SARA-R4 series - System integration manual
UBX-16029218 - R20
Design-in
Page 101 of 128
C1-Public
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.
Ensure appropriate RF precautions for the GNSS and Cellular technologies coexistence.
2.15.3
Antenna 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
Europe, in section
for GITEKI Japan, etc.
Ensure high isolation between the cellular antenna and any other antennas or transmitters
present on the end device.
For SARA-R422M8S, ensure high isolation between the Cellular and the GNSS antennas
