4. Now, since we don't need these set as a differential pair, click the Delete button. Those differential pair names (DP1_
DUMMY) will be cleared (see below).
5. Click the Close button at the bottom of the Create Differential Pair window. You will return to the worksheet from where
you created the differential pairs.
6. Scroll up to DDR2_DQS0, then click the arrow button to expand the list, which shows the differential pair nets, DDR2.
DQS#0 and DDR2.DQS0, which are strobe signals for the data group (DDR2.DQ0 through DDR2.DQ7)
Copying Constraint Sets
Now that we have differential pairs already, we need some rules. You can simply copy a differential pair constraint set (right
click, then copy and them from existing constraint sets and confirm. Rename the ECSet as needed), then apply those rules to
the appropriate differential pair.
For example, in the Constraint Manager:
1. Go to the Electrical Constraint Set > Routing > Differential Pair worksheet.
2. Right click on the Dsn element called HSD_FPGA, then create a new Electrical Constraint Set named DDR2_D0_DIFF as
shown below.
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OrCAD X High-Speed Digital Design Guide
