AD8003 Datasheet, PDF (14/16 Pages) Analog Devices – Triple, 1.5 GHz Op Amp

AD8003
Minimizing the trace length and widening the trace from the
capacitors to the amplifier reduces 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 distortion due to high frequency compression at the
output. The use of vias should be minimized 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 provide a low thermal path for the
amplifier. Ground and power planes should not be used under
any of the pins of the AD8003. 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.
Rev. A | Page 14 of 16