Nokia 6275 Guide

Nokia Customer Care
6275/6275i (RM-154)
Mobile Terminals
Issue 1 - September 2006 Company Confidential ©2006 Nokia Corporation
RF Description and
Troubleshooting

6275/6275i (RM-154)
RF Description and Troubleshooting
Page 2 Company Confidential Issue 1 - September 2006
Contents Page
Introduction ..................................................................................................................................................... 5
Preliminary RF Troubleshooting ..............................................................................................................6
RF Troubleshooting Equipment List ........................................................................................................7
Transmitter RF Troubleshooting ................................................................................................................. 8
Transmitter Schematics .............................................................................................................................9
Transmitter Troubleshooting Guidelines .............................................................................................11
Transmitter Troubleshooting Setup ......................................................................................................11
AMPS Tx Setup ....................................................................................................................................... 12
Cell Tx Setup ........................................................................................................................................... 13
PCS Setup................................................................................................................................................. 15
Transmitter RF Troubleshooting Procedures ......................................................................................16
Failed Test: Tx PA Detector ................................................................................................................. 17
Tx Output Spectrum.............................................................................................................................. 18
Tx RF Component Diagram ................................................................................................................. 19
Tx DC Probe Points ................................................................................................................................ 19
Tx RF Probe Points................................................................................................................................. 20
DC Test Points......................................................................................................................................... 20
Receiver RF Troubleshooting .................................................................................................................... 20
Receiver Block Diagram ...........................................................................................................................21
Receiver Schematics .................................................................................................................................22
RF AGC Status ............................................................................................................................................24
Turning on the Rx Path ............................................................................................................................25
Switching the Rx Gain States ................................................................................................................27
Receiver Diagnostic Signal Tracing ......................................................................................................27
Receiver RF Probe Points..................................................................................................................... 28
Receiver IF Probe Points ...................................................................................................................... 29
Receiver DC Probe Points .................................................................................................................... 30
Receiver Logic Input Voltages ................................................................................................................31
Rx Front-End Receiver Troubleshooting .............................................................................................31
Synthesizer Troubleshooting .................................................................................................................... 33
Synthesizer Block Diagram .....................................................................................................................34
Synthesizer Schematics ...........................................................................................................................35
Synthesizer Troubleshooting Setup ......................................................................................................36
Incorrect PLL Frequencies.................................................................................................................... 37
VCTCXO Troubleshooting .........................................................................................................................37
AFC Voltage Troubleshooting .................................................................................................................38
VCTCXO Manual Tuning....................................................................................................................... 39
UHF Synthesizer Schematic ....................................................................................................................41
UHF Synthesizer Troubleshooting .........................................................................................................41
PCS UHF LO CH600 Typical Spectrum .................................................................................................43
Rho and UHF LO..................................................................................................................................... 43
CELL UHF LO CH384 Typical Spectrum ...............................................................................................44
Rho and UHF LO..................................................................................................................................... 44
Rx VHF LO (Rx Back-End IC) Troubleshooting ...................................................................................45
Tx UHF LO Schematic ...............................................................................................................................46
Tx UHF LO (Tx IC) Troubleshooting .......................................................................................................46
UHF PCS Tx LO (3700 ~ 3819.90)/2MHz Typical Spectrum ..........................................................47

