Direct logic diagnostics with signature-based fault dictionaries
First Claim
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1. A method of diagnosing faults in a circuit, comprising:
- receiving a signature produced by a signature generator, the signature corresponding to the circuit'"'"'s response to no more than one test pattern;
comparing the signature to entries of a fault dictionary;
matching an entry of the fault dictionary to the signature if the entry identifies a fault that explains the signature; and
storing the fault in a list of fault candidates.
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Abstract
Disclosed herein are representative embodiments of methods, apparatus, and systems for performing diagnostic from signatures created during circuit testing. For example, in one exemplary method disclosed herein, a signature produced by a signature generator is received. In this embodiment, the signature corresponds to the circuit'"'"'s response to no more than one test pattern. The signature is compared to entries of a fault dictionary, an entry of the fault dictionary is matched to the signature if the entry identifies a fault that explains the signature, and the fault is stored in a list of fault candidates.
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Citations
45 Claims
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1. A method of diagnosing faults in a circuit, comprising:
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receiving a signature produced by a signature generator, the signature corresponding to the circuit'"'"'s response to no more than one test pattern;
comparing the signature to entries of a fault dictionary;
matching an entry of the fault dictionary to the signature if the entry identifies a fault that explains the signature; and
storing the fault in a list of fault candidates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of diagnosing faults in a circuit, comprising:
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receiving a signature produced by a signature generator, the signature corresponding to the circuit'"'"'s response to five or fewer test patterns;
comparing the signature to entries of a fault dictionary;
matching an entry of the fault dictionary to the signature if the entry identifies a fault that explains the signature; and
storing the fault in a list of fault candidates. - View Dependent Claims (21)
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22. A method of producing a signature-based fault dictionary for use in diagnosing faults in a circuit, comprising:
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receiving a description of a circuit design;
simulating a response of the circuit design to application of a test pattern, the simulating including simulating the presence of one or more faults in the circuit design;
simulating a signature generator at least partially loading the test response and generating a signature for the at least partially loaded test response; and
storing an entry in a fault dictionary associated with the signature and indicative of the one or more faults if the signature is a failing signature. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A system, comprising:
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a circuit-under-test having one or more scan chains;
a signature generator having inputs coupled to outputs of the one or more scan chains, the signature generator being operable to generate signatures associated with at least a portion of one or more circuit test responses captured in the scan chains, the signature generator being further operable to output the signatures after an interval of scan cycles; and
a signature analysis subsystem coupled to receive the signatures from the signature generator, the signature analysis subsystem being configured to compare a respective signature received from the signature generator to entries of a fault dictionary and to create a list of potential fault candidates if the respective signature is a failing signature and if the failing signature matches one or more entries in the fault dictionary, the potential fault candidates in the list being identified by the one or more matching entries of the fault dictionary, - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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Specification