Transition delay fault test pattern generation considering supply voltage noise in a SOC design

Due to shrinking technology, increasing functional frequency and density, and reduced noise margins with supply voltage scaling, the sensitivity of designs to supply voltage noise is increasing. The supply noise is much larger during at-speed delay test compared to normal circuit operation since large number of transitions occur within a short time frame. Existing commercial ATPG tools do not consider the excessive supply noise that might occur in the design during test pattern generation. In this paper, we first present a case study of a SOC design and show detailed IR-drop analysis, measurement and its effects on design performance during at-speed test. We then propose a novel method to measure the average power of at-speed test patterns, referred to as switching cycle average power (SCAP). A new practical pattern generation methodology is proposed to generate supply noise tolerant delay test patterns using existing capabilities in commercial ATPG tools. The results demonstrate that the new patterns generated using our technique will minimize the supply noise effects on path delays.