Nokia Customer Care RF Description and Troubleshooting
6275/6275i (RM-154)
Issue 1 - September 2006 Company Confidential Page 3
UHF CELL Tx LO (3296.16 ~ 3395.88)/4MHz Typical Spectrum ...................................................48
GPS Troubleshooting................................................................................................................................... 49
GPS RF Block Diagram .............................................................................................................................49
GPS RF Schematic .....................................................................................................................................49
GPS Troubleshooting Setup ....................................................................................................................50
HW Self Test Failure.............................................................................................................................. 51
Oscillator Test Failure........................................................................................................................... 51
CW (Mode 3) Test Failure.................................................................................................................... 51
GPS DC Test Points................................................................................................................................ 52
GPS RF Troubleshooting Setup........................................................................................................... 53
GPS RF Probe Points.............................................................................................................................. 54
FM Radio Troubleshooting ........................................................................................................................ 55
FM Radio Schematic .................................................................................................................................55
FM Radio Testing .......................................................................................................................................55
FM Radio Parts Layouts ...........................................................................................................................56
FM Radio Probe Points .............................................................................................................................56
Bluetooth Troubleshooting ....................................................................................................................... 57
Bluetooth Schematic ................................................................................................................................57
Test Setup 1 ................................................................................................................................................58
Test Setup 2 ................................................................................................................................................59
Test Setup 3 ................................................................................................................................................60
Test Setup 4 ................................................................................................................................................61
Test Setup 5 ................................................................................................................................................62
Bluetooth Troubleshooting Flowchart .................................................................................................63
Bluetooth DC and RF Probe Points .......................................................................................................64

6275/6275i (RM-154)
RF Description and Troubleshooting Nokia Customer Care
Page 4 Company Confidential Issue 1 - September 2006
This page intentionally left blank.

Nokia Customer Care RF Description and Troubleshooting
6275/6275i (RM-154)
Issue 1 - September 2006 Company Confidential Page 5
Introduction
The 6275/6275i mobile terminal is based on tri-mode, code division multiple access or
“CDMA,” dual-band engine. The variants include tri-mode terminals with and without
the GPS component.
Note: The 6275 variant is identical to the 6275i variant, except that the GPS is not
supported in the 6275 variant.
Figure 1: PWB components - top
D2800
UEMEK

6275/6275i (RM-154)
RF Description and Troubleshooting
Page 6 Company Confidential Issue 1 - September 2006
Figure 2: PWB components - bottom
Preliminary RF Troubleshooting
Verify the following if the mobile terminal cannot make a call:
• The mobile terminal is in Normal or Test Mode (i.e., the mobile terminal is
searching for a signal, net server is on).
Coupler
TX ASIC
Diplexer
Duplexer
PA DC/DC converter
PCS PA
Cell PA
VCO synthesizer
Bluetooth
GPS
RX circuits

Nokia Customer Care RF Description and Troubleshooting
6275/6275i (RM-154)
Issue 1 - September 2006 Company Confidential Page 7
• The Preferred Roaming List (PRL) is loaded into the mobile terminal (for Normal
mode).
• The mobile terminal is tuned and has passed tuning. Read the tuning parameters
using the Read Parameters component in Phoenix. An untuned mobile terminal
has all zeros in the tuning file.
• The call box channel is set for a channel in PRL.
• The SID is correct and entered into the mobile terminal. For Test mode, SID is 4
and paging channel is: 385/Cell and 1175/PCS.
• The VCTCXO is centered properly within tuning limits as described in the
"VCTCXO Manual Tuning" section on page 39.
• The transmitter and receiver are working properly in Local mode. See "Transmitter
RF Troubleshooting"onpage8and "Receiver RF Troubleshooting"onpage20 for
detailed information.
RF Troubleshooting Equipment List
You will need the following equipment for RF troubleshooting:
• Computer with AMS version of Phoenix
• Agilent 8960 CDMA call box (or equivalent)
• Signal generator
• Power supply
• Digital multimeter
• Diagnostic test jig
• Spectrum analyzer
• AMS RF Probe, AAS-10A or AAS-10B
• Oscilloscope
• RF connectors and cables
• High impedance probe (optional)

6275/6275i (RM-154)
RF Description and Troubleshooting
Page 8 Company Confidential Issue 1 - September 2006
Transmitter RF Troubleshooting
Following is the block diagram for the Tx RF system.
Figure 3: Transmitter system block diagram

