Compactor independent fault diagnosis
First Claim
1. A method, comprising:
- receiving a failure log comprising one or more entries indicative of failing test responses captured in a circuit-under-test and compressed by a compactor, the circuit-under-test comprising scan cells that receive test responses from corresponding logic cones;
identifying one or more candidate logic cones for a selected entry of the failure log using a transformation function indicative of which logic cones in the circuit-under-test at least partially contribute to respective failing test responses;
finding fault candidates in the one or more candidate logic cones using a representation of the circuit-under-test; and
storing a list of the fault candidates in a computer-readable medium.
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Accused Products
Abstract
Methods, apparatus, and systems for performing fault diagnosis are disclosed herein. In certain disclosed embodiments, methods for diagnosing faults from compressed test responses are provided. For example, in one exemplary embodiment, a circuit description of an at least partially scan-based circuit-under-test and a compactor for compacting test responses captured in the circuit-under-test is received. A transformation function performed by the compactor to the test responses captured in the circuit-under-test is determined. A diagnostic procedure for evaluating uncompressed test responses is modified into a modified diagnostic procedure that incorporates the transformation function therein. Computer-readable media comprising computer-executable instructions for causing a computer to perform any of the disclosed methods are also provided. Likewise, computer-readable media comprising lists of fault candidates identified by any of the disclosed methods or circuit descriptions created or modified by the disclosed methods are provided.
70 Citations
46 Claims
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1. A method, comprising:
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receiving a failure log comprising one or more entries indicative of failing test responses captured in a circuit-under-test and compressed by a compactor, the circuit-under-test comprising scan cells that receive test responses from corresponding logic cones; identifying one or more candidate logic cones for a selected entry of the failure log using a transformation function indicative of which logic cones in the circuit-under-test at least partially contribute to respective failing test responses; finding fault candidates in the one or more candidate logic cones using a representation of the circuit-under-test; and storing a list of the fault candidates in a computer-readable medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method, comprising:
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transforming a representation of a circuit-under-test into a representation of a transformed circuit-under-test, storing the representation of the transformed circuit-under-test in a computer-readable medium; wherein the circuit-under-test comprises scan cells that capture test responses from respective logic cones and a compactor that compresses the captured test responses, and wherein the transformed circuit-under-test replaces one or more of the scan cells in the circuit-under-test with one or more pseudo-scan-cells configured to capture respective compacted test responses, the one or more pseudo-scan-cells being associated with corresponding logic cones in the transformed circuit-under-test via a representation of the compactor. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A method, comprising:
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receiving a failure log, the failure log being indicative of compressed, failing responses of a circuit-under-test to test patterns applied to the circuit-under-test, the failing responses having been first captured in scan cells of the circuit-under-test and then compressed by a compactor; applying a mathematical representation of the compactor to one or more failing responses associated with one of the test patterns to identify one or more respective candidate logic cones wherein a fault causing the one or more failing responses might exist; applying an effect-cause diagnostic procedure to the one or more respective candidate logic cones to produce diagnostic procedure results; and storing the diagnostic procedure results in a computer-readable medium. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A method, comprising:
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receiving information indicative of one or more failing test responses of a circuit-under-test to one or more test patterns applied to the circuit-under-test, the failing test responses being first captured in scan cells of the circuit-under-test and then compressed by a compactor; identifying fault candidates for one or more of the failing test responses using a path-tracing technique applied to a representation of a transformed circuit-under-test, wherein the representation of the transformed circuit-under-test represents the failing test responses as being compacted first and then captured in pseudo-cell-scans; and storing a list of the identified fault candidates in a computer-readable medium. - View Dependent Claims (31, 32, 33, 34, 35)
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36. A method, comprising:
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receiving a circuit description of an at least partially scan-based circuit-under-test and a compactor for compacting test responses captured in the circuit-under-test; determining a transformation function performed by the compactor to the test responses captured in the circuit-under-test; modifying a diagnostic procedure for evaluating uncompressed test responses into a modified diagnostic procedure that incorporates the transformation function therein; and storing the diagnostic procedure in a computer-readable medium. - View Dependent Claims (37, 38, 39, 40, 41)
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42. A method, comprising:
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receiving a circuit description of an at least partially scan-based circuit-under-test and a compactor for compacting test responses captured in scan cells of the circuit-under-test, the scan cells being located upstream of the compactor; determining a transformation function performed by the compactor to the test responses captured in the scan cells of the circuit-under-test; modifying the circuit description to remove the compactor and embed the transformation function upstream of the scan cells in the circuit-under-test, thereby replacing the scan cells with pseudo-scan-cells; and storing the modified circuit description in a computer-readable medium. - View Dependent Claims (43, 44, 45, 46)
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Specification