As digital designs scale down into the sub-100nm regime, the effects of variations are seen to dramatically affect the behavior of the circuit. These may arise from.
Citation:
Keith Bowman, Michael Orshansky, Sachin S. Sapatnekar, "Tutorial II: Variability and Its Impact on Design," isqed, pp.5, 7th International Symposium on Quality Electronic Design (ISQED'06), 2006