Datasheet

ADA4411-3
Rev. 0 | Page 13 of 16
PRINTED CIRCUIT BOARD LAYOUT
As with all high speed applications, attention to printed
circuit board layout is of paramount importance. Standard high
speed layout practices should be adhered to when designing
with the ADA4411-3. A solid ground plane is recommended,
and surface-mount, ceramic power supply decoupling
capacitors should be placed as close as possible to the supply
pins. All of the ADA4411-3 GND pins should be connected to
the ground plane with traces that are as short as possible.
Controlled impedance traces of the shortest length possible
should be used to connect to the signal I/O pins and should not
pass over any voids in the ground plane. A 75 Ω impedance
level is typically used in video applications. All signal outputs of
the ADA4411-3 should include series termination resistors
when driving transmission lines.
When the ADA4411-3 receives its inputs from a device
with current outputs, the required load resistor value for
the output current is often different from the characteristic
impedance of the signal traces. In this case, if the intercon-
nections are sufficiently short (<< 0.1 wavelength), the trace
does not have to be terminated in its characteristic impedance.
Traces of 75  can be used in this instance, provided their
lengths are an inch or two at the most. This is easily achieved
because the ADA4411-3 and the device feeding it are usually
adjacent to each other, and connections can be made that are
less than one inch in length.
VIDEO ENCODER RECONSTRUCTION FILTER
The ADA4411-3 is easily applied as a reconstruction filter at
the DAC outputs of a video encoder.
Figure 24 illustrates how to
use the ADA4411-3 in this type of application with an ADV7322
video encoder in a single-supply application with ac-coupled
outputs.