Efficient adaptive voltage scaling system through on-chip critical path emulation

Conventional voltage scaling techniques rely on the characterization and monitoring of a unique critical path. However, the uniqueness of the critical path is a difficult requirement to establish in modern VLSI technologies due to the growing impact of process variations and interconnect parasitics on delay. This paper presents an on-chip critical path emulator architecture which tracks the changing critical path. The ability to emulate the actual critical path recovers most of the large margin added by conventional systems to guarantee a robust operation at all conditions. Due to the reduced margin, the proposed architecture is up to 43% and 23% more energy efficient compared to conventional open-loop and closed-loop voltage scaling systems respectively.