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4.4 Antenna Switch / External Antenna Connector
(electrical/mechanical only C55)
The mechanical antenna switch for the differentiation between the internal and external
antenna.
to / from
diplexer
4.5 Frontendmodul (Electrical Antenna Switch)
EGSM900/GSM1800 <> Receiver/Transmitter
The frontend has two functions.
-
to select the different GSM bands
-
to switch between RX and TX mode
Inside the frontendmodul SAW filters are integrated in the RX paths.
For dual band mode the FEM needs two supply voltages (VC1, VC2) that are directly
provided by the Smarti DC (FEM1 and FEM2). The following logical table shows the
different modes of the FEM.
Mode Selection
EGSM900 RX
EGSM900 TX
GSM1800 RX
GSM1800 TX
GSM1900 RX
GSM1900 TX
Two balanced SAW filters are integrated to have good stop-band attenuation in the GSM
and the PCN RX paths.
Block diagram
V 1.10
A52/A55/C55 IFX
External
Vc. 1
LOW
HIGH
LOW
LOW
LOW
LOW
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Vc.2
Vc.3
LOW
LOW
LOW
LOW
LOW
LOW
HIGH
LOW
LOW
HIGH
HIGH
LOW
Top View
Internal
ICM MP CCQ GRM
08/03
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