谈谈开关元件的特性

开关是常用的电气元件之一。当开关元件被打开时,不管其两端的电压值是多少,电流恒为零;当它被合上时,不管流经开关元件的电流值是多少,电压恒为零。本文通过电路实例进一步讨论了开关元件的电路特性,得出了在某些情况下,即开关元件两端存在电压跃变,且有冲激电流流经时,开关元件将消耗电路的能量的结论。同时讨论了用阶跃函数简化表示含开关元件的电路时两者的区别。本文的分析。对电路理沦和电路分析的教学具有一定的意义。     

大规模RapidIO协议交换的FPGA实现

RapidIO交换模块是RapidIO系统的核心模块,决定了整个RapidIO系统的数据带宽.文中介绍了一种大规模RapidIO协议交换的FPGA实现方式,并且在基于VPX总线的RapidIO交换模块中得到实际应用.该交换模块除具有RapidIO协议交换功能,还具有RapidIO系统主控功能以及以太网交换功能.经过使用实际的RapidIO端点模块进行测试,该交换模块实现了RapidIO交换功能以及RapidIO系统主控功能.     

一种基于输入队列的新型交换机结构的研究

日前广泛使用的交换机采用输出队列结构，系统可扩展性差、通信速度有限等缺点。文章提出一种基于输入队列的新型交换机结构，通过采用双口存储器来实现交换机的输入缓冲区，通过多数据包查询技术来提高交换机的通信性能。分析结果表明：文章设计的交换机系统吞吐量可达到理论吞吐量的95．748％．接近于输出队列交换机，但需要的存储器带宽只有输出队列交换机的1/N为交换机的端口数），大大提高了系统的可扩展性。     

Tandem-crosspoint ATM switch with input and output buffers

This letter proposes a high-speed input and output buffering asynchronous transfer mode (ATM) switch, named the tandem-crosspoint (TDXP) switch, The TDXP switch consists of multiple crossbar switch planes, which are connected in tandem at every crosspoint. The TDXP switch does not increase the internal line speed in eliminating head-of-line (HOL) blocking. In addition, since the TDXP switch employs a simple cell reading algorithm at the input buffer in order to retain the cell sequence, the TDXP switch does not require the cell sequences to be rebuilt at output buffers using time stamps, as is required by a parallel switch. It is shown that the TDXP switch can eliminate the HOL blocking effectively and achieve high throughput     

一种高线性度CMOS自举采样开关

作为ADC系统与外界的接口,采样开关的性能优劣直接决定了ADC所接收到的信号纯度和真实性。高线性度的CMOS开关可在极大程度上抑制采样时间不确定、时钟馈通和电荷注入等非线性误差。文章首先讨论了MOS采样开关非线性的来源和互补型CMOS采样开关的不足之处,然后设计实现了一种高线性度CMOS自举采样开关。仿真结果表明所设计的高线性度CMOS自举开关的SFDR达101.5dB,可以适用于16位精度的ADC应用要求。     

A High Power CMOS Switch Using Substrate Body Switching in Multistack Structure

A novel high power CMOS RF switch using the substrate body switching technique in a multistack structure is designed, implemented, and characterized in a standard 0.18- triple-well CMOS process. One of the stacked devices in the receive side has a body switch at the bulk port in order to provide high power handling capability to the transmit switch side without compromising insertion loss to the receiver switch. The body switch connected to the bulk port at one of the receiver switches turns on in mode to minimize leakage current into path. In the meanwhile, that switch turns off in mode so that the bulk port can have body floating to reduce leakage current to substrates. Experimental data show that the switch using the body-switching technique has 1 dB of 31.5 dBm that is 2.5 dB higher than the one using the body floating technique. Insertion loss is 1.5 dB at 1.9 GHz in the transmit switch and 1.8 dB in the receiver switch. Isolation is less than 30 dB for switch and 20 dB for switch at 1.9 GHz.     

一种新型的负载均衡-交叉点缓冲交换结构

针对混合输入-交叉点队列(CICQ)交换结构受限于"流控通信延时"、"需要2倍内部加速仿真输出队列(OQ)交换"以及单纯交叉点缓冲(CQ)存在"非均衡流量模式下吞吐量性能不足"等问题,本文提出一种新型的"负载均衡交叉点缓冲交换结构".采用固定模式时隙轮转匹配进行负载均衡处理,将到达输入端口的非均衡流量转化为近似均衡流量并且平均分配到同一输出端口对应的交叉缓冲中,从而可以利用较小的交叉点缓冲来模拟输出队列调度,简化调度过程并且提高吞吐量.理论分析证明了这种新结构的稳定性以及模拟输出队列交换的能力.同时仿真表明,采用该交换结构可以在不需要内部加速的条件下获得相当于输出队列交换的性能,并且有效地解决了交叉点缓冲队列非均衡流量性能不足的问题.     

