EP2S90F1020C5 Datasheet, PDF (754/768 Pages) Altera Corporation – Stratix II Device Handbook, Volume 1

Routing Schemes for Minimizing Crosstalk & Maintaining Signal Integrity
Figure 11–20. Serpentine Routing
Termination
Resistor
Device 1
Clock
Source
S
Termination
Resistor
Device 2
1 Altera recommends avoiding serpentine routing, if possible.
Instead, use arcs to create equal-length traces.
Differential Trace Routing
To maximize signal integrity, proper routing techniques for differential
signals are important for high-speed designs. Figure 11–21 shows two
differential pairs using the microstrip layout.
Figure 11–21. Differential Trace Routing Note (1)
W
W
S
D
W
W
S
H
Dielectric Material
GND
Note to Figure 11–21:
(1) D = distance between two differential pair signals; W = width of a trace in a differential pair; S = distance between
the trace in a differential pair; and H = dielectric height above the group plane.
Use the following guidelines when using two differential pairs:
■ Keep the distance between the differential traces (S) constant over
the entire trace length.
11–18
Stratix II Device Handbook, Volume 2
Altera Corporation
May 2007