Technology flavor selection and adaptive techniques for timing-constrained 45nm subthreshold circuits

  • Authors:
  • David Bol;Denis Flandre;Jean-Didier Legat

  • Affiliations:
  • Université catholique de Louvain, Louvain-la-Neuve, Belgium;Université catholique de Louvain, Louvain-la-Neuve, Belgium;Université catholique de Louvain, Louvain-la-Neuve, Belgium

  • Venue:
  • Proceedings of the 14th ACM/IEEE international symposium on Low power electronics and design
  • Year:
  • 2009

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Abstract

We investigate techniques to design 45nm minimum-energy subthreshold CMOS circuits under timing constraints, considering the practical case of an 8-bit multiplier. We first show that technology flavor and Vt selections shift minimum-energy point to different operating frequencies, thereby enabling minimum energy in either low- or mid-performance applications. However, we demonstrate that independent dual-Vt assignment to save leakage in non-critical paths is not feasible. We then show that reverse adaptive body biasing (ABB) is potentially more efficient to compensate for global process/temperature variations than adaptive voltage scaling and forward ABB. Nevertheless, its practical efficiency is limited by the affordable VBB range and the value of the body-effect coefficient.