LG U880 Service Manual

Date: November, 2005 / Issue 1.0

Service Manual

Model : U880

Service Manual

U880

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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...........................................201

3.2.1 GSM Receiverv................................20

3.2.2 GSM Transmitter..............................22

3.3 WCDMA Mode .......................................23

3.3.1 Receiver...........................................23

3.3.2 Transmitter.......................................25

3.4 Phase-locked Loop ................................26

3.4.1 UMTS Rx PLL (PLL2) ......................26

3.4.2 Transceiver PLL (PLL1)...................27

3.5 Off-chip RF Components .......................28

3.5.1 Front End Module(U1006) ...............28

3.5.2 UMTS duplexer (FL1000) ................29

3.5.3 UMTS Power Amplifier (U1002).......29

3.5.4 Thermistor (RT1000)........................31

3.5.5 UMTS transmit power detector

(U1001)............................................31

3.5.6 Dual band GSM power amplifier

(U1005)............................................32

3.5.7 GSM transmit VCO (U1003) ............34

3.5.8 UMTS Rx RF filter (FL1001) ............34

3.5.9 VCTCXO (X1000) ............................35

3.5.10 Bluetooth........................................35

3. BB Technical Description............. 37

3.6 Baseband(DBB/MSM6250)....................37

3.6.1 General Description .........................37

3.7 Hardware Architecture ...........................38

3.7.1 Block Diagram(MSM6250)...............39

3.8 Subsystem(MSM6250) ..........................40

3.8.1 ARM Microprocessor Subsystem.....40

3.8.2 UMTS Subsystem............................40

3.8.3 GSM Subsystem..............................40

3.8.4 RF Interface .....................................40

3.8.5 Serial Bus Interface(SBI) .................40

3.8.6 Wideband CODEC...........................41

3.8.7 Vocoder Subsystem.........................41

3.8.8 HKADC ............................................41

3.8.9 General-Purpose Input/Output

Interface...........................................41

3.8.10 UART .............................................42

3.8.11 USB ...............................................42

3.9 External memory interface .....................43

3.10 H/W Sub System..................................44

3.10.1 RF Interface ...................................44

3.10.2 MSM Sub System ..........................46

3.10.3 Power Block...................................50

3.10.4 Key Pad .........................................55

3.10.5 Camera Interface ...........................56

3.10.6 Folder ON/OFF Operation .............58

3.10.7 Camera Direction Detection...........59

3.10.8 Keypad Light..................................60

3.10.9 LCD Module...................................61

3.10.10 Display & LCD FPC Interface ......62

3.10.11 Audio and Sound .........................63

3.10.12 Trans Flash..................................67

3.11 Main Features ......................................68

3.11.1 LG-U880(MUSE) Main features.....68

3.11.2 LG-U880 Main Components ..........69

Table Of Contents

Table Of Contents

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4. TROUBLE SHOOTING ...................74

