消除LGⅡ广播系统开机“噗噗”声

LGII调频立体声广播发射机由机电部第十研究所研制,该系列发射机被国内许多中小城市及县级广播电台所采用。 LGII发射机的调制器是锁相频率合成式立体声调频器。由于开机后的最初几秒钟内,锁相环在捕捉载波频率的过程中产生的调频射频(此处的调频射频不同于环路锁定后由环外调制信号对压控振荡器调频所产生的调频射频,前者是环路捕捉载频的过程中,鉴相器输出的控制信号力图把压控振荡器的振荡频率牵     

脉冲调相式调频广播发射机

调频广播发射机的调制方式有许多种,其中广泛使用的是电抗管调频和脉冲调相两种方式.电抗管调频的优点是调制电路简单、倍频级数少.但因振荡器不能用石英控制,必须使用自动频率控制电路来稳定载波频率.当自动频率控制部分发生故障,载波频率就会有大的偏差.脉冲调相电路用石英振荡器,因而不需要自动频率控制.但总的倍频数在一千倍左右,倍频级数多.这两种方式的发射机所用电子管总数和电声指标都不相上下,由于后者的稳定性较好,所以现代的调频广播发射机和电视伴音发射机多半采用脉冲     

基于锁相环的2FSK电路的设计及实现

调制器是通信系统中发射机的重要组成部分,可以由此获得调频信号。其中基于锁相环的调制器,所获得调频信号,其载频稳定度很高,可以达到晶体振荡器的频率稳定度。该方法的优点是集成度高且功耗低,所需硬件少。基于国家半导体的锁相环芯片LMX2326,设计了实际应用电路,实现了数字信号的频率调制,得到很好的效果,具有实际的工程意义。     

875机房调频发射机的改频

调频发射机改频需根据发射机的具体工作情况。采取不同的改频调整方法，早期生产的发射机改频过程比较繁琐，需要对激励器锁相环中的数字分频电路进行分析计算，根据所要更改频率的不同。采用硬开关编码方式设置分频电路的分频次数，然后再对每一级功放的输入、输出电路进行调整。“西新工程”建设中875机房更新的调频发射机均为全固态发射机，激励器全部采用意大利R．V．R公司生产，具有操作简捷直观。现将我对新旧调频发射机改频方法的两个特例提供给同行，以供参考。     

锁相环频率合成技术及其应用

在当今的调频广播发送技术中,为了适应对发射机输出频率稳定度和频率准确度的严格要求 ,以及方便更换发射机频率的需要,在固态调频发射机中普遍使用了锁相技术和频率合成技术.锁相环频率合成器成为固态调频发射机重要的组成部分.     

基于多相子载波生成和高增益射频振荡器的高数据率超宽带调频发射机

描述了高数据率超宽带调频(FM-UWB)发射机的系统结构和电路设计.该发射机采用内含8相环形振荡器的有限模小数分频型锁相环(PLL)生成频率键控正弦波信号,以降低子载波频率和噪声.该环形振荡器输出的差分正弦波信号直接调制高增益射频(RF)环形振荡器,生成带宽为2 GHz且满足UWB频谱掩膜的信号.在65 nm TSMC...     

调频广播发射天线特殊故障一例

调频广播发射天线特殊故障一例王永强（杭后广播电视台）我单位新购一台ＴＦ—１０００频率合成调频广播发射机。该机末级采用一只ＦＣ—１０Ｆ电子管作为功率放大。激励级采用锁相环频率合成电路，末前级采用高频晶体管功放，激励器与末级腔体间加有环形器作保护之用，并...     

光纤通信系统中光发射机的设计

按照光纤通信系统的原理,对光发射机的主要组成部分电源、调频电路及锁相环在原理和实现电路上进行设计.使信号源发出的信号经过光发射机后信号失真小,信噪比高,满足信号传输高质量的要求.     

DMR终端锁相调频发射机设计

文章介绍了一种DMR数字终端锁相调频发射机的设计与实现,首先阐述了其设计原理,然后利用振荡器芯片设计宽带调频VCO,再与频率合成芯片构造锁相环调频器,最后利用RF2117进行功率放大,测试结果表明该设计具有良好的应用价值。     

使用VCO实现变容二极管直接调频

介绍了一种使用VCO实现调频的锁相环电路并给出了关键技术,变容二极管直接调频和锁相,环路滤波器的设计及实验结果。该电路不仅具有低相位噪声、高稳定载波、很小的非线性失真,而且具有理想的音频调制频响。     

Interfacial reaction and shear strength of SnAgCu-xNi/Ni solder joints during aging at 150 °C

