FPU加法器的设计与实现

浮点运算器的核心运算部件是浮点加法器,它是实现浮点指令各种运算的基础,其设计优化对于提高浮点运算的速度和精度相当关键。文章从浮点加法器算法和电路实现的角度给出设计方法,通过VHDL语言在QuartusII中进行设计和验证,此加法器通过状态机控制运算,有效地降低了功耗,提高了速度,改善了性能。     

性能改进的16位超前进位加法器

加法运算是最重要最基本的运算,所有的其他基本算术运算,减、乘、除、模乘运算最终都能归结为加法运算。在不同的场合使用的加法器对其要求也不同,有的要求速度更快,有的要求面积更小。基于速度更快的要求,对3种常用加法器从结构与性能上进行比较,给出了综合面积与速度的比较。进而对超前进位加法器进行了进一步改进,加入了流水线结构设计,大大提高了其速度性能。     

一种三级流水线加法器设计

加法器是最基本的运算单元,决定了运算单元的速度。论文对一种采用流水线结构的12位加法器进行设计,提出了设计结构,进行电路仿真,最终采用CSMC0.6um数字工艺进行硬件综合,并采用Encounter进行布局布线等后端设计,最终得到整个加法器的物理版图。     

运算流水线的实现和优化

文章在对流水线性能进行分析的基础上，以双精度浮点运算流水线为例子，阐述了实现多条运算流水机制的方法。并对单条流水线，从设计结构和运算的分段两个方面详细介绍了设计的优化方案，并对优化后流水化设计和传统流水设计进行了可靠性和速度的比较，其速度可以提高近1倍。     

一种高速浮点加法器的设计实现

浮点加法器是协处理器的核心运算部件，是实现浮点指令各种运算的基础，其设计优化是提高浮点运算速度和精度的关键途径。文章从浮点加法器算法和电路实现的角度给出设计方法，并且提出动态与静态结合设计进位链的方案以及前导O预测面积与速度的折衷方法。动态与静态结合设计进位链的方法有效地降低了功耗，提高了速度，改善了性能。目前已经嵌入协处理器的设计中，并且流片测试成功。     

条件推测性十进制加法器的优化设计

随着商业计算和金融分析等高精度计算应用领域的高速发展,提供硬件支持十进制算术运算变得越来越重要,新的IEEE 754-2008浮点运算标准也添加了十进制算术运算规范。该文采用目前最佳的条件推测性算法设计十进制加法电路,给出了基于并行前缀/进位选择结构的条件推测性十进制加法器的设计过程,并通过并行前缀单元对十进制进位选择加法器进行优化设计。采用Verilog HDL对32 bit, 64 bit和128 bit十进制加法器进行描述并在ModelSim平台上进行了仿真验证,在Nangate Open Cell 45nm标准工艺库下,通过Synopsys公司综合工具Design Compiler进行了综合。与现有的条件推测性十进制加法器相比较,综合结果显示该文所提出的十进制加法器可以提升12.3%的速度性能。     

数字信号处理器中阵列乘法器的研究与实现

文章讨论了基本的线形阵列加法器和基于水平压缩矩阵的并行阵列加法器，在此基础上提出了一种改进的阵列乘法器结构．通过生成多位的部分积，大大减少进位传输的延迟，提高乘法器的速度，并通过对三种结构的实现效率进行对比得到了验证。     

64位超前进位对数加法器的设计与优化

设计一个应用于高性能微处理器的快速64位超前进位对数加法器.通过分析超前进位对数加法器原理,提出了改进四进制Kogge-Stone树算法的64位超前进位对数加法器结构,并结合使用多米诺动态逻辑、时钟延迟多米诺逻辑和传输门逻辑等技术来设计和优化电路.该加法器采用SMIC 0.18 μm CMOS工艺实现,在最坏情况下完成一次加法运算时间为486.1 ps,与相同工艺和相同电路结构采用静态CMOS实现相比,大大减少了加法器各级门的延迟时间,取得良好的电路性能.     