4.1 RF Component.......................................74

4.2 SIGNAL PATH .......................................75

4.3 Checking VCXO Block ...........................76

4.4 Checking Ant. SW Module Block ...........79

4.5 Checking WCDMA Block .......................81

4.5.1 Checking VCXO Block.....................82

4.5.2 Checking Ant. SW module...............82

4.5.3 Checking RF TX Level.....................82

4.5.4 Checking PAM Block .......................84

4.5.5 Check RF Rx Level..........................85

4.6 Checking GSM Block .............................87

4.6.1 Checking VCO Block .......................88

4.6.2 Checking Ant. SW Module...............90

4.6.3 Checking RF Tx level.......................90

4.6.4 Checking PAM Block .......................92

4.6.5 Checking RF Rx Block.....................93

4.7 Bluetooth RF Block ................................95

4.8 Power ON Trouble .................................98

4.9 USB Trouble ........................................100

4.10 SIM Detect Trouble ............................101

4.11 Key Sense Trouble ............................102

4.12 Camera Trouble .................................103

4.13 Main LCD Trouble..............................104

4.14 Keypad Backlight Trouble ..................106

4.15 Folder ON/OFF Trouble .....................107

4.16 Camera Direction Detection Trouble..108

4.17 Trans Flash Trouble...........................109

4.18 Audio Trouble Shooting .....................110

4.19 Charger Trouble Shooting..................120

5. DOWNLOAD .................................123

5.1 Introduction ..........................................123

5.2 Downloading Procedure.......................123

5.3 Troubleshooting Download Errors .......136

6. BLOCK DIAGRAM ........................141

6.1 BLK diagram ........................................141

6.2 GSM & WCDMA RF Block...................142

6.3 Interface Diagram ................................144

7. Circuit Diagram ............................147

8. pcb layout .....................................155

9. CALIBRATION ..............................161

9.1 HOT KIMCHI........................................161

9.1.1 Directory structure..........................161

9.1.2 Setup file (Info_Db.txt) ...................162

9.1.3 Setup file item ................................163

9.1.4 Example for setting file ..................164

9.2 How to use Hot Kimchi.........................165

9.3 HOT KIMCHI Example.........................166

10. EXPLODED VIEW &

REPLACEMENT PART LIST ..... 170

10.1 EXPLODED VIEW ............................ 170

10.2 Replacement Parts

<Mechanic component>.................... 173

<Main component> ........................... 177

10.3 Accessory ......................................... 196

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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
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

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2. PERFORMANCE

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2.1 System Overview

2. PERFORMANCE

Item Specification

Shape GSM900/1800/1900 and WCDMA Folder Handset

Size 98.8 X 49.0 X 18.2 mm

Weight 93 g (with 800mAh Battery)

Power 4.0V normal, 800 mAh Li-Polymer

Talk Time Over 125 min (WCDMA, Tx=12 dBm, Voice)

(with 800mAh) Over 160 min (GSM, Tx=Max, Voice)

Standby Time Over 200 Hrs (WCDMA, DRX=1.28)

(with 800mAh) Over 220 Hrs (GSM, Paging period=9)

Antenna Internal type

LCD Main 176 X 220 pixel (TFT) / sub 96 X 96 pixel (TFT)

LCD Backlight White LED Back Light (2way ; main/sub common)

Camera 1.3 Mega pixel (CMOS)

Vibrator Yes (Cylinder Type)

LED Indicator No

C-MIC Yes

Receiver Yes

Earphone Jack Yes (12 pin)

Connectivity Bluetooth, USB

Volume Key Push Type(+, -)

External Memory Trans-Flash

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

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Item Specification

Voltage 4.0 V(Typ), 3.38 V(Min), [Shut Down : 3.28 V]

Operation Temp -20 ~ +60 °C

Storage Temp -20 ~ +70 °C

Humidity 85 % (Max)

Reference Spec. Min Typ. Max Unit

TA Power Available power 100 220 240 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

1 Spurious 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

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* 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

3 Frequency Error ±0.1ppm ±0.1ppm

4 Phase Error

±5(RMS) ±5(RMS)

±20(PEAK) ±20(PEAK)

3dB below reference sensitivity 3dB below reference sensitivity

Frequency Error RA250 : ±200Hz RA250: ±250Hz

5 Under 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

6 1800 ~ 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

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No Item GSM DCS & PCS

Frequency offset 800kHz

7 Intermodulation 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

8 Transmitter 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

9 Burst timing Mask IN Mask IN

2. PERFORMANCE

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2) Transmitter - WCDMA Mode

No Item Specification

1 Maximum Output Power

Class3: +24dBm(+1/-3dB)

Class4: +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

4 Inner 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(10equal command group)

+1 +8/+12 +16/+24

5 Minimum Output Power -50dBm(3.84MHz)

Qin/Qout : PCCH quality levels

6 Out-of-synchronization handling of output power 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

±25us

9 Change 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

-49 dBc@∆f=8.5~12.5MHz, 1M

3)Receiver - GSM Mode

2. PERFORMANCE

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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)

3 Adjacent 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

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4) Receiver - WCDMA Mode

No Item Specification

1 Reference Sensivitivity Level -106.7dBm(3.84 MHz)

-25dBm(3.84MHz)

2 Maximum 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

5 Out-band Blocking 2230~2255MHz

UE@+20dBm output power(Class3)

-15dBm/3.84MHz@f=1~2025 and

2255~12500MHz

UE@+20dBm output power(Class3)

6 Spurious Response

-44dBm CW

UE@+20dBm output power(Class3)

