LISA-U2 series - System integration manual
UBX-13001118 - R27
System description
Page 45 of 183
C1-Public
1.7
RF connection
The
ANT
pin, provided by all LISA-U2 modules, represents the main RF input/output used to transmit
and receive the 2G and 3G RF signal: the main antenna must be connected to this pad. The
ANT
pin
has a nominal characteristic impedance of 50
and must be connected to the antenna through a 50
transmission line to allow transmission and reception of radio frequency (RF) signals in the 2G and
3G operating bands.
The
ANT_DIV
pin, provided by LISA-U230 modules, represents the RF input for the integrated
diversity receiver implemented for both 2G and 3G cases: the antenna for the Rx diversity must be
connected to this pad. The
ANT_DIV
pin has a nominal characteristic impedance of 50
and must be
connected to the antenna for the Rx diversity through a 50
transmission line to allow reception of
radio frequency (RF) signals, improving the cellular link quality and reliability on all 2G and 3G
operating bands except the 2G DCS 1800.
Name
Module
Description
Remarks
ANT
All
RF input/output for main Tx/Rx
antenna
Zo = 50
nominal characteristic impedance.
ANT_DIV
LISA-U230
RF input for Rx diversity antenna
Zo = 50
nominal characteristic impedance.
Table 20: Antenna pins
☞
The ESD immunity rating of the
ANT
port is 1000 V (according to IEC 61000-4-2). Higher
protection level could be required if the line is externally accessible on the application board (for
further details, see section
Choose an antenna with optimal radiating characteristics for the best electrical performance and
overall module functionality. An internal antenna, integrated on the application board, or an external
antenna, connected to the application board through a suitable 50
connector, can be used. See
section
and section
for further details regarding antenna guidelines.
⚠
The recommendations of the antenna producer for correct installation and deployment (PCB
layout and matching circuitry) must be followed.
If an external antenna is used, the PCB-to-RF-cable transition must be implemented using either a
suitable 50
connector, or an RF-signal solder pad (including GND) that is optimized for 50
characteristic impedance.
If antenna supervisor functionality is required, the main antenna connected to the
ANT
pin should
have a built-in DC diagnostic resistor to ground to achieve reliable detection functionality (see section
☞
Connect the Rx diversity antenna to the
ANT_DIV
pin of LISA-U230 modules, unless the 2G and
3G Rx diversity feature is disabled by the AT command (see the u-blox AT commands manual
+URXDIV command). The same pin (74) is marked
RSVD
(reserved) on the other modules that do
not implement Rx diversity: in this case the
RSVD
pin can be left unconnected.
