Driving toward higher I/sub DDQ/ test quality for sequential circuits: A generalized fault model and its ATPG

We propose a generalized stuck-at fault model for sequential circuits under the selective I/sub DDQ/ test strategy. The proposed fault model makes a pessimistic assumption on the Boolean fault effects when the fault is activated. We show that by using the proposed fault model, test sequences of higher quality can be generated and/or selected. We further propose a test vector generation and selection method for this fault model. We present results to illustrate that a high fault coverage for the proposed fault model can be achieved by a small test set under the selective I/sub DDQ/ test environment.