A reconfigurable 8T ultra-dynamic voltage scalable (U-DVS) SRAM in 65 nm CMOS

Mahmut E. Sinangil, Naveen Verma, Anantha P. Chandrakasan

Research output: Contribution to journalArticlepeer-review

106 Scopus citations


In modern ICs, the trend of integrating more on-chip memories on a die has led SRAMs to account for a large fraction of total area and energy of a chip. Therefore, designing memories with dynamic voltage scaling (DVS) capability is important since significant active as well as leakage power savings can be achieved by voltage scaling. However, optimizing circuit operation over a large voltage range is not trivial due to conflicting trade-offs of low-voltage (moderate and weak inversion) and high-voltage (strong inversion) transistor characteristics. Specifically, low-voltage operation requires various assist circuits for functionality which might severely impact high-voltage performance. Reconfigurable assist circuits provide the necessary adaptability for circuits to adjust themselves to the requirements of the voltage range that they are operating in. This paper presents a 64 kb reconfigurable SRAM fabricated in 65 nm low-power CMOS process operating from 250mV to 1.2V. This wide supply range was enabled by a combination of circuits optimized for both subthreshold and above-threshold regimes and by employing hardware reconfigurability. Three different write-assist schemes can be selectively enabled to provide write functionality down to very low voltage levels while preventing excessive power overhead. Two different sense-amplifiers are implemented to minimize sensing delay over a large voltage range. A prototype test chip is tested to be operational at 20 kHz with 250 mV supply and 200 MHz with 1.2 V supply. Over this range leakage power scales by more than 50 X and a minimum energy point is achieved at 0.4 V with less than 0.1 pJ/bit/access.

Original languageEnglish (US)
Article number5308728
Pages (from-to)3163-3173
Number of pages11
JournalIEEE Journal of Solid-State Circuits
Issue number11
StatePublished - Nov 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


  • Cache memories
  • Circuit reconfigurability
  • Dynamic voltage scaling
  • Low-power SRAM design


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