-46dBm CW@10MHz

7 Intermodulation Characteristic -46dBm/3.84MHz@20MHz

UE@+20dBm output power(Class3)

-57dBm@f=9KHz~1GHz, 100K BW

8 Spurious Emissions -47dBm@f=1~12.5GHz, 1M BW

-60dBm@f=1920MHz~1980MHz, 3.84M BW

-60dBm@f=2110MHz~2170MHz, 3.84M BW

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

2. PERFORMANCE

- 14 -

Stand by Voice Call VT

WCDMA

Under 4.0 mA Under 384 mA Under 533mA

(DRX=1.28) (Tx=12dBm) (Tx=12dBm)

Under 3.6 mA Under 300 mA

(Paging=9period) (Tx=Max)

GSM Under 5.3 mA

(@Bluetooth Connected,

Paging=9period)

Level Change WCDMA GSM

BAR 4 → 3 -87 ±2 dBm -91 ±2 dBm

BAR 3 → 2 -97 ±2 dBm -96 ±2 dBm

BAR 2 →1 -107 ±2 dBm -101 ±2 dBm

BAR 1 → 0 -111 ±2 dBm -106 ±2 dBm

Indication Standby

Bar 4 Over 3.82 ±0.03V

Bar 4 → 3 3.81 ±0.03V

Bar 3 → 2 3.74 ±0.03V

Bar 2 → 1 3.67 ±0.03V

Bar 1 → Empty 3.50 ±0.03V

Low Voltage, 3.38 ±0.03V (Stand-by) / 3.50 ±0.03V (Talk)

Warning message+ Blinking [Interval : 3min(Stand-by) / 1min(Talk)]

Power Off 3.28 ±0.03V↓

2. PERFORMANCE

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2.7 Sound Pressure Level

No Test Item Specification

1 Sending Loudness Rating (SLR) 8 ±3 dB

2 Receiving Loudness Rating (RLR)

Nor -4 ±3 dB

Max -15 ±3 dB

3 Side Tone Masking Rating (STMR) Min 17 dB

4 Echo Loss (EL) Min 40 dB

5 Sending Distortion (SD) Refer to Table 30.3

6 Receiving Distortion (RD) Refer to Table 30.4

7 Idle Noise-Sending (INS) Max -64 dBm0p

8 Idle Noise-Receiving (INR)

Nor Under -47 dBPA

Max Under -36 dBPA

9 Sending 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 : -15 ±3dB / -12dB

(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 : 600 mA

• Normal Battery Capacity : 800 mAh

• Charging Time : Max 3.5 hours (except for trickle charging time)

• Full charging indication current (charging icon stop current) : 60 mA

• Cut-off voltage : 3.28 V

2. PERFORMANCE

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3. TECHNICAL BRIEF

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3.1 General Description

The U880 supports UMTS-2100 DS-WCDMA, EGSM-900, DCS-1800, and PCS-1900. All receivers
and the UMTS transmitter use the radioOne1Zero-IF architecture to eliminate intermediate
frequencies, directly converting signals between RF and baseband. The EGSM, DCS1800 and
PCS1900 transmitters use a baseband-to-IF upconversion followed by an offset phase-locked loop
that translates the GMSK-modulated signal to RF.

1

QUALCOMM’s branded chipset that implements a Zero-IF radio architecture.

3. TECHNICAL BRIEF

U880 high-level RF functional block diagram

A generic, high-level functional block diagram of U880 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 switch module (plus a duplexer for UMTS-2100 operation).

UMTS band signals at the antenna are switched to the relevant UMTS duplexer.
The UMTS receive band signals are amplified by the front-end LNAs of the RFR6250 IC before
passing through a band-pass filter and being applied to the mixer inputs of the RFR6250 IC. On-chip
circuits down-convert the received signal directly from RF to baseband using radioOne Zero-IF
techniques. Generation and distribution of the UMTS LO, for the down-converter, is performed entirely
on-chip (except for the loop filter).
The RFR6250 IC outputs analog baseband signals for processing by the MSM device. This baseband
interface is shared with the RTR6250 GSM receiver outputs, but is separate from the GPS baseband
interface.

