Nokia 3510 Service Manual
NHM-8NX
Troubleshooting Instructions
PAMS Technical Documentation
Page 20
ãNokia Corporation
Issue 1 05/02
Figure 2: Transmitter signal path
PLL
The PLL supplies Local Oscillator (LO) signals for the RX and TX-mixers. In order to be able
to generate LO-frequencies for the required EGSM and PCN channels a regular synthe-
siser-circuit is used. All blocks for the PLL except for the VCO, reference X-tal and loopfil-
ter is located in the Mjoelner IC.
to generate LO-frequencies for the required EGSM and PCN channels a regular synthe-
siser-circuit is used. All blocks for the PLL except for the VCO, reference X-tal and loopfil-
ter 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 (
(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 (
ϕ
).
The PLL is a feedback control system controlling the phase and frequency of the LO-sig-
nal. Building blocks for the PLL are: Phase detector, Charge Pump, Voltage Controlled
Oscillator (VCO), N-Divider and loopfilter. As mentioned earlier only the VCO and loopfil-
ter is external to the Mjoelner IC.
nal. Building blocks for the PLL are: Phase detector, Charge Pump, Voltage Controlled
Oscillator (VCO), N-Divider and loopfilter. As mentioned earlier only the VCO and loopfil-
ter is external to the Mjoelner IC.
The VCO (G600) is the component that actually generates the LO-frequency. Based on
the control voltage input the VCO generates a single-ended RF output. The signal is then
differentiated through a balun. This signal is fed to the Prescaler and N-divider in Mjoel-
ner, these 2 block will together divide the frequency by a ratio based on the selected
channel. The divider output is supplied to the phase detector which compares the fre-
quency and phase to the 400kHz reference clock. Based on this comparison the phase
the control voltage input the VCO generates a single-ended RF output. The signal is then
differentiated through a balun. This signal is fed to the Prescaler and N-divider in Mjoel-
ner, these 2 block will together divide the frequency by a ratio based on the selected
channel. The divider output is supplied to the phase detector which compares the fre-
quency and phase to the 400kHz reference clock. Based on this comparison the phase
1/2
1/4
OUTHP
OUTHM
OUTLP
OUTLM
PWC
DET
VB_DET
VANTL / VANTM
PA
N700
Dir.
Coupler
TX
C
TX
P
VBATTRF
PCN
V701
EGSM
V702
VTXLOL
TX
IP
/
TX
IM
TX
Q
P
/
TX
Q
M
2
2
2
2
2
2
2
PLFB1
PLFB2
VPCH/VPCL
2
SAW
Z603
Z603
VT
X
VTX
TX
C
TX
P
V
DDT
X
Supply
filter
VR2
VTXBH
VTXBL
VANTH
VDDDIG
VTXLOH
VDDRXBB
DET
RF
Controls
RF
Controls
Buffer
Buffer
Balun
PW-
loop
filter
loop
filter
An
t
Sw
itch
RX
RX
TX
TX
PCN
GSM
2
RX/TX
Z700
Mjoelner
N600
L709
L704