LG KB770 User manual

Service Manual Model : KB770
Internal Use Only
Service Manual
KB770
Date: November, 2008 / Issue 1.0

- 3 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
Table Of Contents
1. INTRODUCTION...............................................5
1.1 Purpose......................................................................5
1.2 Regulatory Information.................................................5
2. PERFORMANCE............................................... 7
2.1 System Overview.........................................................7
2.2 Usable environment.....................................................8
2.3 Radio Performance......................................................8
2.4 Current Consumption.................................................14
2.5 RSSI BAR..................................................................14
2.6 Battery BAR ..............................................................14
2.7 Sound Pressure Level ................................................15
2.8 Charging...................................................................16
3. TECHNICAL BRIEF......................................... 17
3.1 General Description ...................................................17
3.2 GSM Mode................................................................19
3.3 UMTS Mode..............................................................23
3.4 LO generation and distribution circuits........................26
3.5 Off-chip RF Components............................................26
3.6 Digital Baseband (MSM6280).....................................42
3.7 Subsystem(MSM6280) ..............................................44
3.8 Power Block..............................................................51
3.9 External memory interface .........................................56
3.10 H/W Sub System .....................................................58
3.11 MAIN Features ........................................................74
4. TROUBLE SHOOTING..................................... 79
4.1 RF Component Description.........................................79
4.2 WCDMA RF Signal Path .............................................80
4.3 GSM RF Signal Path ..................................................81
4.4 Checking VCTCXO Block ............................................82
4.5 Checking Front-End Module Block..............................85
4.6 Checking WCDMA Block ............................................87
4.7 Checking GSM Block .................................................94
4.8 Checking Bluetooth Block ........................................100
4.9 Power ON Troubleshooting .......................................103
4.10 Charger Troubleshooting ........................................105
4.11 USB Troubleshooting..............................................107
4.12 USIM Detect Troubleshooting..................................108
4.13 Camera Troubleshooting ........................................110
4.14 Keypad Backlight Troubleshooting...........................112
4.15 LCD Troubleshooting..............................................114
4.16 Receiver Path........................................................115
4.17 Headset path.........................................................117
4.18 Speaker phone path ..............................................119
4.19 Main microphone ..................................................121
4.20 Headset microphone..............................................123
4.21 Vibrator.................................................................125
4.22 Checking DVB-T/H Block( The DVB-T/H function is for
KB770 )................................................................126
5. DOWNLOAD & S/W UPGRADE..................... 131
6. BLOCK DIAGRAM........................................146
7. CIRCUIT DIAGRAM...................................... 157
8. BGA PIN MAP.............................................. 167
9. PCB LAYOUT ...............................................171
10. CALIBRATION............................................177
10.1 USAGE OF HOT-KIMCHI .........................................177
11. EXPLODED VIEW & REPLACEMENT
PART LIST ................................................. 181
11.1 EXPLODED VIEW ...................................................181
11.2 Replacement Parts ................................................183
11.3 Accessory .............................................................207

- 4 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes

- 5 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
1. INTRODUCTION
1. INTRODUCTION
1.1 Purpose
This manual provides the information necessary to repair, calibration, description and download the
features of this model.
1.2 Regulatory Information
A. Security
Toll fraud, the unauthorized use of telecommunications system by an unauthorized part (for example,
persons other than your company’s employees, agents, subcontractors, or person working on your
company’s behalf) can result in substantial additional charges for your telecommunications services.
System users are responsible for the security of own system. There are may be risks of toll fraud
associated with your telecommunications system. System users are responsible for programming and
configuring the equipment to prevent unauthorized use. The manufacturer does not warrant that this
product is immune from the above case but will prevent unauthorized use of common-carrier
telecommunication service of facilities accessed through or connected to it. The manufacturer will not
be responsible for any charges that result from such unauthorized use.
B. Incidence of Harm
If a telephone company determines that the equipment provided to customer is faulty and possibly
causing harm or interruption in service to the telephone network, it should disconnect telephone
service until repair can be done. A telephone company may temporarily disconnect service as long as
repair is not done.
C. Changes in Service
A local telephone company may make changes in its communications facilities or procedure. If these
changes could reasonably be expected to affect the use of the phones or compatibility with the net
work, the telephone company is required to give advanced written notice to the user, allowing the user
to take appropriate steps to maintain telephone service.

