LG CX380 Service Manual

CX380

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CDMA Mobile Subscriber Unit

LG-CX380

SERVICE MANUAL

TRI BAND, TRI MODE

[PCS/GPS/CELLULAR]

CDMA MOBILE PHONE

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LG Electronics Inc.

CX380

Table of contents

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General Introduction ……………4

CHAPTER 1. System Introduction

1. System Introduction………..………….4

2. Features and Advantages of CDMA Mobile Phone (For AMPS as well)…..5

3. Structure and Functions of dual-band CDMA Mobile Phone………………….8

4. Specification………………….…………9

5. Installation………………..……………14

CHPATER 2. NAM Input Method

1. NAM Program Method and Telephone Number Inputting Method……………16

CHAPTER 3. Circuit Description

1. RF Transmit/Receive Part……………19

2. Digital/Voice Processing Part………..25

CHAPTER 4. Trouble Shooting

1. Rx Part Trouble………………….…….28

1. When Rx Power isn’t enough …..28

2. Checking Regulator Circuit……….30

3. Checking VCTCXO Circuit……….31

4. Checking Mobile SW & Triplexer & Duplexer(DCN,PCS)…………………32

5. Checking Control Signal………….37

6. Checking Rx I/Q data……………..38

2. Tx Part Trouble………………………..39

1. Check Regulator(PMIC) Circuit….40

2. Check VCTCXO Circuit…………..41

3. Check SBI Control Signal………..42

4. Check RFT6150 Circuit…………..43

5. Check HDET Circuit………………46

6. Check PAM Circuit………………..47

7. Check Duplexer & Triplexer & Mobile SW…………………………….50

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3. Bluetooth Part Trouble………………..52

1. Bluetooth Block ………….………..52

4. Logic Part Trouble…………………….54

1. Power On Trouble…………………55

2. Charging Trouble………………….57

3. Receiver Trouble………………….59

4. USB Interface Trouble…………....61

5. Speaker Trouble…………………..64

6. MIC Trouble………………………..66

7. Vibrator Troble…………………….68

8. Key Backlight LED Trouble………70

9. Earphone Trouble…………………72

10. LCD Trouble……………………..76

11. Camera Trouble…………………80

CHAPTER 5. Safety…..…………….…..83

CHAPTER 6. Glossary………….……...86

Appendix………….……...……...…..…..99

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General Introduction

The LG-CX380 phone has been designed to operate on the latest digital mobile communication technology, Code Division Multiple Access (CDMA). This CDMA digital technology has greatly enhanced voice clarity and can provide a variety of advanced features. Currently, CDMA mobile communication technology has been commercially used in Cellular and Personal Communication Service (PCS). The difference between them is the operating frequency spectrum. Cellular uses 800Mhz and PCS uses 1.9Ghz. The LG-CX380 support GPS Mode, we usually call it tri-band phone. The CDMA technology adopts DSSS (Direct Sequence Spread Spectrum). This feature of DSSS enables the phone to keep communication from being crossed and to use one frequency channel by multiple users in the same specific area, resulting that it increases the capacity 10 times more compared with that in the analog mode currently used. Soft/Softer Handoff, Hard Handoff, and Dynamic RF power Control technologies are combined into this phone to reduce the call being interrupted in a middle of talking over the phone. Cellular and PCS CDMA network consists of MSO (Mobile Switching Office), BSC (Base Station Controller), BTS (Base station Transmission System), and MS (Mobile Station). The following table lists some major CDMA Standards.

CDMA Standard Designator Description

Basic air interface TIA/EIA/IS-95-A/B/C

ANSI J-STD-008

Network TIA/EIA/IS-634

TIA/EIA/IS/651

TIA/EIA/IS-41-C

TIA/EIA/IS-124

Service TIA/EIA/IS-96-B

TIA/EIA/IS-99

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TIA/EIA/IS-637 TIA/EIA/IS-657

Performance TIA/EIA/IS-97

TIA/EIA/IS-98

ANSI J-STD-018

Protocol between MS and BTS for Cellular & AMPS

Protocol between MS and BTS for PCS

MAS-BS

PCSC-RS

Intersystem operations

Nom-signaling data comm.

