How to Live with Uncertainties: Exploiting the Performance Benefits of Self-Timed Logic In Synchronous Design

Ultra low power digital systems are key for any future wireless sensor nodes but also inside nomadic embedded systems (such as inside the digital front end of software defined radios). These systems require the highest possible energy efficiency of logic, which can only be achieved by operating in moderate inversion. Unfortunately, when operating near the threshold voltage, transistors become highly sensitive to process variations, thereby increasing leakage currents and complicating timing closure. Rather than pursuing a worst-case design approach for dealing with these uncertainties, we present a hybrid self-timed/synchronous approach. It will be demonstrated on the VEX VLIW core designed for ultra low-power operations. Experimental results of our approach demonstrate performance benefits up to 2times and significant energy savings at low throughput rates.