LG GM730 User manual

Service Manual Model : GM730/GM735
Internal Use Only
Service Manual
GM730/GM735
Date: November, 2009 / Issue 1.0

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Copyright © 2009 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......................................................9
2.4 Current Consumption ................................................13
2.5 RSSI BAR..................................................................14
2.6 Battery BAR ..............................................................14
3. TECHNICAL BRIEF......................................... 15
3.1 GENERAL DESCRIPTION.............................................15
3.2 GSM MODE...............................................................16
3.3 UMTS MODE.............................................................20
3.4 GPS MODE ...............................................................23
3.5 LO GENERATION and DISTRIBUTION CIRCUIT ..............23
3.6 OFF-CHIP RF COMPONENTS......................................24
3.7 Main Features...........................................................28
3.8 Digital Baseband(DBB/MSM7200A) ............................33
3.9 Hardware Architecture ...............................................34
3.10 Subsystem(MSM7200A) ..........................................36
3.11 Power Block............................................................39
3.12 External memory interface .......................................44
3.13 H/W Sub System .....................................................46
3.14 Audio and sound .....................................................55
3.15 Camera interface.....................................................62
3.16 Proximity Sensor .....................................................69
3.17 Luminance Sensor...................................................70
3.18 Motion Sensor.........................................................71
4. TROUBLE SHOOTING..................................... 72
4.1 RF Component ..........................................................72
4.2 SIGNAL PATH ............................................................74
4.3 Checking TCXO Block ................................................78
4.4 Checking Front End Module(FEM) Block......................80
4.5 Checking WCDMA Block ............................................83
4.6 Checking GSM Block .................................................95
4.7 Power ON Troubleshooting .......................................102
4.8 Charger Troubleshooting ..........................................104
4.9 USB trouble.............................................................107
4.10 Audio trouble.........................................................109
4. 11 5M Camera trouble...............................................119
4.12 VGA Camera trouble ..............................................122
4.13 Main LCD trouble ..................................................125
4.14 SIM Detect Troubleshooting....................................127
4.15 Keypad Backlight Troubleshooting...........................129
4.16 LINEAR MOTOR.....................................................130
4.17 Proximity Sensor on/off trouble...............................131
4.18 Luminance Sensor on/off trouble............................133
4.19 Motion Sensor on/off trouble ..................................135
5. Downloading .............................................. 137
5.1 Introduction.............................................................137
5.2 Downloading Procedure...........................................138
6. BLOCK DIAGRAM........................................ 147
7. CIRCUIT DIAGRAM...................................... 157
8. BGA Pin Map ..............................................165
9. PCB LAYOUT ...............................................173
10. Calibration & RF Auto Test Program
(Tachyon)..................................................177
10.1 Confi guration of Tachyon.......................................177
10.2 How to use Tachyon...............................................179
11. Test Mode................................................. 182
12. EXPLODED VIEW & REPLACEMENT
PART LIST ................................................191
12.1 EXPLODED VIEW ...................................................191
12.2 Replacement Parts ................................................193
12.3 Accessory .............................................................219

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LGE Internal Use Only Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes

- 5 -
Copyright © 2009 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.
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.

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LGE Internal Use Only Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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. Pi ct ur es
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.

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Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
2. PERFORMANCE
2.1 System Overview
400x240 / 176x144,
SXGA, VGA, QVGA, CIF, QCIFImage Sca
Video
ling Down
8. Main Camera
(3M)
30 fps at Preview modeFrame Rate
0.162mmPixel Pitch
400 x 240Dot
Progressive, <=X2
2592(H) X 1944(V) pixels. WQVGA
CMOS image sensor
Typ. 400:1
Min. 65%, Typ. 70%
a-Si TFT, Trans missive
262,000
3 inch
Type
Resolution
Digital Zoom
Size
7. LCD
Color
Display Type
NTSC
Contrast Ratio
MSM7200A, RTR6285, PM75405. MSM Chipset
4Gb(Flash) / 2Gb(SDRAM) /User Memory : 100 MB(TBD)6. Memory
1000mAh (Li-Ion)4. Power
106g3. Weight
109.8 x 56.5 x 11.9 (mm)2. Size
Bar Type1. Phone Type
Type / Spec.
4Mbps
Throughput
IEEE 802.11b/g
11. WLAN
1m
10. Bluetooth
50 ~ 200m
Speaker/Receiver3) Receiver
18x12 oval type speaker2) Mono
72poly, SW MIDI1) MIDI
9. Audio

