LG CU920, CU915 Service Manual

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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..................................9

2.4 Current Consumption.............................16

2.5 RSSI BAR ..............................................16

2.6 Battery BAR ...........................................17

2.7 Charging ................................................17

2.8 Sound Pressure Level............................18

3. TECHNICAL BRIEF ........................19

3.1 General Description ...............................19

3.2 GSM Mode.............................................21

3.3 UMTS Mode...........................................25

3.4 LO generation and distribution circuits...28

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

3.6 Digital Baseband (MSM6281)................46

3.7. Subsystem(MSM6281) .........................48

3.8 Power Block...........................................57

3.9 External memory interface.....................62

3.10 H/W Sub System..................................64

3.11 MAIN Features.....................................80

4. TROUBLE SHOOTING ...................85

4.1 RF Component.......................................85

4.2 Component Description .........................88

4.3 WCDMA RF Signal Path........................89

4.4 GSM RF Signal Path..............................90

4.5 Checking VCTCXO Block ......................91

4.6 Checking Front-End Module Block ........94

4.7 Checking WCDMA Block .......................96

4.8 Checking GSM Block...........................101

4.9 Checking Bluetooth Block....................107

4.10 Power ON Troubleshooting................110

4.11 Charger Troubleshooting ...................112

4.12 USB Troubleshooting.........................115

4.13 USIM Detect Troubleshooting............117

4.14 Camera Troubleshooting ...................119

4.15 Keypad Backlight Troubleshooting ....121

4.16 LCD Troubleshooting.........................122

4.17 Receiver Path ....................................123

4.18 Headset path......................................125

4.19 Speaker phone path...........................127

4.20 Main microphone ...............................129

4.21 Headset microphone..........................131

4.22 Vibrator ..............................................133

4.23 Checking Media FLO Block ...............134

5. DOWNLOAD .................................138

5.1 Introduction ..........................................138

5.2 Downloading Procedure.......................138

5.3 Troubleshooting download errors ........152

5.4 Caution.................................................159

6. BLOCK DIAGRAM ........................160

7. Circuit Diagram ............................171

8. BGM Pin Map................................181

9. PCB LAYOUT................................183

10. Calibration & RF Auto Test

Program (Hot Kimchi)................187

10.1 Configuration of HOT KIMCHI ...........187

10.2 How to use HOT KIMCHI...................188

11. EXPLODED VIEW &

REPLACEMENT PART LIST ..... 191

11.1 EXPLODED VIEW ............................ 191

11.2 Replacement Parts

<Mechanic component>.................... 193

<Main component> ........................... 195

11.3 Accessory ......................................... 212

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 commoncarrier 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

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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 System Overview

2. PERFORMANCE

Item Specification

Shape GSM 850/900/1800/1900 and WCDMA850/1900 - Bar type Handset

Size 108 X 54.8 X 12.9 mm

Weight 93 g (include 1,000mAh Battery )

Power 3.7 V normal, 1000 mAh Li-ion

Talk Time Over 180 min ↑ (WCDMA, Tx=12 dBm, Voice)

(with 1000mAh) Over 180 min ↑ (GSM, Tx=Level 5, Voice)

Standby Time Over 250 Hrs ↑ (WCDMA, DRX=1.28)

(with 1000mAh) Over 250 Hrs ↑ (GSM, Paging period=6)

Antenna Internal type

LCD TFT WQVGA LCD(3°Ø, 262K, 240 x 400)

LCD Backlight White LED Back Light

Camera Auto Focus - 2.0 Mega pixel (CMOS)

Vibrator Yes (Coin Type)

MIC Yes

Receiver Yes

Earphone Jack Yes (18 pin)

Connectivity Bluetooth, USB

Volume Key Push Type (+, -)

External Memory Yes

I/O Connect 18 Pin

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2.2 Usable environment

1) Environment

2) Environment (Accessory)

* CLA : 12~24V(DC).

