Missing Negative Net in Differential Pair

Parent category: Violations Associated with Nets

Default report mode: 

Summary

This violation appears when a negative polarity net has not been detected for a particular differential pair object within a design. The positive polarity net for the pair does exist.

Notification

If compiler errors and warnings are enabled for display on the schematic (enabled on the Schematic - Compiler page of the Preferences dialog), an offending object will display a colored squiggle beneath it. Hovering over the object will display a pop-up hint that summarizes the violation. A notification is also displayed in the Messages panel in the following format:

Missing Negative Net for differential pair <PairName>, positive net <NetName>

where:

• PairName is the name of the differential pair for which a positive polarity net has already been defined (e.g., V_RX1)
• NetName is the name of the positive polarity net (e.g., V_RX1_P).

Recommendation for Resolution

This violation typically arises in the following situations:

• A differential pair directive has not been attached to the negative polarity wire of the signal pairing. The required net label (e.g., V_RX1_N) has been attached to the wire as required.
• An appropriately-named net label (e.g., V_RX1_N) has not been attached to the negative polarity wire of the signal pairing. The required differential pair directive has been attached to the wire as required.

To resolve this violation, locate the negative wire object for the pair and ensure that both the net label and differential pair directive are attached and that the name of the net label is specified as required. The net label for the negative wire will be essentially the same as that for the positive wire, but with an _N suffix instead of an _P.

Tip

• Object hints will only appear provided the Enable Connectivity Insight option is enabled on the System - Design Insight page of the Preferences dialog. Use the controls associated with the Object Hints entry in the Connectivity Insight Options region of the page to determine the launch style for such hints (Mouse Hover and/or Alt+Double Click).