Digitally Assisted On-Chip Body Bias Tuning Scheme for Ultra Low-Power VLSI Systems

Hayate Okuhara, Akram Ben Ahmed, Hideharu Amano

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Body bias control is one of the most efficient means to reduce leakage power, adjust process variation, and apply performance boost. However, such control incurs a certain power overhead that has to be reduced, especially in ultra low-power systems. In order to exploit the advantages of body bias control while guaranteeing power efficiency, an on-chip control scheme is required. Conventionally, on-chip body bias control relies on the use of digital-analog converters. However, such analog circuits require a high power supply voltage and an additional power source, resulting in a considerable power overhead and an increased system cost. In this paper, an on-chip 'Digitally assisted Automatic Body-bias Tuning' (DABT) scheme for ultra low-power systems is proposed and evaluated. The proposed scheme controls the body bias voltage so as to meet the timing constraints of a given target system. Since DABT is based on 'Digitally assisted' circuitries, it can decrease the power supply voltage to near-threshold region and, therefore, a significant amount of power overhead can be reduced. The proposed system is fabricated with the 65-nm silicon on thin box (SOTB) process, a fully depleted silicon on insulator technology. We demonstrate that the chip can achieve the expected functionality, even with 0.35 V of power supply voltage, and with only a few micro watts of power overhead. Moreover, the efficiency of the proposed system is evaluated with a MIPS processor, adopted as a case study. According to the obtained evaluation results, the proposed system can enable 80% of leakage reduction while maintaining the frequency required to meet the timing constraints of the adopted target MIPS processor.

Original languageEnglish
Article number8315472
Pages (from-to)3241-3254
Number of pages14
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Volume65
Issue number10
DOIs
Publication statusPublished - 2018 Oct

Keywords

  • Ultra low-power designs
  • automatic body biasing
  • body bias control
  • near-threshold
  • on-chip
  • system design

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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