Single Electron Tunneling Delay Insensitive and fluctuation based computation paradigms and circuits

This paper presents two computational paradigms in single electron tunneling (SET) technology that address the unpredictability caused by the stochastic nature of tunneling, which is a widely recognized weakness of SET. The first paradigm is based on circuits that are insensitive to their signal delays. Called delay-insensitive, these circuits work without a clock, and are thus free of any timing restrictions that may interfere with the SET stochastic behavior. The second paradigm goes one step further and allows its signals to be affected by fluctuations, which are expected to be a major problem in nanometer-scale SET circuits. We discuss the SET-based implementations of the basic building blocks required for each paradigm and the techniques for constructing larger circuits from them, taking into account the pros and cons with respect to circuit complexity (area) and technological applicability. Our analysis clearly indicates that, if utilized in the right way, SET probabilistic behavior can become an asset in building predictable SET based circuits and systems, rather than an impediment.