Connected Comp

This rule checks for the proper use of special purpose components.

When a trace has noise or EMI problem or it is very weak against ESD, designer may not have any other routing option to resolve the problem. In such case, special purpose components, such as shunts, beads, damping resistors and filters, may be used. If those components are used in circuit, this DFE rule checks whether they are used properly. In many cases, those components should be placed near active drivers with controlled signal lengths. For example, damping resistors should be placed closest to driver pins. The Connected Pin rule checks for the validity of component usage and whether the routing length and component clearance from driver pins are within the specified distance.
  • Item: Input item name.
  • Net: Select a target net group that needs a rectification filter component.
  • Connected Comp: Select a rectification filter component group.
  • Start Comp: Select a starting component group.
  • Net Distance Type: Select one of the following three distance value types to be used for distance measure from net to component.
    • Distance (Location): Distance between pad centers.
    • Length: Distances between connected patterns of pad centers
    • Distance (PAD): Distance between pad edges.
    • Length (PAD): Distance between connected patterns of pad edges
  • Check Value: Assign distance value to which a rectification filter component must be located from the staring component.
  • Nearest Comp: If multiple components are selected, only the components nearest the selected component are inspected. This rule check reports the following messages:
    • No Filter: when there is no rectification component in target nets.
    • No Start Comp: when there is no starting component in target nets.
    • Distance Fail: when there is a rectification component in target net, but it violates the distance rule. In this case, it also reports the reference distance and measured distance.

There are several types of rectification filter components - noise filter, EMI filter, bead, SAW filter, LC filter and capacitor. To achieve stability from signal noise, these types of filter components should be connected to noise sensitive signals. However, in complex circuits, they may be omitted by design error and it is very difficult to detect the omission. Using PollEx DFE, you can easily detect them and achieve stability against noise.

Remember to consider the design location of filter component in signal.

Figure 1.
Locations of p1, p2 and p3 are decided depending on the circuit characteristics and environment. Between p1 and p3, it is necessary to define maximum distance.