- 6 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
1. INTRODUCTION
D. Maintenance Limitations
Maintenance limitations on the phones must be performed only by the manufacturer or its authorized
agent. The user may not make any changes and/or repairs expect as specifically noted in this manual.
Therefore, note that unauthorized alternations or repair may affect the regulatory status of the system
and may void any remaining warranty.
E. Notice of Radiated Emissions
This model complies with rules regarding radiation and radio frequency emission as defined by local
regulatory agencies. In accordance with these agencies, you may be required to provide information
such as the following to the end user.
F. Pictures
The pictures in this manual are for illustrative purposes only; your actual hardware may look slightly
different.
G. Interference and Attenuation
A phone may interfere with sensitive laboratory equipment, medical equipment, etc. Interference from
unsuppressed engines or electric motors may cause problems.
H. Electrostatic Sensitive Devices
ATTENTION
Boards, which contain Electrostatic Sensitive Device (ESD), are indicated by the sign.
Following information is ESD handling:
• Service personnel should ground themselves by using a wrist strap when exchange system boards.
• When repairs are made to a system board, they should spread the floor with anti-static mat which is
also grounded.
• Use a suitable, grounded soldering iron.
• Keep sensitive parts in these protective packages until these are used.
• When returning system boards or parts like EEPROM to the factory, use the protective package as
described.

- 7 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
2. PERFORMANCE
2.1 System Overview
Item Specification
Shape GSM900/1800/1900 and WCDMA bar type Handset
Size 108 X 54.5 X 18.3 mm
Weight 93 g (with 1000mAh Battery)
Power 4.0V normal, 1000 mAh(Li-ion) inner-pack
Talk Time Over 180 min (WCDMA, Tx=12 dBm, Voice)
(with 1000mAh) Over 180 min (GSM, Tx=Max, Voice)
Standby Time Over 250 Hrs (WCDMA, DRX=1.28)
(with 1000mAh) Over 320 Hrs (GSM, Paging period=5)
Antenna Internal type
LCD 400 x 240 pixel (TFT)
LCD Backlight White LED Back Light
Camera 3.0 Mega (CMOS) / VGA (CMOS).
Vibrator Yes
LED Indicator No
MIC Yes
Receiver Yes
Earphone Jack Yes (18 pin)
Connectivity Bluetooth, USB
Volume Key Push Type(+, -)
External Memory Trans-Flash
I/O Connect 18 Pin

- 8 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
2.2 Usable environment
1) Environment
2) Environment (Accessory)
Reference Spec. Min Typ. Max Unit
TA Power Available power 100 220 240 Vac
* CLA : 12 ~ 24 V(DC)
2.3 Radio Performance
1) Transmitter - GSM Mode
No Item GSM DCS & PCS
9k ~ 1GHz -39dBm
100k~1GHz -39dBm
1G~[A]MHz -33dBm
[A]M~[B]MHz -39dBm
MS allocated
Channel
1G~12.75GHz -33dBm
[B]M~12.75GHz -33dBm
100k~880MHz -60dBm 100k~880MHz -60dBm
880M~915MHz -62dBm 880M~915MHz -62dBm
915M~1GHz -60dBm 915M~1GHz -60dBm
1G~[A]MHz -50dBm 1G~[A]MHz -50dBm
[A]M~[B]MHz -56dBm [A]M~[B]MHz -56dBm
1
Conducted
Spurious
Emission
Idle Mode
[B]M~12.5GHz -50dBm [B]M~12.5GHz -50dBm
* In case of DCS : [A] -> 1710, [B] -> 1785 * In case of PCS : [A] -> 1850, [B] -> 1910
Item Specification
Voltage 4.0 V(Typ), 3.28 V(Min), [Shut Down : 3.25 V]
Operation Temp -20 ~ +60 °C
Storage Temp -20 ~ +70 °C
Humidity 85 % (Max)

