EP2S130F1020I4 Datasheet, PDF (756/768 Pages) List of Unclassifed Manufacturers – Stratix II Device Handbook, Volume 1

Termination Schemes
Figure 11–23. Simple Parallel Fly-By Termination
Source
Zo = 50 Ω
Receiver / Load
Pad
RT = Zo
Thevenin Parallel Termination
An alternative parallel termination scheme uses a Thevenin voltage
divider (see Figure 11–24). The R_T is split between R₁ and R₂, which equals
the line impedance when combined.
Figure 11–24. Thevenin Parallel Termination
VCC
Stub
R1
S
Zo= 50 Ω
L
R1 R2 = Zo
R2
As noted in the previous section, stub length is dependent on signal rise
and fall time and should be kept to a minimum. If your design requires a
long termination line between the terminator and receiver, use fly-by
termination or Thevenin fly-by termination (see Figures 11–23 and
11–25).
11–20
Stratix II Device Handbook, Volume 2
Altera Corporation
May 2007