User's Manual

Control the impedance of RF trace as close as possible to 50Ω. If the thickness between
RF_ANT pad and the ground layer is less than 0.4mm, it could significantly decrease the
output power. Therefore, when they are too close, we strongly suggest removing the copper in
the layer beneath the RF_ANT pad. If RF trace routes to another layer, add GND via along
with it to keep GND integral. The clearance between RF trace and ground plane in same layer
should be at least twice the RF trace width.
 Make RF trace as short as possible
Place the module and the matching circuit near the antenna pad. Shorten the length of RF
trace. Place the antenna PAD in the corner or at the edge of host board.
 Protect RF trace
Avoid placing noise generating traces such as digital signal or clock line near RF trace in the
same layer. Carefully route other traces in the layers adjacent to the RF trace, remember not to
route in parallel with the RF trace. If possible, keep those traces far away from the RF trace.
 An RF test point is located at the bottom side of M10 for manufacture purpose. The copper
which is close to this test point in the top layer of customer’s host board must be kept out or
removed. No signal trace should be placed in the top layer and the second layer beneath this
test point.
Insert a picture.
 Customer can use either antenna PAD or RF connector to connect the antenna.
If antenna PAD is adopted, Figure 9 is a reference design for a four-layer PCB. Make the
space on all layers beneath antenna pad keep-out. Place a ground PAD near the antenna PAD.
The distance between GND PAD and antenna PAD can be around 1.8mm. The size of
antenna PAD can be 1.8mm*1.8mm, and the GND PAD should be a little bigger, e.g.
2.5mm*2.5mm. Add several GND via near or on the GND PAD to reduce impedance from
the GND PAD to the RF reference ground.