Nokia 3595 Service Manual 07npm10_3595RFtrouble

CC Technical Documentation

NPM-10 (3595) Series Transceivers

Troubleshooting - RF

NPM-10 (3595) Troubleshooting - RF CC Technical Documentation

Contents Page

RF Troubleshooting ....................................................................................................... 3

Abbreviations in Troubleshooting Charts ....................................................................3

Introduction ..................................................................................................................3

General Description of the RF Circuits .......................................................................4

Receiver Signal Path ................................................................................................. 4

Transmitter Signal Path............................................................................................. 5

PLL............................................................................................................................ 5

Key RF Component Placement................................................................................. 7

Power Supply Configuration..................................................................................... 8

Receiver .....................................................................................................................10

General Instructions for GSM 850 Rx Troubleshooting......................................... 10

Troubleshooting Chart for the GSM 850 Receiver................................................. 12

General Instructions for GSM 1900 Rx Troubleshooting....................................... 13

Troubleshooting Chart for PCS Receiver................................................................ 15

Measurement Points in the Receiver....................................................................... 17

Transmitter .................................................................................................................18

Measurement Points for the Transmitter................................................................. 18

General Instructions for GSM Tx Troubleshooting................................................ 19

Troubleshooting Chart for GSM 850 Transmitter................................................... 21

General instructions for PCS Tx troubleshooting................................................... 23

Synthesizer .................................................................................................................26

General Instructions for Synthesizer Troubleshooting............................................ 26

26 MHz Reference Oscillator (VCXO)................................................................... 27

VCO ........................................................................................................................ 28

Troubleshooting Chart for PLL Synthesizer.......................................................... 28

Measurement Points for the PLL ............................................................................ 31

Frequency Lists....................................................................................................... 33

Alignment ..................................................................................................................35

NPM-10 (3595) Manual Align with Phoenix.......................................................... 35

Rx Calibration......................................................................................................... 36

Rx Channel Select Filter ......................................................................................... 39

Rx Band Filter Response......................................................................................... 40

Tx Tuning ..................................................................................................................42

Tx Power Tuning GSM 850.................................................................................... 42

Tx Power Tuning PCS 1900.................................................................................... 44

Tx I/Q Tuning ............................................................................................................44

RF Control .................................................................................................................48

Call Testing ................................................................................................................48

NPM-10 (3595)

CC Technical Documentation Troubleshooting - RF

RF Troubleshooting

Abbreviations in Troubleshooting Charts

Table 1: Troubleshooting Abbreviations

Abbreviation Definition

BB Base band

DC Direct current

ESD Electrostatic discharge

FEM Front End Module

LF Low frequency

LO Local oscillator

LPF Low pass filter

Introduction

Two types of measurements are used in this chapter. It will be specified if the measurement type is RF or LF.

• Use a spectrum analyzer with a high impedance probe for RF measurements.

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

Also, it is recommended that you use a good phone as a benchmark for the measurement technique because signal levels can vary depending on the measurement setup. Measurements stated in this section were done with an HP85024 high-impedance probe.

Note: The test jigs have some losses which must be taken into consideration when calibrating the test system.

• Use a 10:1 probe and an oscilloscope to measure the LF (low frequency) and DC (direct current). The probe used in this chapter is an 10MΩ/8pF passive probe. If using another probe, keep in mind that the voltages displayed may be slightly different.

NPM-10 (3595) Troubleshooting - RF CC Technical Documentation

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 realigning the phone.

Most RF semiconductors are static-discharge sensitive. Use ESD protection 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 components (resistors, inductors, and capacitors) for which troubleshooting is done by checking whether the soldering of the component is done properly, and whether the component is missing from the PWB. Capacitors can be checked for short-circuits and resistors for value by means of an ohmmeter, but be aware that in-circuit measurements should be evaluated carefully.

In this chapter, both GSM and GSM 850 will be used for the lower band and both PCS and GSM 1900 will be used for the upper band.

General Description of the RF Circuits

Figure 1 and Figure 2 include different colors in the block diagrams. The GSM 850 signal route is red, the GSM 1900 route is green, and the common signal lines are blue. Control, supply voltage, and unused lines are shown in black.