2. PERFORMANCE

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Item Specification

Voltage 3.7V(Typ), 3.2V(Min), [Shunt Down : 3.2V]

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

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2. PERFORMANCE

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2.3 Radio Performance

1) Transmitter-GSM Mode

* In case of DCS : [A] -> 1710, [B] -> 1785* In case of PCS : [A] -> 1850, [B] -> 1910

No Item GSM850/900 DCS & PCS

1 Conducted MS allocated 100k~1GHz -39dBm 9k ~ 1GHz -39dBm

Spurious Channel 1G~[A]MHz -33dBm

Emission 1G~12.75GHz -33dBm [A]M~[B]MHz -39dBm

[B]M~12.75GHz -33dBm

Idle Mode 100k~880MHz -60dBm 100k~880MHz -60dBm

880M~915MHz -62dBm 880M~915MHz -62dBm

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 Radiated MS allocated 30M ~ 1GHz -36dBm 30M~1GHz 36dBm

Spurious Channel 1G~[A]MHz -30dBm

Emission 1G ~ 4GHz -30dBm [A]M~[B]MHz -36dBm

[B]M~4GHz -30dBm

Idle Mode 30M ~ 880MHz -57dBm 30M~880MHz -57dBm

880M ~ 915MHz -59dBm 880M~915MHz -59dBm

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

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* In case of DCS : [A] -> 1710, [B] -> 1785* In case of PCS : [A] -> 1850, [B] -> 1910

2. PERFORMANCE

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No Item GSM850/900 DCS & PCS

3 Frequency Error ± 0.1ppm ± 0.1ppm

4 Phase Error ± 5(RMS) ± 5(RMS)

± 20(PEAK) ± 20(PEAK)

5 Frequency Error 3dB below reference sensitivity 3dB below reference sensitivity

Under Multipath and RA250 : ± 200Hz RA250: ± 250Hz

Interference Condition HT100 : ± 100Hz HT100: ± 250Hz

TU50 : ± 100Hz TU50: ± 150Hz

TU3 : ± 150Hz TU1.5: ± 200Hz

6 Output RF Due to 0 ~ 100kHz +0.5dB 0 ~ 100kHz +0.5dB

Spectrum modulation 200kHz -30dB 200kHz -30dB

250kHz -33dB 250kHz -33dB

400kHz -60dB 400kHz -60dB

600 ~ 1800kHz -66dB 600 ~ 1800kHz -60dB

1800 ~ 3000kHz -69dB 1800 ~ 6000kHz -65dB

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

7 Intermodulation attenuation - Frequency offset 800kHz

Intermodulation product should

be Less than 55dB below the

level of Wanted signal

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No Item GSM850/900 DCS & PCS

8Transmitter Output Power Level Power Toler. Level Power Toler.

533 ±3030 ±3

631 ±3128 ±3

729 ±3226 ±3

827 ±3324 ±3

925 ±3422 ±3

10 23 ±3 5 20 ±3

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

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2. PERFORMANCE

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2. PERFORMANCE

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2) Transmitter-WCDMA Mode

No Item Specification

1 Maximum Output Power Class 3 : +24dBm(+1/-3dB)

2 Frequency Error ± 0.1ppm

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

4 Inner Loop Power control in uplink Adjust output(TPC command)

cmd 1dB 2dB 3dB

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

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 Out-band Blocking -50dBm(3.84MHz)

6Out-of-synchronization handling of output power Qin/Qout : PCCH quality levels

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

9 Change of TFC ± 25us

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%)

12 Spectrum emission Mask -35-15*(∆f-2.5)dBc@∆f=2.5~3.5MHz,30k

-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

13 Adjacent Channel Leakage Ratio(ACLR) 33dB@5MHz, ACP>-50dBm 43dB@10MHz,

ACP>-50dBm

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No Item Specification

14 Spurious Emissions (*: additional requirement) -36dBm@f=9~150KHz, 1K BW -

36dBm@f=50KHz~30MHz, 10K BW -

36dBm@f=30MHz~1000MHz, 100K BW

-30dBm@f=1~12.5GHz, 1M BW (*)-

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

-15dB@SF=4.768Kbps, Multi-code

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2. PERFORMANCE

3)Receiver-GSM Mode

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No Item GSM850/900 DCS & PCS

1 Sensitivity (TCH/FS Class II) -105dBm -105dBm

2 Co-Channel Rejection (TCH/FS C/Ic=7dB Storage -30 ~ +85

Class II, RBER, TU high/FH)