EGSM, DCS and PCS receive signals from the antenna switch module pass through their band-pass
filters, then are applied to the RTR6250 IC. In a similar fashion to the UMTS paths, RTR6250 IC
circuits down-convert the received signals directly from RF to baseband.
The GSM LO for multiband down conversion is entirely generated within the RTR6250 IC (PLL and
distribution functions) with exception of the off-chip loop filter. The RTR analog baseband outputs are
routed to the MSM6250 IC for further processing (an interface shared with the RFR UMTS receive
paths).

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 high­level 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 EGSM-900, DCS-1800, and PCS-1900 transmit path begins with the same baseband
interface from the MSM6250 IC that is used for the UMTS band. A single EGSM/DCS/PCS quadrature
upconverter translates the GMSK-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-modulated signal to the desired EGSM-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.

3. TECHNICAL BRIEF

- 18 -

3. TECHNICAL BRIEF

- 19 -

U880 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.

3.2 GSM Mode

3.2.1 GSM Receiver

The Dual-mode U880’s receiver functions are split between the two RFICs as follows:

• UMTS-2100 operation uses the RFR6250 Receiver ICs to implement the receive signal path,
accepting an RF input and delivering analog baseband outputs (I and Q).

• EGSM-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.

The EGSM, DCS, and PCS receiver inputs of RTR6250 are connected directly to the transceiver front­end circuits(filters and antenna switch module). EGSM, DCS, and PCS receiver inputs are similar to
the RFR6200 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 EGSM, 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 EGSM, DCS, and PCS receive signals are routed to the RTR6250 through band selection filters
and matching networks that transform single-ended 50-Ωsources 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 processing. These filter circuits
include DC offset corrections.
The filter outputs are buffered and passed on to the MSM6250 IC for further processing (an interface
shared with the RFR6200 UMTS receiver outputs).

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.

3. TECHNICAL BRIEF

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3. TECHNICAL BRIEF

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3.2.2 GSM Transmitter

The shared GSM Low-band (EGSM900) and High-band (DCS1800, PCS1900) transmit path begins
with the baseband inputs from the MSM6250 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 GMSKmodulated 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 1.2.2-1.

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.

3. TECHNICAL BRIEF

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Figure 3.2.2-1 Offset phase-locked loop interfaces

3. TECHNICAL BRIEF

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The waveform at the dual Tx VCO output is the GMSK-modulated signal centered at the desired GSM
channel frequency. A phase-locked loop circuit is used to translate the GMSK-modulated signal from IF
to RF primarily for two reasons:

1. Phase-locked loops provide a lowpass filter function from the reference input to the VCO output. This
results in a bandpass function centered at the desired channel frequency that provides steep, well­controlled rejection of the out-of-band spectrum.

2. The resulting output bandpass function is virtually unchanged as the transmitter is tuned over
channels spanning the GSM operating band.

The PA is a key component in any transmitter chain and must complement the rest of the transmitter
precisely. For GSM band operation, the closed-loop transmit power control functions add even more
requirements relative to the UMTS PA. In addition to gain control and switching requirements, the usual
RF parameters such as gain, output power level, several output spectrum requirements, and power
supply current are critical. The gain must be sufficient and variable to deliver the desired transmitter
output power given the VCO output level, the subsequent passive devices’ losses, and the control set
point. The maximum and minimum transmitter output power levels depend upon the operating band
class and mobile station class per the applicable standard. Transmitter timing requirements and inband
and out-of-band emissions, all dominated by the PA, are also specified by the applicable standard.

The active dual Tx VCO output is applied to the dual power amplifier to continue the transmit path, and
feedback to the RTR6250 IC to complete the frequency control loop. The PA operating band (EGSM or
DCS/PCS) is selected by the MSM device GPIO control (GSM_PA_BAND).

3.3 WCDMA Mode

3.3.1 Receiver

The UMTS duplexer receiver output is routed to LNA circuits within the RFR6250 IC. The LNA gain is
dynamically controlled by the MSM6250 IC to cover full receiver dynamic range and to save current
consumption.

The UMTS LNA output is routed to the down conversion mixer inputs, in the RFR6250 IC, through a
band selection filter that transforms a single-ended 50-Ω source to differential 100-Ω load impedance
that is matched to the RFR6250 IC. The RFR input uses a differential configuration to improve second­order inter-modulation and common mode rejection performance. The RFR6250 IC input stages
include MSMcontrolled gain adjustments that further extend receiver dynamic range.

