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4.3 Antenna switch (electrical/mechanical only C55)
Internal/External <> GSM1800/900 <> Receiver/Transmitter
The C55 mobile has two antenna switches. A55 has no external antenna
connector/mechanical antenna switch.
a)
The mechanical antenna switch for the differentiation between the internal and
external antenna
b)
The electrical antenna switch, for the differentiation between the receiving and
transmitting signals.
To activate the correct settings of this diplexer, the EGOLD+ signals
and
TXON_GSM
As a new feature the A55/C55 has an integrated "SAR detection" circuit. This circuit is
used to decide if the internal antenna or an external antenna is used. The goal is, to
reduce the transmit power when the internal antenna is used and the mobile is held
very close to the body. On the other hand, the mobile can send with more power, if the
external antenna is used. This distinction is done by the SAR detection circuit which
consists of the voltage divider R872 and R873. The
level when the external antenna is used.
the EGOLD+
a)
Internal/External antenna switch
to / from
diplexer
V1.20
A55/C55_Hitachi
are required
ANT_DET
External
to EGOLD
Page 13 of 48
Company Confidential © Copyright Siemens AG
ANT_DET
output provides a high
is connected to
(Serial Interface L16)
Internal
ICM MP CCQ GRM
RF_SW
04/03
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