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LGE Internal Use Only Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
2.2 Usable environment
1) Environment
2) Environment (Accessory)
Item Specification
Voltage 3.7 (Typ), 4.2 (Max)V
Operation Temp -20 ~ +60°C
Storage Temp -30 ~ +85°C
Humidity 65 % (Max)
Reference Spec.
TA Power AC 110 ~ 240V, 60Hz

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Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
2.3 Radio Performance
1) Transmitter - GSM Mode
SpecificationItem
-98dBm/-96dBm (2.439%)
AM Suppression
-GSM : -31dBm - DCS : -29dBm
0.5TTiming Advance
800kHz, 1600kHz
: -98dBm/-96dBm (2.439%)
Intermodulation rejection – Speech
channels
400kHz : -19dBm/-22dBm(5/0), -23dBm
600kHz : -21dBm/-24dBm(5/0), -26dBm
Spectrum due to switching transient
Class II(RBER) : -105dBm(2.439%)Reference Sensitivity – TCH/FS
0.012(-15 - -40dBm)Usable receiver input level range
GSM :
1800-3000kHz :< -63dBc(-46dBm)
3000kHz-6000kHz : <-65dBc(-46dBm)
6000kHz < : < -71dBc(-46dBm)
DCS :
1800-3000kHz :< -65dBc(-51dBm)
6000kHz < : < -73dBc(-51dBm)
Spectrum due to modulation out to larger
than 1800kHz offset to the edge of the
transmit band
200kHz : -36dBm
600kHz : -51dBm/-56dBm
Spectrum due to modulation out to less
than 1800kHz offset
<3.69usBurst Timing
GSM : 5dBm – 33dBm 3dB
DCS/PCS : 0dBm – 30dBm 3dB
Transmitter Output power and Burst
Timing
GSM/DCS : < -28dBm
EMC(Radiated Spurious Emission
Disturbance)
GSM : 0.1 ppm
DCS/PCS : 0.1 ppm
Frequency Error
RMS : 5
Peak : 20 
Phase Error

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LGE Internal Use Only Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
2) Transmitter - WCDMA Mode
+24 dBm / 3.84 MHz, +1 / -3 dB
Maximum Output
Power
< -15 dB at Pout t-20 dBm
Peak Code Domain
Error
< 17.5 %, when Pout ≥-20 dBmError Vector Magnitude
< -31 dBc @ 5 MHz & < -41 dBc @ 10 MHz
when Interference CW Signal Level = -40 dBc
Transmit
Intermodulation
< -36 dBm / 1 kHz RW @ 9 kHz ≤f < 150 kHz
< -36 dBm / 10 kHz RW @ 150 KHz ≤f < 30 MHz
< -36 dBm / 100 kHz RW @ 30 MHz ≤f < 1 GHz
< -30 dBm / 1 MHz RW @ 1 GHz ≤f < 12.75 GHz
< -41 dBm / 300 kHz RW @ 1893.5 MHz < f < 1919.6 MHz
< -67 dBm / 100 kHz RW @ 925 MHz ≤f≤935 MHz
< -79 dBm / 100 kHz RW @ 935 MHz < f ≤960 GHz
< -71 dBm / 100 kHz RW @ 1805 MHz ≤f≤1880 MHz
Spurious Emissions
|f-fc| > 12.5 MHz
> 33 dB @ 5 MHz,
> 43 dB @ 10 MHz
Adjacent Channel
Leakage
Power Ratio (ACLR)
< 5 MHz at 3.84 Mcps (99% of power)
Occupied Bandwidth
< -50 dBm /3.84 MHz
Minimum Transmit
Power
Normal Conditions : within 9 dB,
Extreme Conditions : within 12 dB
Open Loop Power
Control
within 0.1 PPMFrequency Error
WCDMA850 : 824 MHz ~ 849 MHz
WCDMA900 : 880 MHz ~ 915MHz
WCDMA1900 : 1850 ~1910 MHz
WCDMA2100 : 1920 MHz ~ 1980 MHz
Transmit Frequency
SpecificationItem