6275/6275i (RM-154)
Nokia Customer Care RF Description and Troubleshooting
Issue 1 - September 2006 Company Confidential Page 9
Transmitter Schematics
The following schematics are for general reference only. See the Schematics chapter for detailed versions.
Figure 4: Transmitter schematic 1
18p
C7012
100n
GND
L7003
GND
C7002
27nH
33p
C7013
12nH
L7005
GND
VR1B
150R
R7011
GND
GND
GND
VR2
R7000
0R
C7018
10p
R7002
VR6
GND
27k
C7016
10n
4p7
C7008
33p
VIO
GND
GND
GND
C7015
C7000
10n
GND
VR2
GND
C7005
100p
10k
SHORT_CIRCUIT
R7005
VR2
R7001
C7006
2n2
GND
L7006
6n8H
0p5
C7027
SHORT_CIRCUIT
R7004
GND
VR2
VR2
GND
GND
VIO
R7009
12k
27nH
L7000
SHORT_CIRCUIT
R7006
C7022
3p3
C7023
1p2
6n8H
L7004
VR2
10n
GND
C7004
220p
GND
OUT
C7021
VR6
1850-1910MHz
Z7001
B39192-B9014-E910
IN
18p
C7014
GND
GND
GND
GND
18p
C7020
1u0
C7009
22k
R7007
GND
C7010
3p3
C7011
10n
12p
C7019
0R
R7010
GND
VR2
GND
30p
C7031
3p3
100p
C7007
C7003
CP
4VCC_LO 5
VCC_PA(4.75V) 6
ISET_PA
IPA1 7
8
IPA2
BBI
9
31
32 DATA
CLOCK
33
34 TX_GATE
35 VDD_BUS
FREF
36
37 VDD_PLL
38 VDD_CP
39
23
POUTX 24
POUT 25
VCC_PDRV 27
28
PDET_OUT 29
PDET_REF
3VCC_VCO 30
PDET_IN
ENABLE
AGC1
AGC2
17
18 VCC_RF
ISET_DRV 19
2VTUNE
VCC_CDRV 20
NC 21
COUT 22
COUTX
1GND_CP
10 BBIX
11 BBQ
BBQX
12
14 VCC_MOD
15 AGC_REF
16
OUT
GND
GND
GND
GND
BOTTOM PLATE=
JUPITER_D4_PMB3365G
N7000
GND
836.5MHz
Z7000
B39841-B9003-E910
IN
C7029
3p3
1p2
C7024
SHORT_CIRCUIT
R7003
GND
GND
VR6
180R
R7012
C7017
47p
C7026
0p5
27nH
L7001
GND
L7002
33nH
C7025
GND
C7001
10n
GND
R7008
43k
GND
GND
PA_BIAS
PWROUT
C7030
3p3
FALSE_DET
TX_IP
TX_IN
TX_QP
TX_QN
RF_BUS_DATA
RF_BUS_CLK
TX_GATE
PA_INPUT_CEL
PA_INPUT_PC
S
RF_BUS_ENABLE
TX_AGC1
F_REF_TX
IREF_PCS
IREF_CEL
PWROUT_1
TEMP
TEMP
DCOUT
DCOUT
TX LO lock voltage
Loop filter
TX IC Cell TX filter
PCS TX filter

