Synthesis of multiple input-change hazard-free combinational switching circuits without feedback†

Abstract

This paper deals with hazards on outputs of combinational circuits without feedback for multiple input changes. A procedure is given to decompose a Boolean function into a feedback free circuit. The procedure either gives a logic hazard-free circuit or shows that the Boolean function cannot be broken down into a feedback free circuit which is free of logic hazards for multiple input changes. The procedure proves that all multiple input change combinational circuits cannot be implemented without dynamic logic hazards with no internal feedback. The result is therefore considerably different than the single input change and multiple input change static logic hazard cases.