Achieving optimum performance with a high-frequency amplifier like the OPA817 requires careful attention to board layout parasitics and external component types. Recommendations that will optimize performance include the following:

1. Minimize parasitic capacitance to any ac ground for all of the signal I/O pins. Parasitic capacitance on the output and inverting input pins can cause instability. On the noninverting input, parasitic capacitance can react with the source impedance to cause unintentional bandlimiting. Ground and power metal planes act as one of the plates of a capacitor while the signal trace metal acts as the other separated by PCB dielectric. To reduce this unwanted capacitance, care must be taken to minimize the routing of the feedback network. A plane cutout around and underneath the inverting input pin on all ground and power planes is recommended. Otherwise, ground and power planes should be unbroken elsewhere on the board.
2. Minimize the distance (less than 0.25-in) from the power-supply pins to high-frequency decoupling capacitors. Use high quality, 100-pF to 0.1-µF, C0G and NPO-type decoupling capacitors with voltage ratings at least three times greater than the amplifiers maximum power supplies to ensure that there is a low-impedance path to the amplifiers power-supply pins across the amplifiers gain bandwidth specification. At the device pins, do not allow the ground and power plane layout to be in close proximity to the signal I/O pins. Avoid narrow power and ground traces to minimize inductance between the pins and the decoupling capacitors. Larger (2.2-µF to 6.8-µF) decoupling capacitors, effective at lower frequency, must be used on the supply pins. These can be placed further from the device and are shared among several devices in the same area of the PC board.
3. Careful selection and placement of external components will preserve the high frequency performance of the OPA817. Use low-reactance resistors. Surface-mount resistors work best and allow a tighter overall layout. Never use wirewound type resistors in a high frequency application. Because the output pin and inverting input pin are the most sensitive to parasitic capacitance, always position the feedback and series output resistor, if any, as close as possible to the inverting input and the output pin, respectively.
   Other network components, such as noninverting input termination resistors, should also be placed close to the package. Even with a low parasitic capacitance at the noninverting input, high external resistor values can create significant time constants that can degrade performance. When OPA817 is configured as a conventional voltage amplifier, keep the resistor values as low as possible and consistent with the load driving considerations. Decreasing the resistor values keeps the resistor noise terms low and minimizes the effect of the parasitic capacitance. However, lower resistor values increase the dynamic power consumption because R_F and R_G become part of the output load network of the amplifier.
4. Heat dissipation is important for a high voltage device like OPA817. For good thermal relief, the thermal pad should be connected to a heat spreading plane that is preferably on the same layer as OPA817 or connected by as many vias as possible, if the plane is on a different layer. It is recommended to have at least one heat spreading plane on the same layer as the OPA817 that makes a direct connection to the thermal pad with wide metal for good thermal conduction when operating at high ambient temperatures. If more than one heat spreading plane is available, then connect them by a number of vias to further improve the thermal conduction.