Scan chain design for shift power reduction in scan-based testing

Test power of VLSI systems has become a challenging issue nowadays. The scan shift power dominates the average test power and restricts clock frequency of the shift phase, leading to excessive thermal accumulation and long test time. This paper proposes a scan chain design technique to solve the above problems. Based on weighted transition metric (WTM), the proposed extended WTM (EWTM) that is utilized to guide the scan chain design algorithm can estimate the scan shift power in both the shift-in and shift-out phases. Moreover, the wire length overhead of the proposed scan chain design can also be reduced by the proposed distance of EWTM (DEWTM) metric. Experimental results confirm that the proposed approach can significantly reduce scan shift power with low wire length overhead.