Adaptive fault diagnosis of compressed test responses

A computer-implemented method, comprising:

• identifying one or more failing scan cells of a circuit-under-test from signatures indicative of one or more errors in corresponding compressed test responses received from a feedback-free compactor coupled to the circuit-under-test, the act of identifying comprising,
• selecting one or more scan cell candidates from a set of scan cell candidates, wherein information about one or more previously identified failing scan cells at least partially determines which of the one or more scan cell candidates are selected,
• determining whether the selected one or more scan cell candidates justify the one or more errors in a respective signature, and
• storing scan cell candidates determined to justify the one or more errors in the respective signature in a solution set of one or more failing scan cells associated with the respective signature.

A method, comprising:

• as part of a fault diagnosis process,
• identifying a value in a compressed test response that indicates that an error was captured in at least one scan cell of a circuit-under-test upon application of a test pattern;
• selecting a scan cell candidate from a set of scan cells known to affect the value, the selection being based at least partially on at least one of the following criteria:
• (a) whether the scan cell candidate is known to have captured errors upon application of other test patterns;
• (b) whether the scan cell candidate is located in a scan chain known to have captured errors upon application of other test patterns;
• or (c) the number of error bits in the error signature that are determined in part by scan cells output during the same time period as the scan cell candidate;
• and
• determining whether the scan cell candidate at least partially explains the error in the compressed test response.