Jitter

Definition: Jitter is the variation in the timing of a signal’s edges from their ideal positions.

Key Points:

  • Deviation from true periodicity of a presumably periodic signal
  • Measured in time units or phase angle
  • Critical in high-speed digital and communication systems

Types:

  • Random Jitter: Unpredictable electronic timing noise
  • Deterministic Jitter: Predictable sources like crosstalk or power supply noise

Causes:

  • Phase noise in oscillators
  • Power supply fluctuations
  • Thermal noise
  • Electromagnetic interference

Effects:

  • Reduced timing margins
  • Increased bit error rates in communication systems
  • Limits maximum operating frequency

Mitigation Techniques:

  • Phase-locked loops (PLLs)
  • Clean power supply design
  • Proper shielding and layout techniques
  • Jitter cleaning circuits

Importance:

  • Critical for high-speed interfaces
  • Affects signal integrity and system reliability
  • Key parameter in clock distribution networks

Understanding and managing jitter is crucial for designing reliable high-speed digital systems and communication interfaces in VLSI.