EP2S90F1020C5 Datasheet, PDF (749/768 Pages) Altera Corporation – Stratix II Device Handbook, Volume 1

High-Speed Board Layout Guidelines
Figure 11–12. Separating Traces for Crosstalk
A
A
4A
Compared with high dielectric materials, low dielectric materials help
reduce the thickness between the trace and ground plane while
maintaining signal integrity. Figure 11–13 plots the relationship of height
versus dielectric constant using the microstrip impedance and stripline
impedance equations, keeping impedance, width, and thickness
constant.
Figure 11–13. Height Versus Dielectric Constant
30
25
20
H (mil) 15
10
5
0
2.2
2.9
3.3
4.1
4.5
ε_r
Microstrip
Stripline
T = 1.4
Z₀ = 50 Ω
W_stripline = 9.0 mils
W_microstrip = 8.0 mils
Signal Trace Routing
Proper routing helps to maintain signal integrity. To route a clean trace,
you should perform simulation with good signal integrity tools. The
following section describes the two different types of signal traces
available for routing, single-ended traces, and differential pair traces.
Altera Corporation
May 2007
11–13
Stratix II Device Handbook, Volume 2