SleepRider: a 5.5µW/MHz Cortex-M4 MCU in 28nm FD-SOI with ULP SRAM, Biomedical AFE and Fully-Integrated Power, Clock and Back-Bias Management

Dekimpe, Rémi;Schramme, Maxime;Lefebvre, Martin;Kneip, Adrian;Bol, David;et.al.
(2021) 2021 Symposium on VLSI Circuits — Location: Kyoto (Japan) (13.June.2021)

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Authors
  • Author
  • Schramme, MaximeUCLouvain
    Author
  • Author
  • Kneip, AdrianUCLouvain
    Author
  • Saeidi, RoghayehUCLouvain
    Author
  • Xhonneux, MathieuUCLouvain
    Author
  • Moreau, LudovicUCLouvain
    Author
  • Gonzalez Gonzalez, Marco Antonioorcid-logoUCLouvain
    Author
  • Author
  • Bol, Davidorcid-logoUCLouvain
    Author
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Abstract
Ultra-low-power microcontrollers (ULP MCUs) face a performance trade-off between energy-efficient computing during activity periods and low sleep power, associated with limited wake-up time and energy. Adaptive back-biasing in FD-SOI, along with near-threshold operation at ultra-low voltage, has brought significant improvements by dynamically shifting the minimum energy point (MEP) along the frequency axis. This work introduces a highly-integrated 64-MHz ULP Cortex-M4 MCU with 96-kB SRAM in 28nm FD-SOI. A clock and power management unit (CPMU) generates all internal supplies and clocks from a 1.8-V supply, while unified frequency and back-bias regulation (UFBBR) performs PVT compensation. Custom 16-kB ULP SRAMs achieve low read/write access energy, 1.2/0.84pJ/32-bit access respectively, and provide 0.98nW/kB ultra-low-leakage data retention. A low-power biomedical analog front-end enables biopotential monitoring. The MEP is 5.5µW/MHz (8.2µW/MHz including conversion losses). Sleep power is 7.7µW with retention of logic state and 32-kB memory.
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Citations

Dekimpe, R., Schramme, M., Lefebvre, M., Kneip, A., Saeidi, R., Xhonneux, M., Moreau, L., Gonzalez Gonzalez, M. A., Pirson, T., & Bol, D. (2021). SleepRider: a 5.5µW/MHz Cortex-M4 MCU in 28nm FD-SOI with ULP SRAM, Biomedical AFE and Fully-Integrated Power, Clock and Back-Bias Management. Proceedings of the 2021 Symposium on VLSI Circuits, 2. https://doi.org/10.23919/VLSICircuits52068.2021.9492365 (Original work published 2021)