双极晶体管关键参数的研究

本文基于双极晶体管的工艺,就如何对电流增益和特征频率两个参数进行优化研究.首先对其进行了器件工艺模拟分析优化,得到模拟特征频率在10 GHz,电流增益为160,而后进行了流片,通过测试得到特征频率为9.5 GHz,电流增益在160以上,最后进行了测试结果和模拟结果的比较分析.     

一种低功耗高噪声源真随机数设计

通过对一种低功耗高噪声源真随机数发生器(TRNG)的研究，设计了一种新型的低频时钟电路，可以把电阻热噪声放大100倍以上，从而减少低频时钟电路的带宽和电阻值，使电路的面积和功耗减少，并且使低频时钟的jitter到达58.2 ns。电路采用SMIC 40 nm CMOS工艺设计，完成了流片和测试，真随机数产生器输出速度范围为1.38～3.33 Mbit/s，电路整体功耗为0.11 mW，面积为0.00789 mm2。随机数输出满足AIS31真随机数熵源测试要求，并且通过了国密2安全测试。     

宽带低相噪CMOS LC VCO的设计

设计了一款宽带CMOSLCVCO,在分析VCO相位噪声来源的基础上,对VCO进行了结构优化和噪声滤除,并采用了开关电容阵列以增加带宽。电路采用0.18μmCMOS射频工艺进行流片验证,芯片面积为0.4mm×1mm。测试结果显示:芯片的工作频率为3.34～4.17GHz,中心频率为4.02GHz时输出功率是-9.11dBm,相位噪声为-120dBc/Hz@1MHz,在1.8V工作电压下的功耗为10mW。     

一个高电源抑制比的有源电感射频放大电路

提出了一种使用有源电感的电路实现方案,可用于宽带无线收发机射频放大电路的设计中.分析了有源电感的阻抗与各元件取值的关系,设计了中心频点调节电路和具有鲁棒性的偏置电路,保证工艺偏差和电源电压波动对有源电感的阻抗具有很弱的影响.在SMIC 0.18-μm工艺下进行了电路设计和流片验证,测试结果表明,使用有源电感的射频放大电路,可以得到期望的射频信号,其中心频点的调节范围为0.5～2 GHz, 能够抵御高达0.8 V的电源偏差.     

单片GaAs 3bit相位DAC的设计与实现

详细论述了用于数字射频存储器系统的单片超高速GaAs 3bit相位DAC的设计、制造及测试.在南京电子器件研究所标准75mm GaAs工艺线采用0.5μm全离子注入MESFET工艺完成流片.芯片输入输出阻抗实现在片50Ω匹配.测试结果表明,其工作带宽大于1.5GHz,相位精度小于4%,电路的码流翻转速率大于12Gbps.     

用于Ka波段卫星通信系统的LTCC滤波器

通过对自主设计流片的Ka波段LTCC滤波器的分析,总结出了一套行之有效的Ka波段LTCC模块的设计方法。试验结果表明,这种将电磁场仿真和实际测试相结合的方法,有效地减小由于模型和工艺误差带来的电路性能的降低,其最终测试结果为在26～30GHz的4GHz带宽范围内带内损耗为1.3dB,输入输出驻波均小于1.5dB。     

应用于无源超高频射频识别标签的嵌入亚阈值参考源电流模稳压电路

本文设计了一种应用于无源超高频射频识别标签的电流模稳压电路。无源标签的能量必须通过整流电路从射频能量中获取。由于输入射频功率的巨大变化，整流电路的输出需经过稳压后才能为标签提供稳定的电源。通过嵌入亚阈值参考源对流向负载的电流进行精确控制，稳压电路的输出在-20-80℃温度范围内稳定在1-1.3V，并实现了约100kHz的带宽，保证了电源的快速恢复。电路在UMC 0.18um混合CMOS工艺下流片实现，电流功耗为1uA。     

一种接收超宽带射频信号的方法研究与仿真分析

在射频接收机的设计中,由于滤波器的带宽和频率源的限制,一般接收机的带宽无法达到几百兆的超带宽范围.设计一种超带宽射频信号的接收方法,通过五路功分和合理选择射频器件,可以在保证信号指标要求的情况下,有效地对250 MHz带宽的射频信号进行接收和下变频.最后通过ADS软件进行射频仿真分析,验证了本接收方法的主要指标满足要求.     

