PADS I/O Designer recognizes differential signals in an HDL source file. To enable this, select Setup > Settings + Advanced and under HDL source, select the Recognize differential signals option.
PADS I/O Designer recognizes differential signals in an HDL design if the differential buffers are instantiated in the top-level design unit. A successfully recognized differential signal is displayed as a single signal in the Signals List. The signal may then be assigned to a pair of differential pins. If the by regular expressions option is selected PADS I/O Designer will try to recognize differential signals using regular expressions set in Recognition of differential signal with regular expressions.