User's Manual

Bluegiga Technologies Oy
Page 16 of 40
5 Layout Guidelines
Use good layout practices to avoid excessive noise coupling to supply voltage traces or sensitive analog
signal traces, such as analog audio signals. If using overlapping ground planes use stitching vias separated
by max 3 mm to avoid emission from the edges of the PCB. Connect all the GND pins directly to a solid GND
plane and make sure that there is a low impedance path for the return current following the signal and supply
traces all the way from start to the end.
A good practice is to dedicate one of the inner layers to a solid GND plane and one of the inner layers to
supply voltage planes and traces and route all the signals on top and bottom layers of the PCB. This
arrangement will make sure that any return current follows the forward current as close as possible and any
loops are minimized.
Signals
GND
Power
Signals
Figure 7: Typical 4-layer PCB construction
Overlapping GND layers without
GND stitching vias
Overlapping GND layers with
GND stitching vias shielding the
RF energy
Figure 8: Use of stitching vias to avoid emissions from the edges of the PCB