Speech CODEC

Assign data and fax

Short message service

Packet data

Cellular base station

Cellular mobile station

PCS personal station

ANSI J-STD-019

TIA/EIA/IS-125

* TSB –74: Protocol between an IS-95A system and ANSI J-STD-008

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PCS base station

Speech CODEC

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Chapter 1. System Introduction

1. System Introduction

1.1 CDMA Abstract

The CDMA mobile communication system has a channel hand-off function that is used for collecting the information on the locations and movements of mobile telephones from the cell site by automatically controlling several cell site through the setup of data transmission routes, and then enabling one switching system to carry out the automatic remote adjustment. This is to maintain continuously the call state through the automatic location confirmation and automatic radio channel conversion when the busy subscriber moves from the service area of one cell site to that of another by using automatic location confirmation and automatic radio channel conversion functions. The call state can be maintained continuously by the information exchange between switching systems when the busy subscriber moves from one cellular system area to the other cellular system area.

In the cellular system, the cell site is a small-sized low output type and utilizes a frequency allocation system that considers mutual interference, in an effort to enable the re-use of corresponding frequency from a cell site separated more than a certain distance. The analog cellular systems are classified further into an AMPS system, E-AMPS System, NMT system, ETACS system, and JTACS system depending on technologies used.

Unlike the time division multiple access (TDMA) or frequency division multiple access (FDMA) used in the band limited environment, the Code Division Multiple Access (CDMA) system which is one of digital cellular systems is a multi-access technology under the interference limited environment. It can process more number of subscribers compared to other systems (TDMA system has the processing capacity three times greater than the existing FDMA system whereas CDMA system, about 12~15 times of that of the existing system).

CDMA system can be explained as follows; TDMA or CDMA can be used to enable each person to talk alternately or provide a separate room for each person when two persons desire to talk with each other at the same time, whereas FDMA can be used to enable one person to talk in soprano, whereas the other in bass (one of the two talkers can carry out synchronization for hearing in case there is a bandpass filter function in the area of the hearer). Another available method is to make two persons to sing in different languages at the same time, space, and frequency when wishing to let the audience hear the singing without being confused. This is the characteristic of CDMA.

On the other hand, when employing the CDMA technology, each signal has a different pseudo-random binary sequence used to spread the spectrum of carrier. A great number of CDMA signals share the same frequency spectrum. In the perspective of frequency area or time area, several CDMA signals are overlapped. Among these types of signals, only desired signal energy is selected and received through the use of pre-determined binary sequence; desired signals can be separated, and then received with the correlator used for recovering the spectrum into its original state. At this time, the spectrums of other signals that have different codes are not recovered into its original state, and appears as the self-interference of the system.

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2. Features and Advantages of CDMA Mobile Phone

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2.1 Various Types of Diversities

When employing the narrow band modulation (30kHz band) that is the same as the analog FM modulation system used in the existing cellular system, the multi-paths of radio waves create a serious fading. However, in the CDMA broadband modulation (1.25MHz band), three types of diversities (time, frequency, and space) are used to reduce serious fading problems generated from radio channels in order to obtain hig h-quality calls. Time diversity can be obtained through the use of code interleaving and error correction code whereas frequency diversity can be obtained by spreading signal energy to wider frequency band. The fading related to normal frequency can affect the normal 200~300kHz among signal bands and accordingly, serious effect can be avoided. Moreover, space diversity (also called path diversity) can be realized with the following three types of methods. First, it can be obtained by the duplication of cell site receive antenna. Second, it can be obtained through the use of multi-signal processing device that receives a transmit signal having each different transmission delay time and then, combines them. Third, it can be obtained through the multiple cell site connection (Soft Handoff) that connects the mobile station with more than two cell sites at the same time.