The interfacial microstructure and shear strength of Sn3.8Ag0.7Cu-xNi (SAC-xNi, x = 0.5, 1, and 2) composite solders on Ni/Au finished Cu pads were investigated in detail after aging at 150 °C for up to 1000 h. The interfacial characteristics of composite solder joints were affected significantly by the weight percentages of added Ni micro-particles and aging time. After aging for 200 h, the solder joints of SAC, SAC-0.5Ni and -1Ni presented duplex intermetallic compound (IMC) layers regardless of the initial interfacial structure on as-reflowed joints, whose upper and lower IMC layers were comprised of (CuNi)₆Sn₅ and (NiCu)₃Sn₄, respectively. Only a single (NiCu)₃Sn₄ IMC layer was ever observed at the SAC-2Ni/Ni interface on whole aging process. Based on the compositional analysis, the amount of Ni within the IMC regions increased as the proportion of Ni addition increased. The IMC (NiCu)₃Sn₄ layer thickness on the interface of SAC and SAC-0.5Ni grew more slowly when compared to that of SAC-1Ni and -2Ni, while for the (CuNi)₆Sn₅ layer the reverse is true. Except the IMCs sizes are increased with increased aging time, the interfacial IMCs tended to transfer their morphologies to polyhedra. In all composite joints testing, the shear strengths were approximately equal to non-composite joints. The fracturing observed during shear testing of composite joints occurred in the bulk solder, indicating that the SAC-xNi/Ni solder joints had a desirable joint reliability.     

有机发光二极管中ADN掺杂ErQ的1.54μm电致发光

自行设计了基于8-羟基喹啉铒(ErQ)为发射层(EMLs)和二硝酰胺铵(ADN)为蓝光主体材料的近红外有机发光二级管.器件的基本结构为(p-Si/NPB/EML/Bphen/Bphen:Cs2CO3/Sm/Au),设计并比较了三套不同发射层结构(ErQ/ADN为双层结构器件,(ErQ/ADN)×3为多层结构器件,ErQ:ADN为掺杂结构器件)的器件.三组器件在一定的偏压下,均可发出1.54μm的光,对应三价铒离子4I13/2→4I15/2的跃迁.其中,ADN:ErQ(1∶1)掺杂结构的近红外电致发光强度是ADN/ErQ双层结构中的三倍.此外,不同掺杂浓度的ADN:ErQ复合膜做了以下表征:吸收谱、光致发光谱和荧光寿命谱.实验结果证实了在近红外电致发光过程中存在从ADN主体分子到ErQ发射分子的高效率的能量转移.     

BNBST无铅压电陶瓷的制备工艺研究

设计了（Bi0.55Na0.5）1-X（BaaSrb）xTiO3（BNBST[100x-100a／100b]）无铅压电陶瓷新体系。该体系压电陶瓷具有工艺特性及压电响应好，压电常数高的特点，且有实际应用前景的新型压电陶瓷材料体系。采用传统的陶瓷工艺制备了（Bi0.55Na0.5）1-X（BaaSrb）xTiO3无铅压电陶瓷，研究了制备工艺参数对其物化结构性能的影响。生料的热重-差热（TGA-DTA）分析表明，粉料合成过程中，先是SrTiO3、BaTiO3的形成，然后是（Bi0．5Na0．5）Tio，的形成，同时三者形成固溶体；密度测试表明，陶瓷的体积密度随烧结温度的升高而增大，可较易获得理论密度94％的陶瓷；X-射线能谱分析（EDAX）研究表明，陶瓷的Bi、Na的挥发随着烧结温度的升高而加剧。研究结果表明，要制备性能优良的无铅压电陶瓷，需要精确控制制备工艺。     

Emerging interconnects: a state-of-the-art review and emerging solutions

Aluminium was a primary material for interconnection in integrated circuits (ICs) since their inception. Later, copper was introduced as interconnect material which has better metallic conductivity and resistance to electromigration. As the aggressive technology scaling continues, the copper resistivity increased because of size effects, which causes increase in delay, power dissipation and electromigration. The need to reduce the resistor-capacitor??????? delay, dynamic power utilisation and the crosstalk commotion is as of now the fundamental main impetus behind the presentation of new materials. The purpose of this paper is to do a survey of interconnect material used in IC from introduction of ICs to till date. This paper studies and reviews new materials available for interconnect application which are optical interconnects, carbon nanotube (CNT), graphene nanoribbons (GNRs) and silicon nanowires which are alternatives to copper. While doing a survey of interconnect material, it is found that multiwalled CNTs, multilayer GNR and mixed CNT bundles are promising candidates and are ultimate choice that can strongly address the problems faced by copper but on integration basis copper would last for coming years.     