Receiver Signal Path

The signal from the antenna pad is routed to the front end module (N700). The GSM 850 signal passes through the switch inside the FEM to TGSM_Rxout, and the GSM 1900 signal passes through the switch inside the FEM to PCS_Rxout.

R XSUPPL

FEM N700

SAW

R X

GSM

T X

R X

SAW

S T

VANTL / VANTM/ VANTH

Z60

BIA

INP

INM INP

INM

L M

M H

R FCONTROL S

INP

RX85

INM

RX190

RX180

YFILTE R

X R

D D V

PRE

-GAI

PRE

-GAI

VDDDI

DCN

RXI

RXQ

B X R

D D V

DCN

LPF

BBAM

LPF

BBAM

222

DCN

Mjoelner

LPF

BIQUA

2BIQUA D

N600

Figure 1: Receiver signal path

From the FEM PA, the GSM 850 signal is routed to the SAW filter (Z602). The purpose 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 a pre-gain amplifier before the mixers.

NPM-10 (3595)

CC Technical Documentation Troubleshooting - RF

The output from the mixer is fed to the Mjoelner BB where the signal is amplified in the BBAMP, and the low pass is filtered in LPF1 before the DC compensation circuits in DCN1. The DCN1 output is followed by a controlled attenuator and a second low pass filter (LPF2). The output from LPF2 is DC centered in DCN2 before being fed to the BB for demodulation.

The GSM 1900 signal chain is similar to GSM 850, but the signal is routed through the SAW filter (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 GSM 850 or a balun (T602) for GSM 1900. The amplitude’s limited signal is then amplified in the PA of the FEM (N700). The internal FEM detector, some discrete components, and the Mjoelner IC (N600) make up the transmitter gain control circuitry. In order to establish the right Tx output power level, a sample of the signal is taken from the FEM detector and used in the gain control loop. The Tx signal from the FEM is routed to the antenna, which depends on the internal switch setting of the FEM.

VANTL / VANTM / VANTH

Controls

VTXLOL

FEM N700

S w

GSM

i t

PCN

DET

SAW Z603

VBATTRF

Balun

Loop

filter

VTXBH

VTX

PLFB1

PLFB2

Controls

OUTHP

OUTHM

OUTLP

OUTLM

DET

VPCH/VPCL

VDDDIG

VDDRXBB

PWC

1/2

1/4

Mjoelner

N600

TXP

TXC

VDDT

Suppl

filter

VTX

VR2

TXC

TXIM

TXIP/

TXQM

TXQP/

Figure 2: Transmitter signal path

PLL

The phase-locked loop (PLL) supplies local oscillator (LO) signals for the Rx and Tx mixers. In order 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.

NPM-10 (3595) Troubleshooting - RF CC Technical Documentation

The reference frequency is generated by a 26 MHz, voltage-controlled X-tal oscillator (VCXO), which is located in Mjoelner. Only the X-tal is external. Twenty-six MHz is supplied to the BB, where a divide-by-2 circuit (located in the UPP IC) generates the BB clock at 13 MHz. The reference frequency is supplied to the reference divider (RDIV) where the frequency is divided by 65. The output of RDIV (400 kHz) is used as the reference clock for the phase detector (ϕ).

The PLL is a feedback control system, which controls the phase and frequency of the LO signal. Building blocks for the PLL include:

• Phase detector

•Charge pump

• Voltage-controlled oscillator (VCO)

• N-divider

• Loop filter

Note: 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. The VCO generates a differential RF output based on the control voltage input. This signal is fed to the prescaler and N-divider in Mjoelner. Together, these two blocks divide the frequency 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 400 kHz reference clock. Based on this comparison, the phase detector controls the charge pump to either charge or discharge the capacitors in the loop filter. By charging/discharging the loop filter, the control voltage to the VCO changes and the LO frequency changes. Therefore, the PLL keeps the LO frequency locked to the 26 MHz 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 receiving 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.

Table 2 shows the PLL frequency plan.