2.2 Power Control

The CDMA system utilizes the forward (from a base station to mobile stations) and backward (from the mobile station to the base station) power control in ord er to in crease the call p ro cessing capacity an d ob tain h igh -q uality calls. In case the originating signals of mobile stations are received by the cell site in the minimum call quality level (signal to interference) through the use of transmit power control on all the mobile stations, the system capacity can be maximized.If the signal power of mobile station is received too strong, the performance of that mobile station is improved. However, because of this, the interference on other mobile stations using the same channel is increased and accordingly, the call quality of other subscribers is reduced unless the maximum accommodation capacity is reduced. In the CDMA system, forward power control, backward open loop power control, and closed loop power control methods are used. The forward power control is carried out in the cell site to reduce the transmit power on mobile stations less affected by the multi-path fading and shadow phenomenon and the interference of other cell sites when the mobile station is not engaged in the call or is relatively nearer to the corresponding cell site. This is also used to provide additional power to mobile stations having high call error rates, located in bad reception areas or far away from the cell site. The backward open loop power control is carried out in a corresponding mobile station; the mobile station measures power received from the cell site and then, reversely increases/decreases transmit power in order to compensate channel changes caused by the forward link path loss and terrain characteristics in relation to the mobile station in the cell site. By doing so, all the mobile transmit signals received by the base station have same strength. Moreover, the backward closed loop power control used by the mobile station is performed to control power using the commands issued out by the cell site. The cell site receives the signal of each corresponding mobile station and compares this with the pre-set threshold value and then, issues out power increase/decrease commands to the corresponding mobile station every 1.25msec (800 times per second). By doing so, the gain tolerance and the different radio propagation loss on the forward/backward link are complemented.

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2.3 Voice Encoder and Variable Data Speed

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The bi-directional voice service having variable data speed provides voice communication which employs voice encoder algorithm having power variable data rate between the base station and the mobile station. On the other hand, the transmit voice encoder performs voice sampling and then, creates encoded voice packets to be sent out to the receive voice encoder, whereas the receive voice encoder demodulates the received voice packets into voice samples. One of the two voice encoders described in the above is selected for use depending on inputted automatic conditions and message/data; both of them utilize four-stage frames of 9600, 4800, 2400, and 1200 bits per second for cellular and 14400,7200,3600,1800 bits per second for PCS, so PCS provide relatively better voice quality (almost twice better than the existing celluar system). In addition, this type of variab le voice encoder utilizes adaptive threshold values on selecting required data rate. It is adjusted in accordance with the size of background noise and the data rate is increased to high rate only when the voice of caller is inputted. Therefore, background noise is suppressed and high-quality voice transmission is possible under the environment experiencing serious noise. In addition, in case the caller does not talk, data transmission rate is reduced so that the transmission is carried out in low energy. This will reduce the interference on other CDMA signals and as a result, improve system performance (capacity increased by about two times).

2.4 Protecting Call Confidentiality

Voice privercy is provided in the CDMA system by means of the private long code mask used for PN spreading. Voice privacy can ve applied on the traffic channels only. All calls are initiated using the public long code mask for PN spreading. The mobile station user may request voice privacy during call setup using the origination message or page response message, and during traffic channel operation using the long code transition request order. The Transition to private long code mask will not be performed if authentication is not performed. To initiate a transition to the private or public long code mask, either the base station or the mobile station sends a long code transition request order on the traffic channel.

2.5 Soft Handoff

A handoff in which the mobile station commences communications with a new base station without interrupting communications with the old base station. Soft handoff can only be used between CDMA channels having identical freqeuncy assignments.

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2.6 Frequency Re-Use and Sector Segmentation

Unlike the existing analog cellular system, the CDMA system can reuse the same frequency at the adjacent cell. there is no need to prepare a separate frequency plan. Total interference generated on mobile station signals

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received from the cell site is the sum of interference generated from other mobile stations in the same cell site

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and interference generated from the mobile station of adjacent cell site. That is, each mobile station signal generates interference in relation to the signals of all the other mobile stations . Total interference from all the adjacent cell sites is the ratio of interference from all the cell sites versus total interference from other mobile stations in the same cell site (about 65%). In the case of directional cell site, one cell normally uses a 120°sector antenna in order to divide the sector into three. In this case, each antenna is used only for 1/3 of mobile stations in the cell site and accordingly, interference is reduced by 1/3 on the average and the capacity that can be supported by the entire system is increased by three times.

2.7 Soft Capacity

The subscriber capacity of the CDMA system is flexible depending on the relation between the number of users and service classes. For example, the system operator can increase the number of channels available for use during the busy hour despite the drop in call quality. This type of function requires 40% of normal call channels in the standby mode during the handoff, in an effort to avoid call disconnection resulting from the lack of channels. In addition, in the CDMA system, services and service charges are classified further into different classes so that more transmit power can be allocated to high class service users for easier call set-up; they can also be given higher priority of using hand-off function than the general users.

