Optimised bit serial modular multiplier for implementation on fieldprogrammable gate arrays

A high-speed architecture for bit serial modular multiplication is presented. The design of this array is highly regular, allowing the specific logic and routing resources available in field programmable gate arrays (FPGAs) to be exploited. Furthermore, an optimised array is presented which exploits the reprogrammability of the FPGA, such that a longer bit length can be implemented on the same FPGA     

An architecture for electrically configurable gate arrays

An architecture for electrically configurable gate arrays using a two-terminal antifuse element is described. The architecture is extensible, and can provide a level of integration comparable to mask-programmable gate arrays. This is accomplished by using a conventional gate array organization with rows of logic modules separated by wiring channels. Each channel contains segmented wiring tracks. The overhead needed to program the antifuses is minimized by an addressing scheme that utilizes the wiring segments, pass transistors between adjacent segments, shared control lines, and serial addressing circuitry at the periphery of the array. This circuitry can also be used to test the device prior to programming and observe internal nodes after programming. By providing sufficient wiring tracks segmented into carefully chosen lengths and a logic module with a high degree of symmetry, fully automated placement and routing is facilitated     

Effect of the prefabricated routing track distribution on FPGAarea-efficiency

In most commercial field programmable gate arrays (FPGA's) the number of wiring tracks in each channel is the same across the entire chip. A long-standing open question for both FPGA's and channeled gate arrays is whether or not some uneven distribution of routing tracks across the chip would lead to an area benefit. For example, many circuit designers intuitively believe that most congestion occurs near the center of a chip, and hence expect that having wider routing channels near the chip center would be beneficial. In this paper, we determine the relative area-efficiency of several different routing track distributions. We first investigate FPGA's in which horizontal and vertical channels contain different numbers of tracks in order to determine if such a directional bias provides a density advantage. Second, we examine routing track distributions in which the track capacities vary from channel to channel. We compare the area efficiency of these nonuniform routing architectures to that of an FPGA with uniform channel capacities across the entire chip. The main result is that the most area-efficient global routing architecture is one with uniform (or very nearly uniform) channel capacities across the entire chip in both the horizontal and vertical directions. This paper shows why this result, which is contrary to the intuition of many FPGA architects, is true. While a uniform routing architecture is the most area-efficient, several nonuniform and directionally biased architectures are fairly area-efficient provided that appropriate choices are made for the pin positions on the logic blocks and the logic block array aspect ratio     

Design and analysis of a dynamically reconfigurablethree-dimensional FPGA

This paper presents the design and analysis of a dynamically reconfigurable field programmable gate array (FPGA) that consists of three physical layers: routing and logic block layer, routing layer, and memory layer. The architecture was developed using a methodology that examines different architectural parameters and how they affect different performance criteria such as speed, area, and reconfiguration time. The resulting architecture has high performance while the requirement of balancing the areas of its constituent layers is satisfied     

Antifuse field programmable gate arrays

An antifuse is an electrically programmable two-terminal device with small area and low parasitic resistance and capacitance. Field-programmable gate arrays (FPGAs) using antifuses in a segmented channel routing architecture now offer the digital logic capabilities of an 8000-gate conventional gate array and system speeds of 40-60 MHz. A brief survey of antifuse technologies is provided. the antifuse technology, routing architecture, logic module, design automation, programming, testing and use of ACT antifuse FPGAs are described. Some inherent tradeoffs involving the antifuse characteristics, routing architecture and logic module are illustrated     

Programmable multiplierless digital filter array for embedded SoCapplications

The authors present a novel, programmable logic array for implementing high performance filter functions within embedded system-on-chip platforms. The novelty of the architecture is demonstrated through its specially tailored configurable logic units, and hierarchical routing scheme. The architecture and routing hierarchy are described using a filter example and results are provided demonstrating scalability, speed, and array utilisation using a typical SoC bus specification     

