Clock Skew

Definition: Clock skew is the difference in arrival time of a clock signal at different parts of a digital circuit.

Key Points:

  • Can be positive or negative
  • Affects timing margins and maximum operating frequency
  • Critical in synchronous digital designs

Causes:

  • Unequal wire lengths in clock distribution
  • Variation in buffer delays
  • Process, voltage, and temperature variations

Effects:

  • Can lead to setup and hold time violations
  • Impacts maximum achievable clock frequency
  • May cause functional failures if severe

Mitigation Techniques:

  • Balanced clock tree synthesis
  • Clock mesh networks
  • Buffer insertion and sizing
  • Useful skew exploitation in some cases

Importance:

  • Critical for timing closure
  • Affects overall system performance
  • Key consideration in high-speed designs

Managing clock skew is essential for ensuring reliable operation and achieving performance targets in synchronous VLSI designs.