基于共振隧穿二极管的蔡氏电路设计研究

首次提出一种基于共振隧穿二极管的蔡氏电路.利用共振隧穿二极管(RTD)的负微分电阻特性,采用驱动点特性合成的方法,实现了蔡氏电路中的分段线性电阻,通过一组参数的选取,进而实现了蔡氏电路,并用PSpice模拟软件进行了仿真验证.相对于用传统方法实现的蔡氏电路,基于RTD的蔡氏电路具有电路结构更加简洁、便于集成的特点.     

高温处理对镍诱导晶化硅上的薄膜晶体管性能的影响

采用标准双栅 CMOS工艺在镍诱导非晶硅横向晶化形成的多晶硅上制造了高性能的薄膜晶体管 ,并详细研究了器件制备前高温预处理对薄膜晶体管性能的影响 .实验发现不同的温度处理 ,将引起器件性能的显著变化 .在10 0 0℃预处理温度下获得了最好的器件性能 .10 0 0℃在 NMOS管中测得的电子迁移率达 314 cm2 / (V· s) ,分别比在 110 0℃和未做高温处理下的大 10 %和 2 2 % .10 0 0℃下器件的最大开关电流比也达到了 3× 10 8.对器件的进一步重复性研究证实了上述结果的可靠性     

Tuning the Optoelectronic Properties of Carbazole/Oxadiazole Hybrids through Linkage Modes: Hosts for Highly Efficient Green Electrophosphorescence

A series of bipolar transport host materials: 2,5‐bis(2‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (o‐CzOXD) ( 1 ), 2,5‐bis(4‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (p‐CzOXD) ( 2 ), 2,5‐bis(3‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (m‐CzOXD) ( 3 ) and 2‐(2‐(9H‐carbazol‐9‐yl)phenyl)‐5‐(4‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (op‐CzOXD) ( 4 ) are synthesized through simple aromatic nucleophilic substitution reactions. The incorporation of the oxadiazole moiety greatly improves their morphological stability, with T_d and T_g in the range of 428–464 °C and 97–133 °C, respectively. The ortho and meta positions of the 2,5‐diphenyl‐1,3,4‐oxadiazole linked hybrids ( 1 and 3 ) show less intramolecular charge transfer and a higher triplet energy compared to the para‐position linked analogue ( 2 ). The four compounds exhibit similar LUMO levels (2.55–2.59 eV) to other oxadiazole derivatives, whereas the HOMO levels vary in a range from 5.55 eV to 5.69 eV, depending on the linkage modes. DFT‐calculation results indicate that 1 , 3 , and 4 have almost complete separation of their HOMO and LUMO levels at the hole‐ and electron‐transporting moieties, while 2 exhibits only partial separation of the HOMO and LUMO levels possibly due to intramolecular charge transfer. Phosphorescent organic light‐emitting devices fabricated using 1 – 4 as hosts and a green emitter, Ir(ppy)₃ or (ppy)₂Ir(acac), as the guest exhibit good to excellent performance. Devices hosted by o‐CzOXD ( 1 ) achieve maximum current efficiencies (η_c) as high as 77.9 cd A^?1 for Ir(ppy)₃ and 64.2 cd A^?1 for (ppy)₂Ir(acac). The excellent device performance may be attributed to the well‐matched energy levels between the host and hole‐transport layers, the high triplet energy of the host and the complete spatial separation of HOMO and LUMO energy levels.     

固体火箭发动机水下超音速射流数值研究

固体火箭发动机水下点火射流是高温高压条件下复杂的多相流过程,为研究其流场特性与推力特性,选取扩张比分别为3.4和14.0的拉瓦尔喷管模型进行数值模拟。采用计算流体力学方法分析高速燃气超音速射流过程的流场与推力演化过程,揭示高温高压气体与水环境之间的相互作用规律。结果表明：固体火箭发动机水下射流流场结构与推力特性呈周期性变化,根据流场特征可分为颈缩、胀鼓、回击3个阶段;水环境与射流气体之间的相互作用是导致背压振荡的直接原因,同时导致激波运动、动量推力与压差推力的振荡。对比两种扩张比喷管的射流可知,扩张比为14.0的喷管射流形貌与流场结构的周期性变化更明显,扩张比为3.4的喷管背压振荡频率高、周期性特征弱、推力更稳定。     

