ABSTRACT
Testing complex logic circuits has been a challenge for decades. With ever-increasing complexities, test access is becoming the main bottleneck. Furthermore, circuits manufactured in smaller technologies and operating at higher speeds tend to show a tendency towards dynamic rather than static faults. Making a sequential circuit combinational for test application and test output observation is the most popular solution. An automatic test pattern generation (ATPG) tool categorizes faults into fault classes, based on how the faults were detected or why they could not be detected. Each fault class has a unique name and two-character class code. When reporting faults, the tool uses either the class name or the class code to identify the fault class to which the fault belongs. When reporting faults, ATPG tools identify each fault by three ordered fields: the stuck value, the two-character fault class code, and the pin path name of the fault site.
