Elmore Delay: Limitations and Extensions

• The Elmore delay is limited to:

  • RC- tree topologies (not applicable with internodal capacitances)
  • Circuits with a “reasonably” dominant time-constant (most linear RC-trees)
    • Penfield, Rubinstein (DAC 1981): best and worst- case bounds for delay in RC trees
    • Raghunathan, Thompson (Asilomar Conf. 1985): handled slight deviations from RC- tree topology
    • Lin, Mead (TCAD - March 1984): Non- monotonic step-response waveforms
    • Chu, Horowitz (TCAD - June 1987): Second- order (two time-constant) approximations

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