A testability measure for hierarchical design environments

In this paper a new approach is proposed to compute testability of a combinational circuit in a hierarchical design environment. The testability of a circuit is first computed at the functional level using the Walsh expression of the functional block, and its complexity is linear with respect to the number of functional blocks. The functional level testability measure is then used to compute the testability at the gate/switch level. Our extensive simulation results show that the testability measure of the proposed method reflects closely to the actual testability measure (both at the functional level and the gate level) when the granularity of a functional block is much higher than that of primitive gates