Test Data Compression for Transparent-Scan Sequences
Irith Pomeranz · IEEE Transactions on Very Large Scale Integration (VLSI) Systems · 2023
Test data compression allows compressed tests to be stored on a tester and decompressed on-chip. Test data compression has not been applied before to transparent-scan sequences in spite of their ability to provide test compaction beyond conventional scan-based tests. A transparent-scan sequence$T$can be obtained from a conventional compact scan-based test set$C$. In this case, the length of$T$is equal to the number of clock cycles required for applying$C$. Test compaction applied to$T$can reduce its length well below the number of clock cycles required for$C$. To allow test data compression and test compaction to be applied together to a transparent-scan sequence, this brief defines a format for a conventional compressed scan-based test set$C$that supports features of a compact transparent-scan sequence, and allows a compact transparent-scan sequence$T$to be obtained from$C$. Using this format, compaction of$T$is achieved by modifying certain parameters of$C$. The decompression logic remains similar to the conventional logic used for$C$. Experimental results for the set of single stuck-at faults in benchmark circuits demonstrate significant reductions in the length of$T$starting from a compressed and compacted scan-based test set$C$.