AD8129/AD8130
LAYOUT, GROUNDING, AND BYPASSING
The AD8129/AD8130 are very high speed parts that can be
sensitive to the PCB environment in which they operate.
Realizing their superior specifications requires attention to
various details of standard high speed PCB design practice.
The first requirement is for a good solid ground plane that
covers as much of the board area around the AD8129/AD8130
as possible. The only exception to this is that the ground plane
around the FB pin should be kept a few millimeters away, and
the ground should be removed from the inner layers and the
opposite side of the board under this pin. This minimizes the
stray capacitance on this node and helps preserve the gain
flatness vs. frequency.
The power supply pins should be bypassed as close as possible
to the device to the nearby ground plane. Good high frequency
ceramic chip capacitors should be used, and the bypassing
should be done with a capacitance value of 0.01 μF to 0.1 μF for
each supply. Farther away, low frequency bypassing should be
provided with 10 μF tantalum capacitors from each supply to
ground.
The signal routing should be short and direct to avoid parasitic
effects. Where possible, signals should be run over ground
planes to avoid radiating or to avoid being susceptible to other
radiation sources.
Rev. C | Page 38 of 40
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