NINA-B2 series - System integration manual
UBX-18011096 - R05
Design-in
Page 24 of 35
C1- Public
General considerations for schematic design and PCB floor-planning
•
Verify which signal bus requires termination and add series resistor terminations to the
schematics.
•
Carefully consider the placement of the module with respect to antenna position and host
processor.
•
Verify with PCB manufacturer allowable stack-ups and controlled impedance dimensioning.
•
Verify that the power supply design and power sequence are compliant with the specification of
NINA-B2 series module.
Module placement
•
Accessory parts like bypass capacitors should be placed as close as possible to the module to
improve filtering capability, prioritizing the placement of the smallest size capacitor close to
module pads.
⚠
Particular care should be taken not to place components close to the antenna area. The designer
should carefully follow the recommendations from the antenna manufacturer about the distance
of the antenna vs. other parts of the system. The designer should also maximize the distance of
the antenna to Hi-frequency busses like DDRs and related components or consider an optional
metal shield to reduce interferences that could be picked up by the antenna thus reducing the
module’s sensitivity.
•
An optimized module placement allows better RF performance. For more information about
antenna considerations during module placement, see also
Layout and manufacturing
•
Avoid stubs on high-speed signals. Even through-hole vias may have an impact on signal quality.
•
Verify the recommended maximum signal skew for differential pairs and length matching of
buses.
•
Minimize the routing length; longer traces will degrade signal performance. Ensure that maximum
allowable length for high-speed busses is not exceeded.
•
Ensure that you track your impedance matched traces. Consult with your PCB manufacturer early
in the project for proper stack-up definition.
•
RF and digital sections should be clearly separated on the board.
•
Ground splitting is not allowed below the module.
•
Minimize bus length to reduce potential EMI issues from digital busses.
•
All traces (including low speed or DC traces) must couple with a reference plane (GND or power);
Hi-speed busses should be referenced to the ground plane. In this case, if the designer needs to
change the ground reference, an adequate number of GND vias must be added in the area of
transition to provide a low impedance path between the two GND layers for the return current.
•
Hi-Speed busses are not allowed to change reference plane. If a reference plane change is
unavoidable, some capacitors should be added in the area to provide a low impedance return path
through the different reference planes.
•
Trace routing should keep a distance greater than 3W from the ground plane routing edge.
•
Power planes should keep a distance from the PCB edge sufficient to route a ground ring around
the PCB, the ground ring must then be connected to other layers through vias.
3.6
Module footprint and paste mask
The mechanical outline of NINA-B2 series modules can be found in the NINA-B2 series data sheet [2]
The proposed land pattern layout reflects the pads layout of the module.
The Non-Solder Mask Defined (NSMD) pad type is recommended over the Solder Mask Defined (SMD)
pad type, which implements the solder mask opening 50
μ
m larger per side than the corresponding
copper pad.
It is advisable to follow the copper mask layout described in the NINA-B2 series data sheet [2] .