3 Adjacent 200kHz C/Ia1=-12dB C/Ia1=-12dB

Channel

Rejection 400kHz C/Ia2=-44dB C/Ia2=-44dB

4 Intermodulation Rejection Wanted Signal :-98dBm 1st Wanted Signal :-96dBm 1st

interferer :-44dBm 2nd interferer :-44dBm 2nd

interferer :-45dBm interferer :-44dBm

5Blocking Response (TCH/FS Wanted Signal :-101dBm Wanted Signal :-101dBm

Wanted Signal :-101dBm Unwanted : Depend on Unwanted : Depend on

Frequency Frequency

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2. PERFORMANCE

4) Receiver-WCDMA Mode

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No Item Specification

1 Reference Sensitivity Level -106.7 dBm(3.84 MHz)

2Maximum Input Level -25dBm(3.84MHz)

-44dBm/3.84MHz(DPCH_Ec)

UE@+20dBm output power(Class3)

3 Adjacent Channel Selectivity (ACS) 33dB

UE@+20dBm output power(Class3)

4In-band Blocking -56dBm/3.84MHz@10MHz

UE@+20dBm output power(Class3)

-44dBm/3.84MHz@15MHz

UE@+20dBm output power(Class3)

5 Out-band Blocking -44dBm/3.84MHz@f=2050~2095 and

2185~2230MHz

UE@+20dBm output power(Class3)

-30dBm/3.84MHz@f=2025~2050 and

2230~2255MHz

UE@+20dBm output power(Class3)

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

2255~12500MHz

UE@+20dBm output power(Class3)

6Spurious Response -44dBm CW

UE@+20dBm output power(Class3)

7Intermodulation Characteristic -46dBm CW@10MHz

-46dBm/3.84MHz@20MHz

UE@+20dBm output power(Class3)

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

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

60dBm@f=1850 MHz ≤ f ≤ 1910 MHz,

3.84M BW

-60dBm@f=824 MHz ≤ f ≤ 849 MHz, 3.84M BW

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2. PERFORMANCE

2.4 Current Consumption

1) CU920 Current Consumption

2.5 RSSI BAR

• Ucell power

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WCDMA Only GSM Only

Sleep Mode 1.5mA(sleep current) ↓ 1.5mA(sleep current) ↓

Standby 3.0mA(DRX=1.28sec) ↓ 2.5mA(MF=5) ↓

Talk Mode VC 12dBm : 310 mA↓ 310 ßÃ(Tx Lvl:5) ↓

NO SVC Mode TBD TBD

Off 300 µA ↓ 300 µA ↓

(Backup Battery Charging) 500 µA ↓ 500 µA ↓

Stand by Voice Call VT

WCDMA Only 250 hours ↑ = 4.0mA↓ 180 mins ↑ = 333µA↓ /

(1000mAh battery ±, (1000mAh battery ±,

DRX cycle = 1.28sec) TX = 12dBm)

GSM Only 250 hours ↑ = 4.0mA↓ 180 mins ↑ = 333µA↓

(1000mAh battery ±, (1000mAh battery ±,

Paging frame class5) Paging frame class5)

No WCDMA GSM

1 BAR 5 -87 ± 2 dBm ↑ -87 ± 2 dBm ↑

2 BAR 5 → 4 -87 ± 2 dBm -87 ± 2 dBm

3 BAR 4 → 3 -92 ± 2 dBm -92 ± 2 dBm

4 BAR 3 → 2 -97 ± 2 dBm -97 ± 2 dBm

5 BAR 2 → 1 -100 ± 2 dBm -102 ± 2 dBm

6 BAR 1 → 0 -103 ± 2 dBm -107 ± 2 dBm

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2. PERFORMANCE

2.6 Battery BAR

2.7 Charging

• Charging Method : CC & CV (Constant Current and Constant Voltage)

• Maximum Charging Voltage : 4.2 V

• Maximum Charging Current : 900 mA

• Normal Battery Capacity : 1050 mAh

• Charging Time : Max 2.5 hours (except for trickle charging time)

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

• Cut-off voltage : 3.20 V

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Indication Standby

Bar 3 4.20 ± 0.05V

Bar 3 → 2 3.77 ± 0.05V

Bar 2 → 1 3.67 ± 0.05V

Bar 1 → Empty 3.59 ± 0.05V

Low Voltage, 3.54 ± 0.05V (Stand-by) / 3.55 ± 0.05V (Talk)

