悬臂式RF MEMS开关的设计与研制

介绍了一种制作在低阻硅(3～8Ω·cm)上的悬臂式RF MEMS开关.在Cr/ Au CPW共面波导上,金/Si Ox Ny/金三明治结构或电镀金作为悬置可动臂,静电受激作为开关机理.当开关处于“关断”态,其隔离度小于- 35 d B(2 0～4 0 GHz) ;阈值电压为13V ;开关处于“开通”态,插入损耗为4～7d B(1～10 GHz) ,反射损耗为- 15 d B.另外,还分析了开关的悬臂梁弯曲度与驱动电压的关系,并应用ANSYS软件对开关进行了电学、力学及耦合特性的计算机模拟     

Threshold-based selective drop for shared buffer packet switches

We propose a novel buffer management scheme called threshold-based selective drop (TSD) to improve the overall loss performance and fairness by regulating the buffer sharing in a packet switch. A transient analysis of TSD is derived to prove the fairness of buffer allocation. Computer simulation shows that the overall loss performance of TSD approaches to the pushout (PO) scheme, which is considered as an optimal solution with implementation difficulties in high-speed Internet. However, unlike the PO, the TSD will block the unwanted packets before they enter the queue, and does not need to pre-empty the queue for accepting new packets.     

Fabrication and characteristics of high-speed implant-confined index-guided lateral-current 850-nm vertical cavity surface-emitting lasers

Process technology of high-speed implant-apertured index-guide lateral-current-injection top dielectric-mirror quantum-well 850-nm vertical cavity surface-emitting lasers (VCSELs) has been developed. Oxygen and helium implantation for aperture definition and extrinsic capacitance reduction, dielectric mirror formation, p- and n-ohmic contact formation, VCSEL resistance, and thermal analysis were investigated. Employing this technology, GaAs/AlGaAs-based 850-nm VCSELs with small signal modulation bandwidths up to 11.5 Gb/s and an eye diagram generated at 12 Gb/s by a pseudorandom bit sequence of 2/sup 31/-1 were achieved. The bit-error rates were below 10/sup -13/. The threshold current is as low as 0.8 mA for 7-/spl mu/m-diameter current apertures and typical slope efficiencies of 0.45-0.5 mA/mW were obtained.     

A note on the equivalence between strict optical orthogonal codes and difference triangle sets

Zhang (see IEEE Trans. Commun., vol.47, p.967-973, July 1999) proposed a special family of optical address codes, called strict optical orthogonal codes (S-OOCs), was proposed for fiber-optic code-division multiple-access (FO-CDMA) networks. Such codes can strictly guarantee both cross-correlation and autocorrelation functions constrained to have the value one in fully asynchronous data communications and ultra fast switching. In Zhang's work the theory and designs of S-OOC, plus several examples, comparison tables, and performance analyses were presented. In this article, we set up the equivalence between S-OOC and so-called difference triangle sets (DTS), which have been extensively studied previously. Thus, all the known constructions, bounds, and analyses for DTS can be directly applied to S-OOC.     

非球面光学设计技术综述

非球面光学在工业、国防和商业等领域的应用中具有十分重要的意义。当用非球面设计光学系统时,非球面方程的选用十分重要,决定着系统最佳优化结果。文章介绍了非球面光学技术的发展过程。分析了常用非球面的应用方程,井对非球面应用方程的特点及非球面系数的关系进行了概述,较详细地分析了各类非球面应用方程的适用范围,最后概述了非球面光学在军事、工业等领域的应用以及发展趋势。     

Using metal/organic junction engineering to prepare an efficient organic base-modulation triode and its inverter

In this study, we investigated the influence of a buffer layer of molybdic oxide (MoO₃) at the metal/organic junction on the behavior of organic base-modulation triodes. The performance of devices featuring MoO₃/Al as the emitter electrode was enhanced relative to that of corresponding devices with Au and Ag, presumably because of the reduced in the contact barrier and the prevention of metal diffusion into the organic layer. The device exhibited an output current of ?16.1 μA at V_B = ?5 V and a current ON/OFF ratio of 10³. Using this architecture, we constructed resistance–load inverters that exhibited a calculated gain of 6.     

有机小分子掺杂的聚合物发光二极管电致发光及其发射机制

在新型空穴传输聚合物聚TPD(PTPD)中掺杂电子传输有机小分子荧光染料Rubrene制成薄膜器件.考察了影响聚合物掺杂小分子薄膜器件发光性能的因素.实验表明,通过在器件中掺杂,可以控制器件所发光的颜色.研究了PTPD掺杂Rubrene分子薄膜的电致发光光谱和光致发光光谱.由实验可知.在光致发光中存在从PTPD向Rubrene的能量传递和电荷转移,而电致发光则存在从PTPD向Rubrene的能量传递和Rubrene分子对载流子的俘获.即掺杂器件的发射机制为载流子陷阱和Forster能量转换过程的共同作用.     

自适应光学系统中的波前曲率传感技术

本文阐述了波前曲率传感技术的基本原理,分析了传统实现方案的优缺点;重点介绍了近年发展起来的的基于衍射光栅的渡前曲率传感器及其工作原理;对比分析了波前曲率传感器的两种相位恢复算法;介绍了波前曲率传感器的最新应用情况以及国内对波前曲率传感器研究和应用的最新进展.     

一种应用于IEEE 802.11 b/g/n无线局域网收发机的CMOS模拟基带电路

本文提出了一种应用于直接变频无线局域网收发机的模拟基带电路,该电路采用标准的0.13微米CMOS工艺实现,包括了采用有源RC方式实现的接收4阶椭圆低通滤波器、发射3阶切比雪夫低通滤波器、包含直流失调消除伺服环路的接收可变增益放大器及片上输出缓冲器。芯片面积共1.26平方毫米。接收基带链路增益可在-11dB至49dB间以2dB步长调节。相应地,基带接收输入等效噪声电压（IRN）在50 nV/sqrt(Hz) 至30.2 nV/ sqrt(Hz)间变化而带内输入三阶交调（IIP3）在21dBm至-41dBm间变化。接收及发射低通滤波器的转折频率可在5MHz、10MHz及20MHz之间选择以符合包含802.11b/g/n的多种标准的要求。接收基带I、Q两路的增益可在-1.6dB至0.9dB之间以0.1dB的步长分别调节以实现发射IQ增益失调校正。通过采用基于相同积分器的椭圆滤波器综合技术及作用于电容阵列的全局补偿技术,接收滤波器的功耗显著降低。工作于1.2V电源电压时,整个芯片的基带接收及发射链路分别消耗26.8mA及8mA电流。     

掺铒硫系玻璃光纤的中红外增益特性模拟研究

实验制备了Er3+掺杂质量分数为1%的Ga5Ge20Sb10S65硫系玻璃,测试了其折射率、吸收光谱和荧光光谱,利用Judd-Ofelt和Futchbauer-Ladenburg理论计算了Er3+离子的自发辐射几率、吸收截面和受激发射截面等光谱参数。在综合考虑Er3+离子的交叉弛豫、能量上转换和激发态吸收效应的基础上,应用四能级粒子数速率-光功率传输方程模型,模拟计算了Er3+掺杂Ga5Ge20Sb10S65硫系玻璃光纤的中红外2.74μm波段的增益特性。结果显示,Er3+掺杂硫系玻璃光纤在2.74μm中红外波段具有较高的信号增益和较宽的增益谱,最大增益值和20dB增益带宽分别超过了40dB和200nm,表明其是可用于中红外2.74μm波段宽带放大的理想增益介质。