超高频无源射频标签的射频接口设计

对射频标签能量供应原理进行了详细的理论分析,设计了一个超高频远距离无源射频标签芯片的射频接口电路,包括电源恢复电路、稳压电路及解调整形电路。解决了超高频无源射频标签远距离能量供应和信号获取的问题。射频接口电路采用UMC 0.18μm混合信号工艺流片验证。测试结果表明,射频接口电路的性能可满足超高频远距离无源射频标签芯片的要求。     

一种平面宽带Marchand Balun的新型模型

本文提出了一种新的Marchand Balun 模型。通过对构成Balun基本单元的λ/4耦合线进行奇、偶模分析,获得了耦合线的基本等效表达式。基于所提出的5阶集总元件等效电路,耦合线的自感、互感系数和电容均能根据奇偶模特性阻抗计算得到,从而可以较为方便的得到Balun的模型参数。为对模型进行验证,本文基于GaAs工艺设计了一个单片宽带Marchand Balun,并使用三维电磁场工具对其进行了仿真验证,最后通过流片测试对模型进行了实验验证。电磁场仿真与实验结果与所提的模型仿真结果相一致,应用该模型可以使对Marchan Balun的设计变得更为快速和便捷,并且适用于较宽的频带范围。     

一种具有新型分立介质支撑的翼片加载螺旋带慢 波结构的研究

本文研究了一种具有新型分立介质支撑的翼片加载螺旋带慢波系统,该种慢波系统具有较高的功率容量和较宽的带宽.通过用切比雪夫多项式来展开螺旋带上的面电流,用真空层来模拟螺旋带的厚度,用均匀分层介质来等效新型分立介质支撑,考虑到过渡连接金属块的影响,用场论的方法得到了非常实用的色散方程和耦合阻抗的表达式,同时进行了HFSS模拟,发现用场论的方法所得出的结果与用HFSS模拟的结果吻合良好.本文的结果对这种新型慢波结构的设计具有指导意义.     

A Computer Designed, 720 To 1 Microwave Compression Filter

Compression filters with bandwidths up to 1000 MHz have application in high-resolution RADAR system and rapid-scan receiver systems. A technique is presented for realizing a microwave linear delay (quadratic phase) versus frequency compression filter with sufficient delay accuracy to make compression ratios of up to 1000 to 1 feasible. The dispersive element in the compression filter is a silver tape with its broad side placed perpendicularly between the ground planes (instead of parallel, as in conventional stripline). The tape is folded back and forth upon itself in such a way that substantial coupling takes place between adjacent turns of the tape. A computer program has been written to determine the dimensions of the tape to achieve a linear delay versus frequency characteristic. A folded tape compression filter was constructed with a differential delay of 1.2 /spl mu/s over a bandwidth of 600 MHz centered at 1350 MHz giving a compression factor of 720 to 1. This filter was constructed in four identical sections, each section of which had a differential delay of 0.3 /spl mu/s over the same bandwidth as the complete filter. The entire filter (four sections) occupies a volume about 16 by 4 by 5 inches. Measurement data are presented which illustrate that the desired accurate delay characteristic was realized to within the /spl plusmn/ 1 ns measurement uncertainty.     

一种基于端到端测量的路径性能参数估计算法

现有的网络性能估计技术不能实现对路径容量和可用带宽的同时测量.该文通过对存在拥塞链路的路径作随机分析,得到了一种对路径可用带宽的近似估计式,并通过对Kapoor(2004)中的方法进行改进,提出了一种基于端到端的可以同时对单拥塞路径的容量及可用带宽进行估算的算法.在较准确估算路径容量的同时,达到了用同一组样本实例同时估计路径容量和可用带宽的目的.仿真验证了算法的有效性和准确性.     

Multitrack Recording of Reduced Bandwidth TV Signals

The system described here was developed in order to record the pseudorandom scan television signal developed by Deutsch. The objective was to investigate the possibility of recording a 200 kHz video signal on a 1/4 in tape running at 15 in/s. The difficulties which arise in such a task are two-fold: 1) bandwidth limitations of the recorder; and 2) flutter and skew of the recorder. Since a tape recorder at this speed has a bandwidth of about 45 kHz, time-division multiplexing was used to reduce the signal into low-frequency signals. The problem is to reassemble the signals at playback. This is a difficult task since these signals are shifted in time randomly by flutter and skew. Experiments disclose that the skew is linearly distributed across the tape; therefore, by knowing this time shift between two tracks at any instant, the position of the appropriate sample at any other track can be predicted. For skew and flutter compensation purposes two reference signals are recorded on the two outer tracks of the tape. The phaseshift of the reference signals at playback is used as a measure for the skew prediction system for each track. Thus the video signals are sampled at the correct value. In order to reassemble the samples in the correct time sequence, they are stored in analog memory cells. The memory cells are read out with the aid of an oscillator which is in turn synchronized with flutter. The deflection waveforms are also generated synchronous with this oscillator.     