Table 2: PLL Frequency Plan

Frequency

Band

Channel #

System Frequency

Band [MHz]

PLL Frequency

Band [MHz]

GSM RxTx128 - 251 869.2 - 893.8

824.2 - 848.8

PCS RxTx512 - 810 1930.2 - 1989.8

1850.2 - 1909.8

3476.8 - 3575.2

3296.8 - 3395.2

3860.4 - 3979.6

3700.4 - 3819.6

NPM-10 (3595)

CC Technical Documentation Troubleshooting - RF

As Table 2 indicates, the PLL must be able to cover the frequency range from 3296.8 MHz to 3979.6 MHz.

To PCS RX

mixer

2 22

To GSM RX

mixer

1/2

1/4

64/

1/2

To PCS

Modulator

1/4

222

To GSM

Modulator

Mjoelner

N600

VDDRXBB

Resistor Ext/R2H/R2

VBEXT

Ref. filter

VREF1

RFCONV_0(9)

Main Bias

Circuit

RBEXT

Key RF Component Placement

RESETX

VCOSENSE

Charge

Pump

Lock Detect

1/2

I/O

level shift

LOCNT

REFCNT

2,7k

NDIV ADIV

VCXO Bias

VDDRXBB

SENSE

Rpa

RDIV

R2H/

VDDTX

Sensor

BIST / Temp.

AFC/CAL

AGC

Control

Buf/

Digital

Control

Figure 3: Synthesizer block diagram

Buffer

VDDLO VDDPLL VDDPRE

VDDCP

CPOUT

VDDXO VDDBBB

REFOUT XTALM XTALP

INPLO

INMLO

VDDDIG

VDDDL SELADDR

RESETX

RF_EN

RF_CLK

RF_DATA

Synth supply

filter Vcp

supply

filter PLL

VCTRL

loop

filter

VCXO supply

filter

REFOUT (26MHz)

26MH

VCO (G600)

VBB (1.8V)

RESETX_Mjoel

VPLL

VXO

VVCO

Ref clk set

RFBUSX RFBUSDA RFBUSCLK

VR1A

VIO

VIO GENIO6

Refer to Table 3 and Figure 4 for key RF component locations.

Table 3: Key RF Components

Component Description

N600 Mjoelner RF IC

Z601 PCS Rx SAW

Z602 GSM Rx SAW

Z603 GSM Tx SAW

B600 26MHz crystal

G600 VCO (3.6GHz UHF VCO)

N700 Front End Module (FEM)

NPM-10 (3595) Troubleshooting - RF CC Technical Documentation

Figure 4: Key RF 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.

NPM-10 (3595)

CC Technical Documentation Troubleshooting - RF

Figure 5 shows the power supply configuration used in the NPM-10 (3595) phone.

UEM

Battery

VR2

VR3

VR5

VR1A

VR6

VIO

MJOELNER

Vtx

VXO

VPLL

VCP

Vrx

Vbb

Vref1

VddXO Vddbbb

VddRXF

VddRXBB

Vbext

VddTX

Vdddig

VddPLL

VddLO VddPre

VddCP

Sel_addr

VddDL

Vref01

VR7

Vvco

VCO

module

Figure 5: Power supply configuration

The names in bold are signal names, which are used in the RF schematics. The names in the boxes within the Mjoelner and VCO refer to pin names on the respective ICs (N600, G600).

Table 4: Power Supply Details

RF Supply Name

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

UEM Supply Name

Minimum Type Maximum Unit

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

NPM-10 (3595) Troubleshooting - RF CC Technical Documentation

Figure 6 shows the measuring points at the UEM (D200).

VR2=Vtx (C643) VR5=Vpll (C226)

VR7=Vvco (C224)

VR3=Vvcxo (C227)

VR6=Vrx (C225)

Vref01=Vref2 (C231)

Figure 6: Supply points at the UEM (D200)

Figure 7 shows the supply point at the Mjoelner (N600).

