A perpetuum mobile 32bit CPU on 65nm SOTB CMOS technology with reverse-body-bias assisted sleep mode

Koichiro Ishibashi, Nobuyuki Sugii, Shiro Kamohara, Kimiyoshi Usami, Hideharu Amano, Kazutoshi Kobayashi, Cong Kha Pham

Research output: Contribution to journalArticle

17 Citations (Scopus)


A 32bit CPU, which can operate more than 15 years with 220mAH Li battery, or eternally operate with an energy harvester of in-door light is presented. The CPU was fabricated by using 65nm SOTB CMOS technology (Silicon on Thin Buried oxide) where gate length is 60nm and BOX layer thickness is 10nm. The threshold voltage was designed to be as low as 0.19V so that the CPU operates at over threshold region, even at lower supply voltages down to 0.22V. Large reverse body bias up to -2.5V can be applied to bodies of SOTB devices without increasing gate induced drain leak current to reduce the sleep current of the CPU. It operated at 14MHz and 0.35V with the lowest energy of 13.4 pJ/cycle. The sleep current of 0.14μA at 0.35V with the body bias voltage of -2.5V was obtained. These characteristics are suitable for such new applications as energy harvesting sensor network systems, and long lasting wearable computers.

Original languageEnglish
Pages (from-to)536-543
Number of pages8
JournalIEICE Transactions on Electronics
Issue number7
Publication statusPublished - 2015 Jul 1



  • Low power design
  • Microprocessor

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials

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