Multicycle Tests With Fault Detection Test Data for Improved Logic Diagnosis
Irith Pomeranz · IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems · 2021
Volume logic diagnosis is typically applied in two phases. In the first phase, a fault detection test set is used for collecting fail data and performing logic diagnosis. If the fail data based on a fault detection test set is not sufficient for accurate logic diagnosis, a faulty unit is considered again in the second phase with a larger diagnostic test set. When diagnostic tests are generated, the defects present in the faulty units they target are unknown, and the tests are generated for target faults. This article suggests that the use of multicycle tests with the same input test data (scan-in states and primary input vectors) as the tests in a fault detection test set can address this issue. Under the approach suggested in this article, a multicycle test is considered useful for diagnosis when it causes the faulty unit to produce more fail data than tests with fewer cycles and the same input test data. The volume of fail data is obtained directly from the faulty unit and does not require the use of target faults. This article discusses the tester support needed for this approach, and its effect on the logic diagnosis procedure. It presents experimental results for benchmark circuits to demonstrate the extent to which it is effective.