A New Scan Chain Reordering Method for Low Power Consumption based on Care Bit Density

Scan-based testing, though widely used in modern digital designs, causes more power consumption than in functional mode. This excessive power consumption can cause severe hazards such as circuit reliability and yield loss. To solve this problem, a new scan chain reordering method based on care bit density is proposed in this paper. This proposed method helps merging care bits toward the front end of scan chains. Thus, it can reduce scan cell switching activities during scan shift operation. Experimental results on ISCAS’89 benchmark circuits show that the proposed scan chain reordering method reduces test power consumption compared to the previous work.