6275/6275i (RM-154)
RF Description and Troubleshooting Nokia Customer Care
Page 10 Company Confidential Issue 1 - September 2006
Figure 5: Transmitter schematic 2
PCS
CELL
10nH
L7304
GND
BLACKCOMB
R7351
GND
NA
8k2
GND
L7351
1u5H
Bias
Gnd1
C2
RFIn
C3
GND
TP7300
GND
STPAC01F2
N7302
VTemp A2
DCout A3
B1
Gnd2
Gnd1 B2 Gnd1
B3
C1
56R
R7301
GND
GND
56R
R7307
In C1
In R2
GND
GND
X7300
R7310
0R
0R
R7306
GND
C7326
3p3
RX
ANT
R7305
SHORT_CIRCUIT
FILTER
DUPLEX
Z7300 PCS
TX
C7350
GND
GND
47p
GND
GND
GND
R7304
SHORT_CIRCUIT
C7317
10U
10n
GND
GND
GND
GND
C7356
C7354
GND
GND
GND
GND
4u7
1k8
R7352
3
NA(CX2)
NA(CX2) 4
RFin
5
NA
6
Vcc1
7
Vcc1
89
GND
RFout
17
GND
GND/NC 18
2
GND/NC
Vcc2
20 GND 22
23 Iref/Vref
24 Vcc1
GND
N7300
RF3448E5
BOT_SURF=
1Vid
Vcc2
13 GND 14
RFout 15
16
GND
GND
ANT
C7316
3n3
TX RX
C7300
GND
FILTER
DUPLEX
Z7302
1n0
6
42R/100MHz
L7350
L7305
EHF4CM0836A
OUT1
GND
2
IN
3
DOUT
4
GND
5
ROUT
C7352
10p
47p
C7351
GND
3n3
C7315
GND
L7397
10nH
VBAT
C7324
3p3
10p
GND
GND
GND
GND
GND C7311
C7319
270p 1n0
C7323
GND
1n0
C7322
3RFin
GND/NC 4
Vid
6
7Vcc1 8
GND
17
GND
18 Vcc2
GND 2
20
NC
NC 21
GND 23
Iref
24
GND
1Vbias
12 Vcc2
13
GND/NC
GND 14
15
RFout
RFout 16
GND
VR2
GND
BOT_SURF=
RF3449E4
N7301
GND
GND
GND
GND
C7357
10U
GND
GND
GND
GND
10U
C7358
10n
C7313
GND
GND
VCC_PA
C7312
47p
NA
GND
GND
GND
C7307
L7303
33nH
10p
C7306
SHORT_CIRCUIT
R7302
C7325
7p5
GND
NA
47p
C7370
10U
C7318
10n
C7302
6n8
C7320
47k
R7308
GND
10p
C7314
1
P2
2
P1
3
4
P3
5
6
GND
DIPLEXER
Z7301
0R
R7300
GND
GND
GND
5
GND
6
7GND
8NC VOUT 9
C7355
4u7
NC 10 VOUT
VOUT 11
VOUT 12
13
VBAT 14
VBAT
VBAT 15
16
VRCVSET
2
3EN
4CF
VSENS
GND
VBAT
17= GND
RF4013E2.2
N7350
U//U
1
TP7301
OUT
1
GND
IN 3
DOUT 4
GND
6
ROUT
R7350
100R
GND
GND
L7302
EHF4CM1880
C7305
GND
GND
1n015p
C7304
GND
L7306
22nH
3p3
C7303
1n0
C7321
VCC_PA
GND
3n9H
L7301
3p3
C7301
47p
GND
ANT_SENSE
C7353
IREF_CEL
PA_DC_DC_ENABLE
PA_DC_DC_PDM
PA_INPUT_CEL
PA_INPUT_PCS LNA_PCS
PA_TEMP
LNA_CEL
TEMP
DCOUT
IREF_PCS
PCS PA PCS duplexer
Couplers
Cell PA
Cell duplexer
Power detector

Nokia Customer Care RF Description and Troubleshooting
6275/6275i (RM-154)
Issue 1 - September 2006 Company Confidential Page 11
Transmitter Troubleshooting Guidelines
Use the following guidelines when troubleshooting.
• Always perform visual inspection of PCB under microscope to check proper
placement, rotation, and soldering of components.
• Look for the presence of a well-defined CDMA modulated signal on a spectrum
analyzer at the correct frequency. If a signal is present but off frequency or the
shape looks distorted, check the synthesizer. Possibly, one of the synthesizers is
not locked or the VCO has no output signal. Check the synthesizers for proper
frequency and amplitude. See "Tx Output Spectrum" on page 18 and "Synthesizer
Troubleshooting"onpage33.
• Check that power supplies to the transmitter have the correct voltage. See "Tx RF
Component Diagram" on page 19.
• If the signal is very low in amplitude, check the probing diagram to determine
what part of the TX chain is ‘broken’. See "DC Test Points" on page 20.
• Check that AGC PDMs produce and adjust TX power within the proper limits.
Transmitter Troubleshooting Setup
Use the following sets of procedures to troubleshoot the transmitter using Phoenix.
1. Tx power at the RF connector.
2. All Tx DC points.
3. All soldering jig points for the whole Tx chain.
4. UHF LO presence:
• If the UHF LO is present, check the N7000 output.
• If the UHF LO is not present, it is a synthesizer problem.
5. If there is no N7000 output:
a. Change the N7000.
b. If the problem persists, reflow the duplexers, diplexer, and couplers.
c. If the problem persists, change the PA.
6. If there are several failed mobile terminals with the same symptoms, it may be
necessary to break one to determine the cause.
Use the following sections to set up troubleshooting in Phoenix according to the band
you are using:
•"AMPS Tx Setup"onpage12
•"Cell Tx Setup"onpage13
•"PCS Setup"onpage15