The amplifier output drives the RF port of the quadrature RF-to-baseband downconverter.
The down-converted baseband outputs are routed to low-pass filters (one I and one Q) having pass­band and stop-band characteristics suitable for DSWCDMA processing. The filter outputs are buffered
and passed on to the MSM6250 IC for further processing. This baseband interface is shared with the
RTR6250 GSM receiver outputs.
The RFR6250 IC includes LO generation and distribution circuitry to reduce offchip component
requirements. The GPS RX LO source is created using the PLL control elements of the RTR6250
PLL2, via a discrete loop filter components, in tandem with the VCO in the RFR6250. Using only this
PLL signal, the RFR6250 LO generation and distribution circuits create the necessary LO signals for
the UMTS quadrature down-converter. By definition, the ZIF down-converter requires FLO equal to
FRF, and the RTR6250/RFR6250 design achieves this without allowing FVCO to equal F

RF

.

3. TECHNICAL BRIEF

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Figure 3.3.1-1 RFR6250 IC functional block diagram

3. TECHNICAL BRIEF

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3.3.2 Transmitter

The UMTS transmit path begins with analog baseband signals from the MSM device that drive the
RTR6250 IC. The RTR6250 IC provides all the UMTS transmitter active signal-path circuits except the
power amplifiers. Analog (I and Q) differential signals from the MSM device are buffered, filtered, and
applied to Baseband-to-RF quadrature upconverters. Gain control is implemented on-chip.
The RF outputs include an integrated matching inductor, reducing the off-chip matching network to a
single series capacitor.

The RTR6250 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.
The PA device used in U880 is “Load Insensitive PA”- no need to use isolator - and routed to the
duplexer Tx port directly. Transmit power is delivered from the duplexer to the antenna through the
switch module.

The RTR6250 IC integrates LO generation and distribution circuits on-chip, substantially reducing off­chip requirements. Various modes and programmable features result in a highly flexible transceiver LO
output that supports not only UMTS transmissions, but all EGSM900 and DCS1800/PCS1900 Rx and
Tx modes as well.

The UMTS Tx LO (PLL1) is generated almost entirely on-chip, requiring only the loop filter off-chip
(two capacitors and two resistors); all UMTS Tx VCO and PLL circuits are on-chip. An internal
RTR6250 switch routes the internal VCO signal to the LO generation and distribution circuits to create
the necessary UMTS Tx LO signals.

3.4 Phase-locked Loop

Most LO functions are fully integrated on-chip, do not require user adjustment, and need not be
considered by handset designers. QUALCOMM has established and implemented frequency plans
and LO generation schemes that support the radioOne 6250-IIseries chipset while requiring minimal
off-chip design effort. Only one area requires handset designer attention: the loop filters of each
phase-locked loop (PLL).

3.4.1 UMTS Rx PLL (PLL2)

UMTS Rx LO functional blocks are distributed between the RFR6250 IC, RTR6250 IC, and external
UMTS_RX_CH_VCO and loop filter components (Figure 1.4.1-1).
The external UMTS_RX_CH_VCO must be enabled for UMTS Rx operation and disabled otherwise; a
dedicated MSM6250 IC signal (UHF_VCO_EN ) enables the VCO.

The RFR6250 IC accommodates single-ended or differential LO inputs; if singleended, either pin can
be active. AC-couple the inactive pin to ground using an appropriately valued capacitor (12 pF is used
in U880). The 27 pF capacitor should be used to AC-couple the active pin to the VCO signal. Using
only the selected VCO signal, the RFR6250 IC LO generation and distribution circuits create the
necessary LO signals for the active quadrature downconverter.

