Extended binary nonlinear codes and their application in testing and compression

In this paper, we show that the binary linear codes can be extended by a relatively big number of check bits in such a way that the code words preserve the value of a maximum number of independently specified bits from the original linear code words. It can improve pattern compression and-or pseudo-exhaustive testing. Existing linear compression and testing techniques adopt linear codes either for pattern expansion in the decompressor or for pattern generation. The minimum code distance of the dual linear code determines the encoding efficiency, the greater distance causes the bigger maximum number of independently specified bits on the decompressor outputs. While keeping the number of specified bits for longer code words the extended codes provide a possibility of feeding more parallel scan chains with the decompressor output bits. In the case of pseudo-exhaustive test pattern generators, the extended nonlinear codes guarantee an existence of the universal pseudo-exhaustive test set with better parameters than can be obtained for linear test pattern generators. We compare the properties of the extended non-linear and linear codes and demonstrate the effectiveness of the decompressors using these codes.