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Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
3) Receiver - WCDMA Mode
< -57 dBm / 100 kHz BW @ 9 kHz ≤f < 1 GHz
< -47 dBm / 1 MHz BW @ 1 GHz ≤f≤12.75 GHz
Spurious Emissions
Adjust output(TPC command)
cmd 1dB 2dB 3dB
+1 +0.5/1.5 +1/3 +1.5/4
0 -0.5/+0.5 -0.5/+0.5 -0.5/+0.5
-1 -0.5/-1.5 -1/-3 -1.5/-4
group(10equal command group)
+1 +8/+12 +16/+24
Inner Loop Power Control
In Uplink
BER < 0.001 when Îor= -103.7 dBm / 3.84 MHz
& Iouw1 = -46 dBm @ Fuw1(offset) = 10 MHz
& Iouw2 = -46 dBm / 3.84 MHz @ Fuw2(offset) = 20 MHz
Intermodulation
BER < 0.001 when Îor = -103.7 dBm / 3.84 MHz & Iblocking = -44 dBmSpurious Response
BER < 0.001 when Îor = -103.7 dBm / 3.84 MHz
& Iblocking = -56 dBm / 3.84 MHz @ Fuw(offset) = 10 MHz
or Iblocking = -44 dBm / 3.84 MHz @ Fuw(offset) = 15 MHz
Blocking Characteristic
ACS > 33 dB where BER < 0.001 when Îor = -92.7 dBm / 3.84 MHz
& Ioac = –52 dBm / 3.84 MHz @ 5 MHz
Adjacent Channel
Selectivity (ACS)
BER < 0.001 when Îor = -25 dBm / 3.84 MHzMaximum Input Level
BER < 0.001 when Îor = -106.7 dBm / 3.84 MHzReference Sensitivity Level
WCDMA850 : 849 MHz ~ 894 MHz
WCDMA900 : 925MHz ~ 960 MHz
WCDMA1900 : 1930 ~1990 MHz
WCDMA2100 : 2110 ~ 2170 MHz
Receive Frequency
SpecificationItem

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LGE Internal Use Only Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
4) Transmitter - HSDPA Mode
Sub-Test
1=1/15, 2=12/15 21~25dBm / 3.84 MHz
3=13/15 4=15/8 20~25dBm / 3.84 MHz
5=15/7 6=15/0 19~25dBm / 3.84 MHz
Maximum Output
Power
3GPP Not CompleteError Vector Magnitude
Sub-Test : 1=1/15, 2=12/15, 3=13/15, 4=15/8, 5=15/7, 6=15/0
> 33 dB @ 5 MHz
> 43 dB @ 10 MHz
Adjacent Channel
Leakage
Power Ratio (ACLR)
Sub-Test : 1=1/15, 2=12/15, 3=13/15, 4=15/8, 5=15/7, 6=15/0
Spectrum Emission
Mask
HS-DPCCH
824 MHz ~ 849 MHz
880 MHz ~ 915 MHz
1850MHz ~ 1910 MHz
1920 MHz ~ 1980 MHz
Transmit Frequency
SpecificationItem
+/- 2.35End of CQI4
+/- 0.60Middle of CQI3
+/- 0.61Start of CQI2
+/- 2.36Start of Ack/Nack1
5
Transmitter
power step
tolerance
[dB]
Power
step size,
P [dB]
Power step slot boundary
Power
step
Sub-
test in
table
C.10.1.
4
1 MHz-49dBc8.5 ~ 12.5 MHz
1 MHz-35-10×(△f-7.5)dBc7.5 ~ 8.5 MHz
1 MHz-35-1×(△f-3.5)dBc3.5 ~ 7.5 MHz
30 kHz-35-15×(△f-2.5)dBc2.5 ~ 3.5 MHz
Measurement
Bandwidth
Minimum requirement
Frequency offset from
carrier △f

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Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
5)Receiver - HSDPA Mode
2.4 Current Consumption
1) Current Consumption
(Stand by and Voice Call Test Condition : Bluetooth off, LCD backlight off,Neighbor Cell off) (VT Test
Condition : Speaker off, LCD backlight On)
No Item Specification
1 Receive Frequency 849 MHz ~ 894 MHz
1930 MHz ~1990 MHz
2110 ~ 2170 MHz
2 Maximum Input Level Sub-Test : 1=1/15, 2=12/15, 3=13/15, 4=15/8, 5=15/7, 6=15/0
(BLER or R), 16QAM Only BLER < 10% or R >= 700kbps
Stand by Voice Call VT
Bluetooth Bluetooth
Off Connected
WCDMA
Under 3.00 mA Under 4.50 mA Under 250 mA N/A
(DRX=1.28) (DRX=1.28) (TX=12dBm low)
GSM Under 3.00 mA Under 4.50 mA Under 350 mA
Paging=5 period Paging=5 period (TX Power Level 5)
Sub-Test : 1=1/15, 2=12/15, 3=13/15, 4=15/8, 5=15/7, 6=15/0
BLER < 10% or R >= 700kbps
Maximum Input Level
(BLER or R), 16QAM Only
849 MHz ~ 894 MHz
925 MHz ~ 960 MHz
1930 MHz ~1990 MHz
2110 ~ 2170 MHz
Receive Frequency
SpecificationItem

























