Star Connection

This rule checks whether power pin connected to decap via separation path to form a Star Connection.

In order to stabilize a power supply, designers use de-coupling capacitors (by-pass capacitors). A fluctuation of power/ground affects component driving and results in bad signal transmitting. In case more than two power pins share one decoupling capacitor, the designer should carefully consider their connection to decoupling capacitor. Each power pin should have a direct connection to decoupling capacitor. The direct connection between two power pins is not allowed in order to prevent power noise coupled with each other. It means that the connection between power pins and decoupling capacitor forms like a Star Connection shape.
  • Item: Input item name.
  • Star Component: Define component group for star connection.
  • Connected Component: Define passive component group for star connection.
  • Check Net: Define net for star connection.
  • Assign net in order to determine required pin of component and passive component.
  • Composite Power Net: DFE uses composited power net instead of single power net.
    • Composite Power Net
      • Passive Comp: The DFE makes composite nets that are connected through this passive component.
      • Exception Net: Nets that should not be merged into composite net.