11–20
Altera Corporation
Stratix II Device Handbook, Volume 2
May 2007
Termination Schemes
Figure 11–23. Simple Parallel Fly-By Termination
Thevenin Parallel Termination
An alternative parallel termination scheme uses a Thevenin voltage
divider (see Figure 11–24). The RT is split between R1 and R2, which equals the line impedance when combined.
Figure 11–24. Thevenin Parallel Termination
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
Zo = 50 Ω
RT = Zo
Receiver / Load
Pad
Source
Zo= 50 Ω
R2
R1
R2 = Zo
S
L
VCC
Stub
