基于与非锥的新型FPGA逻辑簇互连结构研究

该文针对新型FPGA可编程逻辑单元与非锥(And-Inverter Cone, AIC)的结构特性,提出一系列方案以得到优化的逻辑簇互连结构,包括:移除输出级交叉矩阵,单级反相交叉矩阵,低负载电路优化,将反馈和输出选择功能分开,限制AIC输出级数的基础上移除中间级交叉矩阵,与LUT架构进行混合等。通过大量的实验,得出针对面积延时积最优的AIC簇互连结构,与Altera公司的FPGA芯片Stratix-IV结构相比,该结构逻辑功能簇本身面积减小9.06%, MCNC应用电路集在基于优化的AIC FPGA架构上实现的平均面积延时积减小40.82%, VTR应用电路集平均面积延时积减小17.38%;与原有的AIC结构相比,簇面积减小23.16%, MCNC应用电路集平均面积延时减小27.15%, VTR应用电路集平均面积延时积减小15.26%。     

一种基于与非锥簇架构FPGA输入交叉互连设计优化方法

该文针对与非锥(And-Inverter Cone, AIC)簇架构FPGA开发中面临的簇面积过大的瓶颈问题,对其输入交叉互连设计优化进行深入研究,在评估优化流程层次,首次创新性提出装箱网表统计法对AIC簇输入和反馈资源占用情况进行分析,为设计及优化输入交叉互连结构提供指导,以更高效获得优化参数。针对输入交叉互连模块,在结构参数设计层次,首次提出将引脚输入和输出反馈连通率分离独立设计,并通过大量的实验,获得最优连通率组合。在电路设计实现层次,有效利用AIC逻辑锥电路结构特点,首次提出双相输入交叉互连电路实现。相比于已有的AIC簇结构,通过该文提出的优化方法所得的AIC簇自身面积可减小21.21%,面积制约问题得到了明显改善。在实现MCNC和VTR应用电路集时,与Altera公司的FPGA芯片Stratix IV(LUT架构)相比,采用具有该文所设计的输入交叉互连结构的AIC架构FPGA,平均面积延时积分别减小了48.49%和26.29%;与传统AIC架构FPGA相比,平均面积延时积分别减小了28.48%和28.37%,显著提升了FPGA的整体性能。     

一种低延迟低功耗的片上全局互连方法

提出了一种用于片上全局互连的混合插入方法.该方法利用中继驱动器和低摆幅差分信号电路在驱动不同长度连线时的优点,将它们混合插入到连线的合适位置,从而降低互连的延时和功耗.模拟结果表明,该方法与已有方法相比在延时、能耗、能耗延时积以及面积等方面都获得了一定程度的改善.     

一种低延迟低功耗的片上全局互连方法

提出了一种用于片上全局互连的混合插入方法. 该方法利用中继驱动器和低摆幅差分信号电路在驱动不同长度连线时的优点，将它们混合插入到连线的合适位置，从而降低互连的延时和功耗. 模拟结果表明，该方法与已有方法相比在延时、能耗、能耗延时积以及面积等方面都获得了一定程度的改善.     

基于正交矩阵的8行寻址LCD驱动电路

在驱动大尺寸STN-LCD屏时,多行寻址(MLA)LCD驱动方式具有比IAPT驱动方式更优良的对比度和抗串扰能力,功耗更低。基于正交矩阵算法,在分析驱动电路原理的基础上设计了一种8行寻址(MLA-8)LCD驱动电路。基于Maxchip 0.18 μm 18 V CMOS工艺实现了流片。测试结果表明,该8行寻址LCD驱动电路比传统IAPT驱动电路的功耗降低了70%。     

C 波段小型化高精度驱动延时组件的研制

介绍了延时线在雷达中的工作原理,分析了延迟时间误差与延迟幅度误差对信号合成的影响。针对驱动延时组件小型化、高精度设计的难点进行了评估,并提出采用微波多层印制电路实现小型化、采用新型调相电路与衰减电路解决延时高精度的设计方案。在此基础上,设计并实现了一种集成延时、放大与功率分配/合成功能的驱动延时组件。根据驱动延时组件各态收发指标测试结果,幅度带内平坦度优于±0.4 d B,延时相位精度≤±5°,延时幅度精度≤±0.5 d B。     

基于增强型延时感知CSE算法的AES S盒电路优化设计

针对高级加密标准（AES）S-盒优化,提出了一种增强型延时感知公共项消除（CSE）算法.该算法能够在不同延时约束条件下优化多常数乘法运算电路,并给出从最小延时到最小面积全范围的面积-延时设计折中.采用该算法优化了基于冗余有限域算术的S盒实现电路,确定了延时最优、面积最优的两种S盒构造.实例优化结果表明所提出算法的优化效率高、优化结果整体延时小.所设计的S盒电路基于65nm CMOS工艺库综合,结果表明,对比于已有文献中S盒复合域实现电路,所提出面积最优S盒电路的面积-延时积最小,比目前最小面积与最短延时的S盒组合逻辑分别减少了17.58%和19.74%.     