基于DSP处理器的加法器的设计

从延迟、功耗、面积等方面对加法器的实现方式性能的比较，适应兼容TMS320C54XDSP处理器的高速、低功耗的需要和结构特点，而采用超前进位加法器的两种设计方案，通过两种方案性能对比和结果分析，最终采用4位一组的分组结构．完成了DSP处理器的40位加法器的设计。     

优化FIR数字滤波器的FPGA实现

基于提高速度和减少面积的理念,对传统的FIR数字滤波器进行改良。考虑到FPGA的实现特点,研究并设计了采用Radix2的Booth算法乘法器以及结合了CSA加法器和树型结构的快速加法器,并成功应用于FIR数字滤波器的设计中。滤波器的系数由Matlab设计产生。仿真和综合结果表明,Booth算法乘法器和CSA算法加法器树,在满足FIR数字滤波器的性能要求的同时,在电路实现面积上、尤其是速度上有明显的优化;并且当数据量越多时,优化也越明显。     

流水线技术在高速数字电路设计中的应用

流水线技术是设计高速数字电路的一种最佳选择之一，对其实现原理作了较形象的阐述。针对加法器在DSP中的重要作用，对流水线加法器中流水线技术的应用作了较深入的说明。同时，对流水线技术中引入寄存器事项也作了较全面的阐述。     

An 800-MHz 1-μm CMOS pipelined 8-b adder using true single-phaseclocked logic-flip-flops

An 8-b adder composed of carry-increment full adders has been designed and implemented in a standard 1.0 μm CMOS technology and successfully tested up to 800 MHz. The performance of this adder is based on a fine-grain pipeline technique using so called “logic-flip-flops”. These edge triggered logic-flip-flops are true single-phase clocked and reduce the cycle time of pipeline stages by combining logic and storage. For low power applications, the power consumption of the 8-b adder can be reduced from 777 mW (5 V Vdd, 800 MHz) down to 144 mW (3 V Vdd, 480 MHz)     

Threshold logic circuit design of parallel adders using resonanttunneling devices

Resonant tunneling devices and circuit architectures based on monostable-bistable transition logic elements (MOBILEs) are promising candidates for future nanoscale integration. In this paper, the design of clocked MOBILE-type threshold logic gates and their application to arithmetic circuit components is investigated. The gates are composed of monolithically integrated resonant tunneling diodes and heterostructure field-effect transistors. Experimental results are presented for a programmable NAND/NOR gate. Design related aspects such as the impact of lateral device scaling on the circuit performance and a bit-level pipelined operation using a four phase clocking scheme are discussed. The increased computational functionality of threshold logic gates is exploited in two full adder designs having a minimal logic depth of two circuit stages. Due to the self-latching behavior the adder designs are ideally suited for an application in a bit-level pipelined ripple carry adder. To improve the speed a novel pipelined carry lookahead addition scheme for this logic family is proposed     

4 GHz bit-stream adder based on ∑△ modulation

The conventional circuit model of a bit-stream adder based on sigma delta(∑Δ) modulation is improved with pipeline technology to make it work correctly at high frequencies.The integrated circuit(IC) of the bit-stream adder is designed with the source coupled logic structure and designed at the transistor level to increase the operating frequency.The IC is fabricated in TSMC's 0.18-μm CMOS process.The chip area is 475×570μm~2.A fully digital∑Δsignal generator is designed with a field programmable gate arr...     

A comparative study on performance and reliability of 32-bit binary adders

In this paper, the performance and reliability of different binary adder families are studied for both the superthreshold and the near-threshold regions of operation. The adder structures are selected from both the carry propagate adders (CPAs) and parallel prefix adders (PPAs). The performance parameters which are used in the comparative study include delay, power, energy, and energy-delay-product (EDP) of the adders. Additionally, the impacts of the process variation and negative bias temperature instability (NBTI) on the delays of the adders under the aggressive supply voltage scaling are investigated. Also, the efficacies of the adders are compared using a merit function based on their performance and reliability parameters for a wide range of supply voltage levels, from the nominal voltage down to the near-threshold voltage. The study is performed for the 32-bit adder structures designed based on the 14-nm FinFET and 45-nm bulk CMOS technologies. The results which are obtained using HSPICE simulations, reveal that the reliability parameters similar to the performance parameters are a function of the adder architectures and those are the key components to determine the efficiencies of the adders. Also, the results show that the impacts of the process variation and NBTI on the delays of the high performance PPA structures are more than those of the CPA structures for the whole range of the supply voltage. The PPAs, however, have the higher merit factors compared to the CPAs under a wide range of supply voltage levels. The results presented in this paper may provide some guidelines for the designers to select proper adder structures based on their design requirements and constraints.     