6275/6275i (RM-154)
RF Description and Troubleshooting
Page 12 Company Confidential Issue 1 - September 2006
AMPS Tx Setup
Use the following procedures to prepare for AMPS Tx troubleshooting using Phoenix.
Note the 6236i variant does not support AMPS.
1. Connect the RF test connector to a spectrum analyzer.
2. Connect the mobile terminal to the PC via a test jig. (The bottom connector is a
USB port.)
3. Connect a power supply to the mobile terminal.
4. Open the Troubleshooting menu, and click Phone Control. The Phone Control
dialog box appears.
5. Click the LOCAL button in the Phone State tab to put the mobile terminal into
Local Mode.
Figure 6: Phone Control dialog box
6. Open the Troubleshooting menu, point to AMPS, and click AMPS Control. The
AMPS Control dialog box appears.

Nokia Customer Care RF Description and Troubleshooting
6275/6275i (RM-154)
Issue 1 - September 2006 Company Confidential Page 13
Figure 7: AMPS Control dialog box
7. In the Function field, select Tx Control.
8. In the Set Channel field, type 384.
9. In the Power Level field, type 5.
10. Select the Transmitter ON and Use DSP 2 codes options.
11. Click Execute.
12. Configure the spectrum analyzer using the following values:
• Center Frequency = 836.52 MHz
• Span = 100 MHz
• Amplitude = 20 dBm
• Attenuation = Auto
• BW = Auto
Cell Tx Setup
Use the following procedures to prepare for Cell Tx troubleshooting using Phoenix.
1. Connect an RF test connector to a call box.
2. Connect the mobile terminal to the PC via a test jig. (The bottom connector is a
USB port.)
3. Connect a power supply to the mobile terminal.
4. On the Phone Control dialog box, click the LOCAL button in the Phone State
area to put the mobile terminal into Local Mode. (See Figure 6 on page 12.)
Table 1: RF PDM Values at Power Level 5
Description/Field Reference Value
AGC1 -512
PA_Bias 129
PA_DC_DC 197

6275/6275i (RM-154)
RF Description and Troubleshooting
Page 14 Company Confidential Issue 1 - September 2006
5. Open the Troubleshooting menu, point to RF, and click RF Main Mode. The RF
Main Mode dialog box appears.
Figure 8: RF Main Mode dialog box for Cell Mode
6. Select the following values on the RF Main Mode dialog box:
•Band = Cell (CDMA)
•Channel = 384
•Mode = Rx/Tx
7. Click Set.
Note: Be sure that the “RF Main Mode set successfully” message appears in
the status bar.
8. Open the Troubleshooting menu, point to RF, and click CDMA Control. The
CDMA Control dialog box appears.
Figure 9: CDMA Control dialog box for Cell Tx troubleshooting
9. Select the following values:
•State = Rho ON
•Band = Cell
•Radio Configuration = Mode 1: IS-95 Voice
Note: Do NOT select the Set default PDM values option.
10. Click Execute.
Do NOT select this option

