last highlighted date: 2024-09-20

Highlights

  • In general, most clock sources have low impedance outputs.
  • The value of R can be larger than the impedance difference in order to create a slightly over damped condition and still eliminate reflections from the clock source.
  • The major draw back for a Series termination is:  Increases rise and fall times of the signal at the load; this may not be acceptable in some high- speed applications  Not able to drive multiple loads
  • Employing good design practices during the printed circuit board layout process will minimize the signal degradations previously discussed. Some common guidelines for PCB designs are:  Physically locate the clock source as close to the load as possible  Limit trace lengths for clock signals  Do not route clock signals close to the board edge  Try to avoid using vias in clock signal routings. Vias change the trace impedance causing reflection.  Do not route signal traces on the power and ground layer