Circuit speed timing jitter increase in random logic operation after NBTI stress

Recently, much effort has been spent trying to relate NBTI observations to real circuit impacts. While many of these efforts rely on circuit simulation to bridge this gap, an experimental approach is, of course, preferred. In this study we provide this experimental solution in the form of eye-diagram measurements to quantify NBTI-induced changes in timing jitter. We investigate these NBTI-induced jitter increases using a variety of ring-oscillator as well as pseudo-random gate patterns. The pseudo-random gate pattern is a close approximation to real world random logic. We observe that the NBTI-induced jitter increase depends strongly on the chosen gate pattern and is most severe for the pseudo-random case. These observations strongly suggest that more regular gate pattern (ring-oscillator) measurements underestimate the circuit impact of NBTI.