Medium-Grain Cells for Reconfigurable DSP Hardware

Reconfigurable hardware contains an array of programmable cells and interconnection structures. Field-programmable gate arrays use fine-grain cells that implement simple logic functions. Some proposed reconfigurable architectures for digital signal processing (DSP) use coarse-grain cells that perform 16-b or 32-b operations. A third alternative is to use medium-grain cells with a word length of 4 or 8 b. This approach combines high flexibility with inherent support for binary arithmetic such as multiplication. This paper presents two medium-grain cells for reconfigurable DSP hardware. Both cells contain an array of small lookup tables, or ldquoelementsrdquo, that can assume two structures. In memory mode, the elements act as a random-access memory. In mathematics mode, the elements implement 4-b arithmetic operations. The first design uses a matrix of 4 times 4 elements and operates in bit-parallel fashion. The second design uses an array of five elements and computes arithmetic functions in bit-serial fashion. Layout simulations in 180-nm CMOS indicate that the parallel cell operates at 267 MHz, whereas the serial cell runs at 167 MHz. However, the parallel design requires over twice the area. The proposed medium-grain cells provide the performance and flexibility needed to implement DSP. To evaluate the designs, the paper estimates the execution time and resource utilization for common benchmarks such as the fast Fourier transform. The architecture model used in this analysis combines the cells with a pipelined hierarchical interconnection network. The end results show great promise compared to other devices, including field-programmable gate arrays.     

延迟优化的统一可编程互连电路设计和实现

本文设计了一种对可编程逻辑单元CLB和可编程输出单元IOB均具有统一结构的可编程互连电路。通过偏移互连线和回线技术,使得同种可编程互连线的负载分布均匀,保证了可编程逻辑器件FPGA芯片中信号传输的可预测性和规整性;同时,设计过程中对编程点和驱动器电路进行专门的优化设计,减少了5%延时。运用该互连电路到实例FPGA芯片--FDP芯片中,流片后实测数据表明：该可编程互连电路中各种互连线功能正确,可以正确地完成各种信号的互连,整个芯片的延迟统一而且可预测。     

高速大容量FLASH存储系统设计

介绍所设计的高速、大容量存储卡的组成机制和系统实现方案.采用固态存储芯片FLASH(闪存)为存储介质,FPGA(现场可编程门阵列)为存储阵列的控制核心,针对外部高速数据的输入,引入了多级流水和冗余校验技术,并自动屏蔽了FLASH的坏块.成功实现了用高密 度、相对低速的FLASH存储器对高速实时数据的可靠存储.另外,通过USB和CPCI接口,可以同主机进行良好的数据通信.     

Digit pipelined arithmetic on fine-grain array processors

In this paper, we present a novel scheme for performing fixed-point arithmetic efficiently on fine-grain, massively parallel, programmable architectures including both custom and FPGA-based systems. We achieve anO(n) speedup, wheren is the operand precision, over the bit-serial methods of existing fine-grain systems such as the DAP, the MPP and the CM2, within the constraints of regular, near neighbor communication and only a small amount of on-chip memory. This is possible by means of digit pipelined algorithms which avoid broadcast and which operate in a fully systolic manner by pipelining at the digit level. A base 4, signed-digit, fully redundant number system and on-line techniques are used to limit carry propagation and minimize communication costs. p ]Although our algorithms are digit-serial, we are able to match the performance of the bit-parallel methods, while retaining low communication complexity. Reconfigurable hardware systems built using field programmable gate arrays (FPGA's) can share in the speed benefits of these algorithms. By using the organization of logic blocks suggested in this paper, problems of placement and routing that exist in such systems can be avoided. Since the algorithms are amenable to pipelining, very high throughput can be obtained.     

A Low-Power Field-Programmable Gate Array Routing Fabric

This paper describes a new programmable routing fabric for field-programmable gate arrays (FPGAs). Our results show that an FPGA using this fabric can achieve 1.57 times lower dynamic power consumption and 1.35 times lower average net delays with only 9% reduction in logic density over a baseline island-style FPGA implemented in the same 65-nm CMOS technology. These improvements in power and delay are achieved by 1) using only short interconnect segments to reduce routed net lengths, and 2) reducing interconnect segment loading due to programming overhead relative to the baseline FPGA without compromising routability. The new routing fabric is also well-suited to monolithically stacked 3-D-IC implementation. It is shown that a 3-D-FPGA using this fabric can achieve a 3.3 times improvement in logic density, a 2.51 times improvement in delay, and a 2.93 times improvement in dynamic power consumption over the same baseline 2-D-FPGA.     

Design and Application of a 20K Gate Array

This paper describes the design and architecture of a novel VLSI gate array in CMOS technology and its application for a 3-bit error checking and correcting (ECC) unit. The cell rows of the master are arranged without intermediate channels for routing (``sea of gates'). This scheme can be utilized to build large macro cells and functional blocks like data paths or systolic array cells which are very area consuming to realize in conventional gate arrays. In addition, special pull-up/pull-down cells are included on the chip which can be used for data buses and timing circuits. The technology used is an advanced p-well CMOS process with 1.8-μm geometric channel lengths and a two-layer metallization. There are 260 programmable pads for input/output functions and 20 additional power pads (280 pads in total). Depending on the logic, circuits with up to 25 000 gates can be realized with this device.     