MUX-buffer开关互连结构的FPGA芯片I/O互连设计

硬件结构及电子设计的质量是决定FPGA性能的两个重要因素。针对这两个方面,提出了一种通用的FP-GA芯片I/O互连结构,利用"回线"的终端互补原理对各种互连线的悬空终端进行连接。根据所提出的I/O互连结构的特点,在较少编程点的前提下,减少传输管级联个数,对多路选择器和缓冲器进行优化,提出了一种节省芯片面积且速度较快的基于MUX-Buffer结构的布线开关。该结构已在FPGA芯片中实现,对I/O互连的仿真及测试结果表明,所提出的结构及电路实现具有很好的延时可预测性,与常规MUX结构相比,面积-延时乘积降低了10%左右。     

基于数据驱动动态逻辑电路的桶形移位器设计

介绍了一种新型数据驱动的动态逻辑电路。该电路去除了时钟信号,利用适当的输入数据来保持电路正确的逻辑操作。基于数字驱动的动态逻辑电路,设计了一种新型低功耗、高性能的8位桶形移位器。仿真结果表明,在相同的工作频率下,与基于传统动态逻辑电路的8位桶形移位器相比,新型8位桶形移位器的版图面积减少了40%,速度提高了17%,功耗-延迟积减少了14%。     

AC-PDP能量恢复驱动电路的研究

根据表面放电AC-PDP的特性及驱动原理,提出了一种两级的能量恢复电路,并对电路工作过程进行了详细的分析。通过3种结构的能量恢复电路效率进行的详细比较,本电路相对于一级能量恢复电路来说效率得到了很大的提高,相对于多级能量恢复电路,电路的高压MOS管减少了25%,其他元件也相应减少,效率提高了15%。并通过实验证明了此电路的可用性及实用性。     

FPGA的布线开关和互连线段的优化设计

文章以TSMC'0.35μm,三层金属CMOS工艺为基础,对FPGA互连资源中布线开关和互连线段进行了具体分析。研究表明,布线开关中同时混合使用传输门和三态缓冲器以及采用不同逻辑长度的互连线段组合时将会产生较好的面积-延时值。     

Using bus-based connections to improve field-programmable gate-array density for implementing datapath circuits

As the logic capacity of field-programmable gate arrays (FPGAs) increases, they are increasingly being used to implement large arithmetic-intensive applications, which often contain a large proportion of datapath circuits. Since datapath circuits usually consist of regularly structured components (called bit-slices) which are connected together by regularly structured signals (called buses), it is possible to utilize datapath regularity in order to achieve significant area savings through FPGA architectural innovations. This paper describes such an FPGA routing architecture, called the multibit routing architecture, which employs bus-based connections in order to exploit datapath regularity. It is experimentally shown that, compared to conventional FPGA routing architectures, the multibit routing architecture can achieve 14% routing area reduction for implementing datapath circuits, which represents an overall FPGA area savings of 10%. This paper also empirically determines the best values of several important architectural parameters for the new routing architecture including the most area efficient granularity values and the most area efficient proportion of bus-based connections.     

High-speed and low-cost carry select adders utilizing new optimized add-one circuit and multiplexer-based logic

In this paper, we propose some SQuare-RooT (SQRT) Carry SeLect Adder (CSLA) architectures including a high-speed design, a design with the lowest area compared to previous CSLAs, and two hybrid designs. The first proposed architecture is an optimized design of the Binary to Excess-1 Converter (BEC)-based CSLA by employing a new fast and merged add-one and multiplexing circuit. This architecture in addition to attaining much lower area, delay and energy consumption compared to the BEC CSLA, requires almost the same area compared to the best existing CSLA i.e. IRredundant Carry Generation and Selection scheme (IRCGS CSLA) while providing a higher speed. The second proposed CSLA as the lowest-area design is the area-optimized architecture of IRCGS CSLA that exploits a new logic optimization while maintaining its speed. This scheme makes use of a multiplexer-based logic to reduce the number of gates and to achieve a more compact design. In addition, two hybrid CSLAs are proposed by exploiting the benefits of both proposed CSLA architectures. Experimental results show that the hybrid CSLAs lead to lowest area-delay product and energy-delay product among all the proposed and previous designs in a wide range of 8-bit to 128-bit adder size. In fact, 10–48% reduction in area-delay product and 8–65% reduction in energy-delay product are achieved compared to previous designs. Moreover, the hybrid CSLAs outperform the best existing design with respect to all three parameters of area, delay and energy.     

