A novel automatic test pattern generator for asynchronous sequential digital circuits

A novel automatic test pattern generator (ATPG) for stuck-at faults of asynchronous sequential digital circuits is presented. The developed ATPG does not require support by any design-for-testability method nor external software tool. The shortest test sequence generation is guaranteed by breadth-first search. The contribution is unique hazard identification before the test generation process, state justification on the gate level, sequential fault propagation based on breadth-first search and stepwise composition of state graphs for sequential test generation. A new six-valued logic together with a new algorithm was developed for hazardous transition identification. The internal combinational ATPG allows to generate test patterns one by one and only if it is required by sequential test generation. The developed and implemented ATPG was tested with speed-independent and quasi-delay-insensitive benchmark circuits.