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LGE Internal Use Only Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. PERFORMANCE
2.5 RSSI BAR
2.6 Battery BAR
Indication Standby
Bar 4 →3 72%
Bar 3 →2 47%
Bar 2 →1 25%
Bar 1 →05%
Low Battery Alarm 15%
Critical Low Battery Alarm 5%
POWER OFF 0%
Level Change WCDMA GSM
BAR 4 → 3-82±2 dBm -91 ±2 dBm
BAR 3 → 2-92±2 dBm -96 ±2 dBm
BAR 2 → 1 -102 ±2 dBm -101 ±2 dBm
BAR 1 → 0 -112 ±2 dBm -106 ±2 dBm

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Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
3. TECHNICAL BRIEF
3. TECHNICAL BRIEF

3.1. GENERAL DESCRIPTION
The GM730/GM735 supports UMTS-900(Band VIII), UMTS-1900(Band II), UMTS-2100(Band I), GSM-850, GSM-
900, GSM-1800, and GSM-1900 based GSM/GPRS/EDGE/UMTS. 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 up-conversion followed by an offset
phase-locked loop that translates the GMSK-modulated or 8-PSK-modulated signal to RF.
[Figure 1-1] Block diagram of RF part
A generic, high-level functional block diagram of GM730/GM735 is shown in Figure 1-1. One antenna collects
base station forward link signals and radiates handset reverse link signals. The antenna connects with receive
and transmit paths through a SKY77521 (FEM, Front End Module + GSM PAM). 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 RTR6285 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 RTR6285 IC outputs deliver fairly high-level RF signals that are first filtered by
TX SAWs and then amplified by their respective UMTS PAs.
1QUALCOMM’s branded chipset that implements a Zero-IF radio architecture.
TX_ON
DAC_IREF
TX_IQ
TCXO
TCXO_EN
TRK_LO_ADJ
RF_ON
DAC_IREF
SBDT
VCTCXO
19.2MHz
RTR6285 MSM7200A
HB_RF_OUT3
PRX_IQ
PRX_IQ
LB_RF_OUT1
FRONT
END
MODULE
SKY77521
G850/900
WCDMA
Dual PAM
SSBDT_RTR
PMIC_SSBI
DCS/PCS HB_RF_OUT1
PDET_IN
PM7540
TX_IQ
EGSM_INP
EGSM_INN
DCS_INP
DCS_INN
GPCS_INP
GPCS_INN
GCELL_INP
GCELL_INN
EGSM_INP
EGSM_INN
DCS_INP
DCS_INN
GPCS_INP
GPCS_INN
GPCS_INP
GPCS_INN
GCELL_INP
GCELL_INN
W2100
Duplexer
LB_RF_OUT2
WPRXLBN
WPRXLBP
WPRXSE2_OUT
WB_MX_INM
WB_MX_INP TCXO
DRX_IQ
DRX_IQ
W1900
PAM
TX SAW
FILTER
WPRXSE2
RX SAW
FILTER GPS_IN
VCONT
SBDT_SSBI
ANT_SEL0/1/2/3
CTRL0/1/2/3
PMIC_TCXO
PA_POWER_CTL
GSM_PA_RAMP
VAPC
+VPWR
VBATT
RX4
RX3
RX2
RX1
GSM850
EGSM900
DCS1800
PCS1900
HB_RF_IN
LB_RF_IN
TX SAW
FILTER
TX SAW
FILTER
RX SAW
FILTER
RX SAW
FILTER
RX SAW
FILTER
RX SAW
FILTER
RX SAW
FILTER
HB_RF_OUT2
WPRXHBN
WPRXHBP
W900
Duplexer
W1900
Duplexer
LNA
WCDMA900 TX
WCDMA2100 TX
WCDMA1900 TX
49.9R
I
O
C
T
I
O
C
T
I
O
C
T
I
O
C
T
IO
CT
IO
CT
PA_RANGE0
VMODE1
VMODE2
VMODE2
VMODE1
Coupler
Coupler
Coupler
GPS_LNA_EN
WCDMA_900_ON
WCDMA_2100_ON
GPIO58
GPIO22
GPIO110
WCDMA_1900_ON
PA_ON0
GPS_LNA_EN
WCDMA_900_ON
WCDMA_2100_ON
WCDMA_1900_ON
WDRXHB2
RX SAW
FILTER
WCDMA2100
DIVERSITY

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LGE Internal Use Only Copyright © 2009 LG Electronics. Inc. All right reserved.
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3. TECHNICAL BRIEF


