Z-sets and z-detections: circuit characteristics that simplify fault diagnosis
Irith Pomeranz, Srikanth Venkataraman, Sudhakar M. Reddy, Bharath Seshadri · 2004
We define the concepts of z-sets and z-detections for combinational circuits (or the combinational logic of scan circuits). Based on these concepts we define structural characteristics and characteristics based on fault simula-tion. We show that these characteristics determine the numbers of fault pairs that are guaranteed to be dis-tinguished by a given fault detection test set. These fault pairs do not need to be considered during diagnostic fault simulation or test generation. We demonstrate that bench-mark circuits as well as industrial circuits have these characteristics to a larger extent than may be expected. As a result, only small percentages of fault pairs need to be considered during diagnostic fault simulation or test generation once a fault detection test set is available. In addition, these fault pairs can be identified efficiently. 1.