浅谈RS-485串行总线及其通信实现

以某消声水池研制为基础,由与编码器之间的通信,结合理论知识,在总线匹配、网络连接方式和接地等问题上,对RS-485串行总线通信问题进行了详细分析。综合考虑消声水池现场的实际限制因素,给出了硬件相应解决方法和软件通信实现开发方面需注意的问题,再予以验证,有效地提高了其通信的可靠性。     

EMBLAZE-VCON公司看好中国视频通信市场的未来发展

通过多年来信息技术和业务的不断发展，人们之间的交流方式变得多种多样，电信用户不再满足于电话形式的语音通信，而希望能够进行更多面对面地交流，所以视频通信近年来得到了迅速发展。以色列EMBLAZE—VCON公司成立十多年来一直致力于网络多媒体即时通信系统的开发、制造和销售，并提供视频通信整体解决方案。EMBLAZE—VCON公司总部设在以色列，目前已经在中国、美国、德国、法国、英国、西班牙等国家设有分公司。     

马拉松赛事辅助系统实现

随着经济水平的提高,人们越来越关注身体健康,注重运动,与此同时健身文化迅速传播.在这种背景之下,马拉松运动开始进入一个快速增长、迅速扩张的新阶段.在近几年,由政府和地方企业合办的马拉松如雨后春笋般陆续涌现.伴随这种现象的产生,也出现了一些亟待解决的问题.在这种情况下,迫切需要一套有效的辅助系统,来帮助人们更好地、安全地参加马拉松赛事,让人们体会到马拉松赛事的魅力,减少举办方的举办成本.马拉松赛辅助系统,就是基于Android系统和百度地图开放API等技术,为实现这个目的而开发的一款安卓应用.     

集成抗ESD二极管的SOI LIGBT/LDMOS器件结构及其制作方法

为探索与国内VLSI制造工艺兼容的新型SOI LIGBT/LDMOS器件与PIC的设计理论和工艺实现方法,首次提出含有抗ESD二极管的集成SOI LIGBT/LDMOS器件截面结构和版图结构,并根据器件结构给出了阻性负载时器件的大信号等效电路.探讨了该结构器件的VLSI工艺实现方法,设计了工艺流程.讨论了设计抗ESD二极管相关参数所需考虑的主要因素,并给出了结构实现的工艺控制要求.     

Broadband high-efficiency circularly polarized active antenna and array for RF front-end application

This paper presents a broadband high-efficiency circularly polarized (CP) active integrated antenna, and a broadband CP active array at 2 GHz. To realize the broadband CP antenna, a circular patch is aperture coupled by crossed slots in the ground plane, which are fed by an L-shaped microstrip feed line below the ground. The antenna is designed to serve the functions of both a radiator and a harmonics-terminated load for class-E high-efficiency power-amplifier (PA) integration. The broadband CP active antenna is realized by directly integrating the broadband CP antenna with the class-E PA. It achieves a 9% bandwidth (1.84-2.01 GHz) for axial ratio (AR) below 3 dB, and a 12% bandwidth for power-added efficiency (PAE) over 60%. To form the broadband CP active array, four active antenna elements are sequentially rotated, and each element is directly integrated with broadband class-E PA. A low-cost printed-circuit-board technology is employed in fabrication and a pseudomorphic high electron-mobility transistor is used. A peak drain efficiency of 71.5% for the class-E amplifier is measured at 1.95 GHz. The active array achieves a peak-effective radiated power of 39.7 dBm, and PAE is over 50% within a 22.6% bandwidth (1.72-2.16 GHz). The AR is below 3 dB over a 27% bandwidth (1.72-2.26 GHz).     

带有USB接口的16位立体声数模转换器PCM2702

PCM2702是Burr-Brown公司新近推出的一种带有USB接口的16们立体声数模转换器芯片。文中简要分析了该芯片的性能特点和工作原理,最后给出了PCM2702的典型应用电路。