1. Jing Ye 1,2, Yu Hu 1, and Xiaowei Li 1 1 Key Laboratory of Computer System and Architecture Institute of Computing Technology Chinese Academy of Sciences 2 Graduate University of Chinese Academy of Sciences Diagnosis of Multiple Arbitrary Faults with Mask and Reinforcement Effect

2. 2 Motivation 1.Multiple arbitrary faults occur in the circuit 2.Single stuck-at fault model is inadequate for diagnosis Source: [L. M. Huisman IEEE TCAD’04] Distribution of multiplet sizes

3. 3 Outline  Introduction Multiple-fault mask and reinforcement effect Prior work  Proposed diagnosis methodology Overview Fault tuple equivalence tree construction Fault tuple equivalence tree scoring Candidate location choosing and ranking Fault tuple equivalence tree pruning  Experimental results

4. 4 Multiple-fault mask and reinforcement effect Multiple-fault mask effect If the fault effect can be propagated to at least one observation point in the single-fault situation, but be blocked in the multiple- fault situation, then the multiple-fault mask effect occurs. Multiple-fault reinforcement effect If the fault effect can not be propagated to an observation point in the single-fault situation, but can be observed in the multiple-fault situation, then the multiple-fault reinforcement effect occurs. Mask /0 /1 Reinforcement /1

5. 5 Prior work Matching the response of the single suspect fault with the response of the circuit-under-diagnosis [S. Venkataraman, S. B. Drummonds ITC00] [Shi-Yu Huang VTS01] Fault simulation with three-valued logic (0, 1, X) [J. B. Liu, A. Veneris IEEE TCAD05] Using Single Location at A Time (SLAT) patterns [T. Bartenstein, et al. ITC01] [D.B. Lavo, et al. ITC02] [Zhiyuan Wang, et al. IEEE TCAD06] Analyzing fault propagation possibility [Xiaochun Yu, R. D. Blanton ITC08]

6. 6 Proposed diagnosis methodology overview Fault-Tuple A fault-tuple is a set consisting of at least one fault. Fault-Tuple Equivalence Tree (FTET) A failing pattern’s FTET describes the relationship among the suspect faults. First Fault-Tuple A failing pattern’s first fault-tuple is defined as the fault-tuple consisting of all faults at the failing observation points.

7. 7 Fault-tuple equivalence tree construction The line under trace is a gate output. The line under trace is a stem’s fanout branch. All the stem’s fanout branches can be traced. Part of the stem’s fanout branches can be traced. First fault-tuple

8. 8 Fault-tuple equivalence tree construction First fault-tuple The line under trace is a gate output. The line under trace is a stem’s fanout branch. All the stem’s fanout branches can be traced. Part of the stem’s fanout branches can be traced.

9. 9 Fault-tuple equivalence tree construction First fault-tuple The line under trace is a gate output. The line under trace is a stem’s fanout branch. All the stem’s fanout branches can be traced. Part of the stem’s fanout branches can be traced.

10. 10 Fault-tuple equivalence tree construction First fault-tuple The line under trace is a gate output. The line under trace is a stem’s fanout branch. All the stem’s fanout branches can be traced. Part of the stem’s fanout branches can be traced.

11. 11 Fault-tuple equivalence tree construction First fault-tuple The line under trace is a gate output. The line under trace is a stem’s fanout branch. All the stem’s fanout branches can be traced. Part of the stem’s fanout branches can be traced.

12. 12 Fault-tuple equivalence tree scoring The highest score : 1 The faults in a fault-tuple equally share the score of the fault-tuple. Two equivalent fault-tuples get the same score.

13. 13 Candidate location choosing and ranking Having the highest score Appearing the most times The candidate locations chosen at earlier iterations have higher ranks

14. 14 Fault-tuple equivalence tree pruning When a fault is pruned, its equivalent fault-tuple will be pruned. Only when all the faults in a fault-tuple is pruned, the fault- tuple can be pruned.

15. 15 Proposed diagnosis methodology review

16. 16 Arbitrary faults Experimental setup Benchmarks ISCAS’89 ITC’99 Test patterns Nearly 100% single stuck-at fault coverage 5-detect Injected fault types Stuck-at faults Dominant bridging nonfeedback faults Transition faults

17. 17 Evaluation Metrics Run time Diagnosability = The number of identified actual fault locations The number of actual fault locations Resolution = The number of identified actual fault locations The number of final candidate fault locations First-hit 100%, Top-ranked candidate location is an actual fault location 0, Top-ranked candidate location isn’t an actual fault location

18. 18 Diagnosability, Resolution, Run time and First-hit s385842 faults4 faults7 faults Fault Type Diag.Res.R.T.F.H.Diag.Res.R.T.F.H.Diag.Res.R.T.F.H. Stuck-at faults 100%1.001.39s100%98%0.972.77s98%99%0.944.29s100% Transition faults 99%1.001.09s100% 0.992.50s100%99%0.953.66s100% Bridging faults 98%0.941.46s96%97%0.872.80s96%97%0.863.99s96% Arbitrary faults 99%0.961.56s98%100%0.942.62s100%97%0.894.15s100% 10 faults13faults17 faults21 faults Diag.Res.R.T.F.H.Diag.Res.R.T.F.H.Diag.Res.R.T.F.H.Diag.Res.R.T.F.H. 98%0.966.05s94%99%0.957.77s100%98%0.9110.2s100%98%0.8913.2s96% 98%0.925.13s98%100%0.946.31s100%98%0.927,25s100%97%0.8910.1s98% 97%0.815.61s100%98%0.838.66s98%97%0.839.06s98%97%0.7912.6s96% 98%0.915.63s98% 0.887.52s100%97%0.889.55s100%97%0.8812.3s100% Diag.:Diagnosability Res.:Resolution R.T.: Run time F.H.:First-hit

19. 19 Comparison * [Xiaochun Yu, R. D. Blanton ITC08] 21 faults (average) 93% vs 66% 21 faults (average) 0.78 vs 0.56

20. 20 Diagnosis quality and test patterns The relation between N-detect patterns and diagnosability The relation between deterministically generated patterns and randomly generated patterns The larger N is, the higher diagnosability is achieved. The diagnosis method is independent of ATPG method.

21. 21 Conclusion Multiple-fault mask and reinforcement effect is a major issue. Built fault-tuple equivalence trees to consider the mask and reinforcement effect. Evaluate the capability of each suspect fault to explain the failing patterns. The proposed diagnosis methodology is effective when confronting a large number of faults. The proposed diagnosis methodology is independent of fault models, and it can also be applied to any kinds of test patterns.

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