A sample of the downconverter LO is buffered and routed from RFR6250 IC pin 19 to RTR6250 IC pin
32 (RX_VCO_IN). This signal requires a terminating resistor near the RTR6250 IC input pin and an AC
coupling capacitor that assures the internal RTR6250 IC biasing is not disrupted in the example. Good
microstrip or stripline controlled-impedance techniques must be used

3. TECHNICAL BRIEF

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Figure 3.4.1-1 UMTS Rx PLL functional block diagram

3. TECHNICAL BRIEF

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Most UMTS Rx PLL circuits are included within the RTR6250 IC: reference divider, phase detector,
charge pump, feedback divider, and digital logic that generate LOCK status. The buffered 19.2 MHz
TCXO signal provides the synthesizer input (REF), the frequency reference to which the PLL is phase
and frequency locked.
The reference is divided by the R-Counter to create a fixed frequency input to the phase detector, FR.
The other phase detector input (FV) varies as the loop acquires lock, and is generated by dividing the
RX_VCO_IN frequency using the feedback path.s N-Counter. The closed loop will force FV to equal
FR when locked.
If the loop is not locked the error between FV and FR will create an error signal at the output of the
charge pump. This error signal is filtered by the loop filter and applied to the VCO, tuning the output
frequency such that the error is decreased.
Ultimately the loop forces the error to approach zero and the PLL is phase and frequency locked.

Many key PLL performance characteristics are largely determined by the loop filter design - stability,
transitory response, settling time, and phase noise.

3.4.2 Transceiver PLL (PLL1)

All LO functional blocks for the other handset modes(UMTS Tx, EGSM Tx/Rx, DCS Tx/Rx, PCS
Tx/Rx) are integrated into the RTR6250 IC except the loop filter components (Figure 1.4.2-1). On-chip
circuits include reference divider, phase detector, charge pump, VCO, feedback divider, and digital
logic status. The functional description given in Section 1.4.1 for the UMTS Rx PLL applies to the
Transceiver PLL as well.

Figure 3.4.2-1 Transceiver PLL functional block diagram

The off-chip loop filter allows optimization of key PLL performance characteristics (stability, transitory
response, settling time, and phase noise) for different applications. Guidelines are provided in the next
subsection for proper implementation of this critical circuit.

3.5 Off-chip RF Components

3.5.1 Front End Module(U1006)

Front End module integrates antenna switch module and GSM Rx filter.
The antenna switch module allows multiple operating bands and modes to share the same antenna. In
the U880 design, a common antenna connects to one of six paths: 1) UMTS-2100 Rx/Tx, 2) EGSM
Rx, 3) DCS-1800 Rx, 4) PCS-1900 Rx, 5)EGSM Tx, and 6) DCS-1800, PCS-1900 Tx. UMTS
operation requires simultaneous reception and transmission, so the UMTS Rx/Tx connection is routed
to a duplexer that separates receive and transmit signals. GSM band of operation is time division
duplexed, so only the receiver or transmitter is active at any time and a frequency duplexer is not
required. The module includes lowpass filters for the GSM bands transmit paths to reduce out-of-band
emissions, PA harmonics in particular.

The GSM mode RF filters are located before their LNAs, so their insertion losses are extremely critical
(1.5 dB typical). Other important parameters are:

• Out-of-band rejection or attenuation levels

- Far out-of-band signals - ranging from DC up to the first band of particular concern and from the
last band of particular concern to beyond three times the highest passband frequency.

- Frequencies of particular concern . bands known to include other wireless transmitters that may
deliver significant power levels to the receiver input.

- GSM band receivers operate while the handset transmitters are off so there are no Tx-band
leakage attenuation requirements.

• Phase and amplitude balance - the UMTS discussion presented above applies for GSM bands as
well. See the data sheet for specific values. Of course, passband ripple and return loss are still
important in all cases for the same reasons explained in the antenna switch module and duplexer
sections.

3. TECHNICAL BRIEF

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3. TECHNICAL BRIEF

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3.5.2 UMTS duplexer (FL1000)

A UMTS duplexer splits a single operating band into receive and transmit paths. Important
performance requirements include:

-. Insertion loss . this component is also in the receive and transmit paths; In the U880 typical losses:
UMTS Tx = 1.2 dB, UMTS Rx = 1.5 dB.

-. Out-of-band rejection or attenuation . the duplexer provides input selectivity for the receiver, output
filtering for the transmitter, and isolation between the two. Rejection levels for both paths are
specified over a number of frequency ranges. Two Tx-to-Rx isolation levels are critical to receiver
performance:

-. Rx-band isolation . the transmitter is specified for out-of-band noise falling into the Rx band. This
noise leaks from the transmit path into the receive path, and must be limited to avoid degrading
receiver sensitivity. The required Rx-band isolation depends on the PA out of-band noise levels and
Rx-band losses between the PA and LNA. Typical duplexer Rx band isolation value is 45 dB.

