Test power reduction with multiple capture orders

This paper proposes a novel method to reduce the excess power dissipation during scan testing. The proposed method divides a scan chain into a number of sub-chains, and enables only one sub-chain at a time for both the scan and capture operations. To efficiently deal with the data dependence problem during the capture cycles, we develop a multiple-capture-orders method to guarantee the full scan fault coverage. A novel test pattern generation procedure is developed to reduce the test application time and a test architecture based on a ring control structure is adopted which makes the test control very simple and requires very low area overhead. Experimental results for large ISCAS'89 benchmark circuits show that the proposed method can reduce average and peak power by 86.8% and 66.1% in average, respectively, when 8 sub-chains are used.