Design of efficient BIST test pattern generators for delay testing

Conventional built-in self-test (BIST) test pattern generators (TPGs) are designed to maximize stuck-at fault coverage in combinational circuits. Such TPGs often provide inadequate coverage of two-pattern tests which are required for the detection of delay faults. In this paper, theoretical results and procedures are presented to design efficient TPGs that ensure high two-pattern coverage for comprehensive delay testing of a circuit under test (CUT). First, new concepts particular to delay testing are identified and exploited to design efficient TPGs based on interleaved cyclic codes. A new concept of test cones is then introduced to further reduce the test length. Finally, the proposed procedures are used to design TPGs for delay testing of ISCAS'89 benchmark circuits and the results demonstrate their effectiveness.