SARA-R5 series - System integration manual
UBX-19041356 - R04
Design-in
Page 97 of 118
C1-Public
2.13.2
Layout checklist
The following are the most important points for a simple layout check:
Check 50
nominal characteristic impedance of the RF transmission line connected to the
ANT
port (cellular antenna RF interface).
Check cellular antenna trace design for regulatory compliance perspective (see section
FCC United States, section
for ISED Canada, and related section
).
For SARA-R510M8S, check 50
nominal characteristic impedance of the RF transmission line
connected to the
ANT_GNSS
port (GNSS antenna RF interface).
Ensure no coupling occurs between the RF interfaces and noisy or sensitive signals (like SIM
signals and high-speed digital lines).
Optimize placement for minimum length of RF lines.
Check the footprint and paste mask designed for SARA-R5 series module as illustrated in
VCC
line should be enough wide and as short as possible.
Route
VCC
supply line away from RF lines / parts (refer to
) and other sensitive analog
lines / parts.
The
VCC
bypass capacitors in the picoFarad range should be placed as close as possible to the
VCC
pins, in particular if the application device integrates an internal antenna.
Ensure an optimal grounding connecting each
GND
pin with application board solid ground layer.
Use as many vias as possible to connect the ground planes on multilayer application board,
providing a dense line of vias at the edges of each ground area, in particular along RF and high
speed lines.
Keep routing short and minimize parasitic capacitance on the SIM lines to preserve signal
integrity.
USB_D+
/
USB_D-
traces should meet the characteristic impedance requirement (90
differential
and 30
common mode) and should not be routed close to any RF line / part.
2.13.3
Antennas checklist
Antenna termination should provide 50
characteristic impedance with V.S.W.R at least less
than 3:1 (recommended 2:1) on operating bands in deployment geographical area.
Follow the recommendations of the antenna producer for correct antenna installation and
deployment (PCB layout and matching circuitry).
Ensure compliance with any regulatory agency RF radiation requirement, as reported in section
for FCC United States, in section
for ISED Canada, and in section
for RED Europe.
Ensure high isolation between the cellular antenna and any other antennas or transmitters
present on the end device.
For SARA-R510M8S, ensure high isolation between the cellular antenna and the GNSS antenna
(see also section
