Method and system for automatically determining transparency behavior of non-scan cells for combinational automatic test pattern generation

摘要

A method and system for generating test vectors for testing scan-based sequential circuits that contain non-scan cells using combinational ATPG techniques. The present invention includes the computer implemented step of receiving a netlist description of an integrated circuit device that comprises scan cells and non-scannable cells. Under certain conditions, some non-scan cells may exhibit sequential transparency behavior. The present invention identifies such conditions and characterizes each non-scan cell as sequentially transparent or non-transparent. Based on such characterization, the present invention transforms non-scan cells exhibiting sequential transparency behavior with transparent logic models during combinational ATPG (Automatic Test Pattern Generation) analysis. Because non-scan cells of exhibiting sequential transparency behavior are not replaced with “force-to-X” models, the fault coverage of the test patterns thus generated is significantly improved.