Poster Presentation 6: Logic Circuits Operating in Both Sub- and Above-Threshold Voltages

Abstract

Interest in VLSI subthreshold design has recently increased due to the emergence of systems that require ultra-low power operation. Furthermore the ever increasing leakage currents, now used to drive logic make subthreshold design an interesting prospect. Subthreshold sacrifices speed for power creating a clear divide between designing for high speed and ultra-low power. It might be beneficial to allow circuits designed for subthreshold operation to become operable at above threshold voltages (super-threshold), depending on processing needs. In this study among other things; the feasibility of optimizing device sizes for both subthreshold and above threshold operations is considered. Three widely publicized body biasing techniques are examined and compared to a newly proposed tunable body biasing scheme. The comparison is in terms of power and energy dissipation as well as speed. A number of logic styles are simulated to draw conclusions on what logic style in conjunction with what body biasing scheme offer improved performance.