Scaling Perspectives of ULV Microcontroller Cores to 28nm UTBB FDSOI CMOS

de Streel, Guerric [UCL] Bol, David [UCL]

Short-channel effects and variability in bulk technolo-gies limit the interest of CMOS technology scaling for ultra-low-voltage (ULV) logic below 65nm because of the resulting penalty in the energy efficiency. FDSOI has already been predicted to be a good candidate to keep an excellent energy efficiency while increasing speed at ULV. In this paper, we confirm this result by synthesis re-sults of microcontrollers at 0.35V. We show that the use of a mix of overdrive forward back biasing (FBB) voltages in 28nm FDSOI fur-ther improves the energy efficiency. Compare to bulk 65nm CMOS, we were able to reduce the energy per cycle by 64% or increase the frequency of operation by 7x while maintaining energy per operation below 3 W/MHz over a wide frequency range.