Scan latch partitioning into multiple scan chains for power minimization in full scan sequential circuits

Abstract

Power dissipated during test application is substantially higher than power dissipated during functional operation which can decrease the reliability and lead to yield loss. This paper presents a new technique for power minimization during test application in full scan sequential circuits. The technique is based on classifying scan latches into compatible, incompatible and independent scan latches. Based on their classification, scan latches are partitioned into multiple scan chains. A new test application strategy which applies an extra test vector to primary inputs while shifting out test responses for each scan chain, minimizes power dissipation by eliminating the spurious transitions which occur in the combinational part of the circuit. Unlike previous approaches which are test vector and scan latch order dependent and hence are not able to handle large circuits due to the complexity of the design space, this paper shows that with low test area and test data overhead substantial savings in power dissipation during test application are achieved in a very low computational time. For example, in the case of benchmark circuit s15850 it takes <3600s in computational time and <1% in test area and test data overhead to achieve 80% savings in power dissipation.