Nokia Customer Care RF Description and Troubleshooting
6275/6275i (RM-154)
Issue 1 - September 2006 Company Confidential Page 15
11. Configure the spectrum analyzer using the following values:
• Center Frequency = 836.52 MHz
• Span = 100 MHz
• Amplitude = 20 dBm
• Attenuation = Auto
• BW = Auto
PCS Setup
Use the following procedures to prepare for PCS Tx troubleshooting using Phoenix.
1. Connect an RF test connector to a call box.
2. Connect the mobile terminal to the PC via a test jig. (The bottom connector is a
USB port.)
3. Connect a power supply to the mobile terminal.
4. Open the Troubleshooting menu, and point to Phone Control. The Phone
Control dialog box appears. (See Figure 6 on page 12.)
5. Click the LOCAL button in the Phone State area to put the mobile terminal into
Local Mode.
6. Open the Troubleshooting menu, point to RF, and click RF Main Mode. The RF
Main Mode dialog box appears. (See Figure 8 on page 14.)
7. Select the following values on the RF Main Mode dialog box:
•Band = PCS (CDMA)
•Channel = 600
•Mode = Rx/Tx
8. Click Set.
Note: Be sure that the “RF Main Mode set successfully” message appears in
the status bar.
9. Open the Troubleshooting menu, point to RF, and click CDMA Control. The
CDMA Control dialog box appears. (See Figure 9 on page 14.)
Table 2: RF PDM Values
Description/Field Reference Value
AGC1 -130
PA_Bias 85
PA_DC_DC 110
Pout 16dBm
Current 340mA

6275/6275i (RM-154)
RF Description and Troubleshooting
Page 16 Company Confidential Issue 1 - September 2006
10. Select the following values on the CDMA Control dialog box.
•State = Rho ON
•Band = PCS
•Radio Configuration = Mode 1: IS-95 Voice
Note: Do NOT select the “Set default PDM values” option.
11. Click Execute.
12. Open the Troubleshooting menu, point to RF, and click PDM Control.
13. Configure the spectrum analyzer using the following values:
• Center Frequency = 1880 MHz
• Span = 100 MHz
• Amplitude = 20 dBm
• Attenuation = Auto
• BW = Auto
Transmitter RF Troubleshooting Procedures
After Phoenix is set up using either the AMPS, Cell, or PCS setup procedures, use the
following steps to troubleshoot the transmitter.
1. Using a voltmeter, check to see that all VR2, VR6, and VR1B are on the transmit
system. (See "Tx RF Component Diagram"onpage19.)
• If any are missing, look for SMD problems around the Tx IC and the UEMEK.
• If SMD is good, replace the UEMEK.
2. After all DC voltages are present, check the AGC control voltages. (See "AMPS Tx
Setup"onpage12, "Cell Tx Setup"onpage13, or "PCS Setup"onpage15.)
• If the voltages are incorrect, check the SMD around TX_AGC1.
• If the SMDs are correct, replace the D2800.
Table 3: RF PDM Values
Description/Field Reference Value
AGC1 -130
PA_Bias 85
PA_DC_DC 110
Pout at RF connector +15dBm
Current 340mA

Nokia Customer Care RF Description and Troubleshooting
6275/6275i (RM-154)
Issue 1 - September 2006 Company Confidential Page 17
3. Using an oscilloscope, check the I and Q input modulation wave forms at test
points. See "Tx RF Components of the PWB"onpage19. They should all be
present with an AC swing of about 500mVpp, with an offset of +1.2V.
• If one or more waveforms is missing, look for SMD problems around these
resistors.
• If the SMD is good, replace the UEMEK.
4. Use an AAS-10 RF probe to probe the Cell Tx output of the Tx IC.
• If there is no RF or low RF, look for a faulty SMD around the Tx IC.
• If the SMD is okay, replace the N7000.
5. Probe the PA input.
• If the level is low, look for an SMD issue on the Tx filter.
• Reflow or replace the filter as necessary.
6. Probe the PA output.
• If the RF is missing or low, look for Vbatt voltages and SMD issues on and
around the PA.
• If these are okay, replace the PA.
7. Probe the duplexer output.
• If the RF is missing or low, reflow or replace the duplexer.
8. Probe the coupler output.
• If the RF is missing or low, reflow or replace the coupler.
9. Probe the diplexer output.
• If the RF is missing or low, reflow or replace the diplexer.
Failed Test: Tx PA Detector
Use the following steps if you encounter a failed test for the Tx PA detector:
10. Use Phoenix to set the mobile terminal into Local Mode and activate the Tx with
default output power.
11. The output power at the RF test connector should be 15dBm ± 4dB. If not, adjust
the PDM values or troubleshoot per procedure above.
12. Using a voltmeter on DC, probe the detector output at C7315. The voltmeter
should read approximately 1.7V. If not, replace N7302.

