In certain emerging applications, such as microsensor nodes, energy efficiency concerns supercede traditional emphasis on speed. These systems can be operated at much reduced performance levels in order to lengthen their battery lifetimes. Many such low-performance systems consume minimum energy in the sub-threshold region, where the power supply voltage is below the device threshold voltage. This motivates the study of sub-threshold circuit behavior and design methodologies.
The MIT Sub-Threshold Circuits Group explores energy-efficient techniques that take advantage of sub-threshold operation. The group's work span different levels of abstraction, from analyzing the optimal energy point of a given system, modeling energy characteristics of sub-threshold circuits, to developing circuit styles for logic and memory elements that operate at ultra-low voltages. Current projects involve sub-threshold circuit design and techniques to mitigate the effects of variations.