4. Now we don't need this net class, because we have a DDR3_D1 class already for a data class. So right click the DDR3_
DUMMY(8) net class and choose Delete.
5. When asked if you wish to delete NetClass DDR3_DUMMY, click Yes (see below).
6. The net class disappears. In the same worksheet, scroll up to the DDR3_D0_EL net class. See how it has already been
set in the design and has a Differential Pair (DPr) in it (as DDR3_DQS0, the data strobe) and Extended Nets (XNet) as well.
Next let's define differential pairs.
Define Differential Pairs
To set up differential pairs in OrCAD X Capture, have the Constraint Manager open:
1. Go to the Electrical > Net > Routing > Wiring worksheet.
2. Select any two signals, like DDR2.DQ3 and DDR2.DQ4 (click, drag and select or use the Ctrl Key + select to choose
multiple), then right click and choose Create > Differential Pair….
23 www.cadence.com
OrCAD X High-Speed Digital Design Guide