一种基于半监督AdaBoost模型树的FPGA性能表征方法

提出了一种基于半监督自适应增强(Ada Boost)模型树的建模方法,用于现场可编程门阵列(FPGA)的性能表征。该方法以半监督学习方式,构建了FPGA性能关于FPGA架构参数的解析模型,同时采用Ada Boost算法提高FPGA性能模型的预测精确度。使用VTR(Verilog To Routing)电路集,基于该方法构建的性能模型在预测FPGA上实现的应用电路面积时,平均相对误差(MRE)为4.42%;预测延时的MRE为1.63%;预测面积延时积时,MRE为5.06%。与全监督模型树算法以及现有的半监督模型树算法相比较,该方法构建的FPGA实现面积模型的预测精确度分别提高了39%,26%。实验结果显示,该方法在确保较少的时间开销前提下,构建了具有高预测精确度的FPGA性能模型,提供了一种高效的FPGA性能表征方法。     

Three-dimensional switchbox multiplexing in emerging 3D-FPGAs to reduce chip footprint and improve TSV usage

Three-dimensional integration technology is proposed to break down long wires and increase integration level of emerging complex designs. However, efficiency of this technology heavily depends on the usage of Through-Silicon Vias. TSVs are key solutions for cooling the 3D-chips but they occupy considerable silicon area. Therefore, reducing the number of required TSVs in routing step is very critical in 3D-chips. In this paper, a TSV multiplexing approach is proposed to reduce the number of required routing TSV. We proposed two multiplexed 3D-switchbox architectures. In the first architecture, the TSVs inside the switchboxes are multiplexed while in the second architecture, TSVs are multiplexed between the switchboxes. Moreover, a routing algorithm is suggested to route the FPGA using the multiplexed switchboxes to evaluate the proposed architectures. Experimental results show that the presented architectures and algorithms reduce the number of used TSVs by 64.58% and 71.27% on average for the first and second architectures respectively, in cost of a negligible overheads in total wire length and auxiliary switches.     

面向密码算法的异步可重构结构设计

针对FPGA和ASIC在实现密码算法时的不足之处，本文介绍了一种面向密码算法的异步可重构结构。该结构的运算功能由一个可重构单元阵列提供，数据通路由可重构单元之间的相互连接实现，异步通信采用握手信号完成。在分析握手信号传输延时对可重构结构的影响后，文章提出了一种适合该结构的单元信号传输握手控制电路。同时在单元结构中，使用改进的DSDCVS逻辑来设计其运算电路，减小了单元的面积，提高了单元的工作速度。应用实例表明，在实现密码算法时，面向密码算法的异步可重构结构表现出了比FPGA更好的性能。     

A novel and efficient routing architecture for multi-FPGA systems

Multi-FPGA systems (MFSs) are used as custom computing machines, logic emulators and rapid prototyping vehicles. A key aspect of these systems is their programmable routing architecture which is the manner in which wires, FPGAs and field-programmable interconnect devices (FPIDs) are connected. Several routing architectures for MFSs have been proposed, and previous research has shown that the partial crossbar is one of the best existing architectures. In this paper, we propose a new routing architecture, called the hybrid complete-graph and partial-crossbar (HCGP) which has superior speed and cost compared to a partial crossbar. The new architecture uses both hard-wired and programmable connections between the FPGAs. We compare the performance and cost of the HCGP and partial crossbar architectures experimentally, by mapping a set of 15 large benchmark circuits into each architecture. A customized set of partitioning and interchip routing tools were developed, with particular attention paid to architecture-appropriate interchip routing algorithms. We show that the cost of the partial crossbar (as measured by the number of pins on all FPGAs and FPIDs required to fit a design), is on average 20% more than the new HCGP architecture and as much as 25% more. Furthermore, the critical path delay for designs implemented on the partial crossbar were on average 20% more than the HCGP architecture and up to 43% more. Using our experimental approach, we also explore a key architecture parameter associated with the HCGP architecture-the proportion of hard-wired connections versus programmable connections-to determine its best value     

Designing a 3-D FPGA: Switch Box Architecture and Thermal Issues

Three-dimensional (3-D) integration is an attractive technology to reduce wirelengths in a field-programmable gate array (FPGA). However, it suffers from two problems: one, the inter-layer vias are limited in number, and second, the increased power density leads to high junction temperatures. In this paper, we tackle the first problem by designing switch boxes that maximize the use of the vias. Compared to the previously used subset switch box, our best switch box reduces the number of vias by about 49% and area-delay product by about 9%. For the second problem, we utilize the difference in power densities between CLBs and some of the hard blocks in modern FPGAs to distribute the power more uniformly across the FPGA. The peak temperature in a two-layer FPGA reduces by about 16degC after our change.