Test power reduction with multiple capture orders

This paper proposes a 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 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.