TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R28
Design-in
Page 133 of 164
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
analog audio input/output signals, SIM signals, high-speed digital lines such as SDIO, USB and
other data lines).
Optimize placement for minimum length of RF line.
Check the footprint and paste mask designed for TOBY-L2 module as illustrated in
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 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.
Keep the SDIO traces short, avoid stubs, avoid coupling with any RF line / part and consider
low value series damping resistors to avoid reflections and other losses in signal integrity.
Ensure appropriate RF precautions for the Wi-Fi and Cellular technologies coexistence as
described in section
and in the Wi-Fi / Cellular Integration Application Note
Ensure appropriate RF precautions for the GNSS and Cellular technologies coexistence as
described in the GNSS Implementation Application Note
Route analog audio signals away from noisy sources (primarily RF interface, VCC, switching
supplies).
The audio outputs lines on the application board must be wide enough to minimize series
resistance.