A Novel Routing Protocol for Supporting QoS for Ad Hoc Mobile Wireless Networks

The main purposes of this article are to lessen the influence of the fastchanging network topology, rapidly varying bandwidth information, and the increasing size of routing tables onquality of service routing. Based on DSDV (Destination-Sequenced Distance-Vector) routing protocol formaintaining up-to-date routing information, the related research has to update routing tables when networktopology changes; moreover, the routing tables must be updated periodically even though the networktopology has not changed. To put emphasis on QoS routing, they also have to exchange routing tables by thetime of bandwidth information changes. Furthermore, the size of routing tables increases with the numberof mobile nodes; therefore, the precious wireless bandwidth is wasted on transmitting the large-scalerouting tables. In this article, we propose an on-demand-based QoS routing protocol to mitigate theseproblems and to achieve the QoS requirement. The goal of this article is to discover an optimal routewith minimum time delay for transmitting real-time data from a source node hop by hop to adestination node under some predefined constraints. Our contributions are as follows: our researchprovides a rigorous bandwidth definition and bandwidth application, a broad view of bandwidth calculationand reservation, minimizing the size of control packets and the number of control packet transmissions,and an efficient QoS routing protocol.     

Broadband suspended patch antennas with ground taper transformer

A novel ground taper has been designed and then fabricated using a laser cutter. The taper is used to match the transition between a suspended microstrip line and a microstrip line. This transition is used in the design of a 25 GHz suspended patch antenna deposited onto a polyimide tape and yields an 18% fractional bandwidth     

On Efficient Traffic Distribution for Disaster Area Communication Using Wireless Mesh Networks

In recent time, a great deal of research effort has been directed toward promptly facilitating post-disaster communication by using wireless mesh networks (WMNs). WMN technology has been considered to be effectively exploited for this purpose as it provides multi-hop communication through an access network comprising wireless mesh routers, which are connected to the Internet through gateways (GWs). One of the critical challenges in using WMNs for establishing disaster-recovery networks is the issue of distributing traffic among the users in a balanced manner in order to avoid congestion at the GWs. To overcome this issue, we envision a disaster zone WMN comprising a network management center. First, we thoroughly investigate the problem of traffic load balancing amongst the GWs in our considered disaster zone WMN. Then, we develop traffic load distribution techniques from two perspectives. Our proposal from the first perspective hinges upon a balanced distribution of the bandwidth to be allocated per user. On the other hand, our second perspective considers the dynamic (i.e., varying) bandwidth demands from the disaster zone users that requires a more practical and refined distribution of the available bandwidth by following an intelligent forecasting method. The effectiveness of our proposals is evaluated through computer-based simulations.     

Bandwidth Estimation for IEEE 802.11-Based Ad Hoc Networks

Since 2005, IEEE 802.11-based networks are able to provide a certain level of Quality of Service by the means of service differentiation, thanks to the IEEE 802.11e amendment. However, no mechanism or method has been standardized to accurately evaluate the amount of resources remaining on a given channel. Such evaluation would however be a good asset for bandwidth-constrained applications. In multi-hop ad hoc networks, such evaluation becomes even more difficult. Consequently, despite the various contributions around this research topic, the estimation of the available bandwidth still represents one of the main issues in this field. In this article, we propose an improved mechanism to estimate the available bandwidth in IEEE 802.11-based ad hoc networks. Through simulations, we compare the accuracy of the estimation we propose to the estimation performed by others state of the art QoS protocols, BRuIT, AAC and QoS-AODV.     

PCB中基于DS-EBG结构的宽频带电源噪声抑制

电磁能带隙（EBG）结构能有效解决高频电源完整性问题,但不利于PCB的微型化设计。文章将三维立体封装中使用的双层EBG（DS-EBG）结构应用到PCB电源完整性设计中。通过理论分析证明了它的宽频带电源噪声抑制性能,并利用Ansoft公司SIwave软件进行仿真,成功对理论分析进行了验证。     

基于带状弹簧的空间望远镜自展开机构设计

为了充分减小空间望远镜发射的质量和体积，适应微小卫星的运载需求，针对某光学系统设计了一种基于带状弹簧的新型空间望远镜自展开机构。首先，根据理论分析确定了所用带状弹簧的几何尺寸，并针对某空间光学系统设计了一种基于带状弹簧的新型展开机构；其次，建立了该展开机构的有限元模型并分析了其展开后的特性；最后，搭建了原理样机并对其进行了实验研究。实验结果表明:该展开机构展开后的高度为500 mm，展开后的重复精度误差小于0.1 mm，偏心小于0.1 mm，且展开后的一阶自然频率为35.5 Hz，与有限元分析出的结果相符，其误差为5.3%，能够满足空间望远镜展开机构的结构简单、质量轻、稳定可靠、精度高等要求。