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4.1.3
Block Diagram
4.1.4
Frequency Plan
Rx: 925 - 960 MHz
RFLO VCO
1/4
3520 - 3840 MHz
Tx: 880 - 915 MHz
4.1.5
Synthesiser
The transceiver IC U500 is capable of supporting quad-band operation (GSM 850, EGSM 900, DCS 1800, and PCS 1900),
but X700 only supports EGS 900, DCS 1800, and PCS 1900. GSM 850 is not used. The transceiver IC has a synthesizer and
VCO for generating appropriate signals for the transmitter and receiver. Channel data is transferred to U500 from the
baseband IC by three-wire bus (Data, Clock and Strobe). Signal output is divided by 4 for EGSM 900 and by 2 for DCS 1800/
PCS 1900. Synthesizer lock time is approximately 130 µs . An external TCXO is used to generate a 26 MHz reference signal
for the transceiver and logic blocks. Automatic Frequency Control (AFC) is employed to maintain stability over changes in
temperature.
PROVISIONAL ISSUE
Figure 4.1: RF Block Diagram
I, Q output to
baseband
Rx: 1805 - 1880 MHz
925 - 960 MHz
RFLO VCO
1/2
3420 - 3760 MHz
880 - 915 MHz
I, Q output from
Tx: 1710 - 1785 MHz
baseband
Figure 4.2: Frequency Plan
I, Q output to
baseband
Rx: 1930 - 1990 MHz
1805 - 1880 MHz
3700 - 3980 MHz
1710 - 1785 MHz
I, Q output from
Tx: 1850 - 1910 MHz
baseband
− 4-2 −
I, Q output to
baseband
1930 - 1990 MHz
1/2
1850 - 1910 MHz
I, Q output from
baseband
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