- 9 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
No Item GSM DCS & PCS
30M~1GHz -36dBm
30M ~ 1GHz -36dBm
1G~[A]MHz -30dBm
[A]M~[B]MHz -36dBm
MS
allocated
Channel 1G ~ 4GHz -30dBm
[B]M~4GHz -30dBm
30M ~ 880MHz -57dBm 30M~880MHz -57dBm
880M ~ 915MHz -59dBm 880M~915MHz -59dBm
915M~1GHz -57dBm 915M~1GHz -57dBm
1G~[A]MHz -47dBm 1G~[A]MHz -47dBm
[A]M~[B]MHz -53dBm [A]M~[B]MHz -53dBm
2
Radiated
Spurious
Emission
Idle
Mode
[B]M~4GHz -47dBm [B]M~4GHz -47dBm
3 Frequency Error ±0.1ppm ±0.1ppm
±5(RMS) ±5(RMS)
4 Phase Error
±20(PEAK) ±20(PEAK)
3dB below reference sensitivity 3dB below reference sensitivity
RA250 : ±200Hz RA250: ±250Hz
HT100 : ±100Hz HT100: ±250Hz
TU50 : ±100Hz TU50: ±150Hz
5
Frequency Error
Under Multipath and
Interference
Condition
TU3 : ±150Hz TU1.5: ±200Hz
0 ~ 100kHz +0.5dB 0 ~ 100kHz +0.5dB
200kHz -30dB 200kHz -30dB
250kHz -33dB 250kHz -33dB
400kHz -60dB 400kHz -60dB
600 ~ 1800kHz -66dB 600 ~ 1800kHz -60dB
1800 ~ 3000kHz -69dB 1800 ~ 6000kHz -65dB
3000 ~ 6000kHz -71dB ≥6000kHz -73dB
Due to
modulati
on
≥6000kHz -77dB
400kHz -19dB 400kHz -22dB
600kHz -21dB 600kHz -24dB
1200kHz -21dB 1200kHz -24dB
6
Output
RF
Spectrum
Due to
Switching
transient
1800kHz -24dB 1800kHz -27dB
*In case of DCS : [A] -> 1710, [B] -> 1785 * In case of PCS : [A] -> 1850, [B] -> 1910

- 10 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
No Item GSM DCS & PCS
Frequency offset 800kHz
7Intermodulation
attenuation –Intermodulation product should
be Less than 55dB below the
level of Wanted signal
Power
control Power Toleranc e
Power
control Power Toleranc e
Level (dBm) (dB) Level (dBm) (dB)
5 33 ±3 0 30 ±3
6 31 ±3 1 28 ±3
7 29 ±3 2 26 ±3
8 27 ±3 3 24 ±3
9 25 ±3 4 22 ±3
10 23 ±3 5 20 ±3
11 21 ±3 6 18 ±3
12 19 ±3 7 16 ±3
13 17 ±3 8 14 ±3
14 15 ±3 9 12 ±4
15 13 ±3 10 10 ±4
16 11 ±5 11 8 ±4
17 9 ±5 12 6 ±4
18 7 ±5 13 4 ±4
19 5 ±5 14 2 ±5
8 Transmitter Output Power
15 0 ±5
9 Burst timing Mask IN Mask IN

- 11 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
2) Transmitter – WCDMA Mode
No Item Specification
1 Maximum Output Power Class3: +24dBm(+1/-3dB)
Class 4 : +21dBm(±2dB)
2 Frequency Error ±0.1ppm
3 Open Loop Power control in uplink ±9dB@normal, ±12dB@extreme
Adjust output(TPC command)
cmd 1dB 2dB 3dB
+1 +0.5/1.5 +1/3
+1.5/4.5
0-0.5/+0.5 -0.5/+0.5 -
0.5/+0.5
-1 -0.5/-1.5 -1/-3 -1.5/-
4.5
Group (10 equel command group)
4 Inner Loop Power control in uplink
+1 +8/+12 +16/+24
5 Minimum Output Power -50dBm(3.84MHz)
6Out-of-synchronization handling of output
power
Qin/Qout : PCCH quality levels
Toff@DPCCH/Ior : -22 -> -28dB
Ton@DPCCH/Ior : -24 -> -18dB
7 Transmit OFF Power -56dBm(3.84MHz)
8 Transmit ON/OFF Time Mask ±25us PRACH,CPCH,uplinlk compressed mode
9 Change of TFC
±25us
Power varies according to the data rate DTX :
DPCH off
(minimize interference between UE)
10 Power setting in uplink compressed ±3dB(after 14slots transmission gap)
11 Occupied Bandwidth(OBW) 5MHz(99%)
12 Spectrum emission Mask
-35-15*(Δf-2.5)dBc@Δf=2.5~3.5MHz,30k
-35-1*(Δf-3.5)dBc@Δf=3.5~7.5MHz,1M
-39-10*(Δf-7.5)dBc@Δf=7.5~8.5MHz,1M
-49dBc@Δf=8.5~12.5MHz,1M

