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Copyright 2005© Siemens AG
Page
11
of
53
TD_Repair_L2.5_A70_A75_R1.0.pdf Release
1.0
6.2 Power Supply RF-Part
The voltage regulator for the RF-part is located inside the
ASIC D361
.It generates the
required 2,8V “RF-Voltages” named
VDD_RF1
and
VDD_RF2
.
VDD_RF2
is passed via a 0
Ω
resistor and renamed as
VDD_BRIGHT
as operating voltage for the BRIGHT.
The voltage
regulator is activated as well as deactivated via
SLEEPQ
(TDMA-Timer R11)
and
VCXOEN_UC
(M4)
provided by the
EGOLDlite
. The temporary deactivation is used to extend the stand by
time.
Circuit diagram
VDD_RF1
VDD_RF2
6.3 Frequency generation
Synthesizer: The discrete VCXO (26MHz)
The A70/A75 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
(
ball B9,. C9)
to
be used as reference frequency inside the Bright (PLL). The signal leaves the Bright IC as
RF_SIN26M
(
ball G9
)
to be further used from the EGOLDlite (
D171
(C8)
).
