Patent ID: 7337379
Filing Date: 2008-02-26
Classification: G01R

Abstract:
1. A diagnosing apparatus for making fault diagnosis to detect a manufacturing failure of an integrated circuit comprising: a pattern generator built in an integrated circuit to generate test patterns; a plurality of shift registers formed by sequential circuit elements, said shift registers being arranged in parallel inside said integrated circuit, the test patterns generated by said pattern generator being shifted into said shift registers, respectively; an output compressor for compressing a plurality of outputs shifted out from said shift registers by converting the outputs into check bits of a Hamming code, and outputting the compressed outputs as a compressed value to the outside of said integrated circuit through pins fewer in number than that of said shift registers; and diagnosing means for comparing an output expected value beforehand obtained with said compressed value from said output compressor to make fault diagnosis, wherein when said diagnosing means diagnoses as a result of the comparison that a fault occurs at one position, said diagnosing means obtains a syndrome by calculating an exclusive OR of the output expected value arid the check bits and specifies a shift register in which the fault exists based on the syndrome and an error vector corresponding to the syndrome which error vector has been beforehand given.