AD8000

Data Sheet

Rev. C | Page 16 of 17

In some cases, bypassing between the two supplies can help to

improve PSRR and to maintain distortion performance in

crowded or difficult layouts. This is as another option to

improve performance.

Minimizing the trace length and widening the trace from the

capacitors to the amplifier reduce the trace inductance. A series

inductance with the parallel capacitance can form a tank circuit,

which can introduce high frequency ringing at the output. This

additional inductance can also contribute to increased distor-

tion due to high frequency compression at the output. Minimize

the use of vias in the direct path to the amplifier power supply

pins because vias can introduce parasitic inductance, which can

lead to instability. When required, use multiple large diameter

vias because this lowers the equivalent parasitic inductance.

GROUNDING

The use of ground and power planes is encouraged as a method

of proving low impedance returns for power supply and signal

currents. Ground and power planes can also help to reduce

stray trace inductance and to provide a low thermal path for the

amplifier. Do not use ground and power planes under any of the

pins of the AD8000. The mounting pads and the ground or

power planes can form a parasitic capacitance at the amplifiers

input. Stray capacitance on the inverting input and the feedback

resistor form a pole, which degrades the phase margin, leading

to instability. Excessive stray capacitance on the output also

forms a pole, which degrades phase margin.