Achieving optimum AC performance with a fast amplifier such as the OPA862 requires careful attention to board layout parasitics and external component types. The OPA862EVM can be used as a reference when designing the circuit board. Recommendations that optimize performance include:

1. Minimize parasitic capacitance to any AC ground for all of the signal I/O pins. Parasitic capacitance on the output and input pins can cause instability. On the noninverting input, VIN, the device can react with the source impedance to cause unintentional band limiting. To reduce unwanted capacitance, open a plane cutout around the signal I/O pins in the ground and power planes below those pins. Otherwise, ground and power planes must be unbroken elsewhere on the board.
2. Minimize the distance (< 0.1") from the power-supply pins to high-frequency, 0.01-µF or 0.1-µF decoupling capacitors. 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. The power-supply connections must always be decoupled with these capacitors. Larger (2.2-µF to 10-µF) decoupling capacitors, effective at lower frequencies, must also be used on the supply pins. These capacitors can be placed somewhat farther from the device and shared among several devices in the same area of the PC board.
3. Careful selection and placement of external components preserve the AC performance of the OPA862. Resistors must be a low reactance type. Surface-mount resistors work best and allow a tighter overall layout. Metal film and carbon composition axially leaded resistors can also provide good high frequency performance. Again, keep their leads and PCB trace length as short as possible. Because the VOUT+ pin and the VFB pin are the most sensitive to parasitic capacitance, always position the feedback and series output resistor, if any, as close as possible to the VFB and VOUT+ pins, respectively.
4. Connections to other wideband devices on the board can be made with short direct traces or through onboard transmission lines. For short connections, consider the trace and the input to the next device as a lumped capacitive load. Relatively wide traces (50 mils to 100 mils) must be used, preferably with ground and power planes opened up around them.
5. Socketing a high-speed part such as the OPA862 is not recommended. The additional lead length and pin-to-pin capacitance introduced by the socket can create troublesome parasitic network that can make achieving a smooth, stable frequency response difficult. Best results are obtained by soldering the OPA862 to the board.