- 12 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
13 Adjacent Channel Leakage Ratio(ACLR) 33dB@5MHz, ACP>-50dBm
43dB@10MHz, ACP>-50dBm
14 Spurious Emissions
(*:additional requirement)
-36dBm@f=9~150KHz, 1K BW
-36dBm@f=50KHz~30MHz, 10K BW
-36dBm@f=30MHz~1000MHz, 100K BW
-30dBm@f=1~12.5GHz,1M BW
(*)-41dBm@f=1893.5~1919.6MHz, 300K
(*)-67dBm@f=925~935MHz, 100K BW
(*)-79dBm@f=935~960MHz, 100K BW
(*)-71dBm@f=1805~1880MHz, 100K BW
15 Transmit Intermodulation -31dBc@5MHz,Interferer -40dBc
-41dBc@10MHz, Interferer -40dBc
16 Error Vector Magnitude (EVM) 17.5%(>-20dBm)
(@12.2K, 1DPDCH+1DPCCH)
17 Transmit OFF Power -15dB@SF=4.768Kbps,
Multi-code transmission
3) Receiver - GSM Mode
No Item GSM DCS & PCS
1 Sensitivity (TCH/FS Class II) -105dBm -105dBm
2Co-Channel Rejection (TCH/FS
Class II, RBER, TU high/FH) C/Ic=7dB Storage -30 ~ +85
200kHz C/Ia1=-12dB C/Ia1=-12dB
3
Adjacent
Channel
Rejection 400kHz C/Ia2=-44dB C/Ia2=-44dB
4 Intermodulation Rejection
Wanted Signal :-98dBm
1st interferer:-44dBm
2nd interferer:-45dBm
Wanted Signal :-96dBm
1st interferer:-44dBm
2nd interferer:-44dBm

- 13 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
5Blocking Response
(TCH/FS Class II, RBER)
Wanted Signal :-101dBm
Unwanted : Depend on
Frequency
Wanted Signal :-101dBm
Unwanted : Depend on
Frequency
4) Receiver - WCDMA Mode
No Item Specification
1 Reference Sensitivity Level -106.7 dBm(3.84 MHz)
2 Maximum Input Level
-25dBm(3.84MHz)
-44dBm/3.84MHz(DPCH_Ec)
UE@+20dBm output power(Class3)
3 Adjacent Channel Selectivity (ACS) 33dB
UE@+20dBm output power(Class3)
-56dBm/3.84MHz@10MHz
UE@+20dBm output power(Class3)
4 In-band Blocking
-44dBm/3.84MHz@15MHz
UE@+20dBm output power(Class3)
-44dBm/3.84MHz@f=2050~2095 and
2185~2230MHz
UE@+20dBm output power(Class3)
-30dBm/3.84MHz@f=2025~2050 and
2230~2255MHz
UE@+20dBm output power(Class3)
5 Out-band Blocking
-15dBm/3.84MHz@f=1~2025 and
2255~12500MHz
UE@+20dBm output power(Class3)
6 Spurious Response -44dBm CW
UE@+20dBm output power(Class3)
7 Intermodulation Characteristic
-46dBm CW@10MHz
-46dBm/3.84MHz@20MHz
UE@+20dBm output power(Class3)
8 Spurious Emissions
-57dBm@f=9KHz~1GHz, 100K BW
-47dBm@f=1~12.5GHz, 1M BW
-60dBm@f=1920MHz~1980MHz, 3.84M BW
-60dBm@f=2110MHz~2170MHz, 3.84M BW

