TOBY-L1 and MPCI-L1 series - System Integration Manual
UBX-13001482 - R04
Advance Information
Design-in
Page 44 of 90
•
The bypass capacitors in the pF range described in Figure 22 and Table 13 should be placed as close as
possible to the
VCC / 3.3Vaux
pins. This is highly recommended if the application device integrates an
internal antenna
•
Since
VCC / 3.3Vaux
is directly connected to RF Power Amplifiers, voltage ripple at high frequency may
result in unwanted spurious modulation of transmitter RF signal. This is more likely to happen with switching
DC-DC converters, in which case it is better to select the highest operating frequency for the switcher and
add a large L-C filter before connecting to the TOBY-L1 or MPCI-L1 module.
•
If
VCC / 3.3Vaux
is protected by transient voltage suppressor to ensure that the voltage maximum ratings
are not exceeded, place the protecting device along the path from the DC source towards the module,
preferably closer to the DC source (otherwise protection functionality may be compromised)
2.2.1.9
Guidelines for grounding layout design
Good connection of the module
GND
pins with application board solid ground layer is required for correct RF
performance. It significantly reduces EMC issues and provides a thermal heat sink for the module.
•
Connect each
GND
pin with application board solid GND layer. It is strongly recommended that each
GND
pad surrounding
VCC / 3.3Vaux
pins have one or more dedicated via down to the application board solid
ground layer
•
The
VCC / 3.3Vaux
supply current flows back to main DC source through GND as ground current: provide
adequate return path with suitable uninterrupted ground plane to main DC source
•
If the application board is a multilayer PCB, then it is required to connect together each GND area with
complete via stack down to main board ground layer
•
It is recommended to implement one layer of the application board as ground plane as wide as possible
•
Good grounding of
GND
pads also ensures thermal heat sink. This is critical during connection, when the
real network commands the module to transmit at maximum power: proper grounding helps prevent
module overheating.