A super-pipelined energy efficient subthreshold 240 MS/s FFT core in 65 nm CMOS

Dongsuk Jeon, Mingoo Seok, Chaitali Chakrabarti, David Blaauw, Dennis Sylvester

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


This paper proposes a design approach targeting circuits operating at extremely low supply voltages, with the goal of reducing the voltage at which energy is minimized, thereby improving the achievable energy efficiency of the circuit. The proposed methods accomplish this by minimizing the circuit's ratio of leakage to active current. The first method, super pipelining, increases the number of pipeline stages compared to conventional ultra low voltage (ULV) pipelining strategies, reducing the leakage/dynamic energy ratio and simultaneously improving performance and energy efficiency. Measurements of super-pipelined multipliers demonstrate 30% energy savings and 1.6× performance improvement. Since super pipelining reduces the logic depth between registers, two-phase latch based design is employed to compensate for reduced averaging effects and provide better variation tolerance. The second technique introduces a parallel-pipelined architecture that suppresses leakage energy by ensuring full utilization of functional units and reduces memory size. We apply these techniques to a 16-b 1024-pt complex-valued Fast Fourier Transform (FFT) core along with low-power first-in first-out (FIFO) design and robust clock distribution network. The FFT core is fabricated in 65 nm CMOS and consumes 15.8 nJ/FFT with a clock frequency of 30 MHz and throughput of 240 Msamples/s at V dd=270 mV, providing 2.4× better nergy efficiency than current state-of-art and > 10× higher throughput than typical ULV designs. Measurements of 60 dies show modest frequency (energy) σ/μ spreads of 7% (2%).

Original languageEnglish (US)
Article number6069820
Pages (from-to)23-34
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Issue number1
StatePublished - Jan 2012
Externally publishedYes


  • Fast Fourier Transform (FFT)
  • subthreshold CMOS circuits
  • super-pipelining
  • ultra low voltage (ULV) design

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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