- 14 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
2.4 Current Consumption
Stand by(BT Off condition) Voice Call VT
WCDMA Under 3.5 mA
(DRX=1.28)
Under 320 mA
(Tx=12dBm)
Under 430mA
(Tx=0dBm)
GSM Under 3.5 mA
(Paging=5period)
Under 300 mA
(Tx=Max)
(Stand by and Voice Call Test Condition : LCD backlight Off)
(VT Test Condition : Speaker off, LCD backlight On)
2.5 RSSI BAR
Level Change WCDMA GSM
BAR 7 >= -91 dBm >= -92 dBm
BAR 7 →6,5 -93 ± 2 dBm -94 ± 2 dBm
BAR 6,5 →4 -105 ± 2 dBm -98 ± 2 dBm
BAR 4 →3,2 -110 ± 2 dBm -102 ± 2 dBm
BAR 3,2 →1 -112 ± 2 dBm -105 ± 2 dBm
BAR 1 →0 -114 ± 2 dBm -107 ± 2 dBm
2.6 Battery BAR
Indication Standby
Bar 3 Over 3.77 ± 0.05V
Bar 3 →2 3.77 ± 0.05V
Bar 2 →1 3.67 ± 0.05V
Bar 1 →Empty 3.50 ± 0.05V
Low Voltage,
Warning message + Blinking
3.50 ± 0.05V
[Interval: 3min(Stand by)/1min(talk)]
Power off 3.25 ± 0.05V

- 15 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
2.7 Sound Pressure Level
No Test Item Specification
1 Sending Loudness Rating (SLR) 8±3 dB
Nor 2±3 dB
2 Receiving Loudness Rating (RLR)
Max -8±3 dB
3 Side Tone Masking Rating (STMR) Min 17 dB
4 Echo Loss (EL) Min 40 dB
5 Idle Noise-Sending (INS) Max -64 dBm0p
Nor Under -58 dBPA
6 Idle Noise-Receiving (INR)
MS
Max Under -58 dBPA
7 Sending Loudness Rating (SLR) 7
±3 dB
Nor -6±3 dB
8 Receiving Loudness Rating (RLR)
Max -13±3 dB
9 Side Tone Masking Rating (STMR) Min 25 dB
10 Echo Loss (EL) Min 40 dB
11 Idle Noise-Sending (INS) Max -55 dBm0p
Nor Under -45 dBPA
12 Idle Noise-Receiving (INR)
Headset
Max Under -40 dBPA
13
TDMA Noise
-. GSM : Power Level : 5
DCS/PCS : Power Level : 0
(Cell Power : -90 ~ -105 dBm)
-. Acoustic (Max Vol.)
MS/Headset SLR : 8 3dB
MS/Headset RLR : -15 3dB / -12dB
(SLR/RLR : Mid-value setting)
MS and
Headset Max Under -62 dBm

- 16 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
2.8 Charging
• Charging Method : CC & CV (Constant Current and Constant Voltage)
• Maximum Charging Voltage : 4.2 V
• Maximum Charging Current : 600 mA
• Normal Battery Capacity : 1000 mAh
• Charging Time : Max 3 hours (except for trickle charging time)
• Full charging indication current (charging icon stop current) :80mA
• Cut-off voltage : 3.2 V

