LG CU500 - Cell Phone User manual

Date: June, 2006 / Issue 1.0
Service ManualModel : CU500_TU500
Service Manual
CU500_TU500

- 3 -
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...........................................22
3.4 LO Phase-locked Loop ..........................26
3.5 Off-chip RF Components .......................28
3.6 Digital Baseband(DBB/MSM6275).........35
3.7 Hardware Architecture ...........................36
3.8 Subsystem(MSM6275) ..........................38
3.9 Power Block ...........................................41
3.10 External memory interface ...................46
3.11 H/W Sub System..................................47
3.12 Main Features ......................................64
4. TROUBLE SHOOTING ...................69
4.1 RF Component.......................................69
4.2 SIGNAL PATH_UMTS RF .....................71
4.3 Checking VCXO Block ...........................73
4.4 Checking Ant. SW Module Block ...........75
4.5. Checking UMTS Block ..........................77
4.6. Checking GSM Block ............................84
4.7 Power ON Troubleshooting....................93
4.8 Charger Troubleshooting .......................95
4.9 USB Troubleshooting.............................98
4.10 SIM Detect Troubleshooting ..............100
4.11 Camera Troubleshooting ...................101
4.12 Keypad Backlight Troubleshooting ....102
4.13 Folder ON/OFF Troubleshooting .......103
4.14 Main LCD Troubleshooting ................104
4.15 Audio Receiver Path .........................105
4.16 Headset path......................................107
4.17 Speaker phone path...........................109
4.18 Main microphone ...............................111
4.19 Headset microphone..........................113
5. DOWNLOAD..................................115
5.1 Introduction ..........................................115
5.2 Downloading Procedure.......................115
5.3 Troubleshooting Download Errors .......129
5.4 Caution.................................................134
6. BLOCK DIAGRAM ........................135
6.1 GSM & UMTS RF Block.......................135
6.2 Interface Diagram ................................137
7. Circuit Diagram ............................137
8. pcb layout .....................................148
9. CALIBRATION ..............................153
9.1 HOT KIMCHI........................................153
9.2 How to use Hot Kimchi.........................157
9.3 HOT KIMCHI Example.........................158
10. EXPLODED VIEW &
REPLACEMENT PART LIST ..... 161
10.1 EXPLODED VIEW ............................ 161
10.2 Replacement Parts
<Mechanic component>.................... 163
<Main component> ........................... 166
10.3 Accessory ......................................... 185
Table Of Contents

- 4 -

- 5 -
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
network, the telephone company is required to give advanced written notice to the user, allowing the
user to take appropriate steps to maintain telephone service.
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.
1. INTRODUCTION
1. INTRODUCTION

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.
1. INTRODUCTION
- 6 -

2. PERFORMANCE
- 7 -
2.1 System Overview
2. PERFORMANCE
Item Specification
Shape GSM850/EGSM/1800/1900 and WCDMA Slim Clamshell
Size 96.5 X 49 X 19.1 mm
Weight 105 g (with Battery)
Power 3.7V normal, 1100 mAh Li-Polymer
Talk Time
Over 180 min (WCDMA, Voice)
Over 180 min (GSM, Voice)
Stand by Time
Over 250 Hrs (WCDMA, DRX=1.28)
Over 250 Hrs (GSM, Paging period=5)
Antenna Intenna Type
LCD TFT Main LCD(2’, 262K, 176 x 220), TFT Sub LCD(65K, 96 x 96)
LCD Backlight White LED Back Light
Camera 1.3 Mega pixel (CMOS)
Vibrator Yes (Cylinder)
LED Indicator No
C-MIC Yes
Receiver Yes
Earphone Jack Yes(2.5mm)
Connectivity Bluetooth, USB
Volume Key Push Type(+, -)
External Memory Micro_SD
I/O Connect 24 Pin

