Nokia NPM-10 Series Guide

CCS Technical Documentation
NPM-10 Series Transceivers
Issue 1 03/2003 Confidential Nokia Corporation
Troubleshooting Instructions RF

NPM-10
Troubleshooting Instructions RF CCS Technical Documentation
Page 2 Nokia Corporation Confidential Issue 1 03/2003

CCS Technical Documentation Troubleshooting Instructions RF
NPM-10
Issue 1 03/2003 Nokia Corporation Confidential Page 3
Contents Page No
Abbreviations in Troubleshooting Charts ....................................................................5
Introduction ..................................................................................................................5
General Description of the RF Circuits .......................................................................6
Receiver Signal Path ................................................................................................. 6
Transmitter Signal Path............................................................................................. 7
PLL............................................................................................................................ 8
Key RF Component Placement............................................................................... 10
Power Supply Configuration................................................................................... 11
Receiver .....................................................................................................................13
General Instructions for GSM850 RX Troubleshooting......................................... 13
Troubleshooting Chart for GSM850 Receiver........................................................ 15
General Instructions for GSM1900 RX Troubleshooting....................................... 16
Troubleshooting Chart for PCS Receiver................................................................ 18
Measurement Points in the Receiver....................................................................... 20
Transmitter .................................................................................................................22
Measurement Points for the Transmitter................................................................. 22
General Instructions for GSM TX Troubleshooting ............................................... 23
Troubleshooting Chart for GSM850 Transmitter.................................................... 24
General instructions for PCS TX troubleshooting .................................................. 26
Synthesizer .................................................................................................................29
General Instructions for Synthesizer Troubleshooting............................................ 29
26 MHz Reference Oscillator ( VCXO )................................................................. 30
VCO ........................................................................................................................ 30
Troubleshooting Chart for PLL Synthesizer.......................................................... 31
Measurement Points for the PLL ............................................................................ 32
Frequency Lists....................................................................................................... 34
Alignment ..................................................................................................................36
3595 Manual Align with Phoenix ........................................................................... 36
RX Calibration ........................................................................................................ 37
RX Channel Select Filter......................................................................................... 39
RX Band Filter Response........................................................................................ 40
Tx Tuning ..................................................................................................................41
TX Power Tuning GSM850.................................................................................... 43
TX Power Tuning PCS1900.................................................................................... 44
TX I/Q Tuning ...........................................................................................................44
RF Control .................................................................................................................48
Call Testing ................................................................................................................48

NPM-10
Troubleshooting Instructions RF CCS Technical Documentation
Page 4 Nokia Corporation Confidential Issue 1 03/2003

CCS Technical Documentation Troubleshooting Instructions RF
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Issue 1 03/2003 Nokia Corporation Confidential Page 5
RF Troubleshooting
Abbreviations in Troubleshooting Charts
BB Base Band
DC Direct Current
ESD ElectroStatic Dicharge
LF Low Frequency
LO Local Oscillator
LPF Low Pass Filter
PA Power Amplifier
PLL Phase Locked Loop
PWB Printed Wiring Board
RCT Radio Communication Tester
RF Radio Frequency
RX Receiver
TX Transmitter
UHF Ultra High Frequency
VCO Voltage Controlled Oscillator
Introduction
Two types of measurements are used in the following. It will be specified if the measure-
ment type is "RF" or "LF".
• RF measurements should be done with a Spectrum Analyzer with a
high impedance probe. (Note Signal levels can vary depending on
measurement setup, therefore it is recommended that a known good
phone is used as a benchmark for the measurement technique used.
Measurements stated in this section were done with a HP85024 high
impedance probe.).
• Note that the test jigs have some losses which must be taken into con-
sideration when calibrating the test system.