Output-queued switch emulation by fabrics with limited memory

The output-queued (OQ) switch is often considered an ideal packet switching architecture for providing quality-of-service guarantees. Unfortunately, the high-speed memory requirements of the OQ switch prevent its use for large-scale devices. A previous result indicates that a crossbar switch fabric combined with lower speed input and output memory and two times speedup can exactly emulate an OQ switch; however, the complexity of the proposed centralized scheduling algorithms prevents scalability. This paper examines switch fabrics with limited memory and their ability to exactly emulate an OQ switch. The switch architecture of interest contains input queueing, fabric queueing, flow-control between the limited fabric buffers and the inputs, and output queueing. We present sufficient conditions that enable this combined input/fabric/output-queued switch with two times speedup to emulate a broad class of scheduling algorithms operating an OQ switch. Novel scheduling algorithms are then presented for the scalable buffered crossbar fabric. It is demonstrated that the addition of a small amount of memory at the crosspoints allows for distributed scheduling and significantly reduces scheduling complexity when compared with the memoryless crossbar fabric. We argue that a buffered crossbar system performing OQ switch emulation is feasible for OQ switch schedulers such as first-in-first-out, strict priority and earliest deadline first, and provides an attractive alternative to both crossbar switch fabrics and to the OQ switch architecture.     

阵元切换时间对单通道阵列测向性能的影响

单通道阵列采用单个通道贯续接入各阵元进行采样,与常规阵列相比,单通道阵列减少了硬件成本以及通道幅相特性不一致问题对估计性能的影响,但现有研究均未考虑单通道阵列的阵元切换时间对系统性能的影响。为填补这一空白,首先参照常规阵列,明确了单通道阵列中窄带信号的带宽限制及其与单通道阵列阵元切换时间的关系;再以单通道阵列MUSIC算法为例,同时考虑信号带宽与单通道阵列阵元切换时间对单通道阵列协方差阵特性的影响,从理论上推导了单通道阵列MUSIC算法关于扩展相对带宽的一阶估计误差。最后对单通道阵列MUSIC算法与单通道阵列空间FFT算法在不同阵元切换时间下进行仿真,对两种算法测向误差与阵元切换时间的关系进行分析,验证了理论推导结果的正确性。      

射频开关及其在通信系统中的应用

主要针对无线通信系统中的身频电子开关进行分类讨论。总结了射频开关的带宽、插入损耗、隔离度、功率容量、开关速度、VSWR、功耗、使用寿命和尺寸等主要性能指标。讨论了铁氧体／机械开关、固态开关(PIN开关和FET开关)和MEMS开关的工作机理、各项技术指标以及优缺点。列表比较了各类开关。简述了开关矩阵在未来无线通信系统阵列天线中的作用及应用。最后,指出了射频开关的发展方向和动态。     

Discrete-Time Queuing Analysis of Dual-Plane ATM Switch with Synchronous Connection Control

In this paper, we propose an ATM switch with the rate more than gigabits per second to cope with future broadband service environments. The basic idea is to separate the connection control flow from the data information flow inside the switch. The proposed switch has a dual-plane switch matrix with the synchronous control algorithm. The queuing behaviors of the proposed switch are shown by the discrete-time queuing analysis. Numerical analyses are taken both in the non-blocking crossbar switch and the banyan switch with internal blocking. Results show that a proposed dual-plane 16×16 switch would have the acceptable performance with maximum throughput of about 95 percent.     

大容量光电交换技术研究

高效灵活地利用已有带宽,充分、高效和灵活地调度和控制各种粒度的业务,保证业务的生存性是光交换网络亟需解决的技术问题。为此文章探讨了融合光通路数据单元（ODUk）/分组的新型交换机制、光纤/ODUk/分组混合交换机制。文章认为新的交换机制和多粒度交换结构是超大容量实现和构建的关键,业务多粒度生存性及协调机制、业务适配、带宽分配、管理和控制、损伤监测等是需要研究的重点问题。     

多层交换技术

交换技术已经成为影响网络发展的一项重要技术 ,从最初的链路层交换发展到IP交换直到今天的多层交换 ,其技术越来越成熟 ,应用前景也越来越广泛。集中介绍和分析了目前出现的多层交换技术并探讨了交换技术的发展方向 ,讨论了未来的技术市场的需求     

Layout techniques for FPGA switch blocks

This paper presents abstract layout techniques for a variety of field-programmable gate array switch block architectures. For subset switch blocks of small size, we find the optimal implementations using a simple metric. We also develop a tractable heuristic that returns the optimal results for small switch blocks and good results for large switch blocks. We show how it is possible to transform universal switch blocks into a subset architecture by using the decomposition property of universal switch blocks. This allows universal switch blocks to exploit the same layout methodologies as presented for subset architectures.     

