Nokia 6020b Service Manual
RM-31
Nokia Customer Care
7 - System Module
46
COMPANY CONFIDENTIAL
Issue 1 03/2005
Copyright © 2005 Nokia. All Rights Reserved.
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Frequency concept
The RF frequency plan is shown below. The VCO operates at the channel frequency multiplied
by two or four depending on the frequency band of operation. This means that the modulated
signals from baseband are directly converted up to the transmission frequency and the re-
ceived RF signals directly down to the baseband frequency.
by two or four depending on the frequency band of operation. This means that the modulated
signals from baseband are directly converted up to the transmission frequency and the re-
ceived RF signals directly down to the baseband frequency.
Figure 16:RF frequency plan
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RF power supply configuration
All power supplies for the RF unit are generated in the UEM ASIC, which contains among other
functions six pieces of 2.78 V linear regulators (VR2 ... VR7), a 4.8 V switching regulator (VR1)
and two 1.35V voltage references (VrefRF01 and VrefRF02).
functions six pieces of 2.78 V linear regulators (VR2 ... VR7), a 4.8 V switching regulator (VR1)
and two 1.35V voltage references (VrefRF01 and VrefRF02).
The regulators are connected to the RF ASIC, except for VR7, which supplies the VCO. The
4.8V supply is required for the charge pump of the PLL to generate the tuning voltage for the
VCO.
4.8V supply is required for the charge pump of the PLL to generate the tuning voltage for the
VCO.
The reference voltages are used as bias reference for the RF ASIC for the RX ADC (analog-
to-digital converter) reference.
to-digital converter) reference.
All RF supplies can be checked either in Small Signal Chamber or in BB Chamber.
The used power supply configuration is shown in the block diagram below. Values of voltages
are given as nominal outputs of UEM. Currents are typical values.
are given as nominal outputs of UEM. Currents are typical values.
GSM900: 925-960 MHz
GSM1800: 1805-1880 MHz
GSM1900: 1930-1990 MHz
f
f
f/4
f/4
f
f
Helgo
f/2
f/2
PLL
3296-
3980
MHz
3980
MHz
I-signal
Q-signal
RX
I-signal
Q-signal
TX
GSM1900: 1850-1910 MHz
GSM1800: 1710-1785 MHz
GSM850: 824-849 MHz
GSM900: 880-915 MHz
GSM900: 880-915 MHz
Buffer
VCTCXO
26 MHz
26 MHz
26 MHz
VCTCXO
VCTCXO
AFC
GSM850: 869-894 MHz