LG KF700Q User manual
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1. INTRODUCTION .............................. 5
1.1 Purpose................................................... 5
1.2 Regulatory Information............................ 5
2. PERFORMANCE...............................7
2.1 Supporting Standard ................................7
2.2 Main Parts : Solution................................7
2.3 HW Features............................................8
2.4 HW SPEC. .............................................10
3. TECHNICAL BRIEF ........................16
3.1 General Description ...............................16
3.2 GSM Mode.............................................18
3.3 UMTS Mode...........................................21
3.4 LO generation and distribution circuits...23
3.5 Off-chip RF Components .......................24
3.6 Digital Base band (DBB/MSM6280).......34
3.7 Subsystem(MSM6280) ..........................36
3.8 Power Block ...........................................45
3.9 External memory interface .....................50
3.10 H/W Sub System..................................52
3.11 Feature List ..........................................63
3.12 Touch Screen Interface........................68
4. TROUBLE SHOOTING ...................69
4.1 Power on trouble....................................69
4.2 USB trouble............................................71
4.3 SIM detect trouble..................................72
4.4 Key sense trouble (KEYPAD) ................73
4.5 Keypad backlight trouble........................76
4.6 Micro SD trouble ....................................77
4.7 Audio trouble..........................................78
4.8 Camera trouble ......................................91
4.9 Main LCD trouble ...................................97
4.10 Bluetooth trouble................................100
4.11 Touch Screen trouble.........................102
4.12 RF Component...................................104
4.13 SIGNAL PATH ...................................105
4.14 Checking VCTCXO Block ..................107
4.15 Checking Front-End Module Block ....109
4.16 Checking UMTS Block .......................111
4.17 Checking GSM Block .........................124
5. DOWNLOAD .................................130
5.1 Introduction ..........................................130
5.2 Downloading Procedure.......................130
5.3 Troubleshooting Download Errors .......144
5.4 Caution.................................................149
6. BLOCK DIAGRAM ........................150
6.1 GSM & UMTS RF Block.......................150
6.2 Interface Diagram ................................152
7. Circuit Diagram ............................155
8. BGM Pin Map................................163
9. PCB LAYOUT................................169
10. CALIBRATION & RF AUTO TEST
(HOT KIMCHI) .............................175
10.1 Usage of Hot-Kimchi ..........................175
11. EXPLODED VIEW &
REPLACEMENT PART LIST ......179
11.1 EXPLODED VIEW .............................179
11.2 Replacement Parts
<Mechanic component>.....................181
<Main component> ............................185
11.3 Accessory ..........................................205
Table Of Contents
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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.
1. INTRODUCTION
1. INTRODUCTION
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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
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2. PERFORMANCE
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2.1 Supporting Standard
2.2 Main Parts : GSM Solution
2. PERFORMANCE
Item Feature Comment
Supporting Standard WCDMA/HSDPA
GSM850/EGSM900/DCS1800/PCS1900
with seamless handover
Phase 2+(include AMR)
SIM Toolkit : Class 1, 2, 3, A-E
Frequency Range GSM850 TX : 824 - 849 MHz
GSM850 RX : 869 - 894 MHz
EGSM900 TX : 880 - 915 MHz
EGSM900 RX : 925 - 960 MHz
DCS1800 TX : 1710 - 1785 MHz
DCS1800 RX : 1805 - 1880 MHz
PCS1900 TX : 1850 - 1910 MHz
PCS1900 RX : 1930 - 1990 MHz
WCDMA850 TX : 824 - 849 MHz
WCDMA850 RX : 869 -894 MHz
WCDMA2100 TX : 1920 - 1980 MHz
WCDMA2100 RX : 2110 - 2170 MHz
Application Standard WAP 2.0, JAVA 2.0
Item Part Name Comment
Digital Baseband MSM6280(Qualcomm)
Analog Baseband MSM6280(Qualcomm)
RF Chip RTR6280(Qualcomm)
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2.3 HW Features
2. PERFORMANCE
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Item Feature Comment
Form Factor Slide
Battery 1) Capacity
Standard : Li-Ion, 1000mAh
2) Packing Type : Soft Pack
Size 102 x 51 x 14.5 mm (?)
