Improved state integrity of flip-flops for voltage scaled retention under PVT variation

Yang, Sheng, Khursheed, Saqib, Al-Hashimi, Bashir M., Flynn, David and Merrett, Geoff V. (2013) Improved state integrity of flip-flops for voltage scaled retention under PVT variation IEEE Transactions on Circuits and Systems I Regular Papers, 60, (11), pp. 1-9. (doi:10.1109/TCSI.2013.2252640).


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Through measurements from 82 test chips, each with a state retention block of 8192 flip-flops, implemented using 65-nm design library, we demonstrate that state integrity of a flip-flop is sensitive to process, voltage, and temperature (PVT) variation. It has been found at 25?C that First Failure Voltage (FFV) of flip-flops varies from die to die, ranging from 245-mV to 315-mV, with 79% of total dies exhibiting single bit failure at FFV, while the rest show multi-bit failure. In terms of temperature variation, it has been found that FFV increases by up to 30-mV with increase in temperature from 25?C to 79?C, demonstrating its sensitivity to temperature variation. This work proposes a PVT-aware state-protection technique to ensure state integrity of flip-flops, while achieving maximum leakage savings. The proposed technique consists of characterization algorithm to determine minimum state retention voltage (MRV) of each die, and employs horizontal and vertical parity for error detection and single bit error correction. In case of error detection, it dynamically adjusts MRV per die to avoid subsequent errors. Silicon results show that at characterized MRV, flip-flop state integrity is preserved, while achieving up to 17.6% reduction in retention voltage across 82-dies.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1109/TCSI.2013.2252640
ISSNs: 1057-7122 (print)
Keywords: state integrity, state retention, voltage scaling, online error detection and correction, leakage power reduction
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Organisations: Electronic & Software Systems
ePrint ID: 348727
Date :
Date Event
2 April 2013e-pub ahead of print
Date Deposited: 18 Feb 2013 15:37
Last Modified: 17 Apr 2017 16:00
Further Information:Google Scholar

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