LG U900 Service Manual

Date: May, 2006 / Issue 1.0

Service Manual

Model : U900

Service Manual

U900

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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.............................................20

3.3 WCDMA Mode.......................................24

3.4 LO Phase-locked Loop ..........................27

3.5 Off-chip RF Components .......................29

3.6 Digital Baseband(DBB/MSM6250A) ......44

3.7 Hardware Architecture ...........................45

3.8 Subsystem(MSM6250A)........................47

3.9 External memory interface.....................50

3.10 H/W Sub System..................................51

3.11 Main Features......................................76

4. TROUBLE SHOOTING ...................82

4.1. RF Component......................................82

4.2. SIGNAL PATH ......................................84

4.3 Checking VCXO Block...........................86

4.4 Checking Ant. Switch Module Block ......89

4.5 Checking WCDMA Block .......................91

4.6 Checking GSM Block...........................100

4.7 Checking VCXO Block.........................103

4.8 Checking Ant. Switch Module Block ....106

4.9 Checking WCDMA Block .....................108

4.10 Checking GSM Block.........................117

4.11 DVB-H Broadcasting signal

reception fail problem.........................119

4.12 Power ON Trouble .............................122

4.13 USB Trouble ......................................124

4.14 SIM Detect Trouble............................125

4.15 Key Sense Trouble ............................126

4.16 Camera Trouble.................................127

4.17 Main LCD Trouble..............................128

4.18 Keypad Backlight Trouble..................130

4.19 Folder ON/OFF Trouble.....................131

4.20 Trans Flash Trouble...........................132

4.21 Audio Trouble Shooting .....................133

4.22 Charger Trouble Shooting..................143

5. DOWNLOAD .................................146

5.1 Introduction ..........................................146

5.2 Downloading Procedure.......................146

5.3 Troubleshooting Download Errors .......164

5.4 Caution.................................................172

6. BLOCK DIAGRAM ........................173

6.1 GSM & WCDMA RF Block...................173

6.2 Interface Diagram ...............................175

7. Circuit Diagram ............................179

8. pcb layout .....................................190

9. EXPLODED VIEW & REPLACEMENT

PART LIST.................................... 198

9.1 EXPLODED VIEW .............................. 198

9.2 Replacement Parts

<Mechanic component>...................... 199

<Main component> ............................. 203

9.3 Accessory ........................................... 228

Table Of Contents

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
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 100.6 x 50.6 x 21.4 mm

Weight 110 g (with 950mAh Battery)

Power 3.7V normal, 950 mAh Li-Polymer

Talk Time Over 150 min (WCDMA, Tx=12 dBm, Voice)

(with 950mAh) Over 175 min (GSM, Tx=Max, Voice)

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

(with 950mAh) Over 220 Hrs (GSM, Paging period=9)

Antenna Internal type and Antenna

LCD Main 240 X 320 pixel TFT (QVGA LCD Module)

LCD Backlight LED Back Light (main only)

Camera Dual Camera ; 1.3 Mega pixel (CMOS), VGA Camera (CMOS)

Vibrator Yes (Cylinder Type)

LED Indicator No

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 3.7 V(Typ), [Shut Down : 3.23 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)

Class 4 : +21dBm(±2dB)

2 Frequency Error ±0.1ppm

3 Open Loop Power control in uplink ±9dB@normal, ±12dB@extreme

Adjust output(TPC command)

cmd 1dB 2dB 3dB

+1 +0.5/1.5 +1/3 +1.5/4.5

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(10 equel 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

-49dBc@∆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 Sensitivity Level -106.7 dBm(3.84 MHz)

-25dBm(3.84MHz)

2 Maximum Input Level -44dBm/3.84MHz(DPCH_Ec)

UE@+20dBm output power(Class3)

3 Adjacent Channel Selectivity (ACS)

33dB

UE@+20dBm output power(Class3)

-56dBm/3.84MHz@10MHz

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. PERFORMANCE

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2.4 Current Consumption

(Stand by Test Condition : Bluetooth off, LCD backlight off)
(Call Test Condition : Bluetooth off, LCD backlight dimming mode)
(VT Test Condition : Speaker off, LCD backlight On)

2.5 RSSI BAR

2.6 Battery BAR

Indication Standby

Bar 4 Over 3.83 ± 0.05V

Bar 4 → 3 3.82 ± 0.05V

Bar 3 → 2 3.72 ± 0.05V

Bar 2 → 1 3.67 ± 0.05V

Bar 1 → Empty 3.50 ± 0.05V

Low Voltage, 3.50 ± 0.05V (Stand-by) / 3.50 ± 0.05V (Talk)

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

Power Off 3.23 ± 0.05V

Stand by Voice Call VT

WCDMA

Under 4.8 mA Under 380 mA Under 475mA

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

Under 4.4 mA

(Paging=9period) Under 325 mA

GSM

Under 6.1 mA (Tx=Max)

(@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 -112 ± 2 dBm -106 ± 2 dBm

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 : 650 mA

• Battery Capacity : Min. 950 mAh/Typ. 980 mAh

• Charging Time : Max 3.0 hours (except for trickle charging time)

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

• Cut-off voltage : 3.23 V

2. PERFORMANCE

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3. TECHNICAL BRIEF

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3.1 General Description

The U900 supports UMTS-2100 DS-WCDMA, EGSM-900, DCS-1800, and PCS-1900. All receivers
and the UMTS transmitter use the radio One1Zero-IF architecture to eliminate intermediate
frequencies, directly converting signals between RF and baseband. The EGSM, DCS1800 and
PCS1900 transmitters use a baseband-to-IF up-conversion followed by an offset phase-locked loop
that translates the GMSKmodulated signal to RF.