聚对苯撑苯并双(口恶)唑发光及其器件制备

采用光谱技术,研究了聚对苯撑苯并双(口恶)唑(PBO)溶液的光敏发光特性,并用相对法估算出溶液发光效率在50%范围.结合光谱技术、半导体电学和电化学等研究手段,具体研究了以PBO为发光层的单层电致发光器件,研究结果显示,电致发光与薄膜的光致发光有具有相同的发光中心,峰值位于510 nm左右.同时发现,由于存制备过程中不同处理条件使得不同厚度薄膜残留的掺杂物质浓度不同,从而引起薄膜的导电性的不同.使得器件的阈值场强随PBO厚度的减小而逐渐增加.     

钠离子对poly(dT).poly(dA).poly(dT)三螺旋DNA分子呼吸模式的影响

利用分子结构的螺旋对称性,建立了一个包括钠离子的三链DNA分子poly(dT)*poly(dA)*poly(dT)的晶格动力学模型,计算了poly(dT)*poly(dA)*poly(dT)的氢键呼吸模式.结果发现钠离子的加入明显地淬灭了位于较低频率的几个最为强烈的Hoogensteen氢键呼吸模式,而对Watson-Crick氢键呼吸模式影响不明显,这说明钠离子能提高poly(dT)*poly(dA)*poly(dT)三螺旋结构的稳定性.该计算结果很好地解释了poly(dT)*poly(dA)*poly(dT)的热融化实验.     

人小肠粘膜免疫酶的定位研究—光镜和电镜免疫组织化学染色法

本文对免疫酶组织化学的样品制备程序和染色方法做了详细的阐述。用直接法、间接法和ABC法,对人小肠免疫酶的定位,进行了光镜和电镜的观察,染色阳性反应显著,获得了满意的效果。并对染色技巧做了分析和探讨。     

Arsenic deposition as a precursor layer on silicon (211) and (311) surfaces

We investigate the properties of arsenic (As) covered Si(211) and Si(311) surfaces by analyzing data from x-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) images. We then create a model using total surface energy calculations. It was found that both Si(211) and Si(311) had 0.68±0.08 surface As coverage. Si(211) had 0.28±0.04 Te coverage and Si(311) had 0.24±0.04 Te coverage. The Si(211) surface replaces the terrace and trench Si atoms with As for a lower surface energy, while the Si edge atoms form dimers. The Si(311) surface replaces all terrace atoms and adsorbs an As dimer every other edge site. These configurations imply an improvement in the mean migration path from the bare silicon surface by allowing the impinging atoms for the next epitaxial layer, tellurium (Te), to bind at every other pair of edge atoms, and not the step terrace sites. This would ensure a nonpolar, B-face growth.     

Joint estimation of TOA and DOA in IR-UWB system using a successive propagator method

Impulse radio ultra-wideband (IR-UWB) ranging and positioning require accurate estimation of time-of-arrival (TOA) and direction-of-arrival (DOA). With receiver of two antennas, both of the TOA and DOA parameters can be estimated via two-dimensional (2D) propagator method (PM), in which the 2D spectral peak searching, however, renders much higher computational complexity. This paper proposes a successive PM algorithm for joint TOA and DOA estimation in IR-UWB system to avoid 2D spectral peak searching. The proposed algorithm firstly gets the initial TOA estimates in the two antennas from the propagation matrix, then utilises successively one-dimensional (1D) local searches to achieve the estimation of TOAs in the two antennas, and finally obtains the DOA estimates via the difference in the TOAs between the two antennas. The proposed algorithm, which only requires 1D local searches, can avoid the high computational cost in 2D-PM algorithm. Furthermore, the proposed algorithm can obtain automatically paired parameters and has better joint TOA and DOA estimation performance than conventional PM algorithm, estimation of signal parameters via rotational invariance techniques algorithm and matrix pencil algorithm. Meanwhile, it has very close parameter estimation to that of 2D-PM algorithm. We have also derived the mean square error of TOA and DOA estimation of the proposed algorithm and the Cramer-Rao bound of TOA and DOA estimation in this paper. The simulation results verify the usefulness of the proposed algorithm.     

系统级封装新型埋入式电源滤波结构的研究

在高密度小尺寸的系统级封装(SiP)中,对供电系统的完整性要求越来越高,多芯片共用一个电源网路所产生的电压抖动除了会影响到芯片的正常工作,还会通过供电网路干扰到临近电路和其他敏感电路,导致芯片误动作,以及信号完整性和其他电磁干扰问题.这种电压抖动所占频带相当宽,几百MHz到几个GHz的中频电源噪声普通方法很难去除.结合埋入式电容和电源分割方法的特点,提出一种新型高性能埋入式电源低通滤波结构直接替代电源/地平面.研究表明,在0.65～4GHz的频带内隔离深度可达-40～75 dB,电源阻抗均在0.25ohm以下,实现了宽频高隔离度的高性能滤波作用.分别用电磁场和广义传输线两种仿真器模拟,高频等效电路模型分析这种低通滤波器的工作原理以及结构对隔离性能的影响,并进行了实验验证.