Effective methodology for mixed scan and reset design based on test generation and structure of sequential circuits

In this paper, a flip-flop selection methodology, which utilizes reachable states of flip-flops, required states for hard-to-detect faults, which are obtained from test generation, and the structural connection relationship of flip-flops, to achieve a nearly optimal mixed partial-scan/reset design, is proposed. The methodology first generates and simulates test patterns for the circuit-under-test to obtain information of reachable states and states needed for excitation and propagation of hard-to-detect faults. It then searches the connection relationship among flip-flops and arranges flip-flops in an appropriate order for mixed partial scan and reset selection. Experimental results show that the method achieves higher testability than reported methods with less number of scan/reset flip-flops.