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Troubleshooting Instructions RF CCS Technical Documentation
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• LF (Low frequency) and DC measurements should be done with a 10:1
probe and an oscilloscope. The probe used in the following is 10MΩ/
8pF passive probe. If using another probe, then bear in mind that the
voltages displayed may be slightly different.
Always make sure the measurement set-up is calibrated when measuring RF parameters
on the antenna pad. Remember to include the loss in the module test jig when realign-
ing the phone.
Most RF semiconductors are static-discharge sensitive. ESD protection must be taken
during repair (ground straps and ESD soldering irons). Mjoelner is moisture-sensitive, so
parts must be pre-baked prior to soldering.
Apart from key components described in this section, there are a lot of discrete compo-
nents (resistors, inductors and capacitors) for which troubleshooting is done by checking
if soldering of the component is done properly and checking if the component is missing
from PWB. Capacitors can be checked for short-circuiting and resistors for value by
means of an ohmmeter, but be aware that in-circuit measurements should be evaluated
carefully.
In the following, both the name GSM and GSM850 will be used for the lower band and
both PCS and GSM1900 will be used for the upper band.
General Description of the RF Circuits
In the following general descriptions, different colors are used in the block diagram. The
GSM850 signal route is shown in red, the GSM1900 route in green, and the common sig-
nal lines are shown in blue. Control, supply voltage, and unused lines are shown in black.
Receiver Signal Path
The signal from the antenna pad is routed to the Antenna switch (Z700). If no control
voltage is present at VANT2 and VANT1, the switch works as a diplexer for the RX signal:
the GSM850 signal passes through the switch to GSM RX and the GSM1900 signal
passes through the switch to PCS RX.
Figure 1: Receiver signal path
1/2 1/4
2
INPL
INML
INPM
INMM
RXQP
RXIP
VANTL / VANTM
SAW
Z602
SAW
Z601
RX
RX
TX
TX
PCS
GSM
VDDRX
BB
Mjoelner
N600
INPH
INMH
RXIM
RXQM
2
VDDRX
F
RX850
RX1900
VR6
VDDDIG
2
LNA
PRE-
GAIN
LNA
BIAS
FILTER
BBAMP LPF1
ANTENNA
SWITCH
Z700
LNA
LNA
DCN1 AGC LPF2
BIQUAD
DCN2
RX1800 222
LPF2
BIQUAD DCN2
BBAMP LPF1 DCN1 AGC
RF
CONTROLS
PRE-
GAIN

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From the Antenna switch, the GSM850 signal is routed to the SAW filter (Z602). The pur-
pose of the SAW filter is to provide out-of-band blocking immunity and to provide the
LNA in Mjoelner (N600) with a balanced signal. The front end of Mjoelner is divided into
an LNA and Pre-Gain amplifier before the mixers.
The output from the mixer is fed to the Baseband part of Mjoelner where the signal is
amplified in the BBAMP and low pass filtered in LPF1 before the DC compensation cir-
cuits in DCN1. The DCN1 output is followed by a controlled attenuator and a second
lowpass filter LPF2. The output from LPF2 is DC centered in DCN2 before being fed to the
BB for demodulation.
The GSM1900 signal chain is similar to GSM850, the SAW filter numbered Z601.
Transmitter Signal Path
The I/Q signal from the BB is routed to the modulators for both 850 MHz and 1900 MHz.
The output of the modulators is either terminated in a SAW filter (Z603) for GSM850 or
a balun (T602) for GSM1900. Both signals are amplified in buffers, which are operated in
a soft compression region to suppress some of the AM contents of the signal and to
maintain a certain signal level at the PA inputs. The amplitude limited signal is then
amplified in the PA (N700). The detector diode (V700), some discrete components, and
the Mjoelner IC (N600) make up the transmitter gain control circuitry. In order to estab-
lish the right TX output power level, a sample of the signal is taken in a directional cou-
pler (L709 for GSM850 and L704 for GSM1900) and used in the gain control loop. The TX
signal from the couplers is fed to the Antenna switch, which is used to select which sig-
nal to route to the antenna.

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Troubleshooting Instructions RF CCS Technical Documentation
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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 GSM and PCS channels, a regular Synthesizer
circuit is used. All PLL blocks except for the VCO, reference X-tal, and loop filter are
located in the Mjoelner IC.
The reference frequency is generated by a 26MHz Voltage Controlled X-tal Oscillator
(VCXO), which is located in Mjoelner. 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 loop filter. As mentioned earlier only the VCO, reference
X-tal, and loop filter are 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 differential RF output. This signal is fed to the
Prescaler and N-divider in Mjoelner, these two blocks will together divide the frequency
1/2 1/4
OUTHP
OUTHM
OUTLP
OUTLM
PWC
DET
VB_DET
VANTL / VANTM
PA
N700
Dir.
coupler
TXC
TXP
VBATTRF
PCS
V701
GSM
V702
VTXLOL
TXIP/
TXIM
TXQP/
TXQM
2
222
2
2
2
PLFB1
PLFB2
VPCH/VPCL
2
SAW Z603
VTX
VTX
TXC
TXP
VDDTX
Supply
filter
VR2
VTXBH
VTXBL
VANTH
VDDDIG
VTXLOH
VDDRXBB
DET
RF
Controls
RF
Controls
Buffer
Balun
Loop
filter
Ant.
switch
Z700
RX
RX
TX
TX
PCN
GSM
2
Mjoelner
N600
L709
L704
Buffer

