SEPTENTRIO mosaic Series, Руководство по оборудованию

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mosaic Integration
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5.5 Layout Recommendations
5.5.1 Coplanarity
It is important to avoid warpage of the motherboard on which the module will be
soldered. More in particular:
• Use a symmetrical layer stack
•
Make sure layers opposite from the center of the board have a similar amount of
copper (copper-balancing).
•
Avoid iron-based soldered shielding cans in the proximity of mosaic
• If the motherboard thickness is 1.2 mm or less, it needs to be supported during
reflow.
5.5.2 Power
The power trace to the VDD_3V3 terminals should be sufficiently wide to avoid excessive
voltage drop. The resistance of the trace to the power supply shall be less than
(<minimum supply voltage> - 3.135V)/0.5A.
Use a ground plane.
5.5.3 Antenna Inputs
The antenna input traces shall be routed as a 50-ohm coplanar waveguide with ground,
as in the picture below. It is best to use stitching vias every few mm for good ground
coherence. The width of the trace to set the impedance to 50 ohm can be calculated with
online tools (e.g.
https://chemandy.com/calculators/coplanar-waveguide-with-ground-
calculator.htm ). Usually it is best to use the top-layer for the coplanar waveguide and the
second layer for ground.
The antenna trace to ANT_1 can be directly routed to the desired type of coax connector,
as all protection circuitry is integrated in mosaic.
For the dual-antenna module, beware that the ANT_2 pin is not protected, and a TVS diode
is recommended. See reference design in section 4.2.3.2.