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

Power Off 3.28 ± 0.05V

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2. PERFORMANCE

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2.8 Sound Pressure Level

No Test Item Specification

1 Sending Loudness Rating (SLR) 8 ±3 dB

2 Receiving Loudness Rating (RLR) Nor 2 ± 3 dB

-13 dB

3 Side Tone Masking Rating (STMR) Min 23 dB

4 Echo Loss (EL) Min 46 dB

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

6 Idle Noise-Receiving (INR) Nor

Under -54 dBPA

7 Sending Loudness Rating (SLR) 8 ± 3dB

8 Receiving Loudness Rating (RLR) Nor -1 ± 3 dB

-12 ±3 dB

9 Side Tone Masking Rating (STMR) Min 25dB

10 Echo Loss (EL) Min 40dB

11 Idle Noise-Sending (INS) Max -55 dBm0p

12 Idle Noise-Receiving (INR) Under -40

dBPA

13 TDMA Noise Max Under -62 dBm

Under -62 dBm

(Cell Power : -90 ~ -105 dBm)

-. Acoustic (Max Vol.)

MS/Headset SLR : 8 ± 3dB

MS/Headset RLR : -15 ± 3dB/-12dB

Headset

MS and

Headset

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3. TECHNICAL BRIEF

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3.1 General Description

The CU920/CU915 supports UMTS-850, UMTS-1900, GSM-850, GSM-900, DCS-1800, and PCS1900 based GSM/GPRS/EDGE/UMTS. All receivers and the UMTS transmitter use the radioOne[1] Zero-IF architecture to eliminate intermediate frequencies, directly converting signals between RF and baseband. The quad-band GSM transmitters use a baseband-to-IF up-conversion followed by an offset phase-locked loop that translates the GMSK-modulated or 8-PSK-modulated signal to RF.

A generic, high-level functional block diagram of CU920/CU915 is shown in Figure 3-1. One antenna collects base station forward link signals and radiates handset reverse link signals. The antenna connects with

3. TECHNICAL BRIEF

Fig. 3.1 Block diagram of RF part

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

MBD1000 RBR1000

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receive and transmit paths through a FEM(Front End Module) (plus two duplexers for UMTS highband and low-band operations).

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 highband UMTS receiver path and low-band path are accommodated int the RFR6275IC. 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(at ADC1).

For the transmit chains, the RTR6275 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 RTR6275 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 RTR6275 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 RTR6275 transceiver IC. These baseband outputs are shared with the UMTS receiver and routed to the MSM IC for further signal processing.

The GSM/EDGE transmit path employs one stage of up-conversion and, in order to improve efficiency, is divided into phase and amplitude components to produce an open-loop Polar topology:

1. The on-chip quadrature up-converter translates the GMSK-modulated signal or 8-PSK modulated

signal, to a constant envelope phase signal at RF;

2. The amplitude-modulated (AM) component is applied to the ramping control pin of Polar power

amplifier from a DAC within the MSM

CU920/CU915 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 offchip 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 undervoltage lockout and crystal oscillator signal presence are monitored to protect against detrimental conditions.

3. TECHNICAL BRIEF

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3. TECHNICAL BRIEF

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3.2 GSM Mode

3.2.1 GSM Receiver

The Dual-mode CU920/CU915’s receiver functions are split between the three RFICs as follows:

■ UMTS-850, UMTS-1900 operation uses the RFR6275 receiver ICs to implement the receive signal path, accepting an RF input and delivering analog baseband outputs (I and Q).

■ GSM-850, GSM-900, DCS-1800, and PCS-1900 modes use the RTR6275 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 SBI[2]-controlled parameters.

RF Front end consists of antenna, antenna switch module(LMSP4LMA-573TEM) which includes four RX saw filters(GSM850, GSM900, GSM900, DCS and PCS). The antenna switch module allows multiple operating bands and modes to share the same antenna. In CU920/CU915, a common antenna connects to one of six paths: 1) UMTS-850 Rx/Tx, 2) UMTS-1900 Rx/Tx, 3) GSM-850 Rx, 4) GSM-900 Rx, 5) GSM- 850/900 Tx(lo band Tx’s share the same path), 6) DCS-1800 Rx, and 7) DCS1800, PCS-1900 Tx(High Band Tx’s share the same path), 8) PCS-1900 Rx. UMTS operation requires simultaneous reception and transmission, so the UMTS Rx/Tx connection is routed to a duplexer that separates receive and transmit signals. GSM850/900, DCS, and PCS operation is time division duplexed, so only the receiver or transmitter is active at any time and a frequency duplexer is not required.

