Abstract
Circuits with supply voltages lower than the threshold voltage are called subthreshold circuits, and circuits operating at near-threshold voltage are called near-threshold circuits. Such ultralow-voltage circuits, which are drawing attention for ultralow-power applications, are reviewed in terms of power dissipation and energy in this paper. For the serious problem that the performance of subthreshold circuits is highly sensitive to manufacturing variability and environmental uctuation, which is preventing their practical use, we introduce a solution based on self-adaptive speed control. In addition, we present soft error rates at ultralow-voltage SRAM, since reliability could be a serious concern in medical applications.