Weight 107 g With Battery
GSM 290 hours @paging period 5
WCDMA 210 hours @DRX=1.28
GSM 210min @ Power Level 5
WCDMA 137min @Tx=12dBm
Charging time 210min @power OFF/1000mAh
RX sensitivity GSM850 : -105dBm
EGSM900 : -105 dBm
DCS1800 : -105 dBm
PCS1900 : -105 dBm
WCDMA850 :-106.7dBm
WCDMA2100 : -106.7 dBm
GSM850 : 33dBm Class4 (GSM850)
EGSM900 : 33 dBm Class4 (EGSM900)
DCS1800 : 30 dBm Class1(DCS)
PCS1900 : 30 dBm Class1(PCS)
GSM850 : 33dBm E2 (GSM850)
EGSM900 : 27 dBm E2 (EGSM900)
DCS1800 : 26 dBm E2 (DCS)
PCS1900 : 26 dBm E2 (PCS)
GPRS compatibility GPRS Class 12
EDGE compatibility EDGE Class 12
Display TFT Main LCD(3’’, 240 x 480)
Built-in Camera 3.0 Mega pixel + VGA Video Call Camera
ANT Main : Internal Fixed Type
System connector 18 Pin
Ear Phone Jack 18pin, 4 Pole, Stereo
PC synchronization Yes
TX output
power
GSM/
GPRS
EDGE
Stand-by
time
Talk time
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2. PERFORMANCE
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Item Feature Comment
Speech coding FR, EFR, HR, AMR
Vibrator Built in Vibrator
Blue Tooth V1.2, A2DP
Voice Recording Yes
Speaker Phone mode Yes
Support
Travel Adapter Yes
CDROM Yes
Stereo Headset Yes
Data Cable Yes
T-Flash Yes
(External Memory)
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2.4 HW Spec.
2.4.1 GSM Transmitter/Receiver spec.
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2. PERFORMANCE
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Item Description Specification
1Frequency Band GSM850
TX : 824 - 849 MHz
RX : 869 -894 MHz
EGSM900
TX : 880 - 915 MHz
RX : 925 - 960 MHz
DCS1800
TX : 1710 - 1785 MHz
RX : 1805 - 1880 MHz
PCS1900
TX : 1850 - 1910 MHz
RX : 1930 - 1990 MHz
2Phase Error Rms : 5°
Peak : 20°
3Frequency Error GSM : 0.1 ppm
DCS/PCS : 0.1 ppm
4EMC(Radiated Spurious GSM/DCS : < -28dBm
Emission Disturbance)
5Transmitter Output power and GSM : 5dBm - 33dBm 3dB
Burst Timing DCS/PCS : 0dBm - 30dBm 3dB
6Burst Timing < 3.69us
7Spectrum due to modulation out 200kHz : -36dBm
to less than 1800kHz offset 600kHz : -51dBm/-56dBm
8Spectrum due to modulation out GSM
to larger than 1800kHz offset to 1800-3000kHz :< -63dBc(-46dBm)
the edge of the transmit band 3000kHz-6000kHz : <-65dBc(-46dBm)
6000kHz < : < -71dBc(-46dBm)
DCS
1800-3000kHz :< -65dBc(-51dBm)
6000kHz < : < -73dBc(-51dBm)
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Item Description Specification
9 Spectrum due to switching 400kHz : -19dBm/-22dBm(5/0), -23dBm
transient 600kHz : -21dBm/-24dBm(5/0), -26dBm
10 Reference Sensitivity - TCH/FS Class II(RBER) : -105dBm(2.439%)
11 Usable receiver input level range 0.012(-15 - -40dBm)
12 Intermodulation rejection - 800kHz, 1600kHz : -98dBm / -96dBm (2.439%)
Speech channels
13 AM Suppression -98dBm/-96dBm (2.439%)
- GSM : -31dBm - DCS : -29dBm
14 Timing Advance 0.5T
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2.4.2 WCDMA 850 Transmitter spec.
