A Comprehensive Analysis of Transition Fault Coverage and Test Power Dissipation for Launch-Off-Shift and Launch-Off-Capture Schemes

摘要

At-speed scan testing has become mandatory due to the extreme CMOS technology scaling. The two main at-speed scan testing schemes are namely Launch-Off-Shift (LOS) and Launch-Off-Capture (LOC). As it can be easily implemented, LOC has been widely investigated in the literature in the last few years, especially regarding test power consumption. Conversely, LOS has received much less attention. In this paper, we propose a comparison between the two testing schemes in terms of transition fault coverage and power consumption, in order to quantify the pros and cons of LOS with respect to LOC. This study shows that LOS exhibits higher performance in transition delay fault coverage and pattern count, and does not require a significant amount of extra power (with respect to LOC), especially in terms of peak power dissipation. These facts may represent convincing arguments for its wider use and development.