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3. Structure and Functions of tri-band CDMA Mobile Phone

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The hardware structure of CDMA mobile phone is made up of radio frequency (RF) part and logic part. The RF part is composed of Receiver part (Rx), Transmitter part (Tx) and Local part (LO). For the purpose of operating on tri-band, It is necessary dual Tx path, tri Rx path, dual PLL and switching system for band selection. The mobile phone antenna is connected with the frequency seperater which divide antenna input/output signals between cellular frequency band (824~894 Mhz) and PCS frequency band (1850~1990Mhz). Each separated path is linked with the cellular duplexer and PCS duplexer. Duplexer carrys out seperating Rx band and Tx band. The Rx signals from the antenna are converted into intermediate frequency(IF) band by the frequency synthesizer and frequency down converter. And then, pass SAW filter which is a band pass filter for removing out image frequency. The IF output signals that have been filtered is converted into digital signals via Analog-to-Digital Converter (ADC). In front of the ADC, switching system is required to choose which band path should be open. The digital signals send to 5 correlators in each CDMA de-modulator. Of these, one is called a searcher whereas the remaining 4 are called data receivers (fingers). Digitalized IF signals include a great number of call signals that have been sent out by the adjacent cells. These signals are detected with pseudo-noise sequence (PN Sequence). Signal to interference ratio (C/I) on signals that match the desired PN sequence are increased through this type of correlation detection process, but other signals obtain processing gain by not increasing the ratio. The carrier wave of pilot channel from the cell site most adjacently located is demodulated in order to obtain the sequence of encoded data symbols. During the operation with one cell site, the searcher searches out multi-paths in accordance with terrain and building reflections. On three data receivers, the most powerful 3 paths are allocated for the parallel tracing and receiving. Fading resistance can be improved a great deal by obtaining the diversity combined output for de-modulation. Moreover, the searcher can be used to determine the most powerful path from the cell sites even during the soft handoff between the two cell sites. Moreover, 3 data receivers are allocated in order to carry out the de-modulation of these paths. Output data that has been demodulated changes the data string in the combined data row as in the case of original signals(deinterleaving), and then, are demodulated by the forward error correction decoder which uses the Viterbi algorithm. Mobile station user information send out from the mobile station to the cell site pass through the digital voice encoder via a mike. Then, they are encoded and forward errors are corrected through the use of convolution encoder. Then, the order of code rows is changed in accordance with a certain regulation in order to remove any errors in the interleaver. Symbols made through the above process are spread after being loaded onto PN carrier waves. At this time, PN sequence is selected by each address designated in each call. Signals that have been code spread as above are digital modulated (QPSK) and then, power controlled at the automatic gain control amplifier (AGC Amp). Then, they are converted into RF band by the frequency synthesizer synchronizing these signals to proper output frequencies. Transmit signals obtained pass through the duplexer filter and then, are sent out to the cell site via the antenna.

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4. Specification

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4.1 General Specification

4.1.1 Transmit/Receive Frequency Interval :

1) CELLULAR : 45 MHz

2) PCS : 80 MHz

4.1.2 Number of Channels (Channel Bandwidth)

1) CELLULAR : 20 Channels

2) PCS : 48 Channels

4.1.3 Operating Voltage : DC 3.3~4.2V

4.1.4 Battery Power Consumption : DC 3.7V

SLEEP IDLE MAX POWER

CELLULAR

PCS

2.0 mA 200mA 900 mA (24 dBm)

4.1.5 Operating Temperature : -20°C ~ +60°C

4.1.6 Frequency Stability

1) CDMA : ±0.5PPM

2) PCS : ±0.1PPM

4.1.7 Antenna : Internal Antenna, 50 Ω

4.1.8 Size and Weight

1) Size : 19.9(H) x 47.5(W) x 93.5(D) mm (with850mAh)

2) Weight : 110g (with 850mAh)

4.1.9 Channel Spacing

1) CELLULAR : 1.25MHz

2) PCS: 1.25 MHz

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4.1.10 Battery Type, Capacity and Orerating Time.

