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4.2.2 Synthesizer : LO1
The first local oscillator (LO1) consists of the
and a VCO (Z530) module. This LO1 circuit generates frequencies from 1445MHz
to 1520MHz for GSM 1800 RX-operation, and from 1285MHz to 1361MHz
for the other operations. The
200kHz. The VCO module is activated by the EGOLD+ signal
PLLON
(TDMA-Timer J12)
realised by the
OSW
signal from the SMARTI
The channel programming happens via the EGOLD+. signals
SYNSTR.
The VCO output signal fulfils three functions:
a) It enables the SMARTI IC to mix the RXIF-Frequency (360 MHz)
b) It enables the SMARTI IC to mix the TXIF-Frequency (424 MHz)
c) It ensures with the help of the 13MHz signal and the SMARTIs PLL part the
frequency stability by generating a control voltage at (SMARTI
The required voltages are:
The picture 4221 shows the VCO output signal
The picture 4222 shows the control voltage
The picture 4223 shows the programming signals for the PLL
4223
V1.0
A35-A36-A40
D400
Z530
is switchable to select the channels in stages of
via V530. The switching between GSM900 and GSM1800 is
(D400 pin
VCC2_8
for
D400
provided by
VCC_SYN
for the VCO provided by
Page 8 of 38
Company Confidential
PLL part, a loop filter
21),
SYGCCL, SYGCDT,
pin
20)
N430.
N431
4222
4221
Notes
ICM MP CC ST
09/01
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