Masking Asymmetric Line Faults Using Semi-Distance Codes


IEICE TRANSACTIONS (1976-1990)   Vol.E73   No.8   pp.1278-1286
Publication Date: 1990/08/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: Special Section PAPER (Special Issue on Fault-Tolerant Systems)

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This paper proposes a new masking method for asymmetric line faults in LSIs using semi-distance codes, a class of non-linear codes. Faults caused by open or short circuit defects in line areas of LSIs can be made asymmetric by controlling the bus drive and the bus terminal gates. The conditions required for codes to mask these faults are clarified and the codes satisfying these conditions for random faults and adjacent faults, caused by line bridging defects, are constructed by using a new concept of semi-distance. This masking technique has the advantage that no additional circuits, such as error decoders, are needed. The codes have been applied to the bus lines in the address decoders of the 4-Mbit ROMs to improve fabrication yield of the LSIs.