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Unit = Hours, Minutes

Standard (850mAh)

PCS(Slot Cycle 2)

Standby Time

DCN (Slot Cycle 2)

PCS(Slot Cycle 2)

Talk Time

DCN (Slot Cycle 2)

4.2 Receive Specification

4.2.1 Frequency Range

1) CELLULAR : 869.820 MHz ~ 893.190 MHz

2) PCS : 1930 MHz ~ 1990 MHz

3) GPS : 1575.42 MHz

4.2.2 Local Oscillating Frequency Range :

1) CELLULAR : 1738.08MHz ~ 1787.94MHz

2) PCS : 1715.56MHz ∼ 1768.89MHz

3) GPS : 3150.84MHz

4.2.3 Sensitivity

About 110 Hrs (SCI=2) About 110 Hrs (SCI=2)

150 Min.(typical duplexer,10dBm output)

1) CELLULAR : -104dBm (C/N 12dB or more)

2) PCS : -104dBm (C/N 12dB or more)

3) GPS : -148.5dBm

4.2.4 Selectivity

1) CELLULAR : 3dB C/N Degration (With Fch±1.25 kHz : -30dBm)

2) PCS : 3dB C/N Degration (With Fch±1.25 kHz : -30dBm)

4.2.5 Interference Rejection

1) Single Tone : -30dBm at 900 kHz (CELLULAR), -30dBm at 1.25MHz(PCS)

2) Two Tone : -43dBm at 900 kHz & 1700kHz(CELLULAR), -43dBm at 1.25 MHz & 2.05 MHz

4.2.6 Spurious Wave Suppression : Maximum of -80dB

4.2.7 CDMA Input Signal Range

z Dynamic area of more than -104~ -25 dB: 79dB at the 1.23MHz band.

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4.3 Transmit Specification

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4.3.1 Frequency Range

1) CELLULAR : 824.820MHz ~ 848.190MHz

2) PCS : 1850 MHz ~ 1910 MHz

4.3.2 Output Power

1) CELLULAR : 0.224W

2) PCS: 0.224W

4.3.3 CDMA TX Frequency Deviation :

1) CELLULAR: +300Hz or less

2) PCS: ± 150Hz

4.3.4 CDMA TX Conducted Spurious Emissions

1) CELLULAR : 900kHz : - 42 dBc/30kHz below

1.98MHz : - 54 dBc/30kHz below

2) PCS : -42 dBc / 30KHz below

4.3.5 CDMA Minimum TX Power Control

1) CELLULAR : - 50dBm below

2) PCS: -50dBm below

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4.4

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MS (Mobile Station) Transmitter Frequency

4.4.1 CELLULAR mode

Ch # Center Freq. (MHz) Ch # Center Freq. (MHz)

1011

70 111 152 193 234 275 316 363

4.4.2 PCS mode

Ch # Center Freq (MHz) Ch # Center Freq (MHz) Ch # Center Freq (MHz)

25 1851.25 425 1871.25 825 1891.25 50 1852.50 450 1872.50 850 1892.50 75 1853.75 475 1873.75 875 1893.75

824.640

825.870

827.100

828.330

829.560

830.790

832.020

833.250

834.480

835.890

404 445 486 527 568 609 650 697 738 779

837.120

838.350

839.580

840.810

842.040

843.270

844.500

845.910

847.140

848.370

100 1855.00 500 1875.00 900 1895.00 125 1856.25 525 1876.25 925 1896.25 150 1857.50 550 1877.50 950 1897.50 175 1858.75 575 1878.75 975 1898.75 200 1860.00 600 1880.00 1000 1900.00 225 1861.25 625 1881.25 1025 1901.25 250 1862.50 650 1882.50 1050 1902.50 275 1863.75 675 1883.75 1075 1903.75 300 1865.00 700 1885.00 1100 1905.00 325 1866.25 725 1886.25 1125 1906.25 350 1867.50 750 1887.50 1150 1907.50 375 1868.75 775 1888.75 1175 1908.75

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4.5

MS (Mobile Station) Receiver Frequency

4.5.1 CELLULAR mode

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Ch. # Center Freq. (MHz) Ch. # Center Freq. (MHz)

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1011

70 111 152 193 234 275 316 363

4.5.2 PCS mode

Ch # Center Freq (MHz) Ch # Center Freq (MHz) Ch # Center Freq (MHz)

25 1931.25 425 1951.25 825 1971.25 50 1932.50 450 1952.50 850 1972.50 75 1933.75 475 1953.75 875 1973.75

