The Biological Property of Synthetic Evolved Digital Circuits with ESD Immunity - Redundancy or Degeneracy?

Abstract In the ongoing evolutionary process, biological systems have displayed a fundamental and remarkable property of robustness, i.e., the property allows the system to maintain its functions despite external and internal perturbations. Redundancy and degeneracy are thought to be the underlying structural mechanisms of biological robustness. Inspired by this, we explored the proximate cause of the immunity of the synthetic evolved digital circuits to ESD interference and discussed the biological characteristics behind the evolutionary circuits. First, we proposed an evolutionary method for intrinsic immune circuit design. The circuits' immunity was evaluated using the functional fault models based on probability distributions. Then, several benchmark circuits, including ADDER, MAJORITY, and C17, were evolved for high intrinsic immunity. Finally, using the quantitative definitions based on information theory, we measured the topological characteristics of redundancy and degeneracy in the evolved circuits and compared their contributions to the immunity. The results show that redundant elements are necessary for the ESD immune circuit design, whereas degeneracy is the key to making use of the redundancy robustly and efficiently.