-. Tx-band isolation . the transmit channel power also leaks into the receiver. In this case, the leakage
is outside the receiver passband but at a relatively high level. It combines with Rx band jammers to
create cross-modulation products that fall inband to desensitize the receiver. The required Tx-band
isolation depends on the PA channel power and Tx-band losses between the PA and LNA. Typical
duplexer Tx-band isolation value is 50 dB.

-. Passband ripple . the loss of this fairly narrowband device is not flat across its passband. Passband
ripple increases the receive or transmit insertion loss at specific frequencies, creating performance
variations across the band.s channels, and should be controlled.

-. Return loss . minimize mismatch losses with typical return losses of 10 dB or more (VSWR <2:1).

-. Power handling . high power levels in the transmit path must be accommodated without degraded
performance. The specified level depends on the operating band class and mobile station class (per
the applicable standard), as well as circuit losses and antenna EIRP. Several duplexer
characteristics depend upon its source and load impedances. QUALCOMM strongly recommends an
isolator be used between the UMTS PA and duplexer to assure proper performance.

3.5.3 UMTS Power Amplifier (U1002)

The SKY77410 Load Insensitive Power Amplifier (LIPA¢‚) module is a fully matched 16-pin surface
mount module developed for Wideband Code Division Multiple Access (WCDMA) applications. This
small and efficient power amplifier packs full coverage of the 1850-1980 MHz bandwidth into a single
compact package.

SKY77410 meets the stringent spectral linearity requirements of WCDMA transmission with high
power added efficiency for power output of up to 28 dBm, even with a load mismatch of 4:1 VSWR ­eliminating the need for an isolator.

A low current (VCONT) pin provides improved operating efficiency in the low RF power range. To
further improve efficiency in this range, a separate VBIAS pin can be directly connected to the battery,
which allows reducing VCC1 and VCC2 voltages to 0.8 V to achieve very low power consumption.

The single Gallium Arsenide (GaAs) Microwave Monolithic Integrated Circuit (MMIC) contains all
active circuitry in the module. The MMIC contains on-board bias circuitry, as well as input and
interstage matching circuits. The output match is realized off-chip within the module package to
optimize efficiency and power performance into a 50 Ω load. This device is manufactured with
Skyworks’ GaAs Heterojunction Bipolar Transistor (HBT) process that provides for all positive voltage
DC supply operation while maintaining high efficiency and good linearity.
Primary bias to the SKY77410 is supplied directly from a three-cell Ni-Cd, a singlecell Li-Ion, or other
suitable battery with an output in the 3.2 to 4.2 volt range.
Power down is accomplished by setting the voltage on the low current reference pin to zero volts. No
external supply side switch is needed as typical “off” leakage is a few microamperes with full primary
voltage supplied from the battery.

An isolator between the Power Amplifier and the duplexer is highly recommended to provide constant
load and source impedances (respectively) to those devices.
This improves PA stability, ACPR performance, and harmonic suppression, as well as duplexer
isolation, insertion loss, and ripple. Transmitter performance is always improved when an isolator is
included and is well worth the added cost.

3. TECHNICAL BRIEF

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Figure 3.5.3-1 UMTS PA functional block diagram

3. TECHNICAL BRIEF

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3.5.4 Thermistor (RT1000)

This thermistor senses temperature variations around UMTS PA to adjust PA gain deviation for assure
compliance with the applicable transmit power control standards. Negative temperature compensation
thermistor is used in the U880.

3.5.5 UMTS transmit power detector (U1001)

This detector couples PA output power level to calibrate the transmitter characteristic over the channel
variation and temperature. Its detector coupling range and converted voltage is based on diode
sensitivity and transmitter power level.
The U880 uses National Semiconductor LMV225TLX power detector IC. In Figure 1.5.5-1, R1 is set to

1.8kΩ resulting in an attenuation of 31.4dB. The output voltage is proportional to the logarithm of the

input power. Figure1.5.5-2 shows the output voltage versus PA output power of the LMV225TLX setup
as depicted in Figure1.5.5-1

Figure 3.5.5-1 Block diagram of LMV225TLX with high resistive tap