869.640

870.870

872.100

873.330

874.560

875.790

877.020

878.250

879.480

880.890

404 445 486 527 568 609 650 697 738 779

882.120

883.350

884.580

885.810

887.040

888.270

889.500

890.910

892.140

893.370

100 1935.00 500 1955.00 900 1975.00 125 1936.25 525 1956.25 925 1976.25 150 1937.50 550 1957.50 950 1977.50 175 1938.75 575 1958.75 975 1978.75 200 1940.00 600 1960.00 1000 1980.00 225 1941.25 625 1961.25 1025 1981.25 250 1942.50 650 1962.50 1050 1982.50 275 1943.75 675 1963.75 1075 1983.75 300 1945.00 700 1965.00 1100 1985.00 325 1946.25 725 1966.25 1125 1986.25

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350 1947.50 750 1967.50 1150 1987.50 375 1948.75 775 1968.75 1175 1988.75

4.5.3 GPS mode : 1575.42MHz

4.6 AC Adaptor : See Appendix

4.7 Cigar Lighter Charger: See Appendix

4.8 Hands-Free Kit : See Appendix

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5. Installation

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5.1 Installing a Battery Pack

1) The Battery pack is keyed so it can only fit one way. Align the groove in the battery pack with the rail on the back of the phone until the battery pack rests flush with the back of the phone.

2) Slide the battery pack forward until you hear a “click”, which locks the battery in place.

5.2 For Adapter Use

1) Plug the adapter into a wall outlet. The adapter can be operated from a 110V source. When AC power is connected to the adapter.

2) Insert the adapter jack into the phone with the installed battery pack.

Red light indicates battery is being charged.. Green light indicates battry is fully charged.

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CHAPTER 2. NAM Input Method

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(Inputting of telephone numbers included)

1. NAM Programming Method and Telephone Number Input Method

1. Press ##2342# (##CDG2#)

2. Enter Service Code “ 000000” .

3. You can see following Menu

CDG-II

1. Service Progra..

2. Field Tests

3. Vocoder Select

4. Reg. Tests

5. Data Setting

4. Select ‘ Service Prog’ , and press OK

You can see following submenus.

Service Program

1. Reset Phone

2. Mobile Phone #

3. Home SID

4. Advanced

4-1) Select ‘ Reset Phone’ , and Press OK

You can reset the phone

4-2) Select ‘ Mobile Phone #’ and press OK

Input Mobile Phone Number and select OK

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Phone Number

0000000000

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4-3) Select ‘ Home SID’ and press OK

Input the Home SID and select OK

Home SID

11111

4-4) Advanced

There are fifteen submenus as below.

4-4.1) Select ‘ MCC’ and press OK

Input the Mobile Country Code and select OK

Country Code

000

4-4.2)Select ‘ NMSI’ and press OK Input the NMSI and select OK

NMSI

001112223333

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4-4.3)Select ‘ True MCC’ and press OK

Input the True MCC and select OK

True MCC

310

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4-4.4) Select ‘ True IMSI NMSI’ and press OK

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Input the True IMSI NMSI and select OK

True IMSI NMSI

001112223333

4-4.5) Select ‘ Home NID’ and press OK

Input the Home NID and select OK

Home NID

65535

4-4.6) Select ‘ Home Sys Reg’ and press OK Select one what you want , and press OK

Home Sys Reg

◉ Yes

◌ No

4-4.7) Select ‘ Forn SID Reg’ and press OK

Select one what you want , and press OK

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Forn SID Reg

◉ Yes

◌ No

4-4.8) Select ‘ Forn NID Reg’ and press OK

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Select one what you want , and press OK

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Forn NID Reg

◉ Yes

◌ No

4-4.9) Select ‘ CDMA Preferred CH’ and press OK

Select one what you want , and press OK

4-4.10) Select ‘ Slot Cycle Idx’ and press OK

Input the Slot Cycle and select OK

CDMAPreferCH

1. System A

2. System B

Slot Cycle

4-4.11) Select ‘ Acc Ovld Class’ and press OK

You can see the Access Overload Class that is automatically set according

to IMSI_M

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Acc Ovld Class

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CHAPTER 3. Circuit Description

1. RF Transmit/Receive Part

1.1 Overview

The Tx and Rx part employs the Direct Conversion system. The Tx and Rx frequencies are respectively

