Multibit retention registers for power gated designs: Concept, design, and deployment

Yu Guang Chen, Hui Geng, Kuan Yu Lai, Yiyu Shi, Shih Chieh Chang

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Retention registers have been widely used in power gated designs to store data during sleep mode. However, their excessive area and leakage power render it imperative to minimize the total retention storage size. The current industry practice replaces all registers with singlebit retention ones, which significantly limits the design freedom and yields suboptimal designs. Toward this, for the first time in the literature, we propose the concept and the design of multibit retention registers, with which only selected registers need to be replaced. The technique can significantly reduce the number of bits that need to be stored and thus the leakage power, but needs several clock cycles for mode transition. In addition, an efficient assignment algorithm is developed to minimize the total retention storage size subject to mode transition latency constraint. Experimental results show that our framework on average can reduce the leakage power in sleep mode by 84% along with additional mode transition latency of 6 to 11 clock cycles, compared with the singlebit retention register-based design.

Original languageEnglish
Article number6774551
Pages (from-to)507-518
Number of pages12
JournalIEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Issue number4
StatePublished - Apr 2014


  • Low power
  • mode transition latency
  • multibit retention register
  • power gating


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