- 17 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
3. TECHNICAL BRIEF
3. TECHNICAL BRIEF
The KB770 supports UMTS-2100, GSM-900, DCS-1800, and PCS-1900 based
GSM/GPRS/EDGE/UMTS. All receivers and the UMTS transmitter use the radioOne[1]Zero-IF
architecture to eliminate intermediate frequencies, directly converting signals between RF and
baseband. The quad-band GSM transmitters use a baseband-to-IF up-conversion followed by an
offset phase-locked loop that translates the GMSK-modulated or 8-PSK-modulated signal to RF.
3.1 General Description
•UMTS Cell + PCS with Rx
diversity IMT primary only
•Quad-band EDGE/GPRS
•Simultaneous-GPS
•EDGE/GPRS Tx/Rx and
WCDMA Tx are on the
RTR6275 IC
•One high-band WCDMA Rx is
on the RTR6275 IC
•Two PLLs on the RTR6275 IC:
–One for EDGE/GPRS Tx/Rx
and WCDMA Tx
–One for WCDMA Rx
•GPS pre-LNA within RFR
•UHF VCOs within RFR
•Two PLLs within RFR:
–One for primary and
diversity receive path
–One for GPS
•LO buffers, etc. within RFR
•No RTR/RFR LO interfaces
–No External VCOs
1
2
LO G enerat ion
& Distribution
VCO
PLL#1
F r ef
Quadrature
Downconverter
Quadrature
Downconver t er
sO/IlatigiD
sl
o
r
t
noc
&
Quadrature
Upc onver t er
LP F & D C
Correction
LP F & D C
Correction
LPF
LPF
DAC_REF
VDDM
Quadrature
Upc onver t er
BPF
BPF
BPF
BPF
FP
L
VCO
PLL#2
F re f
FPL
Quadrature
Downconverter
LO G enera t ion
& Distribution
Power
Det ect or
ctls
WS
H- BP F
L- BPF
U2100
U1900
G1900Rx
G1800Rx
G900 Rx
G850 Rx
U 800/ 850 U850
Tx BPF
U2100
Tx BPF
U1900
Tx BPF
WS
niahcy
s
iad
s
relpuoc
da
p
dap
R
T
R
T
R
T
G850 &
G900
Rx BPF s
G1800 &
G1900
Rx BPF s
U2100
Rx BPF
GPS
Rx BPF
002
7
/08
26
M
S
M
F r ef RFR6275_ TCXO
MS M_ TC X O
RTR6275
PCS
BPF
Cell
BPF
GPS
BPF
pool
retl
i
f
RFR6500
F ref
SBI(s )
and
other
stat us
control
pool
retlif
VDDM
ctls
sO/Ilat
i
giD
slortn
o
C&
CDMA
VCOs
GP S
VCO
LP F
LP F
Pre -
LNA
PLL1
F ref
Diversity
Rx VCO
Diversity
Rx VCO
LO Ge n
& Dist
LP F
LP F
Quad
D’convert
LNA
LNA
PLL0
F ref
LO Gen
& Dist
Quad
D’convert
Quad
D’convert
Primarypath
Secondary path
Jammer
det ect
RFR6 500_TCXO
WS
Cel l
Rx BPF
PCS
Rx BPF
Primary
Antenna
UMTS Diversity
&
GPS Antenna GPS
U800 / 850
U1900
LPF
SAW
Figure 3.1 Block diagram of RF part

- 18 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
receive and transmit paths through a FEM(Front End Module)
A generic, high-level functional block diagram of KB770 is shown in Figure 3.1. One antenna collects
base station forward link signals and radiates handset reverse link signals. The antenna connects with
The UMTS receive paths each include an LNA, an RF band-pass filter, and a downconverter that
translate the signal directly from RF-to-baseband using radioOne ZIF techniques. The RFIC’s Rx
analog baseband outputs, for the receive chains, connect to the MSM IC. The UMTS and GSM Rx
baseband outputs share the same inputs to the MSM IC.
For the transmit chains, the RTR6275 IC directly translates the Tx baseband signals (from the
MSM device) to an RF signal using an internal LO generated by integrated on-chip PLL and VCO.
The RTR6275 IC outputs deliver fairly high-level RF signals that are first filtered by Tx SAWs and
then amplified by their respective UMTS PAs. The high- and low-band UMTS RF transmit signals
emerge from the RTR6275 transceiver.
In the GSM receive path, the received RF signals are applied through their band-pass filters and
down-converted directly to baseband in the RTR6275 transceiver IC. These baseband outputs are
shared with the UMTS receiver and routed to the MSM IC for further signal processing.
The GSM/EDGE transmit path employs one stage of up-conversion and, in order to improve
efficiency, is divided into phase and amplitude components to produce an open-loop Polar topology:
1. The on-chip quadrature up-converter translates the GMSK-modulated signal or 8-PSK
modulated signal, to a constant envelope phase signal at RF;
2. The amplitude-modulated (AM) component is applied to the ramping control pin of Polar power
amplifier from a DAC within the MSM
KB770 power supply voltages are managed and regulated by the PM6650 Power Management IC.
This versatile device integrates all wireless handset power management, general housekeeping,
and user interface support functions into a single mixed signal IC. It monitors and controls the
external power source and coordinates battery recharging while maintaining the handset supply
voltages using low dropout, programmable regulators.
The device’s general housekeeping functions include an ADC and analog multiplexer circuit for
monitoring on-chip voltage sources, charging status, and current flow, as well as user-defined off-
chip variables such as temperature, RF output power, and battery ID. Various oscillator, clock, and
counter circuits support IC and higher-level handset functions. Key parameters such as under-
voltage lockout and crystal oscillator signal presence are monitored to protect against detrimental
conditions.