ANT_SEL0 ANT_SEL1 ANT_SEL2 ANT_SEL3

GSM900/GSM850 TX HIGH HIGH LOW LOW

DCS/PCS TX HIGH LOW LOW LOW

GSM 850 RX LOW LOW LOW LOW

GSM 900 RX LOW LOW HIGH LOW

DCS RX LOW HIGH HIGH LOW

PCS RX LOW HIGH LOW LOW

UMTS 850 HIGH LOW HIGH LOW

UMTS 1900 HIGH HIGH HIGH HIGH

ANENNA SWITCH MODULE LOGIC

Table. 3.2.1 Antenna Switch Module Control logic

[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.

LMSP4LMA_573TEMP_Rew B Later

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The GSM850, GSM900, DCS, and PCS receiver inputs of RTR6275 are connected directly to the transceiver front-end circuits(filters and antenna switch module). GSM850, GSM900, DCS, and PCS receiver inputs are similar to the RFR6275 UMTS Rx input in that they also 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, GSM900, DCS, and PCS signals are time-division duplex (the handset can only eceive or transmit at one time), switches are used to separate Rx and Tx signals in place of frequency duplexers - this is accomplished in the switch module.

The GSM850, GSM900, DCS, and PCS receive signals are routed to the RTR6275 through band selection filters and matching networks that transform single-ended 50-Ωsources 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 RTR6275 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 MSM6281 IC for further processing (an interface shared with the RFR6275 UMTS receiver outputs)

3. TECHNICAL BRIEF

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Fig. 3.2.1 RTR6275 RX feature

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3.2.2 GSM Transmitter

The RTR6275 transmitter outputs(DA_HB2_OUT and DA_LB1_OUT)include on-chip output matching inductors. 50ohm output impedance is achieved by adding a series capacitor at the output pins. The capacitor value may be optimized for specific applications and PCB characteristics based on pass-band symmetry about the band center frequency, the suggested starting value is shown in Figure 3-2-2

The RTR6275 IC is able to support GSM850/900 and GSM 1800/1900 mode transmitting. This design guideline shows a quad-band GSM application.

Both high-band and low band outputs are followed by resistive pads to ensure that the load Presented to the outputs remains close to 50ohm. 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

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Fig. 3.2.2 GSM Transmitter matching

6pF

4pF

82Ω

82Ω82Ω

51Ω

110Ω110Ω

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3.3 UMTS Mode

3.3.1 Receiver

The UMTS duplexer receiver output is routed to LNA circuits within the RFR6275 device. UMTS LNA circuits(one for low-band UMTS and one for high-ban UMTS path) separated from all other

receive functions contained within the RFR6275 receiver IC to improve mixer LO to RF isolation a critical parameter in the ZIF architecture. Isolation is further improved using high-reverse isolation circuits into the LNA designes.

The LNA gains are stepped via API control. The IC operating mode and LNA bias currents reautomatically adjusted via software to minimize DC power consumption.

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 RTR6275 is downconverting GSM signals and on when the UMTS is operating.

Fig. 3.2.2 GSM Transmitter matching

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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 up-converter mixers.

The up-converter output is amplified by multiple variable gain stages that provide transmit AGC control. The AGC output is filtered and applied to the driver amplifier; this output stage includes an integrated matching inductor that simplifies the external matching network to a single series capacitor to achieve the desired 50-Ω interface.

The RTR6275 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 RTR6275 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 RTR6275 IC design achieves this without allowing FVCO to equal FRF.

The RTR6275 IC is able to support UMTS 2100/1900 and UMTS 850 mode transmitting. This design guideline shows only UMTS 1900 and UMTS 850 applications.

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Figure. 3.3.2 RTR6275 IC functional block diagram

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3.4 LO generation and distribution circuits

The integrated LO generation and distribution circuits are driven by internal VCOs to support various modes to yield highly flexible quadrature LO outputs that drive all GSM/EDGE and UMTS band upconverters and downconverters; with the help of these LO generation and distribution circuits, true zero-IF architecture is employed in all GSM and UMTS band receivers and transmitters to translate the signal directly from RF to baseband and from baseband to RF.