2.2 Usable environment
1) Environment
2) Environment (Accessory)
*CLA : 12 ~ 24 V(DC)
2.3 Radio Performance
1) Transmitter - GSM Mode
* In case of DCS : [A] -> 1710, [B] -> 1785 * In case of PCS : [A] -> 1850, [B] -> 1910
2. PERFORMANCE
- 8 -
Item Specification
Voltage 4.0 V(Typ), 3.50 V(Min), [Shut Down : 3.35 V]
Operation Temp -20 ~ +60 °C
Storage Temp -30 ~ +85 °C
Humidity 85 % (Max)
Reference Spec. Min Typ. Max Unit
TA Power Available power 100 110 240 Vac
No Item GSM DCS & PCS
100k~1GHz -39dBm
9k ~ 1GHz -39dBm
MS allocated 1G~[A]MHz -33dBm
Channel
1G~12.75GHz -33dBm
[A]M~[B]MHz -39dBm
Conducted [B]M~12.75GHz -33dBm
1Spurious 100k~880MHz -60dBm 100k~880MHz -60dBm
Emission 880M~915MHz -62dBm 880M~915MHz -62dBm
Idle Mode
915M~1GHz -60dBm 915M~1GHz -60dBm
1G~[A]MHz -50dBm 1G~[A]MHz -50dBm
[A]M~[B]MHz -56dBm [A]M~[B]MHz -56dBm
[B]M~12.5GHz -50dBm [B]M~12.5GHz -50dBm

2. PERFORMANCE
- 9 -
* In case of DCS : [A] -> 1710, [B] -> 1785 * In case of PCS : [A] -> 1850, [B] -> 1910
No Item GSM DCS & PCS
30M ~ 1GHz -36dBm
30M~1GHz -36dBm
MS allocated 1G~[A]MHz -30dBm
Channel
1G ~ 4GHz -30dBm
[A]M~[B]MHz -36dBm
Radiated [B]M~4GHz -30dBm
2Spurious 30M ~ 880MHz -57dBm 30M~880MHz -57dBm
Emission 880M ~ 915MHz -59dBm 880M~915MHz -59dBm
Idle Mode
915M~1GHz -57dBm 915M~1GHz -57dBm
1G~[A]MHz -47dBm 1G~[A]MHz -47dBm
[A]M~[B]MHz -53dBm [A]M~[B]MHz -53dBm
[B]M~4GHz -47dBm [B]M~4GHz -47dBm
3Frequency Error ±0.1ppm ±0.1ppm
4Phase Error
±5(RMS) ±5(RMS)
±20(PEAK) ±20(PEAK)
3dB below reference sensitivity 3dB below reference sensitivity
Frequency Error RA250 : ±200Hz RA250: ±250Hz
5Under Multipath and HT100 : ±100Hz HT100: ±250Hz
Interference Condition TU50 : ±100Hz TU50: ±150Hz
TU3 : ±150Hz TU1.5: ±200Hz
0 ~ 100kHz +0.5dB 0 ~ 100kHz +0.5dB
200kHz -30dB 200kHz -30dB
250kHz -33dB 250kHz -33dB
Due to 400kHz -60dB 400kHz -60dB
Output RF
modulation 600 ~ 1800kHz -66dB 600 ~ 1800kHz -60dB
61800 ~ 3000kHz -69dB 1800 ~ 6000kHz -65dB
Spectrum
3000 ~ 6000kHz -71dB ≥6000kHz -73dB
≥6000kHz -77dB
Due to
400kHz -19dB 400kHz -22dB
Switching
600kHz -21dB 600kHz -24dB
transient
1200kHz -21dB 1200kHz -24dB
1800kHz -24dB 1800kHz -27dB

2. PERFORMANCE
- 10 -
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 Tolerance
Power control
Power Tolerance
Level (dBm) (dB) Level (dBm) (dB)
533±3 030±3
631±3 128±3
729±3 226±3
827±3 324±3
925±3 422±3
10 23 ±3 5 20 ±3
8Transmitter Output Power 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
15 0 ±5
9Burst timing Mask IN Mask IN

