Differential Pair Net Connection Polarity Inversed

Parent category: Violations Associated with Nets

Default report mode: 

Summary

This violation appears when the polarity of a differential pair net is not the same as that of the differential pair pin to which it is connected. For example, the positive net is connected to the negative pin, or vice-versa.

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:

Inversed connection on differential pair <PairName>: net <NetName> is connected to pin <PinDesignator> (<Polarity>)

where:

• PairName is the name of the differential pair (e.g. V_TX1)
• NetName is the name of the offending net (e.g. V_TX1_P)
• PinDesignator is the designator of the device pin to which the offending net is connected (e.g. E6)
• Polarity is the polarity of the pin (e.g. negative).

Recommendation for Resolution

Use the Details region of the Messages panel to quickly cross probe to the differential pair pin to which the connection has been made. Ensure that the net label attached to the connected wire is the same polarity as that of the pin. For example if the pin name is IO_L02N_0 and the net label is V_TX1_P, change the net label to V_TX1_N.

If a pair of violation messages of this type appears - one for the positive net of the pair attached to the negative pin of the device and one for the negative net of the same pair attached to the positive pin - simply swap the attached net labels around.

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).