Abstract: XOR network-based on-chip test compression schemes have been widely employed in large industrial scan designs due to their high compression ratio and efficient decompression mechanism. Due to the highly divergent power impact of distinct seeds appreciable power reductions in the decompressed test data can be attained through the pinpointing of the power-optimal seeds during the compression phase. This work explores the test data compression technique which searches for the power optimal seeds in the compression phase in order to reduce the scan power consumption. The seeds which are identified as power optimal alone will be decompressed in the decompression phase and the power optimization is based on the number of transitions between the seeds. The LFSR is used to generate the sequence of seeds in order to identify the power optimal one from the sequence of seeds which are fed into the XOR based decompression network. Experimental results confirm that the proposed technique delivers significant scan power reduction with negligible impact on the compression ratio.The simulation results are obtained using MODELSIM 6.3f and the power is analysed using XILINX 8.1 software.

Keywords: on-chip test compression, XOR decompression network, scan power reduction, seed selection.