A radiation-hardened SOI-based FPGA

A radiation-hardened SRAM-based field programmable gate array VS 1000 is designed and fabricated with a 0.5 μm partial-depletion silicon-on-insulator logic process at the CETC 58th Institute.The new logic cell (LC),with a multi-mode based on 3-input look-up-table (LUT),increases logic density about 12％ compared to a traditional 4-input LUT.The logic block (LB),consisting of 2 LCs,can be used in two functional modes:LUT mode and distributed read access memory mode.The hierarchical routing channel block and switch block can significantly improve the flexibility and routability of the routing resource.The VS1000 uses a CQFP208 package and contains 392 reconfigurable LCs,112 reconfigurable user I/Os and IEEE 1149.1 compatible with boundaryscan logic for testing and programming.The function test results indicate that the hardware and software cooperate successfully and the VS 1000 works correctly.Moreover,the radiation test results indicate that the VS 1000 chip has total dose tolerance of 100 krad(Si),a dose rate survivability of 1.5 × 1011 rad(Si)/s and a neutron fluence immunity of 1 × 1014 n/cm2.     

The Triptych FPGA architecture

Field-programmable gate arrays (FPGAs) are an important implementation medium for digital logic. Unfortunately, they currently suffer from poor silicon area utilization due to routing constraints. In this paper we present Triptych, an FPGA architecture designed to achieve improved logic density with competitive performance. This is done by allowing a per-mapping tradeoff between logic and routing resources, and with a routing scheme designed to match the structure of typical circuits. We show that, using manual placement, this architecture yields a logic density improvement of up to a factor of 3.5 over commercial FPGAs, with comparable performance. We also describe Montage, the first FPGA architecture to fully support asynchronous and synchronous interface circuits     

Estimating Power for FPGAs Based on Signal Probability Theory

Power dissipation has become one of the key optimization conditions in logic design on field programmable gate arrays (FPGAs), thus the power estimation is necessary for logic design optimization. Nowadays, signal activity data created by logic simulation based on test vectors is essential to be used to determine the toggle rate of each signals and blocks in power estimation tools provided by field programmable gate array (FPGA) electronic design automation (EDA) tools. The accuracy of power estimation highly depends on the quality of test vectors, especially, pattern coverage. As probability distribution can describe the uncertainty signals, this work provides an algorithm which can estimate FPGAs power more effectively and accurately by using signal probability distribution rather than test vectors.     

A CMOS gate array architecture for digital signal processingapplications

A new CMOS gate array architecture for digital signal processing (DSP) is presented. The basic cell structure takes into account the high degree of regularity of DSP datapaths. Therefore, it supports in particular the implementation of systolic arrays in connection with a pipelining scheme of one addition per half clock cycle. Together with a new gate array approach (macrocell design style), macrocells can be implemented efficiently on the new architecture. All DSP macrocells use dynamic transmission gate latches. Furthermore, the routing is done exclusively by cell abutment which results in short intercell routing. The macrocell design style is compared with the conventional gate array approach. In the common gate array approach, conventional gate array architectures are used together with conventional design equipment and layout strategies. The comparison shows a reduction in area and power consumption by a factor of 2.5 and 3.7, respectively. The efficiency increases by a factor of at least nine. These results were proved by analog circuit simulations and test chip measurements     

Clock distribution networks in synchronous digital integratedcircuits

Clock distribution networks synchronize the flow of data signals among synchronous data paths. The design of these networks can dramatically affect system-wide performance and reliability. A theoretical background of clock skew is provided in order to better understand how clock distribution networks interact with data paths. Minimum and maximum timing constraints are developed from the relative timing between the localized clock skew and the data paths. These constraint relationships are reviewed, and compensating design techniques are discussed. The field of clock distribution network design and analysis can be grouped into a number of subtopics: 1) circuit and layout techniques for structured custom digital integrated circuits; 2) the automated layout and synthesis of clock distribution networks with application to automated placement and routing of gate arrays, standard cells and larger block-oriented circuits; 3) the analysis and modeling of the timing characteristics of clock distribution networks; and 4) the scheduling of the optimal timing characteristics of clock distribution networks based on architectural and functional performance requirements. Each of these areas is described the clock distribution networks of specific industrial circuits are surveyed and future trends are discussed