The Statistically-Based Worst-Case Determination with Maximum Probability for RC-Delay

We propose new robust methodology to determine worst/best-case corner using maximum probability. For this, we implemented it into Nanno-WiN (Worst-case Interconnect aNalyzer) and designed 15-stage ring oscillators with 8mm interconnect load, which were fabricated with 0.18um CMOS process. We measured 132 dies for 3 lots using Tektronix TDS 5054 Oscilloscope with 2.5MHz frequency. Consequently, proposed methodology is 2 times faster than Monte Carlo Method-its accuracy of convergence is 1.94% for worst-case and approximately 0% for best-case compared to measurement. This methodology is useful to determine the worst/best-case corner for incomplete distribution and very convenient to employ this approach for variation-aware worst-case decision.

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