In the GSM receive path, the received RF signals are applied through their band-pass filters and down-
converted directly to baseband in the RTR6285 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
GM730/GM735 power supply voltages are managed and regulated by the PM7540 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.
3.2. GSM MODE
3.2.1 GSM RECEIVER
The GSM-850, GSM-900, GSM-1800, and GSM-1900 receiver inputs of RTR6285 are connected to the
transceiver front-end circuits(switch module) through saw filters. GSM-850, GSM-900, GSM-1800, and GSM-
1900 receiver inputs use differential configurations to improve common-mode rejection and second-order
non-linearity performance as shown in Figure 1-2. The balance between the complementary signals is critical
and must be maintained from the RF filter outputs all the way into the IC pins

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Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
3. TECHNICAL BRIEF


[Figure 1-2] GSM Receiver Inputs Topologies
Since GSM-850, GSM-900, GSM-1800, and GSM-1900 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 GSM-850, GSM-900, GSM-1800, and GSM-1900
receive signals are routed to the RTR6285 through saw filters and matching networks that transform single-
ended 50-Ω 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 RTR6285 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 MSM7200A IC for further processing as
shown in Figure 1-3.

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3. TECHNICAL BRIEF
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[Figure 1-3] RTR6285 RX feature

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3.2.2 GSM TRANSMITTER
The RTR6285 transmitter outputs(HB_RF_OUT1 and LB_RF_OUT1) include on-chip output matching
inductors. 50ohm output impedance is achieved by adding a series capacitor at the output pins. The
capacitor value may be optimized for specific applications and PCB characteristics based on pass-band
symmetry about the band center frequency as shown in Figure 1-3.
[Figure 1-4] GSM Transmitter Outputs Topologies
The RTR6285 IC is able to support GSM850/GSM 900 and GSM 1800/1900 mode transmitting. This design
guideline shows a quad-band GSM application. Both high-band and low band outputs are followed by
resistive pads to ensure that the load presented to the outputs remains close to 50ohm.

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3. TECHNICAL BRIEF
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3.3. UMTS MODE
3.3.1 UMTS RECEIVER
The UMTS duplexer receiver output is routed to LNA circuits within the RTR6285 device as shown in Figure 1-
5. The UMTS RX input is provided with an on-chip LNA that amplifies the signal before a second stage filter
that provides differential downconverter as shown in Figure 1-5. This second stage input is configured
differentially to optimize second-order intermodulation and common mode rejection performance. The gain
of the UMTS front end amplifier and the UMTS second stage differential amplifier are adjustable, under MSM
control, to extend the dynamic range of the receivers. The second stage UMTS RX amplifiers drive the RF
ports of the quadrature RF-to-baseband downconverters. The downconverted UMTS RX baseband outputs
are routed to lowpass filters having passband and stopband characteristics suitable for UMTS RX processing.
These filter circuits allow DC offset corrections, and their differential outputs are buffered to interface shared
with GSM RX to the MSM IC. The UMTS baseband outputs are turned off when the RTR6285 is
downconverting GSM signals and on when the UMTS is operating.
[Figure 1-5] UMTS Receiver Inputs Topologies

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3.3.2 UMTS TRANSMITTER
The UMTS TX path begins with differential baseband signals (I and Q) from the MSM device.
These analog input signals are amplified, filtered, and applied to the quadrature up-converter mixers. The up-
converter output is amplified by multiple variable gain stages that provide transmit AGC control. The AGC
output is filtered and applied to the driver amplifier; this output stage includes an integrated matching
inductor that simplifies the external matching network to a single series capacitor to achieve the desired 50-
Ω interface.
The RTR6285 UMTS output is routed to its power amplifier through a bandpass filter, and delivers fairly high-
level signals that are filtered and applied to the PA. Transmit power is delivered from the duplexer to the
antenna through the switch module.
The transceiver LO synthesizer is contained within the RTR6285 IC with the exception of the off-chip loop
filter components and the VC-TCXO. This provides a simplified design for multimode applications. The PLL
circuits include a reference divider, phase detector, charge pump, feedback divider, and digital logic
generator.
UMTS TX Using only PLL1, the LO generation and distribution circuits create the necessary LO signals for nine
different frequency converters. The UMTS transmitter also employs the ZIF architecture to translate the signal
directly from baseband to RF. This requires FLO to equal FRF, and the RTR6285 IC design achieves this without
allowing FVCO to equal FRF.
The RTR6285 IC is able to support UMTS 2100/1900/1800/1700/900 and 850 mode transmitting. This design
guideline shows UMTS 2100, UMTS1900 and UMTS850 applications.