Statistical crosstalk aggressor alignment aware interconnect delay calculation

ABSTRACT

Crosstalk aggressor alignment induces significant interconnect delay variation and needs to be taken into account in a statistical timer. In this paper, we approximate crosstalk aggressor alignment induced interconnect delay variation in a piecewise-quadratic function, and present closed form formulas for statistical interconnect delay calculation with crosstalk aggressor alignment variation. Our proposed method can be easily integrated in a statistical timer, where traditional corner-based timing windows are replaced by probabilistic distributions of crosstalk aggressor alignment, which can be refined by similar delay calculation iterations. Runtime is O(N) for initial delay calculation of N sampling crosstalk aggressor alignments, while pdf propagation and delay updating requires constant time. We compare with SPICE Monte Carlo simulations on Berkeley predictive model 70nm global interconnect structures and 130nm industry design instances. Our experimental results show that crosstalk aggressor alignment oblivious statistical delay calculation could lead to up to 114.65% (71.26%) mismatch of interconnect delay means (standard deviations), while our method gives output signal arrival time means (standard deviations) within 2.09% (3.38%) of SPICE Monte Carlo simulation results.

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INDEX TERMS

Primary Classification:
  B. Hardware
  B.7 INTEGRATED CIRCUITS
      B.7.2 Design Aids

General Terms:
Algorithms, Design, Performance