Two fully functional fractional-N synthesizers, including VCOs and loop filters, are integrated within the RTR6275 IC. The first synthesizer (PLL1) creates the transceiver LOs that support the UMTS 2100/1900/1800 transmitter, and all four GSM band receivers and transmitters including: GSM 850, GSM 900, GSM 1800, and GSM 1900. The second synthesizer (PLL2) provides the LO for the UMTS 2100/1900/1800 receiver. An external TCXO input signal is required to provide the synthesizer frequency reference to which the PLL is phase and frequency locked. The RTR6275 IC integrates most of PLL loop filter components on-chip except two off-chip loop filter series capacitors, and significantly reduces off-chip component requirement. With the integrated fractional-N PLL synthesizers, the RTR6275 has the advantages of more flexible loop bandwidth control, fast lock time, and low-integrated phase error

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3.5 Off-chip RF Components

3.5.1 Front-End Module

Terminal NO. Terminal Name Terminal NO. Terminal Name

(1) GSM1800 Rx (15) UMTS1

(2) GSM1800 Rx (16) UMTS2

(3) GSM1900 Rx (17) NC

(4) GSM1900 Rx (18) GND

(5) GSM900 Rx (19) ANT

(6) GSM900 Rx (20) GND

(7) GSM850 Rx (21) GND

(8) GSM850 Rx (22) GSM1800/1900 Tx

(9) GND (23) GND

(10) Vdd (24) GND

(11) Vc4 (25) GSM850/900 Tx

(12) Vc3 (26) GND

(13) Vc2 (27) GND

(14) Vc1 (28) GND

Mode Vc1 Vc2 Vc3 Vc4 Vdd

GSM850/900 Tx 1.8-3.0V 1.8-3.0V 0-0.2V 0-0.2V 2.4-3.0V

GSM1800/GSM1900 Tx 1.8-3.0V 0-0.2V 0-0.2V 0-0.2V 2.4-3.0V

GSM850 Rx 0-0.2V 0-0.2V 0-0.2V 0-0.2V 2.4-3.0V

GSM900 Rx 0-0.2V 0-0.2V 1.8-3.0V 0-0.2V 2.4-3.0V

GSM1800 Rx 0-0.2V 1.8-3.0V 1.8-3.0V 0-0.2V 2.4-3.0V

GSM1900 Rx 0-0.2V 1.8-3.0V 0-0.2V 0-0.2V 2.4-3.0V

UMTS1 1.8-3.0V 0-0.2V 1.8-3.0V 0-0.2V 2.4-3.0V

UMTS2 1.8-3.0V 0-0.2V 1.8-3.0V 1.8-3.0V 2.4-3.0V

Idle 0-0.2V 0-0.2V 0-0.2V 0-0.2V 0-0.2V

TERMlNAL CONFIGURATION

CONTROL LOGIC

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3.5.2 UMTS Dupexer

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 CU920/CU915 typical losses : UMTS850_ Tx = 1.8 dB, Rx = 2.4 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. Minimum duplexer Rx band isolation value is about 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. Minimum duplexer Txband isolation value is about 50dB.

■ 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 11 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)

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3.5.3 WCDMA Power Amplifier

UMTS850/UMTS1900 Power Amplifier Module

The AWT6321R addresses the demand for increased integration in dual-band in dual-band handsets for North American CDMA network deployments.The small footprint 3mmx5mmx1mm surface mount RoHS compliant pckage contains independent RF PA pats to ensure optional performance in both frequnency bands, while achieving a 25% PCB space savings compared with solutions requiring two single-band Pas.

The package pin out was chosen enable handset manufacturers to easily route VCC to both power amplifiers and simplify control with a common VMODE pin. The device is manufactured on an advanced InGaP HBT MMIC technology offering state-of-the-art reliability, temperatures stability, and ruggedness.

The AWT6321 is part of ANADIGICS’High-Efficiency-at-Low-Power(HELP)family of CDMA power amplifiers, which deliver low quiescent currents and significantly greater efficiency without a costly external DAC or DC-DC converter

Figure. 3.5.3 WCDMA Dual PAM

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