2. PERFORMANCE
- 11 -
2) Transmitter - WCDMA Mode
No Item Specification
1Maximum Output Power Class 3 : +24dBm(+1/-3dB)
2Frequency Error ±0.1ppm
3Open 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
4Inner Loop Power control in uplink 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)
+1 +8/+12 +16/+24
5Minimum Output Power -50dBm(3.84MHz)
Qin/Qout : PCCH quality levels
6Out-of-synchronization handling of output power Toff@DPCCH/Ior : -22 -> -28dB
Ton@DPCCH/Ior : -24 -> -18dB
7Transmit OFF Power -56dBm(3.84MHz)
8Transmit ON/OFF Time Mask
±25us
PRACH,CPCH,uplinlk compressed mode
±25us
9Change of TFC
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%)
-35-15*(∆f-2.5)dBc@∆f=2.5~3.5MHz,30k
12 Spectrum emission Mask
-35-1*(∆f-3.5)dBc@∆f=3.5~7.5MHz,1M
-39-10*(∆f-7.5)dBc@∆f=7.5~8.5MHz,1M
-49dBc@∆f=8.5~12.5MHz,1M

3)Receiver - GSM Mode
2. PERFORMANCE
- 12 -
No Item Specification
13 Adjacent Channel Leakage Ratio(ACLR)
33dB@5MHz, ACP>-50dBm
43dB@10MHz, ACP>-50dBm
-36dBm@f=9~150KHz, 1K BW
-36dBm@f=50KHz~30MHz, 10K BW
-36dBm@f=30MHz~1000MHz, 100K BW
14
Spurious Emissions -30dBm@f=1~12.5GHz, 1M BW
(*: additional requirement) (*)-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
No Item GSM DCS & PCS
1
Sensitivity (TCH/FS Class II) -105dBm -105dBm
2
Co-Channel Rejection
C/Ic=7dB Storage -30 ~ +85
(TCH/FS Class II, RBER, TU high/FH)
3Adjacent Channel 200kHz C/Ia1=-12dB C/Ia1=-12dB
Rejection 400kHz C/Ia2=-44dB C/Ia2=-44dB
Wanted Signal :-98dBm Wanted Signal :-96dBm
4
Intermodulation Rejection 1st interferer:-44dBm 1st interferer:-44dBm
2nd interferer:-45dBm 2nd interferer:-44dBm
5
Blocking Response Wanted Signal :-101dBm Wanted Signal :-101dBm
(TCH/FS Class II, RBER)
Unwanted : Depend on Frequency Unwanted : Depend on Frequency

2. PERFORMANCE
- 13 -
4) Receiver - WCDMA Mode
No Item Specification
1Reference Sensitivity Level -104.7 dBm(3.84 MHz)
-25dBm(3.84MHz)
2Maximum Input Level -44dBm/3.84MHz(DPCH_Ec)
UE@+20dBm output power(Class3)
3Adjacent Channel Selectivity (ACS)
33dB
UE@+20dBm output power(Class3)
-56dBm/3.84MHz@10MHz
4In-band Blocking UE@+20dBm output power(Class3)
-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
5Out-band Blocking 2230~2255MHz
UE@+20dBm output power(Class3)
-15dBm/3.84MHz@f=1~2025 and
2255~12500MHz
UE@+20dBm output power(Class3)
6Spurious Response
-44dBm CW
UE@+20dBm output power(Class3)
-46dBm CW@10MHz
7Intermodulation Characteristic -46dBm/3.84MHz@20MHz
UE@+20dBm output power(Class3)
-57dBm@f=9KHz~1GHz, 100K BW
8Spurious Emissions -47dBm@f=1~12.5GHz, 1M BW
-60dBm@f=1920MHz~1980MHz, 3.84M BW
-60dBm@f=2110MHz~2170MHz, 3.84M BW

