A Scan Matrix Design for Low Power Scan-Based Test

For the scan design, the circuit under test (CUT) in the test mode usually has larger switching activity than in the function mode, causing excessive power dissipation. In this paper, we propose a new Scan Matrix (SM) architecture for the scan-based design to achieve low power testing. The scan flip-flops are connected in a matrix style for test and its addressing is controlled by two ring generators during pattern scanning in. Unlike the traditional scan, for which scan-in data need to pass through a long path and many scan flip-flops switch simultaneously, the proposed approach dynamically forms a low-power scan path to reduce test energy and peak power during shift significantly. The architecture is scalable for large designs and has minimal circuit performance penalty. Experimental results show that, for some larger designs, nearly 99% power savings have been achieved.