1

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

3. TECHNICAL BRIEF

U900 high-level RF functional block diagram

A generic, high-level functional block diagram of U900 is shown in Figure 3-1. One antenna collects
base station forward link signals and radiates handset reverse link signals. The antenna connects with
receive and transmit paths through a switch module (plus 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 band­pass 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 MSM6250AA
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 high-level signals that are filtered and applied to the
power amplifiers (PA). The PA output is routed to the antenna through a duplexer and switch module.

The shared EGSM-900, DCS-1800, and PCS-1900 transmit path begins with the same baseband
interface from the MSM6250AA 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 bandappropriate lowpass filter), and the
antenna.

3. TECHNICAL BRIEF

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3. TECHNICAL BRIEF

- 19 -

U900 power supply voltages are managed and regulated by the PM6250 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 U900’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 RFR6250 UMTS Rx input in that they also use differential configurations to improve common­mode rejection and second-order nonlinearity 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-Ω sources to differential impedances
optimized for gain and noise figure. Similar to the RFR, the RTR input uses a differential configuration
to improve second-order inter-modulation and common mode rejection performance. The RTR6250
input stages include MSMcontrolled gain adjustments that maximize receiver dynamic range.

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

- 21 -

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 MSM6250A IC for further
processing (an interface shared with the RFR6250 UMTS receiver outputs).

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 MSM6250A IC. These differential analog input signals are buffered,
lowpass filtered, corrected for DC offsets then applied to the GSM quadrature upconverter. The
upconverter LO signals are generated from the transceiver VCO signal by the LO distribution and
generation circuits within RTR6250. This upconverter translates the GMSK-modulated signal to a
convenient intermediate frequency (IF) that forms one input to a frequency/phase detector circuit. This
IF signal is the reference input to an offset phase-locked loop (OPLL) circuit as shown in Figure 3.2.2-1.

The feedback path of this OPLL circuit includes a downconversion from the RF output frequency range
to the IF range. The two inputs to this downconversion mixer are formed as follows:

1. The dual Tx VCO output (operating in the desired RF output frequency range) is buffered within the

RTR6250 IC then applied to the mixer RF port.

2. The LO Generation and Distribution circuits that deliver the transmit path.s LO for the baseband-to-IF

upconversion also provides the .offset LO. signal that is applied to the feedback path.s mixer LO port.

The mixer IF port output is the offset feedback signal - the variable input to the frequency/phase
detector circuit. The detector compares its variable input to its reference input and generates an error
signal that is lowpass filtered by the loop filter and applied to the dual Tx VCO tuning port to force the
VCO output in the direction that minimizes errors. As mentioned earlier, the VCO output is connected to
the feedback path thereby creating a closed-loop control system that will force frequency and phase
errors between the variable and reference inputs to zero.

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 in-band
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 MSM6250A 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 DS-WCDMA processing. The filter outputs are buffered
and passed on to the MSM6250A 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 off-chip 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 FLOequal to FRF,
and the RTR6250/RFR6250 design achieves this without allowing F

VCO

to equal FRF.

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Figure 3.3.1-1 RFR6250 IC functional block diagram

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 U900 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.

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3.4 LO 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 3.4.1-1).
The external UMTS_RX_CH_VCO must be enabled for UMTS Rx operation and disabled otherwise; a
dedicated MSM6250AA 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 U900). 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

Figure 3.4.1-1 UMTS Rx PLL functional block diagram

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 NCounter.
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 3.4.2-1). 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.

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Figure 3.4.1-2 Transceiver PLL functional block diagram

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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(U100)

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 U900 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.

3.5.2 UMTS duplexer (FL102)

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 U900 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 in-band 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 bands 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 (U105)

The WS2512, a Wide-band Code Division Multiple Access(WCDMA) Power Amplifier (PA), is a fully
matched 10 -pin surface mount module developed for WCDMA handset applications. This power
amplifier module operates in the 1920-1980MHz band-width. The WS2512 meets the stringent
WCDMA linearity requirements for output power of up to 28dBm. A low current (V cont) pin is

provided for high efficiency improvement of the low output power range.

The WS2512 is manufactured on an advanced InGaP HBT (Hetero-junction Bipolar Transistor)
MMIC (Microwave Monolithic Integrated Circuit) technology offering stateof-the-art reliability,
temperature stability and ruggedness.

The WS2512 is self contained, incorporating 50ohm input and output matching networks.

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3.5.4 Thermistor (R140)

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 U900.

Figure3.5.3-1 UMTS PA functional block diagram