宽带交换技术的演变与进展

本文简要分析了复用与交换技术的演变以及未来的光交换,分析了交换设备的构成及相关的网络控制与管理技术。阐述了作为IP与ATM融合的新一代网络交换技术－多协议标记交换（MPLS）,及其在光网络中的应用。进而分析了基于软交换技术的下一代网络结构,指出了业务、控制与交换将分离的趋势。最后指出,新型交换技术－MPLS和软交换将在网络演进过程中扮演极其重要的角色。     

Matching output queueing with a multiple input/output-queued switch

We have previously proposed an efficient switch architecture called multiple input/output-queued (MIOQ) switch and showed that the MIOQ switch can match the performance of an output-queued switch statistically. In this paper, we prove theoretically that the MIOQ switch can match the output queueing exactly , not statistically, with no speedup of any component. More specifically, we show that the MIOQ switch with two parallel switches (which we call a parallel MIOQ (PMIOQ) switch in this paper) can provide exact emulation of an output-queued switch with a broad class of service scheduling algorithms including FIFO, weighted fair queueing (WFQ) and strict priority queueing regardless of incoming traffic pattern and switch size. To do that, we first propose the stable strategic alliance (SSA) algorithm that can produce a stable many-to-many assignment, and prove its finite, stable and deterministic properties. Next, we apply the SSA algorithm to the scheduling of a PMIOQ switch with two parallel switches, and show that the stability condition of the SSA algorithm guarantees for the PMIOQ switch to emulate an output-queued switch exactly. To avoid possible conflicts in a parallel switch, each input-output pair matched by the SSA algorithm must be mapped to one of two crossbar switches. For this mapping, we also propose a simple algorithm that requires at most 2N steps for all matched input-output pairs. In addition, to relieve the implementation burden of N input buffers being accessed simultaneously, we propose a buffering scheme called redundant buffering which requires two memory devices instead of N physically-separate memories. In conclusion, we demonstrate that the MIOQ switch requires two crossbar switches in parallel and two physical memories at each input and output to emulate an output-queued switch with no speedup of any component.     

基于MEMS的光开关技术研究

介绍了光开关、MEMS和MEMS光开关的基本概念.基于功能实现,重点分析了二维和三维MEMS光开关的实现机理与特性.针对两者不足,研究了一维MEMS光开关.分析了MEMS光开关的驱动方式,并针对静电驱动、二维MEMS光开关,研究了MEMS光开关控制系统.     

一种晶闸管自然关断点检测判断方法

串联逆变器工作在谐振状态时,极易实现开关元件的自然关断,不仅可以省去开关元件关断驱动电路,简化逆变器设计,同时开关元件的开关损耗也达到最小。为了确保半桥串联逆变器工作在谐振状态,使其开关元件工作在自然换向状态,利用过零点和峰值双要素检测方法判断逆变电路开关元件是否自然关断,进而控制开关元件开关的工作点,使逆变电路工作在谐振状态。     

基于ATM的MPLS交换结构研究

文章研究了基于ATM的MPLS交换设备的总体结构,重点研究和分析了具体实现MPLS交换的两种结构,为MPLS交换设备的具体研制提供了交换结构的参考.     

On the speedup required for work-conserving crossbar switches

This paper describes the architecture for a work-conserving server using a combined I/O-buffered crossbar switch. The switch employs a novel algorithm based on output occupancy, the lowest occupancy output first algorithm (LOOFA), and a speedup of only two. A work-conserving switch provides the same throughput performance as an output-buffered switch. The work-conserving property of the switch is independent of the switch size and input traffic pattern. We also present a suite of algorithms that can be used in combination with LOOFA. These algorithms determine the fairness and delay properties of the switch. We also describe a mechanism to provide delay bounds for real-time traffic using LOOFA. These delay bounds are achievable without requiring output-buffered switch emulation