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by a ratio based on the selected channel. The divider output is supplied to the phase
detector, which compares the frequency and phase to the 400kHz reference clock. Based
on this comparison, the phase detector controls the charge pump to either charge or dis-
charge the capacitors in the loop filter. By charging/discharging the loop filter, the con-
trol 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 loop filter 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 PCS band. For the GSM band, the PLL is operating at four times the channel
frequency. Therefore, divide-by-2 and divide-by-4 circuits are inserted between the PLL
output and LO inputs to the PCS and GSM mixers.
The frequency plan is shown in the table that follows:
According to the previous table, the PLL must be able to cover the frequency range
3296.8 MHz to 3979.6 MHz.
Table 1: PLL Frequency Plan
Frequency
Band Channel # System Frequency Band [MHz] PLL Frequency Band [MHz]
GSM RX
TX
128 - 251 869.2 - 893.8
824.2 - 848.8
3476.8 - 3575.2
3296.8 - 3395.2
PCS RX
TX
512 - 810 1930.2 - 1989.8
1850.2 - 1909.8
3860.4 - 3979.6
3700.4 - 3819.6

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Figure 3: Synthesizer
Key RF Component Placement
The following diagram shows key component locations.
Table 2: Key Components
N600 Mjoelner RF IC
Z601 PCS RX SAW
Z602 GSM RX SAW
Z603 GSM TX SAW
B600 26 MHz crystal
G600 VCO (3.6 GHz UHF VCO)
N700 Power Amplifier (PA)
Z700 Antenna switch
64/
65 NDIV
ADIV ϕCharge
Pump
RDIV
1/2 1/4
CPOUT
1/2 1/4
PLL
loop
filter
26MHz
RBEXT
VXO
RF_EN
RF_CLK
RF_DATA
RESETX_Mjoel
1/2
Buffer
VBEXT
LOCNT
REFCNT
Lock
Detect
2XTALM
XTALP
REFOUT REFOUT (26MHz)
VPLL
VDDCP
VDDPRE
VDDLO
VDDPLL
VDDXO
VREF1
VDDDL
VDDDIG
VDDBBB
VBB (1.8V)
Digital
Control
2,7k
Vcp
supply
filter
SENSE
RESETX
INPLO
INMLO
VVCO
VCO (G600)
Rpa
Ref.
filter
3RFBUSX
RFBUSDA
RFBUSCLK
Synth
supply
filter
Ref clk set
VCXO
supply
filter
VR5
VR3
VR7
RFCONV_0(9)
VIO
VCOSENSE
VR2
Main Bias
Circuit
Resistor Ext/R2H/R2
VDDRXBB Sensor
BIST / Temp.
VDDTX
I/O
level
shift
Buf/
AGC
VCXO Bias
R2H/R2
VIO
SELADDR
AFC/CAL
Control RESETX
3
GENIO6
VDDRXBB
222
2222
To PCS
Modulator To GSM Modulator
To PCS RX
mixer To GSM RX mixer
Mjoelner
N600
VR1A
VCTRL

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Figure 4: Key Component Locations
Power Supply Configuration
All power supplies for the RF Unit are generated in the UEM IC (D200). All power outputs
from this IC have a decoupling capacitor at which the supply voltage can be checked.
The power supply configuration used in the 3595 phone is shown in the block diagram
that follows:

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Troubleshooting Instructions RF CCS Technical Documentation
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Figure 5: Power Supply Configuration
The names in bold are signal names which are used on the RF schematic pages. Names in
the boxes within the Mjoelner and VCO refer to pin names on the respective ICs (N600,
G600).
Please see the following graphic for measuring points at the UEM (D200).
Table 3: Power Supply Details
Supply name
RF
Supply name
UEM Min Typ Max Unit
VTX VR2 2.64 2.78 2.86 V
VXO VR3 2.64 2.78 2.86 V
VCP VR1A 4.75 V
VPLL VR5 2.64 2.78 2.86 V
VRX VR6 2.64 2.78 2.86 V
VVCO VR7 2.64 2.78 2.86 V
VBB VIO 1.72 1.8 1.88 V
VREF2 VrelRF01 1.334 1.35 1.366 V
VBATT BATTERY 3.1 3.6 5.2 V
VR2
VR3
VR5
VR6
VR7
VIO
Vref01
Battery UEM
PA
Vtx
VddTX
MJOELNER
VXO
VddXO
VPLL
VddLO
VddPre
VddPLL
Vrx
VddRXF
VddRXBB
Vvco
Vref1
Vbext
Vbb
VddDL
Sel_addr
VCO
module
Vdddig
Vddbbb
VR1A
VddCP
VCP

