Journal ArticleDOI
New Metrics for the Reliability of Approximate and Probabilistic Adders
TLDR
New metrics are proposed for evaluating the reliability as well as the power efficiency of approximate and probabilistic adders and it is shown that the MED is an effective metric for measuring the implementation accuracy of a multiple-bit adder and that the NED is a nearly invariant metric independent of the size of an adder.Abstract:
Addition is a fundamental function in arithmetic operation; several adder designs have been proposed for implementations in inexact computing. These adders show different operational profiles; some of them are approximate in nature while others rely on probabilistic features of nanoscale circuits. However, there has been a lack of appropriate metrics to evaluate the efficacy of various inexact designs. In this paper, new metrics are proposed for evaluating the reliability as well as the power efficiency of approximate and probabilistic adders. Reliability is analyzed using the so-called sequential probability transition matrices (SPTMs). Error distance (ED) is initially defined as the arithmetic distance between an erroneous output and the correct output for a given input. The mean error distance (MED) and normalized error distance (NED) are then proposed as unified figures that consider the averaging effect of multiple inputs and the normalization of multiple-bit adders. It is shown that the MED is an effective metric for measuring the implementation accuracy of a multiple-bit adder and that the NED is a nearly invariant metric independent of the size of an adder. The MED is, therefore, useful in assessing the effectiveness of an approximate or probabilistic adder implementation, while the NED is useful in characterizing the reliability of a specific design. Since inexact adders are often used for saving power, the product of power and NED is further utilized for evaluating the tradeoffs between power consumption and precision. Although illustrated using adders, the proposed metrics are potentially useful in assessing other arithmetic circuit designs for applications of inexact computing.read more
Citations
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Proceedings ArticleDOI
Approximate computing: An emerging paradigm for energy-efficient design
Jie Han,Michael Orshansky +1 more
TL;DR: This paper reviews recent progress in the area, including design of approximate arithmetic blocks, pertinent error and quality measures, and algorithm-level techniques for approximate computing.
Journal ArticleDOI
Design and Analysis of Approximate Compressors for Multiplication
TL;DR: The results show that the proposed designs accomplish significant reductions in power dissipation, delay and transistor count compared to an exact design; moreover, two of the proposed multiplier designs provide excellent capabilities for image multiplication with respect to average normalized error distance and peak signal-to-noise ratio.
Proceedings ArticleDOI
EvoApproxSb: Library of approximate adders and multipliers for circuit design and benchmarking of approximation methods
TL;DR: The EvoApprox8b library provides Verilog, Matlab and C models of all approximate circuits and the error is given for seven different error metrics.
Journal ArticleDOI
Design of Power and Area Efficient Approximate Multipliers
TL;DR: Synthesis results reveal that two proposed multipliers achieve power savings of 72% and 38%, respectively, compared to an exact multiplier, and have better precision when compared to existing approximate multipliers.
Proceedings ArticleDOI
DRUM: A Dynamic Range Unbiased Multiplier for Approximate Applications
TL;DR: This paper designs a novel approximate multiplier to have an unbiased error distribution, which leads to lower computational errors in real applications because errors cancel each other out, rather than accumulate, as the multiplier is used repeatedly for a computation.
References
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