824.04~848.97 and 869.04~893.97 for cellular and 1850~1910 and 1930~1990 for PCS. The block diagram is

shown in [Figure 1-1]. RF signals received through the antenna are seperated by Triplexer. RF Signal fed into the low noise amplifier (LNA) which is embedded in RFR6500 through the duplexer. Then, they are into baseband signal directly. Then, this signal is ch anged into digital signal by the analog to digital converter (ADC, A/D Converter), and the digital circuit part of the MSM(Mobile Station Modem)6500 processes the data from ADC. The digital processing part is a demodulator. In the case of transmission, RFT6150 receives OQPSK-modulated anlog signal from the MSM6500. The RFT6150 connects directly with MSM6500 using an analog baseband interface. In RFT6150, the baseband quadrature signals are upconverted to the Cellular or PCS frequency bands and amplified to provide signal drive capability to the power amp. After that, the RF signal is amplified by the Power Amp in order to have enough power for radiation. Finally, the RF signal is sent out to the cell site via the antenna after going through the isolator and duplexer.

[Figure 1-1] Block Diagram Of CX380

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1.2 Description of Rx Part Circuit

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1.2.1 Triplexer(F100)

The main function of Triplexer is to prohibit the other band signals from flowing into the one band circuit and vice versa. RF designer can use common Tri-band antenna regardless of frequency band (800, 1500, 1900 MHz). The specification of CX380 Triplexer is described below:

Frequency Range

Insertion Loss(Typical)

VSWR

Power Capacity

Temperature Range

1.2.2 Duplexer (DP100, DP101)

Cellular GPS PCS

824 – 894 MHz 1574 – 1577 MHz 1850 – 1990 MHz

0.64 dB (at +25 deg) 1.54 dB (at +25 deg) 0.75 dB (at +25 deg)

1.4 1.2 1.2

38dBm Max. 5dBm Max. 38dBm Max.

-30 to +85 deg

The duplexer consists of the Rx bandpass filter (BPF) and the Tx BPF which has the function of separating Tx and Rx signals in the full duplex system for using the common antenna. The Tx part BPF is used to suppress noises and spurious out of the Tx frequency band. The Rx BPF is used to receive only Rx signal coming from the antenna, which is usually called preselector. It’s main function is to limit the bandwidth of spectrum reaching the LNA and mixer, attenuate receiver spurious response and suppress local oscillator energy. As a result frequency sensitivity and selectivity of mobile phone increase. The specification of LG-CX380 duplexer described below ;

z PCS duplexer:

Pass Band Insertion Loss Return Loss Attenuation

LG Electronics Inc.

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43dB min (1930~1990MHz) 52dB min

Tx Rx Tx to Rx (min)

1850~1910 MHz 1930~1990 MHz

3.5dB max 3.8dB max

9.5dB min 9.5dB min 54dB (1850~1910MHz)

(1850~1910MHz)

45dB (1930~1990MHz)

CX380

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Pass Band Insertion Loss Return Loss Attenuation

45dB min (869~894MHz) 54dB min (824~849MHz) 56dB (824~849MHz)

Tx Rx Tx to Rx (min)

824~849MHz 869~894 MHz

2.3B max 3.1dB max

9.0dB min 7.0dB min

46dB (869~894MHz)

1.2.3 LNAs (U107)

The RFR6500 has cellular and PCS LNAs, respectively. The characteristics of Low Noise Amplifier (LNA) are low noise figure, high gain, high intercept point and high reverse isolation. The frequency selectivity characteristic of mobile phone is mostly determined by LNA. The specification of CX380 LNAs are described below.

● Cellular High current mode Low current mode Passive status

Power Gain

*Gain mode G0(G2)

16dB

14dB

-6.0dB

*Gain mode G1(G3)

Noise Figure Gain mode G0(G2) Gain mode G1(G3)

Input IP3 Gain mode G0(G2) Gain mode G1(G3)

*Gain mode G0 and G1 operate in high and low current mode. *Gain mode G2 and G3 operate in Passive status.

4.0dB

1.4dB

4.0dB

8dB 5dB

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● PCS High current mode Low current mode Passive status

Power Gain

*Gain mode G0(G1)

16dB

3.0dB

1.4dB

4.0dB

-5dB

14dB

-20.0dB

7.0dB

20.0dB

12dB 10dB

-3.0dB

Gain mode G2

Noise Figure

Gain mode G0(G1)

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1.6dB

-20.0dB

4.0dB

CX380

Gain mode G2 X X 20.0dB

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Input IP3 Gain mode G0(G1) Gain mode G2

*Gain mode G0 operate in high and low current mode. *Gain mode G1 and G2 operate in Passive status.

