Similar to all high-speed devices, best system performance is achieved with close attention to board layout. The provides a good example of high-frequency layout techniques as a reference. This EVM includes numerous extra elements and features for characterization purposes that may not
apply to some applications. General high-speed signal path layout suggestions include:
- Continuous ground planes are preferred for signal routing with matched impedance traces for longer runs; however, both ground and power planes must be opened up around the capacitive sensitive input
and output device pins. When the signal goes to a resistor, parasitic capacitance becomes more of a band-limiting issue and less of a stability issue.
- Good high-frequency decoupling capacitors (0.1 µF) are required to a ground plane at the device power pins. Additional higher-value capacitors (2.2 µF) are also required but can be placed further from
the device power pins and shared among devices. For best high-frequency decoupling, consider X2Y supply decoupling capacitors that offer a much higher self-resonance frequency over standard
capacitors.
- Differential signal routing over any appreciable distance must use microstrip layout techniques with matched impedance traces.
- The input summing junctions are very sensitive to parasitic capacitance. Any RG elements must connect into the summing junction with minimal trace length to the device pin side of the
resistor. The other side of the RG elements can have more trace length if needed to the source or to GND.