2. PERFORMANCE
- 14 -
2.4 Current Consumption
(Stand by and Voice Call Test Condition : Bluetooth off, LCD backlight Off)
(VT Test Condition : Speaker off, LCD backlight On)
2.5 RSSI BAR
2.6 Battery BAR
Indication Standby
Bar 4 Over 3.9 ± 0.05V
Bar 4 →33.9 ± 0.05V
Bar 3 →23.77 ± 0.05V
Bar 2 →13.7 ± 0.05V
Bar 1 →Empty 3.6 ± 0.05V
Low Voltage, 3.50 ± 0.05V (Stand-by) / 3.60 ± 0.05V (Talk)
Warning message+ Blinking [Interval : 3min(Stand-by) / 1min(Talk)]
Power Off 3.35 ± 0.05V
Stand by Voice Call VT
WCDMA
Under 4.4 mA Under 366 mA
(DRX=1.28) (Tx=12dBm)
GSM Under 4.4 mA (Paging=5period) Under 366 mA
Under 7.0 mA (Tx=Max)
(@Bluetooth Connected,
Paging=9period)
Level Change WCDMA GSM
BAR 5 → 4-85 ±2 dBm -85 ±2 dBm
BAR 4 → 3-90 ±2 dBm -90 ±2 dBm
BAR 3 → 2-95 ±2 dBm -95 ±2 dBm
BAR 2 → 1-98 ±2 dBm -100 ±2 dBm
BAR 1 → 0-101 ±2 dBm -105 ±2 dBm

2. PERFORMANCE
- 15 -
2.7 Sound Pressure Level
No Test Item Specification
1Sending Loudness Rating (SLR) 8 ±3 dB
2Receiving Loudness Rating (RLR) Nor -7 ± 3 dB
Max -18 ± 3 dB
3Side Tone Masking Rating (STMR) Min 17 dB
4Echo Loss (EL) Min 40 dB
5Sending Distortion (SD) Refer to Table 30.3
6Receiving Distortion (RD) Refer to Table 30.4
7Idle Noise-Sending (INS) Max -64 dBm0p
8Idle Noise-Receiving (INR) Nor Under -47 dBPA
Max Under -36 dBPA
9Sending Loudness Rating (SLR) 8±3dB
10 Receiving Loudness Rating (RLR) Nor -1 ±3 dB
Max -12 ±3 dB
11 Side Tone Masking Rating (STMR) Min 25 dB
12 Echo Loss (EL) Min 40 dB
13 Sending Distortion (SD) Refer to Table 30.3
14 Receiving Distortion (RD) Refer to Table 30.4
15 Idle Noise-Sending (INS) Max -55 dBm0p
16 Idle Noise-Receiving (INR) Nor Under -45 dBPA
Max Under -40 dBPA
TDMA Noise
-. GSM : Power Level : 5
DCS/PCS : Power Level : 0
17 (Cell Power : -90 ~ -105 dBm)
-. Acoustic (Max Vol.)
MS/Headset SLR : 8
±
3dB
MS/Headset RLR : -18 ± 3dB/-15dB
(SLR/RLR : Mid-value setting)
MS
Headset
MS and
Headset
Max -62 dBm

2.8 Charging
• Charging Method : CC & CV (Constant Current and Constant Voltage)
• Maximum Charging Voltage : 4.2 V
• Maximum Charging Current : 650 mA
• Normal Battery Capacity : 1100 mAh
• Charging Time : Max 3.0 hours (except for trickle charging time)
• Full charging indication current (charging icon stop current) : 80 mA
• Cut-off voltage : 3.35 V
2. PERFORMANCE
- 16 -

