Yield-driven near-threshold SRAM design

Gregory K. Chen, David Blaauw, Trevor Mudge, Dennis Sylvester, Nam Sung Kim

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Voltage scaling is desirable in SRAM to reduce energy consumption. However, commercial SRAM is prone to functional failures when Vdd is scaled. Several SRAM designs scale Vdd to 200-300mV to minimize energy per access, but these designs do not consider SRAM robustness, limiting them to small arrays and sensor type applications. We examine the effects on area and energy for a differential 6T, single-ended 6T with power rail collapsing and an 8T bitcell as Vdd is scaled and the bitcells are sized appropriately to maintain robustness. SRAM robustness is examined using importance sampling to reduce simulation runtime. At high voltages, the differential 6T bitcell is the smallest for the same failure rate, but the 8T bitcell is smaller when V dd is scaled below 450mV. For Vdd below Vth, bitcells must be sized greatly to retain robustness and large arrays become impractical. The differential 6T and 8T designs have the lowest dynamic energy consumption, and the single-ended 6T design has the lowest leakage. The supply voltage for minimum energy operation depends on cache configuration and can be well above Vth for large caches with low dynamic activity.

Original languageEnglish (US)
Title of host publication2007 IEEE/ACM International Conference on Computer-Aided Design, ICCAD
Number of pages7
StatePublished - 2007
Externally publishedYes
Event2007 IEEE/ACM International Conference on Computer-Aided Design, ICCAD - San Jose, CA, United States
Duration: Nov 4 2007Nov 8 2007

Publication series

NameIEEE/ACM International Conference on Computer-Aided Design, Digest of Technical Papers, ICCAD
ISSN (Print)1092-3152


Other2007 IEEE/ACM International Conference on Computer-Aided Design, ICCAD
Country/TerritoryUnited States
CitySan Jose, CA

ASJC Scopus subject areas

  • Software
  • Computer Science Applications
  • Computer Graphics and Computer-Aided Design


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