Nokia 2600 服务手册
RH-59/60
Nokia Customer Care
7-System Module
26
COMPANY CONFIDENTIAL
ISSUE 1 09/2004
Copyright © 2004 Nokia. All Rights Reserved.
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Transmitter signal path
The I/Q signal from the BB is routed to the modulators for bothLow band and 1900 MHz. The
output of the modulators is either terminated in a SAW filter (Z603) for Low band or a balun
forHigh band. Both signals are amplified in buffers.
output of the modulators is either terminated in a SAW filter (Z603) for Low band or a balun
forHigh band. Both signals are amplified in buffers.
The amplitude limited signal is then amplified in the PA (N700) where the gain control takes
place. The TX signal from the couplers is fed to the RX/TX switch, used to select which signal
to route to the antenna.
place. The TX signal from the couplers is fed to the RX/TX switch, used to select which signal
to route to the antenna.
Figure 11:Transmitter signal path
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PLL
The PLL supplies Local Oscillator (LO) signals for the RX and TX-mixers. All blocks for the PLL
except for the VCO, reference X-tal and loop filter is located in the Mjoelner IC.
except for the VCO, reference X-tal and loop filter is located in the Mjoelner IC.
The reference frequency is generated by a 26MHz Voltage Controlled X-tal Oscillator (VCXO)
which is located in the Mjoelner IC. Only the X-tal is external. 26MHz is supplied to BB where
a divide-by-2 circuit (located in the UPP IC) generates the BB-clock at 13MHz. The reference
frequency is supplied to the reference divider (RDIV) where the frequency is divided by 65. The
output of RDIV (400kHz) is used as reference clock for the Phase Detector (
which is located in the Mjoelner IC. Only the X-tal is external. 26MHz is supplied to BB where
a divide-by-2 circuit (located in the UPP IC) generates the BB-clock at 13MHz. The reference
frequency is supplied to the reference divider (RDIV) where the frequency is divided by 65. The
output of RDIV (400kHz) is used as reference clock for the Phase Detector (
ϕ).
The PLL is a feedback control system controlling the phase and frequency of the LO-signal.
Building blocks for the PLL include: Phase detector, Charge Pump, Voltage Controlled Oscilla-
tor (VCO), N-Divider and loop filter. As mentioned earlier only the VCO and loop filter is external
to the Mjoelner IC.
Building blocks for the PLL include: Phase detector, Charge Pump, Voltage Controlled Oscilla-
tor (VCO), N-Divider and loop filter. As mentioned earlier only the VCO and loop filter is external
to the Mjoelner IC.