Item Description Specification
1 Transmit Frequency 824 - 849 MHz
2Maximum Output Power +24 dBm / 3.84 MHz, +1 / -3 dB
3Frequency Error within 0.1 PPM
4Open Loop Power Control Normal Conditions : within 9 dB,
Extreme Conditions : within 12 dB
5Minimum Transmit Power < -50 dBm / 3.84 MHz
6Occupied Bandwidth < 5 MHz at 3.84 Mcps (99% of power)
7Adjacent Channel Leakage > 33 dB @ 5 MHz,
Power Ratio (ACLR) > 43 dB @ 10 MHz
8Spurious Emissions < -36 dBm / 1 kHz RW @ 9 kHz ≤ f < 150 kHz
|f-fc| > 12.5 MHz < -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
9Transmit Intermodulation < -31 dBc @ 5 MHz & < -41 dBc @ 10 MHz
when Interference CW Signal Level = -40 dBc
10 Error Vector Magnitude < 17.5 %, when Pout ≥ -20 dBm
11 Peak Code Domain Error < -15 dB at Pout ≥ -20 dBm
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2. PERFORMANCE
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2.4.3 WCDMA 850 Receiver spec.
Item Description Specification
1 Receive Frequency 869 -894 MHz
2Reference Sensitivity Level BER < 0.001 when Îor = -106.7 dBm / 3.84 MHz
3Maximum Input Level BER < 0.001 when Îor = -25 dBm / 3.84 MHz
4Adjacent Channel Selectivity ACS > 33 dB where BER < 0.001 when Îor =
(ACS) -92.7 dBm / 3.84 MHz
& Ioac = -52 dBm / 3.84 MHz @ 5 MHz
5Blocking Characteristic 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
6Spurious Response BER < 0.001 when Îor = -103.7 dBm / 3.84 MHz &
Iblocking = -44 dBm
7Intermodulation 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
8Spurious Emissions < -57 dBm / 100 kHz BW @ 9 kHz ≤ f < 1 GHz
< -47 dBm / 1 MHz BW @ 1 GHz ≤ f ≤ 12.75 GHz
9nner Loop Power control in uplink 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
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2. PERFORMANCE
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2.4.4 WCDMA2100 Transmitter spec.
Item Description Specification
1 Transmit Frequency 1920 MHz ~ 1980 MHz
2Maximum Output Power +24 dBm / 3.84 MHz, +1 / -3 dB
3Frequency Error within 0.1 PPM
4Open Loop Power Control Normal Conditions : within 9 dB,
Extreme Conditions : within 12 dB
5Minimum Transmit Power < -50 dBm / 3.84 MHz
6Occupied Bandwidth < 5 MHz at 3.84 Mcps (99% of power)
7Adjacent Channel Leakage > 33 dB @ 5 MHz,
Power Ratio (ACLR) > 43 dB @ 10 MHz
8Spurious Emissions < -36 dBm / 1 kHz RW @ 9 kHz ≤ f < 150 kHz
|f-fc| > 12.5 MHz < -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
9Transmit Intermodulation < -31 dBc @ 5 MHz & < -41 dBc @ 10 MHz
when Interference CW Signal Level = -40 dBc
10 Error Vector Magnitude < 17.5 %, when Pout ≥ -20 dBm
11 Peak Code Domain Error < -15 dB at Pout ≥ -20 dBm
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2. PERFORMANCE
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2.4.5 WCDMA 2100 Receiver spec.
Item Description Specification
1 Receive Frequency 2110 ~ 2170 MHz
2Reference Sensitivity Level BER < 0.001 when Îor = -106.7 dBm / 3.84 MHz
3Maximum Input Level BER < 0.001 when Îor = -25 dBm / 3.84 MHz
4Adjacent Channel Selectivity ACS > 33 dB where BER < 0.001 when Îor =
(ACS) -92.7 dBm / 3.84 MHz
& Ioac = -52 dBm / 3.84 MHz @ 5 MHz
5Blocking Characteristic 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
6Spurious Response BER < 0.001 when Îor = -103.7 dBm / 3.84 MHz &
Iblocking = -44 dBm
7Intermodulation 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
8Spurious Emissions < -57 dBm / 100 kHz BW @ 9 kHz ≤ f < 1 GHz
< -47 dBm / 1 MHz BW @ 1 GHz ≤ f ≤ 12.75 GHz
9nner Loop Power control in uplink 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
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3.1 General Description
The KF700QQ supports UMTS-850, UMTS-2100, GSM850, EGSM-900, DCS-1800, and PCS-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 upconversion followed by an offset
phase-locked loop that translates the GMSK-modulated or 8-PSK-modulated signal to RF.