6275/6275i (RM-154)
RF Description and Troubleshooting
Page 18 Company Confidential Issue 1 - September 2006
Tx Output Spectrum
Following is the correct output of the mobile terminal on a spectrum analyzer with
100MHz span. Note that if you are using the AAS-10 probe with the mobile terminal
connected to the call box, the amplitude should be approximately -7dBm at the antenna
test point on the top of the PWB.
Figure 10: Correct output spectrum
Following is an example of incorrect output.
Figure 11: Incorrect output spectrum

Nokia Customer Care RF Description and Troubleshooting
6275/6275i (RM-154)
Issue 1 - September 2006 Company Confidential Page 19
Tx RF Component Diagram
Following are the Tx RF components.
Figure 12: Tx RF Components of the PWB
Tx DC Probe Points
Following are the Tx DC probe points of the PWB.
Figure 13: Tx DC probe points
Cell
Tx IC PCS PA PCS
Diplexer Coupler
Power
Duplexer Detector
Cell
Coupler
Cell PA
Cell Tx
SAW Filter
PCS
Duplexer
PCS Tx
SAW filter
Tx UHF LO
VR2:
VR6: VCC_PA:
AGC 1
Lock Voltage
0.1 to1.8V
1.2V
2.76V
2.8V 0-4.6V
PCS:
2.0V @ <5dBm
1.7V @ <15dBm
1.2V @ <23dBm
Cell:
2.0 V @ <5dBm
1.8 V @ <15dBm
1.4 V @ <23dBm
Power Detector Output (DCOUT)
Pin 16
Iref_Cell:
~2.4-3.4V
approx. 500 mV p-p (with O’scope)
2.3-2.9 V
Iref_Pcs:
approx. 1.2 V
Tx IQ inputs
I
Q
0-1.9 V
PA_DC_DC_PDM:

6275/6275i (RM-154)
RF Description and Troubleshooting
Page 20 Company Confidential Issue 1 - September 2006
Tx RF Probe Points
Figure 14 shows the Tx RF probe points of the PWB.
Figure 14: Tx RF probe points
DC Test Points
Figure 15 shows the DC test points.
Figure 15: DC Test Points
Receiver RF Troubleshooting
The heart of the receiver is the Rx Front-end IC, which contains two LNAs and mixers.
The other components are passive. There are two RF SAW filters for the Cell and PCS
bands. In addition, there are two IF filters, an IF SAW for CDMA and an IF Crystal for
AMPS.
Cell TX IC out: -7 dBm
PCS TX IC out:
Cell PA in: -7 dBm
PCS PA in:
Cell PA out: +20 dBm
PCS PA out:
Amps -33 dBm Amps -33 dBm
Diplexer out:
PCS Duplexer
-7 dBm -13 dBm +17 dBm out: +15 dBm
PCS +16 dBm
Cell +10 dBm
Amps +1 dBm
Cell Duplexer out:
Amps -7 dBm
Pwr Detector in
PCS: -13 dBm
Cell: +4 dBm
Amps: -20 dBm
+20 dBm
Cell, Amps Frequency 836.25 MHz
PCS Frequency 1880 MHz
Amps -6 dBm
PCS PDM:
PA_DC_DC = 110
PA_Bias = 85
AGC1 = -130
Amps PDM:
PA_DC_DC = 197
PA_Bias = 129
AGC1 = -512
Cell PDM:
PA_DC_DC = 110
PA_Bias = 85
AGC1 = -130
VIO 1.8 V
VR5: Rx 2.78 V (RX)
VR4: 2.78 V (RX)
Vbatt 3.2 to 4.7 V
VR3: 2.78 V (Synth)
VR7: 2.78 V (RX)
VR1B: 4.75 V (TX)
VR2: 2.78 V (TX)
VR1A: 4.75 V (Synth)
VR6: Rx 2.78 V (TX)