Frequency Generation - Siemens C75 Service Repair Documentation

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Copyright 2005© Siemens AG

4.3 Frequency generation

The C75 mobile is using a reference frequency of 26MHz. The generation of the 26MHz
signal is done via a VCO (Z950). TP (test point) of the 26MHz signal is the TP 820
The oscillator output signal 26MHz_RF is directly connected to the BRIGHT IC
used as reference frequency inside the Bright (PLL). The signal leaves the Bright IC as
RF_SIN26M
(ball G9)
Bright 6E
To compensate frequency drifts (e.g. caused by temperature) the oscillator frequency is
controlled by the (RF_AFC) signal, generated through the internal SGOLDlite
PLL. Reference for the "EGOLD-PLL" is the base station frequency received via the
Frequency Correction Burst.
The required voltage
Waveform of the AFC_PNM signal from SGOLDlite to Oscillator
S ig n a lfo rm
S G O L D lite
R F _ A F C
Service Repair Documentation
Level 2.5e – C75
to be further used from the SGOLDlite
VDD_RF2 is provided by the ASCI
1
1
A F C _ P N M
R 1
G N D
(D1000
VCXO Out
SGOLDlite In
D1300
2
2
R 2
G N D
Page of
8 37
s Com
(ball B9)
).
(Functional AE15)
(D1000
3
3
R 3
G N D
Release 1.0
to be
)
(A10)