1,720,976 research outputs found
Exploiting Temporal Discharge Current Information to Improve the Efficiency of Clustered Power-Gating
No full textRow-Based Power-Gating: A Novel Sleep Transistor Insertion Methodology for Leakage Power Optimization in Nanometer CMOS Circuits
No full textLeakage power has become a serious concern in nanometer CMOS technologies, and power-gating has shown to offer a viable solution to the problem with a small penalty in performance. This paper focuses on leakage power reduction through automatic insertion of sleep transistors for power-gating. In particular, we propose a novel, layout-aware methodology that facilitates sleep transistor insertion and virtual-ground routing on row-based layouts. We also introduce a clustering algorithm that is able to handle simultaneously timing and area constraints, and we extend it to the case of multi- Vt sleep transistors to increase leakage savings. The results we have obtained on a set of benchmark circuits show that the leakage savings we can achieve are, by far, superior to those obtained using existing power-gating solutions and with much tighter timing and area constraints
Physically Clustered Forward Body Biasing for Variability Compensation in Nanometer CMOS Design
No full textTemporal Discharge Current Driven Clustering for Improved Leakage Power Reduction in Row-Based Power-Gating
No full textThe use of sleep transistors as power-gating elements to cut-off sub-threshold leakage stand-by currents has become a very popular solution to tackle the rise of leakage energy consumption in nano-CMOS designs. One of the most critical challenges in sleep-transistor based power gating is the sizing of the sleep transistor, which mainly depends on the discharge current pattern over time of the set of cells that share a single sleep transistor.
In this work we provide a sleep transistor clustering and sizing methodology that improves over previous solutions by (i) accounting for sleep transistor area constraints (thus implying the possibility of gating only a subset of the cells of the design), and (ii) by utilizing the temporal variations in discharge current pattern to achieve improved leakage power-savings. Experimental results on standard benchmarks show that we can achieve improvement in leakage power savings, compared to previous works, ranging from 12% to 17% on average, depending on the allowed area constraint
Temporal Discharge Current Driven Clustering for Improved Leakage Power Reduction in Row-Based Power-Gating
No full textThis book constitutes the thoroughly refereed post-conference proceedings of 18th International Workshop on Power and Timing Modeling, Optimization and Simulation, PATMOS 2008, featuring Integrated Circuit and System Design, held in Lisbon, Portugal during September 10-12, 2008.
The 31 revised full papers and 10 revised poster papers presented together with 3 invited talks and 4 papers from a special session on reconfigurable architectures were carefully reviewed and selected from numerous submissions. The papers are organized in topical sections on low-leakage and subthreshold circuits, low-power methods and models, arithmetic and memories, variability and statistical timing, synchronization and interconnect, power supplies and switching noise, low-power circuits; reconfigurable architectures, circuits and methods, power and delay modeling, as well as power optimizations addressing reconfigurable architectures
Automatic synthesis of near-threshold circuits with fine-grained performance tunability
No full textNear-Threshold Circuits achieve ultra-low energy operating with significant performance improvement and noise immunity as compared to sub-threshold circuits. However, near-threshold circuit performance is highly sensitive to static and dynamic threshold voltage variations. This makes designing circuits for a target performance very difficult, and post-silicon tunability is required to achieve performance targets without taking huge design margins. In this work, we tackle this problem by proposing a novel dual-Vdd technique for near-threshold operation and show that one can tune the performance of a circuit in a fine-grained manner by powering an optimal sub-set of rows with a slightly higher supply voltage than the rest, without incurring the large cost of distributed level shifters. By varying the percentage of rows at a slightly higher voltage, one can trade-off performance and power in a fine-grained manner. Experimental results show that by employing our dual-Vdd technique, we can improve the performance of several benchmarks up-to 45% while achieving more than 50% lower power as compared to single-Vdd implementations
Fast Computation of Discharge Current Upper Bounds for Clustered Power Gating
No full textThe capability of accurately estimating an upper bound of the maximum current drawn by a digital macroblock from the ground or power supply line constitutes a major asset of automatic power-gating flows. In fact, the maximum current information is essential to properly size the sleep transistor in such a way that speed degradation and signal integrity violations are avoided. Loose upper bounds can be determined with a reasonable computational cost, but they lead to oversized sleep transistors. On the other hand, exact computation of the maximum drawn current is an NP-hard problem, even when conservative simplifying assumptions are made on gate-level current profiles. In this paper, we present a scalable algorithm for tightening upper bound computation, with a controlled and tunable computational cost. The algorithm exploits state-of-the-art commercial timing analysis engines, and it is tightly integrated into an industrial power-gating flow for leakage power reduction. The results we have obtained on large circuits demonstrate the scalability and effectiveness of our estimation approach
Design Exploration of a Thermal Management Unit for Dynamic Control of Temperature-Induced Clock Skew
No full textPower densities and temperatures in today's high performance circuits have reached alarmingly high levels due to increased scaling in feature sizes. Subsequently, the various techniques used to keep them under control have also created "zones" of varying temperatures, thus contributing to temperature gradients inside the chip. These gradients have detrimental effects on the delay of wires, as resistance in metals increases with temperature. Clock nets are extremely susceptible to this effect, since they run through the entire chip. Different techniques have been proposed to counter the impact of temperature on clock speed; they range from re-designing the clock network assuming a stationary profile to more adaptive solutions that allow to dynamically compensate the clock skew through replacement of the original buffers with a specially designed counterpart, called tunable delay buffers (TDBs). Dynamic skew management based on TDBs calls for the presence on the chip of a thermal management unit (TMU), whose purpose is that of periodically choosing the actual delay that each TDB must provide in order to achieve skew optimization. Preliminary implementations of such a unit for basic assumptions on the distribution of sensors and their accuracy have indicated negligible impact on the original design. This work aims at exploring in detail several issues related to TMU design, pivoting on the fact that sensor distribution and its accuracy could in fact impact the design in a significant way depending on the design. We provide the results of a careful exploration we have performed on a meaningful case study, quantifying values for area and power consumptio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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