Manualshelf

Integration Manual

ManualsBrandsu-blox ManualsElectronicsGSM/UMTS/LTE Data Module
121122123124125126127128129130
TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R04 Advance Information Design-in
Page 121 of 141
2.17.2 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 ANT1 and
the ANT2 ports (antenna RF interfaces).
Ensure no coupling occurs between the RF interface and noisy or sensitive signals (primarily USB signals,
digital input/output signals, SIM signals, high-speed digital lines such as address and data lines).
Optimize placement for minimum length of RF line.
VCC / 3.3Vaux line should be wide and as short as possible.
Route VCC / 3.3Vaux supply line away from RF lines / parts and other sensitive analog lines / parts.
The VCC / 3.3Vaux bypass capacitors in the picoFarad range should be placed as close as possible to the
VCC / 3.3Vaux pins, in particular if the application device integrates an internal antenna.
Ensure proper grounding.
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.
2.17.3 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).
Follow the additional guidelines for products marked with the FCC logo (United States only) reported in
section 4.2.2.
Ensure high and similar efficiency for both the primary (ANT1) and the secondary (ANT2) antenna.
Ensure high isolation between the primary (ANT1) and the secondary (ANT2) antenna.
Ensure low Envelope Correlation Coefficient between the primary (ANT1) and the secondary (ANT2)
antenna: the 3D antenna radiation patterns should have radiation lobes in different directions.