A methodology for the design of dynamic accuracy operators by runtime back bias
Abstract
Mobile and IoT applications must balance increasing processing demands with limited power and cost budgets. Approximate computing achieves this goal leveraging the error tolerance features common in many emerging applications to reduce
power consumption. In particular, adequate (i.e., energy/qualityconfigurable) hardware operators are key components in an error tolerant system. Existing implementations of these operators require significant architectural modifications, hence they are
often design-specific and tend to have large overheads compared to accurate units.
In this paper, we propose a methodology to design adequate datapath operators in an automatic way, which uses threshold voltage scaling as a knob to dynamically control the power/accuracy tradeoff. The method overcomes the limitations of previous
solutions based on supply voltage scaling, in that it introduces lower overheads and it allows fine-grain regulation of this
tradeoff. We demonstrate our approach on a state-of-the-art 28nm FDSOI technology, exploiting the strong effect of back
biasing on threshold voltage. Results show a power consumption reduction of as much as 39% compared to solutions based only
on supply voltage scaling, at iso-accuracy
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