Datasheet

Data Sheet AD9520-0
Rev. A | Page 79 of 80
Termination at the far end of the PCB trace is a second option.
The CMOS outputs of the AD9520 do not supply enough current
to provide a full voltage swing with a low impedance resistive, far-
end termination, as shown in Figure 75. The far-end termination
network should match the PCB trace impedance and provide the
desired switching point. The reduced signal swing may still meet
receiver input requirements in some applications. This can be
useful when driving long trace lengths on less critical nets.
CMOS CMOS
10Ω
50Ω
100Ω
100Ω
V
S
07213-077
Figure 75. CMOS Output with Far-End Termination
Because of the limitations of single-ended CMOS clocking,
consider using differential outputs when driving high speed
signals over long traces. The AD9520 offers LVPECL outputs
that are better suited for driving long traces where the inherent
noise immunity of differential signaling provides superior
performance for clocking converters.