On Transition Fault Diagnosis Using Multicycle At-Speed Broadside Tests

This paper studies issues related to transition fault diagnosis using multicycle broadside tests that are applied at-speed. Two transition fault models were proposed earlier for at-speed simulation, referred to as d-faults and x-faults. Both fault models account for the extra delay of a transition fault in order to allow at-speed simulation. However, they differ in the following ways. (1) The number of x-faults is equal to the number of conventional transition faults, while the number of d-faults grows with the number of cycles in a test. (2) Output responses of x-faults contain unspecified values that result in lower diagnostic resolution. The paper describes a fault diagnosis procedure that combines the use of x-faults for efficiency with the use of d-faults for diagnostic resolution.