A generic, high-level functional block diagram of KF700QQ is shown in [Fig. 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 FEM(Front End Module).
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.
[Fig. 3.1] Block diagram of RF part
3. TECHNICAL BRIEF
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3. TECHNICAL BRIEF
1QUALCOMM’s branded chipset that implements a Zero-IF radio architecture.
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3. TECHNICAL BRIEF
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For the transmit chains, the RTR6280 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
RTR6280 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 RTR6280 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 RTR6280 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 upconverter 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
KF700Q power supply voltages are managed and regulated by the PM6658 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.
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3.2 GSM Mode
3.2.1 GSM Receiver
The Dual-mode KF700Q’s receiver functions are operated by only one RFIC as follows:
■ GSM850, EGSM-900, DCS-1800, PCS-1900 and UMTS-2100 modes use the 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 (D5015) which includes three RX saw filters
(GSM850, EGSM-900, DCS-1800 and PCS-1900). The antenna switch module allows multiple
operating bands and modes to share the same antenna. In KF700Q, a common antenna connects to
one of eight paths: 1) UMTS-850 Rx/Tx, 2) UMTS-2100 Rx/Tx, 3) GSM850 Rx, 4) EGSM-900 Rx, 5)
DCS-1800 Rx, 6)PCS-1900 Rx, 7) GSM850, EGSM-900 Tx (Low Band Tx’s share the same path) and
8) DCS-1800, PCS-1900 Tx(High Band Tx’s share the same path).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, EGSM900, 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.
The GSM850, EGSM900, DCS1800, and PCS1900 receiver inputs of RTR6280 are connected directly
to the transceiver front-end circuits(filters and antenna switch module). GSM850, EGSM900,
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 GSM850, EGSM900, 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.
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.
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3. TECHNICAL BRIEF
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ANT_SEL0 ANT_SEL1 ANT_SEL2 ANT_SEL3
GSM850/EGSM900 TX HIGH HIGH LOW LOW
DCS1800/PCS1900 TX HIGH LOW LOW LOW
WCDMA850 LOW HIGH LOW HIGH
WCDMA2100 LOW LOW HIGH HIGH
GSM850 RX LOW HIGH HIGH LOW
EGSM900 RX LOW LOW HIGH LOW
DCS1800 RX LOW HIGH LOW LOW
PCS1900 RX LOW LOW LOW LOW
[Table 3.1] Antenna Switch Module Control logic
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3. TECHNICAL BRIEF
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The GSM850, EGSM900, DCS1800, and PCS1900 receive signals are routed to the RTR6280 through
band selection filters and matching networks that transform single-ended 50Ω 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 RTR6280 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 (an interface shared with the RFR6280 UMTS receiver outputs).
[Fig. 3.2] RTR6280 RX feature
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3. TECHNICAL BRIEF
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3.2.2 GSM Transmitter
The RTR6280 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 passband
symmetry about the band center frequency. The suggested circuit is shown in [Fig. 3.3].
The RTR6280 IC is able to support GSM850/EGSM900 and DCS1800/PCS1900 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. The low-band GSM. Tx path also includes a Tx-band SAW filter
to remove noise-spurious components and noise that would be amplified by the PA and appear in the
GSM Rx band.
[Fig. 3.3] GSM Transmitter matching
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3. TECHNICAL BRIEF
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3.3 UMTS Mode
3.3.1 Receiver
The UMTS duplexer receiver output is routed to LNA circuits within the RTR6280 device. The UMTS Rx
input is provided with an on-chip LNA that amplifies the signal before a second stage filter that provides
differential downconverter. This second stage input is configured differentially to optimize second-order
intermodulation and common mode rejection performance. The gain of the UMTS frontend 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 RTR6280 is
downconverting GSM signals and on when the UMTS is operating.
3.3.2 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 upconverter mixers. The
upconverter 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 RTR6280 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 RTR6280 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 RTR6280 IC
design achieves this without allowing FVCO to equal FRF..
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