Analysis of Combinational Circuits (9)

• Propagation Delay

  • Physical characteristics of a logic circuit to be considered:
    • Propagation delays
    • Gate fan-in and fan-out restrictions
    • Power consumption
    • Size and weight
  • Propagation delay: The delay between the time of an input change and the corresponding output change.
  • Typical two propagation delay parameters:
    • tPLH = propagation delay time, low-to-high-level output
    • tPHL = propagation delay time, high-to-low-level output
  • Approximation:

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