Minimizing energy of integer unit by higher voltage flip-flop: V DDmin-aware dual supply voltage technique

Hiroshi Fuketa, Koji Hirairi, Tadashi Yasufuku, Makoto Takamiya, Masahiro Nomura, Hirofumi Shinohara, Takayasu Sakurai

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


To achieve the most energy-efficient operation, this brief presents a circuit design technique for separating the power supply voltage (V DD) of flip-flops (FFs) from that of combinational circuits, called the higher voltage FF (HVFF). Although VDD scaling can reduce the energy, the minimum operating voltage (VDDmin) of FFs prevents the operation at the optimum supply voltage that minimizes the energy, because the VDDmin of FFs is higher than the optimum supply voltage. In HVFF, the VDD of combinational logic gates is reduced below the V DDmin of FFs while keeping the VDD of FFs at their V DDmin. This makes it possible to minimize the energy without power and delay penalties at the nominal supply voltage (1.2 V) as well as without FF topological difications. A 16-bit integer unit with HVFF is fabricated in a 65-nm CMOS process, and measurement results show that HVFF reduces the minimum energy by 13% compared with the conventional operation, which is 1/10 times smaller than the energy at the nominal supply voltage.

Original languageEnglish
Article number6236208
Pages (from-to)1175-1179
Number of pages5
JournalIEEE Transactions on Very Large Scale Integration (VLSI) Systems
Issue number6
Publication statusPublished - 2013
Externally publishedYes


  • Minimum operating voltage
  • subthreshold circuits
  • variations

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture
  • Electrical and Electronic Engineering


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