AD8129ARMZ datasheet(38/40 Pages) AD

38 / 40 page

AD8129/AD8130

Rev. C | Page 38 of 40

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.

AD8129ARMZ Datasheet(PDF) 38 Page - Analog Devices