SLLSF42A March 2018 – May 2018 SN65LVDS93B-Q1
PRODUCTION DATA.
A complete ground plane in high-speed design is essential. Additionally, a complete power plane is recommended as well. In a complex system, several regulated voltages can be present. The best solution is for every voltage to have its own layer and its own ground plane. But this would result in a huge number of layers just for ground and supply voltages. What are the alternatives? Split the ground planes and the power planes? In a mixed-signal design, e.g., using data converters, the manufacturer often recommends splitting the analog ground and the digital ground to avoid noise coupling between the digital part and the sensitive analog part. Take care when using split ground planes because:
For Figure 19, do not route a signal referenced to digital ground over analog ground and vice versa. The return current cannot take the direct way along the signal trace and so a loop area occurs. Furthermore, the signal induces noise, due to crosstalk (dotted red line) into the analog ground plane.