Figure 7: Supply point at the Mjoelner (N600)

Vio=Vbb (C621)

Receiver

General Instructions for GSM 850 Rx Troubleshooting

Use the following steps to troubleshoot the GSM 850 Rx:

1. Connect the phone to a PC with the module test jig.

2. Start Phoenix, and establish a connection to the phone.

3. Open the File menu, and click Scan for Product.

NPM-10 (3595)

CC Technical Documentation Troubleshooting - RF

4. Open the Maintenance menu, point to Testing, and click RF Controls.

5. Select the following values on the RF Controls dialog box:

• Band = GSM 850

• Active Unit = Rx

• Operation Mode = Continuous

• Rx/Tx Channel = 190

• AGC = 9

Figure 8: GSM 850 Rx values on the RF Controls dialog box

NPM-10 (3595) Troubleshooting - RF CC Technical Documentation

Troubleshooting Chart for the GSM 850 Receiver

Apply -55 dBm

881.6 MHz,

offset 67.71 kHz

from generator to

antenna connector

YES

Oscilloscope at

RX I/Q signal

704 mVpp

DC offset 1.38 V

freq. 67.64 kHz

Check FEM

RX 850 at

Pin6 of N700

-56 dBm

Oscilloscope

check

VANT1,VANT2

and VANT3 at

N70

signal 0V

Check Mjoelner

YES

GSM chain

functional

YES

Check

FEM

Spectrum analyzer

GSM SAW filter

Z602

output -59 dBm

Check SAW filter

Z602

YES

Spectrum analyzer

Check signal after

inductors L603 and

L602

-59 dBm

Check inductors

L603, L602

YES

Oscilloscope

VRX 2.7 V

check Mjoelner

serial interface

Check Base band

Figure 9: GSM 850 receiver troubleshooting chart

NPM-10 (3595)

CC Technical Documentation Troubleshooting - RF

Figure 10 shows the results of measuring with an oscilloscope at RXIP or RXQP on a working GSM 850 receiver.

• Signal general frequency = 881.66771 MHz

• Amplitude = -55 dBm

• Signal amplitude peak = 704 mV

• DC offset = 1.38 V

Figure 10: RX850 I/Q signal waveform

General Instructions for GSM 1900 Rx Troubleshooting

Use the following steps to troubleshoot the GSM 1900 Rx:

1. Connect the phone to a PC with the module test jig.

2. Start Phoenix, and establish a connection to the phone.

3. Open the File menu, and click Scan for Product.

4. Open the Maintenance menu, point to Testing, and click RF Controls.

5. Select the following values on the RF Controls dialog box:

• Band = GSM 1900

• Active Unit = Rx

• Operation Mode = Continuous

NPM-10 (3595) Troubleshooting - RF CC Technical Documentation

• Rx/Tx Channel = 661

• AGC = 9

Figure 11: GSM 1900 values on the Rx RF Controls dialog box

NPM-10 (3595)

CC Technical Documentation Troubleshooting - RF

Troubleshooting Chart for PCS Receiver

Apply -55 dBm

1960 MHz,

offset 67.71 kHz

from generator to

antenna connector

YES

Oscilloscope at

RX I/Q signal

416 mVpp

DC offset 1.35 V

freq. 67.68 kHz

Check FEM

RX 1900

at Pin 8 of N700

-58 dBm

YES

Oscilloscope

check

VANT1,VANT2

and

VANT2 at

N700

signal 0V

Check

Mjoelner

YES

PCS chain functional

YES

Spectrum analyzer

PCS SAW filter

Z601

output -66 dBm

Check

FEM

Check SAW filter

Z601

YES

Spectrum analyzer

Check signal after

inductors L611 and

L601

-66 dBm

Check inductors

L611, L601

YES

Oscilloscope

VRX 2.7 V check Mjoelner serial interface

Check Base band

Figure 12: GSM 1900 receiver troubleshooting chart

+ 33 hidden pages

Nokia 3595 Service Manual 07npm10_3595RFtrouble

Specifications and Main Features

Frequently Asked Questions

User Manual

Contents Page

RF Troubleshooting

Abbreviations in Troubleshooting Charts

Introduction

General Description of the RF Circuits

Receiver Signal Path

Transmitter Signal Path

Key RF Component Placement

Power Supply Configuration

Receiver

General Instructions for GSM 850 Rx Troubleshooting

Troubleshooting Chart for the GSM 850 Receiver

General Instructions for GSM 1900 Rx Troubleshooting

Troubleshooting Chart for PCS Receiver