregation‐caused quenching (ACQ) into one nanostructured system, termed AIE and ACQ fluorescence ratio (AAR). Following this strategy, an advanced probe, PEG^5k‐TPE₄‐ICGD₄ (PTI), is developed to track the dynamics change. The extremely sharp fluorescent changes (up to 4008‐fold) in AAR allowed for the clear distinguishing and localization of the intact state and diverse dissociated states. The spatiotemporal distribution and structural dynamics of the PTI micelles can be tracked, quantitatively analyzed in living cells and animal tissue by the real‐time ratio map, and be used to monitor other responsive nanoplatforms. With this method, the dynamics of nanoparticle in different organelles are able to be investigated and validated by transmission electron microscopy. This novel strategy is generally applicable to many self‐assembled nanostructures for understanding delivery mechanism in living systems, ultimately to enhance their performance in biomedical applications.     

基于Simulink的高斯脉冲中频信号的数字解调仿真

在现代导航机载设备中广泛使用超外差接收机和数字中频的架构理念,而Simulink作为一款功能强大的仿真软件,不仅可以模拟连续和离散系统,同时能够提供丰富的数字信号处理模块。从实际工程应用出发,通过Simulink快速构建数字中频处理模型,完成滤波、解调算法的验证,使工程研发人员摆脱繁琐的公式推导,专注于算法理论的工程实现。     

大尺度信干比共享下的基站协作干扰协调

在基于正交频分多址接入(OFDMA)技术的蜂窝移动小区中,小区间的干扰是影响系统性能的主要因素。多点协调(CoMP)技术被视为能够协调小区间干扰的主要手段。在下行多点协作传输系统中,小区基站采用三向天线来对小区划分扇区,从而消除了相邻小区边缘处的干扰。各扇区分别计算扇区内用户的大尺度信干比(SIR),小区之间通过共享大尺度信干比信息,对各自服务的用户按照一定的规则进行匹配,对小区中心用户的SIR和边缘用户的SIR进行了折中,从而有效解决小区边缘用户由于小区间干扰带来的低信干噪比(SINR)问题。仿真结果表明,本文提出的用户匹配算法以较小的反馈开销,较大的提高了小区边缘用户的信干噪比和系统吞吐量。      

综合孔径辐射计可见度函数预处理算法及时域仿真研究

该文研究了干涉式综合孔径辐射计可见度函数的预处理算法,包括A/D偏置校正、三阶数字相关系数到模拟相关系数的校正、IQ非正交校正以及空间去相关的误差校正等等。由于这是首次将三阶量化数字相关的定标方法应用于对地观测领域,对其进行了详细的分析。该文利用蒙特卡洛方法对可见度函数的预处理算法进行了时域仿真的研究。并通过地球同步轨道毫米波大气温度探测仪地面样机系统对算法进行了验证,证明了该算法的正确性。经过可见度预处理算法校正得到的结果的绝对误差小于真值的0.1%。证明该算法可以应用于地球同步轨道毫米波大气温度探测仪星载系统定标中,经过校正得到的相关结果可以直接用于亮温图像的反演。