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Radio Part - Siemens SXG 75 Service Repair Documentation

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5 Radio part

The RF section consists of three data capable transceivers and two further broadcast receivers. The
first transceiver is an IMS UMTS 2100MHz 3G solution which realizes the conversion of the RF
WCDMA signals from the antenna to the baseband and vice versa. The second transceiver is a
GSM part which realizes the conversion of the GMSK-RF-signals from the antenna to the baseband
and vice versa. The third transceiver is a Bluetooth type Personal Wireless LAN system. The first
broadcast receiver is an RDS compliant FM radio solution. The second is a GPS receiver which is
integrated into the UMTS receiver IC. The GPS software will allow assistance from a suitably
enabled network (A-GPS); standalone operation without network assistance is also supported.
The GSM part supports triple band operation in the frequency ranges EGSM900, DCS1800,
PCS1900 respectively supporting GPRS functionality up to multiclass 10. In the receiving direction,
the RF signals are filtered and then directly down-converted and split into the I- and Q-component
and led to the D/A-converter of the logic part. In the transmission direction, the GMSK-signal is
generated in an Up Conversion Modulation Phase Locked Loop by modulation of the I- and Q-
signals which are generated in the logic part. The high power Tx VCO is external to the RFIC. After
that the signals are amplified in the power amplifier. The GSM transmitter and receiver are never
active at the same time (TDMA system).
The Bluetooth solution is realized in a separate IC with an external SAW filter.
The GPS receiver is integrated into the UMTS receiver RFIC. Two stages of filtering are provided in
front of and behind the LNA. The GPS down-conversion is a direct conversion system.
The FM radio solution is also realized in a separate IC.
The RF-circuit consists of the following components:
• Qualcomm chip set
GPS LO
• Qualcomm chip set
VCTCXO 19,2 MHz
• GSM TX VCO
• GSM PA module
• UMTS PA module
• UMTS duplexer and isolator
• BCM2004 Bluetooth IC
• FM radio
Technical Documentation
TD_Repair_L3_SXG75_R1.0.pdf
for GSM TX/ RX, UMTS TX, LO1, PLL for
RTR6250
RFR6250 for UMTS RX, GPS RX, UMTS VCO, GPS VCO
Company Confidential
2006©BenQ
Release 1.0
01/2006
Page 8 of 73

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