NXP Semiconductors
JN-RM-2079
QN9090 module development reference manual
JN-RM-2079
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© NXP Semiconductors N.V. 2020. All rights reserved.
Reference manual
Rev. 1.0
— 17 Jan 2020
17 of 31
4.13 Screening can
The QN9090
doesn’t radiate high spurs and it is very robust to EMC interferers so there
is in principle no need for a screening can (or shielding can). Nevertheless, a footprint for
a can has been added on the NXP modules and NXP recommends adding this footprint
to any PCB. In very specific cases under a very noisy environment it could be helpful to
add a can.
5. Optimal PCB placement of a module
Where the QN9090 is mounted on a module similar to the NXP QN9090-001-M10 care must be
taken when mounting this module onto another PCB.
The area around the antenna must be kept clear of conductors or other metal objects for an
absolute minimum of 20 mm. This is true for all layers of the PCB and not just the top layer. Any
conductive objects close to the antenna could severely disrupt the antenna pattern resulting in
deep nulls and high directivity in some directions.
The diagrams below show various possible scenarios. The top 3 scenarios are correct; ground
plane may be placed beneath QN9090-001-M00 module as long as it does not protrude beyond
the edge of the top layer ground plane on the module PCB.
The bottom 3 scenarios are incorrect; the left-hand side example because there is ground plane
underneath the antenna, the middle example because there is insufficient clearance around the
antenna (it is best to have no conductors anywhere near the antenna), finally the right hand
example has a battery’s metal casing in the recommended keep out area.
