FACTOR: a hierarchical methodology for functional test generation and testability analysis

This paper develops an improved approach for hierarchical functional test generation for complex chips. In order to deal with the increasing, complexity of functional test generation, hierarchical approaches have been suggested wherein functional constraints are extracted for each module under test (MUT) within a design. These constraints describe a simplified ATPG view for the MUT and thereby speed up the test generation process. This paper develops an improved approach which applies this technique at deeper levels of hierarchy, so that effective tests can he developed for large designs with complex submodules. A tool called FACTOR (FunctionAl ConsTraint extractOR), which implements this methodology is described in this work. Results on the ARM design prove the effectiveness of FACTOR-ising large designs for test generation and testability analysis.