Nokia NHM-8NX Series Troubleshooting Instructions page 21

PAMS Technical Documentation
detector controls the charge pump to either charge or discharge the capacitors in the
loopfilter. By charging/discharging the loopfilter the control voltage to the VCO changes
and the LO-frequency will change. Therefore the PLL will make the LO-frequency stay
locked to the 26MHz VCXO frequency.
The loopfilter consists of the following components: C639-C641 and R618-R619.
The PLL is operating at twice the channel center frequency when transmitting or receiv-
ing in the PCN band. For the EGSM band the PLL is operating at 4-times the channel fre-
quency. Therefore divide-by-2 and divide-by-4 circuits are inserted between the PLL
output and LO-inputs to the PCN and EGSM mixers.
Frequency band
EGSM RX
TX
PCN RX
TX
According to the table above the PLL must be able to cover the frequency range
3420.4MHz to 3839.2MHz.
To PCN RX To GSM RX
mixer mixer
2 2 2
2
1/2 1/4
1/2 1/4
2 2 2 2
To P CN To G SM
Modulator Modulator
Mjoelner
N600
VDDRXBB
Resistor Ext/R2H/R2
RFCONV_0(9)
RF Key component placement
Issue 1 05/02
Table 1: Frequency plan
Channel System Frequency Band (MHz)
975-1023 925.2 - 959.8
1 - 12
880.2 – 914.8
512 – 885 1805.2 – 1879.8
1710.2 – 1784.8
Figure 3: Synthesiser
ϕ
64/
NDIV
65
ADIV
LOCNT
RDIV
REFCNT
VCXO Bias
R2H/R2
Main Bias Sensor
BIST / Temp.
Circuit
Ref.
2,7k
Rpa
filter
PA vendor
indication
18k : Hitachi
82k : RFMD
ãNokia Corporation
Troubleshooting Instructions
PLL Frequency band (MHz)
3700.8 - 3839.2
3520.8 – 3659.2
3610.4 – 3759.6
3420.4 – 3569.6
VDDLO
VDDPLL
VDDPRE
VDDCP
Ch arg e
Pump
CPOUT
Lock
Detect
VDDXO
VDDBBB
REFOUT
B uf/
1/2
AGC
XTALM
Buffer
XTALP
INPLO
INMLO
RESETX
AFC/CAL
Control
VDDDIG
VDDDL
SE LADDR
I/O
Digital
RESETX
level
Control
shift
RF_EN
3
RF_CLK
RF_DATA
NHM-8NX
Synth
VPLL
VR5
supply
filter
Vcp
VR1A
su pply
filter
PLL
VCTRL
loop
filter
VCXO
VXO
su pply VR3
filter
REFO UT (26MHz)
VCO (G600)
26MHz
VVCO
VR7
VR2
VBB (1.8V )
VIO
Ref clk set
V IO
RESETX_Mjoel
GENIO6
RFBUSX
3
RFBUSDA
RFBUSCLK
Page 21