基于分段查找表的高速FIR滤波器的设计实现

提出了一种基于分段查找表的高速FIR滤波器的实现结构,该结构可应用于任意阶数的高速FIR滤波器设计中。采用分段查找表代替传统的乘法器、在加法输出级中插入流水线,以提高滤波器的工作速度;同时,通过数据预处理和查找表复用技术,降低了硬件开销。该设计方法已应用于射频识别超高频阅读器接收端的低通滤波器设计中,性能经Altera Stratix II FPGA测试后,可得到最高工作频率为170.44 MHz,比传统结构的提高了96.44 MHz,且硬件资源消耗较少,约为传统结构的三分之一。     

High Speed Error Tolerant Adder for Multimedia Applications

In this paper, a 1-bit modified full adder (MFA) cell is proposed. This eliminates the carry propagation during the addition by allowing errors in the carry bit. Using the proposed MFA, a 16-bit high speed error tolerant adder (HSETA) circuit is designed with conventional carry select adder (CSLA) structure for higher order bits and MFA based structure for lower order bits. The performance of HSETA is compared with existing adders in terms of accuracy, gate count, delay and power dissipation. The gate count of the HSETA is reduced by 23% and speed is improved by 43% compared to a conventional 16-bit adder structure. Further, implementation on FPGA Spartan 6 shows that HSETA uses 53% fewer LUT and 63% fewer slices compared to the conventional adder. Image blending application is used to evaluate the performance of the HSETA. In addition, to perform extensive error analysis, an analytical model is developed for HSETA and tested for varying bit widths and input probabilities. The analytical model is validated through simulation.     

Performance analysis of low-power 1-bit CMOS full adder cells

A performance analysis of 1-bit full-adder cell is presented. The adder cell is anatomized into smaller modules. The modules are studied and evaluated extensively. Several designs of each of them are developed, prototyped, simulated and analyzed. Twenty different 1-bit full-adder cells are constructed (most of them are novel circuits) by connecting combinations of different designs of these modules. Each of these cells exhibits different power consumption, speed, area, and driving capability figures. Two realistic circuit structures that include adder cells are used for simulation. A library of full-adder cells is developed and presented to the circuit designers to pick the full-adder cell that satisfies their specific applications     

Real-time image template matching based on systolic array processor

An architecture based on a systolic array for real-time image template matching is presented. The architecture consists mainly of four elements: a digitizer, a two-dimensional systolic array combined with variable-length shift register arrays, an adder tree, and a comparator. All the elements form a four-stage pipeline. The image data enter the pipe sequentially in the same order as the TV raster scan. The matching computation is, however, performed in a parallel manner. The analyses on time complexity and hardware complexity have shown that real-time performance is achieved. The analyses have also shown that the processing speed is higher and the hardware is simpler when compared to the architecture presented by Chou and Chen.     

Evaluation of three 32-bit CMOS adders in DCVS logic for self-timedcircuits

The efficient implementation of adders in differential logic can be carried out using a new generate signal (N) presented in this paper. This signal enables iterative shared transistor structures to be built with a better speed/area performance than a conventional implementation. It also allows adders developed in domino logic to be easily adapted to differential logic. Based on this signal, three 32-b adders in differential cascode switch voltage (DCVS) logic with completion circuit for applications in self-timed circuits have been fabricated in a standard 1.0-μm two-level metal CMOS technology. The adders are: a ripple-carry (RC) adder, a carry look-ahead (CLA) adder, and a binary carry look-ahead (BCL) adder. The RC adder has the best levels of performance for random input data, but its delay is significantly influenced by the length of the carry propagation path, and thus is not recommended in circuits with nonrandom input operands. The BCL adder is the fastest but has a high cost in chip area. The CLA adder provides an intermediate option, with an area which is 20% greater than that of the RC adder. Its average delay is slightly greater than that of the other two adders, with an addition time which increases slowly with the carry propagate length even for adders with a high number of bits