AD9513
Termination at the far end of the PCB trace is a second option.
The CMOS outputs of the AD9513 do not supply enough
current to provide a full voltage swing with a low impedance
resistive, far-end termination, as shown in Figure 32. 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.
SETUP PINS (S0 TO S10)
The setup pins that require a logic level of ⅓ VS (internal self-
bias) should be tied together and bypassed to ground via a
capacitor.
The setup pins that require a logic level of ⅔ VS should be tied
together, along with the VREF pin, and bypassed to ground via
a capacitor.
POWER AND GROUNDING CONSIDERATIONS AND
POWER SUPPLY REJECTION
V
S
Many applications seek high speed and performance under less
than ideal operating conditions. In these application circuits, the
implementation and construction of the PCB is as important
as the circuit design. Proper RF techniques must be used for
device selection, placement, and routing, as well as power
supply bypassing and grounding to ensure optimum
performance.
100Ω
100Ω
50Ω
10Ω
CMOS
3pF
OUT1/OUT1B
SELECTED AS CMOS
Figure 32. 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 AD9513 offers LVDS outputs that
are better suited for driving long traces where the inherent noise
immunity of differential signaling provides superior
performance for clocking converters.
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