3. TECHNICAL BRIEF
- 17 -
3.1 General Description
The CU500 supports UMTS-850, UMTS-1900, GSM-850, GSM-900, DCS-1800, and PCS-1900 based
GSM/GPRS/EDGE/UMTS/HSDPA. All receivers and the UMTS transmitter use the radioOne1Zero-IF
architecture to eliminate intermediate frequencies, directly converting signals between RF and
baseband. The quad-band GSM transmitters use a baseband-to-IF upconversion followed by an offset
phaselocked loop that translates the GMSK-modulated or 8-PSK-modulated signal to RF.
1QUALCOMM’s branded chipset that implements a Zero-IF radio architecture.
3. TECHNICAL BRIEF
Fig 3.1 Block diagram of RF part

A generic, high-level functional block diagram of CU500 is shown in Figure 3-1. One antenna collects base station
forward link signals and radiates handset reverse link signals. The antenna connects with receive and transmit
paths through a switch module (plus two duplexers for UMTS high-band and low-band operations).
The UMTS receive signal is amplified by the RFL6202 LNA then passes through a bandpass filter before being
applied to the RFR6202 Receiver IC. On-chip circuits downconvert the received signal directly from RF to
baseband using radioOne Zero-IF techniques. Generation of the UMTS downconverter LO is distributed between
the RTR6250 (phase-locked loop), the RFR6202 (buffer amplifiers and LO distribution circuits) and external UHF
VCO and loop filter circuits. The RFR6202 IC outputs analog baseband signals for further processing by the MSM
device. This baseband interface is shared with the RTR6250 GSM850/GSM900/DCS/PCS receiver outputs.
GSM850, GSM-900, DCS and PCS receive signals pass through their bandpass filters then are applied to the
RTR6250 IC. Similar to the UMTS path, RTR6250 circuits downconvert the received signals directly from RF to
baseband. The GSM850/GSM900/DCS/PCS downconverter LO is generated mostly within the RTR6250 (PLL
and distribution functions); the UMTS Rx CH VCO and loop filter are off-chip. The RTR analog baseband outputs
are routed to the MSM6275 IC for further processing (an interface shared with the RFR).
The UMTS transmit path begins with analog baseband signals from the MSM device that drive the RTR6250 IC.
Integrated PLL and VCO circuits generate the Tx LO used in the quadrature upconverter that translates baseband
signals directly to RF. The RTR6250 output driver stages deliver fairly high-level signals that are filtered and
applied to the power amplifiers (PA). The PA output is routed to the antenna through a duplexer and switch
module.
The shared GSM-850, GSM900, DCS-1800, and PCS-1900 transmit path begins with the same baseband
interface from the MSM6275 IC that is used for the UMTS band. A single GSM850/GSM900/DCS/PCS quadrature
upconverter translates the GMSK or 8-PSK-modulated signal to a convenient intermediate frequency (IF) that
forms one input to an offset phase-locked loop (OPLL). OPLL functions are split between the RTR6250 IC and off-
chip loop filter and dual Tx VCO circuits, and translate the GMSK or 8-PSK-modulated signal to the desired GSM-
850, GSM-900, DCS-1800 or PCS-1900 channel frequency. This signal is applied to a dual power amplifier (only
one is active at a time). The enabled path continues with the PA, an automated power control (APC) circuit that
samples the transmit power and adjusts its level, the switch module (which includes a band-appropriate lowpass
filter), and the antenna.
CU500 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.
3. TECHNICAL BRIEF
- 18 -

