A common ground plane for both analog and digital often gives better results. Typically, the second PCB layer is the ground plane. The ADC ground pins are returned to the ground plane through multiple vias (PTH). Good practice is to place analog components on one side and digital components on other side of the ADC (or ADCs). All signals must be routed, assuming there is a split ground plane for analog and digital. Furthermore, splitting the ground initially during layout is better. Route all analog and digital traces so that the traces see the respective ground all along the second layer. Then short both grounds to form a common ground plane. Figure 56 shows a typical layout around the ADC.