LFSR-based test-data compression with self-stoppable seeds
M. Koutsoupia, Emmanouil Kalligeros, Xrysovalantis Kavousianos, Dimitrios Nikolos · 2009
Abstract—The main disadvantage of LFSR-based compression is that it should be usually combined with a constrained ATPG process, and, as a result, it cannot be effectively applied to IP cores of unknown structure. In this paper, a new LFSR-based compression approach that overcomes this problem is proposed. The proposed method allows each LFSR seed to encode as many slices as possible. For achieving this, a special purpose slice, called stop-slice, that indicates the end of a seed's usage is en-coded as the last slice of each seed. Thus, the seeds include by construction the information of where they should stop and, for that reason, we call them self-stoppable. A stop-slice generation procedure is proposed that exploits the inherent test set charac-teristics and generates stop slices which impose minimum com-pression overhead. Moreover, the architecture for implementing the proposed technique requires negligible additional hardware overhead compared to the standard LFSR-based architecture. The proposed technique is also accompanied by a seed calculation algorithm that tries to minimize the number of calculated seeds. Ι.