3. TECHNICAL BRIEF
- 19 -
3.2 GSM Mode
3.2.1 GSM Receiver
The Dual-mode CU500’s receiver functions are split between the three RFICs as follows:
• UMTS-850,1900 operation uses the RFL6202 LNA and RFR6202 Receiver ICs to implement the
receive signal path, accepting an RF input and delivering analog baseband outputs (I and Q).
• GSM-850, GSM-900, DCS-1800, and PCS-1900 modes both use the RTR6250 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(CXG1198AEQ), and three RX saw
filters(GSM850, GSM900, DCS and PCS). The antenna switch module allows multiple operating
bands and modes to share the same antenna. In CU500, a common antenna connects to one of eight
paths: 1) UMTS-850 Rx/Tx, 2) UMTS-1900 Rx/Tx, 3) GSM-850 Rx, 4) GSM-900 Rx, 5) GSM-850
GSM-900 Tx, (Low Band Tx’s share the same path) 6) DCS-1800 Rx, and 7) DCS-1800,PCS-1900
Tx(High Band Tx’s share the same path), 8) 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. GSM850/GSM900, DCS, and PCS operation is time division duplexed,
so only the receiver or transmitter is active at any time and a frequency duplexer is not required.
2The 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.
IN_A IN_B IN_C
GSM850/GSM900 TX HIGH HIGH LOW
DCS/PCS TX HIGH LOW LOW
GSM 850 RX LOW HIGH LOW
UMTS 850 HIGH LOW HIGH
DCS RX LOW HIGH HIGH
PCS RX LOW LOW HIGH
UMTS 1900 HIGH HIGH HIGH
GSM 900 LOW LOW LOW
Table 3.2.1 Antenna Switch Module Control logic

The GSM850, GSM900, DCS, and PCS receiver inputs of RTR6250 are connected directly to the transceiver
front-end circuits(filters and antenna switch module). GSM850, GSM900, DCS, and PCS receiver inputs are
similar to the RFR6202 UMTS Rx input in that they also use differential configurations to improve commonmode
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 GSM850, GSM900, DCS, and PCS 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 GSM850, GSM900, DCS, and PCS receive signals are routed to the RTR6250 through band selection filters
and matching networks that transform single-ended 50-Ω sources to differential impedances optimized for gain
and noise figure. Similar to the RFR, the RTR input uses a differential configuration to improve second-order inter-
modulation and common mode rejection performance. The RTR6250 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 MSM6275 IC for further processing (an interface shared with the
RFR6202 UMTS receiver outputs).
3. TECHNICAL BRIEF
- 20 -
Figure 3.2.1 RTR6250 RX feature

3. TECHNICAL BRIEF
- 21 -
3.2.2 GSM Transmitter
The shared GSM Low-band (GSM850/GSM900) and High-band (DCS1800, PCS1900) transmit path begins
with the baseband inputs from the MSM6275 IC. These differential analog input signals are buffered,
lowpass filtered, corrected for DC offsets then applied to the GSM quadrature upconverter. The upconverter
LO signals are generated from the transceiver VCO signal by the LO distribution and generation circuits
within RTR6250. This upconverter translates the GMSK or 8-PSK-modulated signal to a convenient
intermediate frequency (IF) that forms one input to a frequency/phase detector circuit. This IF signal is the
reference input to an offset phase-locked loop (OPLL) circuit as shown in Figure 3.2.2-1.
The feedback path of this OPLL circuit includes a downconversion from the RF output frequency range
to the IF range. The two inputs to this downconversion mixer are formed as follows:
1. The dual Tx VCO output (operating in the desired RF output frequency range) is buffered within the
RTR6250 IC then applied to the mixer RF port.
2. The LO Generation and Distribution circuits that deliver the transmit path.s LO for the baseband-to-IF
upconversion also provides the .offset LO. signal that is applied to the feedback path.s mixer LO port.
The mixer IF port output is the offset feedback signal - the variable input to the frequency/phase
detector circuit. The detector compares its variable input to its reference input and generates an error
signal that is lowpass filtered by the loop filter and applied to the dual Tx VCO tuning port to force the
VCO output in the direction that minimizes errors. As mentioned earlier, the VCO output is connected to
the feedback path thereby creating a closed-loop control system that will force frequency and phase
errors between the variable and reference inputs to zero.
Figure 3.2.2-1 Offset phase-locked loop interfaces
Other manuals for CU500 - Cell Phone
5
This manual suits for next models
1
Table of contents
Other LG Cell Phone manuals