- 19 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
3. TECHNICAL BRIEF
3.2 GSM Mode
3.2.1 GSM Receiver
The Dual-mode KB770’s receiver functions are split between the three RFICs as follows:
■EGSM-900(GSM900), DCS-1800, and PCS-1900 modes use the RTR6275 IC only. Each mode has
independent front-end circuits and down-converters, but they share common baseband circuits (with only
one mode active at a time). All receiver control functions are beginning with SBI2-controlled parameters.
RF Front end consists of antenna, antenna switch module (LMSP4LMA-573TEMP) which includes three
RX saw filters (EGSM-900, DCS-1800 and PCS-1900). The antenna switch module allows multiple
operating bands and modes to share the same antenna. In KB770, a common antenna connects to one of
six paths: 1) UMTS-2100 Rx/Tx, 2) EGSM-900 Rx, 3) EGSM-900 Tx, 4) DCS-1800 Rx, and 5) DCS-1800,
PCS-1900 Tx(High Band Tx’s share the same path), 6) PCS-1900 Rx. UMTS operation requires
simultaneous reception and transmission, so the UMTS Rx/Tx connection is routed to a duplexer that
separates receive and transmit signals. GSM900, DCS1800, and PCS1900 operation is time division
duplexed, so only the receiver or transmitter is active at any time and a frequency duplexer is not required.
Table 3.2.1 Antenna Switch Module Control logic
2 The RFIC operating modes and circuit parameters are MSM-controlled through the proprietary 3-line Serial Bus Interface (SBI). The
Application Programming Interface (API) is used to implement SBI commands. The API is documented in AMSS Software – please see
applicable AMSS Software documentation for details.

- 20 -
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
The GSM900, DCS1800, and PCS1900 receiver inputs of RTR6275 are connected directly to the
transceiver front-end circuits(filters and antenna switch module). GSM900, DCS1800, and
PCS1900 receiver inputs use differential configurations to improve common-mode rejection and
second-order non-linearity performance. The balance between the complementary signals is critical
and must be maintained from the RF filter outputs all the way into the IC pins.
Since GSM900, DCS1800, and PCS1900 signals are time-division duplex (the handset can only
receive or transmit at one time), switches are used to separate Rx and Tx signals in place of
frequency duplexers – this is accomplished in the switch module.
The GSM900, DCS1800, and PCS1900 receive signals are routed to the RTR6275 through band
selection filters and matching networks that transform single-ended 50W sources to differential
impedances optimized for gain and noise figure. The RTR input uses a differential configuration to
improve second-order inter-modulation and common mode rejection performance. The RTR6275
input stages include MSM-controlled gain adjustments that maximize receiver dynamic range.
The amplifier outputs drive the RF ports of the quadrature RF-to-baseband downconverters. The
downconverted baseband outputs are multiplexed and routed to lowpass filters (one I and one Q)
having passband and stopband characteristics suitable for GMSK or 8-PSK processing. These filter
circuits include DC offset corrections. The filter outputs are buffered and passed on to the
MSM6280 IC for further processing.

- 21 -
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
3. TECHNICAL BRIEF
Figure 3.2.1 RTR6275 RX feature