Localized random access scan: Towards low area and routing overhead

Conventional random access scan (RAS) designs, although economic in test power dissipation, test application time and test data volume, are expensive in area and routing overhead. In this paper, we present a localized RAS architecture (LRAS) to address this issue. A novel scan cell structure, which has fewer transistors than the multiplexer-type scan cell, is proposed to eliminate the global test enable signal and to localize the row enable and the column enable signals. Experimental results on ISCAS'89 and ITC'99 benchmark circuits demonstrate that LRAS has 54% less area overhead than multiplexer-type scan chain based designs, while significantly outperforms the state-of-the-art RAS scheme in routing overhead.