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Figure 6: Supply points at the UEM (D200)
Figure 7: Supply point at the Mjoelner (N600)
Receiver
General Instructions for GSM850 RX Troubleshooting
Connect the phone to a PC with the module test jig.
Start Phoenix and establish connection to the phone.
Select File
V
R2=Vtx (C643)
V
R5=Vpll (C226)
V
R3=Vvcxo (C227)
V
R6=Vrx (C225)
V
ref01=Vref2 (C231
)
V
R7=Vvco (C224)
V
io=Vbb (C621)

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Troubleshooting Instructions RF CCS Technical Documentation
Page 14 Nokia Corporation Confidential Issue 1 03/2003
Scan for Product Ctrl-R
Select Maintenance
Testing
RF Controls
Select:
The setup should now look like this:
Band: GSM850
Active Unit: RX
Operation Mode: Continuous
Rx/Tx Channel: 190
AGC: 9

CCS Technical Documentation Troubleshooting Instructions RF
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Troubleshooting Chart for GSM850 Receiver
Figure 8: GSM850 receiver troubleshooting chart
By measuring with an oscilloscope at RXIP or RXQP on a working GSM850 receiver, the
following picture should be seen.
Signal amplitude peak-peak 704 mV
DC offset 1.38 V
Apply -55 dBm
881.6 MHz,
offset 67.71 kHz
from generator to
antenna connector
Oscilloscope at
RX I/Q signal
704 mVpp
DC offset 1.38 V
freq. 67.64 kHz
GSM chain
functional
Check Antenna
switch
at RX 850 Z700
-56 dBm
Oscilloscope
check VANT1 and
VANT2 at Z700
signal 0V
Spectrum analyzer
GSM SAW filter
Z602
output -59 dBm
Spectrum analyzer
Check signal after
inductors L603 and
L602
-59 dBm
Check SAW filter
Z602
Oscilloscope
VRX 2.7 V
check Mjoelner
serial interface
Check inductors
L603, L602
Check Base band
Check
Antenna switch
Check Mjoelner
YES
YES
YES
YES
NO NO NO
NO
NO
NO
YES
YES
YES
1234
1
2
3
4
5
6

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Figure 9: RX850 I/Q signal waveform
General Instructions for GSM1900 RX Troubleshooting
Connect the phone to a PC with the module test jig.
Start Phoenix and establish connection to the phone.
Select File
Scan for Product Ctrl-R
Select Maintenance
Testing
RF Controls
Band: GSM1900
Active Unit: RX
Operation Mode: Continuous
Rx/Tx Channel: 661
AGC: 9

CCS Technical Documentation Troubleshooting Instructions RF
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The setup should now look like this:

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Troubleshooting Chart for PCS Receiver
Figure 10: GSM1900 receiver troubleshooting chart
By measuring with an oscilloscope at RXIP or RXQP on a working GSM1900 receiver, the
following picture should be seen.
Signal amplitude peak-peak 416 mV
DC offset 1.35 V
Apply -55 dBm
1960 MHz,
offset 67.71 kHz
from generator to
antenna connector
Oscilloscope at
RX I/Q signal
416 mVpp
DC offset 1.35 V
freq. 67.68 kHz
PCS chain
functional
Check
Antenna switch
at RX 1900 Z700
-58 dBm
Oscilloscope
check VANT1 and
VANT2 at Z700
signal 0V
Spectrum analyzer
PCS SAW filter
Z601
output -66 dBm
Spectrum analyzer
Check signal after
inductors L611 and
L601
-66 dBm
Check SAW filter
Z601
Oscilloscope
VRX 2.7 V
check Mjoelner
serial interface
Check inductors
L611, L601
Check Base band
Check
Antenna switch
Check Mjoelner
YES
YES
YES
YES
NO NO NO
NO
NO
NO
YES
YES
YES
1234
1
2
3
4
5
6

CCS Technical Documentation Troubleshooting Instructions RF
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Figure 11: RX1900 I/Q signal waveform

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Measurement Points in the Receiver
Figure 12: RX measurements point at the Antenna switch - Z700
Figure 13: Measurements points at the RX filters – Z601/Z602
RX850 output
Z700