ABSTRACT Future computing systems spanning exascale supercomputers to wearable devices demand orders of magnitude improvements in energy efficiency while providing desired performance. The system-on-chip (SoC) designs need to span a wide range of performance and power across diverse platforms and workloads. The designs must achieve robust near-threshold-voltage (NTV) operation in nanoscale CMOS process while supporting a wide voltage-frequency operating range with minimal impact on die cost. We will discuss circuit and design technologies to overcome the challenges posed by device parameter variations, supply noises, temperature excursions, aging-induced degradations, workload and activity changes, and reliability considerations. The major pillars of energy-efficient SoC designs are: (1) circuit/design optimizations for fine-grain multi-voltage & wide dynamic range, (2) fine-grain on-die power delivery & management, (3) dynamic adaptation & reconfiguration, (4) dynamic on-die error detection & correction, and (5) efficient interconnects.