软件无线电发射机的FPGA实现

本文以软件无线电理论为指导,以π/4DQPSK调制为特例,重点介绍了软件无线电发射机数字信号处理部分在FPGA上的实现,主要包括数据映射、成形滤波、CIC插值滤波和NCO等。在设计上使用了基于多相滤波和单MAC的成形滤波器及高效CIC插值滤波器,使性能和资源占用率获得了较好的突破。与专用芯片相比,用FPGA实现的软件无线电发射机更具灵活性。     

Preparation of high performance thin-film polarizers

<正>The optical performance of thin film polarizers is highly sensitive to the layer thicknesses of thin film.The thicknesses of the sensitive layers are optimized in order to gain broader polarizing zone in such case when the total layer thickness does not increase.An automatic layer thickness control system is established,and errors caused by different monitoring methods are analyzed.With this thickness control system,thin-film polarizers with T_p higher than 98%and T_p/T_s higher than 200:1(T_p and T_s are transmissions for p- and s-polarizations,respectively) with the bandwidth of 11 nm are prepared.Using the system allows for optimum repeatability of three successive runs.     

Surface relief resonant Brewster filters with multiple channels

In this paper, a new type of resonant Brewster filters （RBF） with surface relief structure for the multiple channels is first presented by using the rigorous coupled-wave analysis and the S-matrix method. By tuning the depth of homogeneous layer which is under the surface relief structure, the multiple channels phenomenon is obtained. Long range, extremely low sidebands and multiple channels are found when the RBF with surface relief structure is illuminated with Transverse Magnetic incident polarization light near the Brewster angle calculated with the effective media theory of sub wavelength grating. Moreover, the wavelengths of RBF with surface relief structure can be easily shifted by changing the depth of homogeneous layer while its optical properties such as low sideband reflection and narrow band are not spoiled when the depth is changed. Furthermore, the variation of the grating thickness does not effectively change the resonant wavelength of RBF, but have a remarkable effect on its line width, which is very useful for designing such filters with different line widths at desired wavelength.     

多层介质膜光栅和介质膜反射镜抗激光损伤阈值研究

对多层介质膜光栅以及介质膜反射镜的激光损伤阈值进行了系统的研究。测试方法采用国际测试标准。测试结果表明,介质光栅的损伤阈值远低于未刻蚀的多层介质膜。对样品损伤形貌的扫描电镜照片分析发现,相比于未刻蚀的多层介质膜,介质膜光栅的初始损伤主要发生在光栅槽形的侧壁,且损伤主要是由驻波场的空间分布引起的本征吸收、制备过程中引入的杂质污染以及刻蚀过程中HfO2的化学计量机失衡引起的。     

用于LDD和SST的SiO2边墙干法腐蚀工艺研究

本文从干法腐蚀角度出发,首先从数学上分析了多晶硅角度,SiO_2边墙的宽度和高度,衬底损失与各工艺参数间的关系,指出边墙的宽度和高度分别取决于多晶硅的角度和过腐蚀量。在Tegal1512e设备上,采用Cl_2、SF_6、N_2混合气体,开发了多晶硅干法腐蚀工艺,讨论了LDD的正胶掩膜及SST的SiO_2掩膜对工艺的不同影响。SEM分析发现了SF_6气体腐蚀的各向同性。在Tegal903e设备上,采用CHF_3、SF_6、He混合气体,开发了SiO_2边墙干法腐蚀工艺,研究了腐蚀的各向异性,辐射损伤,选择比,均匀性及重复性的控制方法。取得的工艺结果为,腐蚀速率(?)_(sio_2)≈400nm/min,均匀性U≤±5％,选择比S_(f8)>10,工序能力指数C_p>1。     

高速器件微微秒级的测量系统

新一代高速逻辑器件需要更高速的测量仪器，如微徽秒级的精度和重复性。本文从理论和实验上来讨论怎样建立这种微微秒级的测量系统，提出影响精度的各种因素和有关它们的误差分析，并推荐一套优化系统。     

Influence of coating material on laser damage threshold of TiO_2 films

The optical property,structure,surface properties(roughness and defect density)and laser-induced dam- age threshold(LIDT)of TiO_2 films deposited by electronic beam(EB)evaporation of TiO_2(rutile),TiO_2 (anatase)and TiO_2 Ta_2O_5 composite materials are comparatively studied.All films show the polycrys- talline anatase TiO_2 structure.The loose sintering state and phase transformation during evaporating TiO_2 anatase slice lead to the high surface defect density,roughness and extinction coefficient,and low LIDT of films.The TiO_2 Ta_2O_5 composite films have the lowest extinction coefficient and the highest LIDT among all samples investigated.Guidance of selecting materials for high LIDT laser mirrors is given.     

基于0.35 μm SiGe工艺的高速高精度CORDIC处理器的ASIC实现

针对数字信号处理领域高速高精度实时运算的要求,实现了一种16位全流水高速高精度复数运算的通用CORDIC处理器。电路采用半定制设计方法,用0.35μm SiGe工艺库完成综合、静态时序分析、布局布线,最后在200 MHz时钟频率下通过Nanosim后仿真。结果表明,电路达到了高速高精度的设计要求,可广泛应用于信号处理、雷达、通信等领域。     

臭氧层的化学破坏及其对策

臭氧层的化学破坏是人类的重大环境问题。本文对臭氧层的形成，作用，臭氧层破坏的后果，破坏臭氧层的物质及作用机制和保护臭氧层的对策作了探讨。     

单片机在通信系统中应用的几种典型软件设计

单片机以它优异的性能价格比已风靡于全世界,为各类产品的智能化提供了有力的手段,通信系统产品也不例外。如何应用单片机来提高通信设备的性能或扩展通信设备的功能已是一个十分重要的众所关心的课题。我们结合产品的开发工作,对通信设备中应用单片机的几种典型软件设计作一介绍,以当前广泛采用的Intel公司MCS—51系列单片机指令系统为例。