427 research outputs found

    On-Chip Transparent Wire Pipelining (invited paper)

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    Wire pipelining has been proposed as a viable mean to break the discrepancy between decreasing gate delays and increasing wire delays in deep-submicron technologies. Far from being a straightforwardly applicable technique, this methodology requires a number of design modifications in order to insert it seamlessly in the current design flow. In this paper we briefly survey the methods presented by other researchers in the field and then we thoroughly analyze the solutions we recently proposed, ranging from system-level wire pipelining to physical design aspects

    Throughput-driven floorplanning with wire pipelining

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    The size of future high-performance SoC is such that the time-of-flight of wires connecting distant pins in the layout can be much higher than the clock period. In order to keep the frequency as high as possible, the wires may be pipelined. However, the insertion of flip-flops may alter the throughput of the system due to the presence of loops in the logic netlist. In this paper, we address the problem of floorplanning a large design where long interconnects are pipelined by inserting the throughput in the cost function of a tool based on simulated annealing. The results obtained on a series of benchmarks are then validated using a simple router that breaks long interconnects by suitably placing flip-flops along the wires

    Optimal digital system design in deep submicron technology

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 165-174).The optimization of a digital system in deep submicron technology should be done with two basic principles: energy waste reduction and energy-delay tradeoff. Increased energy resources obtained through energy waste reduction are utilized through energy-delay tradeoffs. The previous practice of obliviously pursuing performance has led to the rapid increase in energy consumption. While energy waste due to unnecessary switching could be reduced with small increases in logic complexity, leakage energy waste still remains as a major design challenge. We find that fine-grain dynamic leakage reduction (FG-DLR), turning off small subblocks for short idle intervals, is the key for successful leakage energy saving. We introduce an FG-DLR circuit technique, Leakage Biasing, which uses leakage currents themselves to bias the circuit into the minimum leakage state, and apply it to primary SRAM arrays for bitline leakage reduction (Leakage-Biased Bitlines) and to domino logic (Leakage-Biased Domino). We also introduce another FG-DLR circuit technique, Dynamic Resizing, which dynamically downsizes transistors on idle paths while maintaining the performance along active critical paths, and apply it to static CMOS circuits.(cont.) We show that significant energy reduction can be achieved at the same computation throughput and communication bandwidth by pipelining logic gates and wires. We find that energy saved by pipelining datapaths is eventually limited by latch energy overhead, leading to a power-optimal pipelining. Structuring global wires into on-chip networks provides a better environment for pipelining and leakage energy saving. We show that the energy-efficiency increase through replacement with dynamically packet-routed networks is bounded by router energy overhead. Finally, we provide a way of relaxing the peak power constraint. We evaluate the use of Activity Migration (AM) for hot spot removal. AM spreads heat by transporting computation to a different location on the die. We show that AM can be used either to increase the power that can be dissipated by a given package, or to lower the operating temperature and hence the operating energy.by Seongmoo Heo.Ph.D

    Analysis of IP Based Implementation of Adders and Multipliers in Submicron and Deep Submicron Technologies

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    Datapath is at the heart of the microprocessor whose performance is a key factor which determines the performance of the processor. Adders and multipliers are the key elements in the datapath which usually are a measure of the performance of the datapath. So, with scaling of MOS transistors down into the deep submicron regime, it is necessary to investigate the performance of these key elements at such small device sizes. This thesis focuses on investigating the performance of existing architectures of adders and multipliers in the submicron and deep submicron technologies at the physical implementation level. Also, an effort has been made to investigate the performance of pipelined implementations of these architectures. Verilog HDL instantiations of adders and multipliers that are available with the DesignWare Building Block IP of Synopsys have been utilized in this thesis. The entire process of the design right from synthesis of the design down to power analysis of the design has been carried out using various EDA tools and has been automated using scripts written in TCL.School of Electrical & Computer Engineerin

    Coarse-grained reconfigurable array architectures

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    Coarse-Grained ReconïŹgurable Array (CGRA) architectures accelerate the same inner loops that beneïŹt from the high ILP support in VLIW architectures. By executing non-loop code on other cores, however, CGRAs can focus on such loops to execute them more efïŹciently. This chapter discusses the basic principles of CGRAs, and the wide range of design options available to a CGRA designer, covering a large number of existing CGRA designs. The impact of different options on ïŹ‚exibility, performance, and power-efïŹciency is discussed, as well as the need for compiler support. The ADRES CGRA design template is studied in more detail as a use case to illustrate the need for design space exploration, for compiler support and for the manual ïŹne-tuning of source code

    Re-visiting the performance impact of microarchitectural floorplanning

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    Journal ArticleThe placement of microarchitectural blocks on a die can significantly impact operating temperature. A floorplan that is optimized for low temperature can negatively impact performance by introducing wire delays between critical pipeline stages. In this paper, we identify subsets of wire delays that can and cannot be tolerated. These subsets are different from those identified by prior work. This paper also makes the case that floorplanning algorithms must consider the impact of floorplans on bypassing complexity and instruction replay mechanisms

    High-performance long NoC link using delay-insensitive current-mode signaling

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    High-performance long-range NoC link enables efficient implementation of network-on-chip topologies which inherently require high-performance long-distance point-to-point communication such as torus and fat-tree structures. In addition, the performance of other topologies, such as mesh, can be improved by using high-performance link between few selected remote nodes.We presented novel implementation of high-performance long-range NoC link based onmultilevel current-mode signaling and delayinsensitive two-phase 1-of-4 encoding. Current-mode signaling reduces the communication latency of long wires significantlycompared to voltage-mode signaling, making it possible to achieve high throughput without pipelining and/or using repeaters. The performance of the proposed multilevel current-mode interconnect is analyzed and compared with two reference voltage mode interconnects. These two reference interconnects are designed using two-phase 1-of-4 encoded voltage-mode signaling, one with pipeline stages and the other using optimal repeater insertion. The proposed multilevel current-mode interconnect achieves higher throughput and lower latency than the two reference interconnects. Its throughput at 8mm wire length is 1.222GWord/swhich is 1.58 and 1.89 times higher than the pipelined and optimal repeater insertion interconnects, respectively. Furthermore, its power consumption is less than the optimal repeater insertion voltage-mode interconnect, at 10mm wire length its power consumption is 0.75mW while the reference repeater insertion interconnect is 1.066 mW. The effect of crosstalk is analyzed using four-bit parallel data transfer with the best-case and worst-case switching patterns and a transmission line model which has both capacitive coupling and inductive coupling.</p

    Floorplanning with wire pipelining in adaptive communication channels

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    A Pixel Vertex Tracker for the TESLA Detector

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    In order to fully exploit the physics potential of a e+e- linear collider, such as TESLA, a Vertex Tracker providing high resolution track reconstruction is required. Hybrid Silicon pixel sensors are an attractive sensor technology option due to their read-out speed and radiation hardness, favoured in the high rate TESLA environment, but have been so far limited by the achievable single point space resolution. A novel layout of pixel detectors with interleaved cells to improve their spatial resolution is introduced and the results of the characterisation of a first set of test structures are discussed. In this note, a conceptual design of the TESLA Vertex Tracker, based on hybrid pixel sensors is presentedComment: 20 pages, 11 figure
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