● GPS Parameter GPS Band Unit Gain 14.5 dB Noise Figure 1.3 dB IIP3 5.0 dBm

6dB

-2dB X

10dB 10dB

1.2.4 Down-converter Mixers

The RFR6500 device performs signal down-conversion for Cellular, PCS and GPS tri-band applications. It contains all the circuitry (with the exception of external filters) needed to support conversion of received RF signals to baseband signals. It consists of the three downconverting Mixers(Cellular, PCS and GPS), and an RX VCO and RX PLL circuit.

The GPS LNA & mixers offer the most advanced and integrated CDMA Rx solution designed to meet cascaded Noise Figure (NF) and Third-order Intercept Point (IIP3) requirements of IS-98C and J-STD-018 specifications for Sensitivity, Two-Tone Intermodulation, and Single-tone Desense.

Operation modes and band selection are specially controlled from the Mobile Station Modem MSM6500. The specification of CX380 Mixers are described below:

● Cellular

High current mode Mid current mode Low current mode

Noise Figure

High Gain mode

10dB

9dB

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Low Gain mode

Input IP3 High Gain mode Low Gain mode

Input IP2 High Gain mode

25dB

4.0dB

-5.0dB

56dB

25dB

4.0dB

-5.0dB

56dB

25dB

-10.0dB

-5.0dB

40dB

Low Gain mode

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30dB

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● Cellular High current mode Mid current mode Low current mode

Noise Figure High Gain mode Low Gain mode

Input IP3 High Gain mode Low Gain mode

Input IP2 High Gain mode Low Gain mode

10dB 25dB

4.0dB

-11.0dB

56dB 30dB

10dB 25dB

-8.0dB

-11.0dB

56dB 30dB

9dB

25dB

-8.0dB

-11.0dB

40dB 30dB

1.2.4 Rx RF SAW FILTER(F101,F102,F103)

The main function of Rx RF SAW filter is to attenuate mobile phone spurious frequency, attenuate direct RF frequency pick up, attenuate noise at the image frequency originating in or amplified by the LNA and suppress second harmonic originating in the LNA. The Rx RF SAW filter usually called image filter.

1.3 Description of Transmit Part Circuit

1.3.1 RFT6150 (U108)

The RFT6150 base-band-to-RF Transmit Processor performs all Tx signal-processing functions required between digital base-band and the Power Amplifier Modulator (PAM). The base-band quadrature signals are up-converted to the Cellular or PCS frequency bands and amplified to provide signal drive capability to the PAM. The RFT6150 includes an RF mixer for upconverting analog baseband to RF, a programmable PLL for generating Tx LO frequency, two cellular and two PCS driver amplifiers and Tx power control through an 85 dB VGA. As added benefit, the single sideband upconversion eliminates the need for a band pass filter normally required between the upconverter and driver amplifier. I, I/, Q and Q/ signals proceed from the MSM6500 to RFT6150 are analog signal. In CDMA mode, These signals are modulated by Quadrature Phase Shift King (QPSK). I and Q are 90 deg. out of phase, and I and I/ are 180 deg. The mixer in RFT6150 converts baseband signals into RF signals. After passing through the upconverter , RF signal is inputted into the Power AMP.

z RFT6150 Cellular and PCS CDMA RF Specifications

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Rated Output Power

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Condition Min. Typ. Max. Units

Average CDMA Cellular 7 dBm

CX380

Average CDMA PCS 9 dBm

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Min Output Power

Rx band noise power

ACPR

1.3.2 Power Amplifier(U104,U105)

The power amplifier that can be used in the PCS and CDMA mode has linear amplification capability and hig h efficiency. For higher efficiency, it is made up of one MMIC (Monolithic Microwave Integrated Circuit) fo r which RF input terminal and internal interface circuit are integrated onto one IC after going through the AlGaAs/GaAs HBT (heterojunction bipolar transistor) process. The module of power amplifier is made up of an output end interface circuit including this MMIC. The maximum power that can be inputted through the input terminal is +10dBm and conversion gain is about 28dB. RF transmit signals that have been amplified through the power amplifier are sent to the duplexer.

Average CDMA Cellular

Average CDMA PCS

CDMA Cellular

CDMA PCS

Cellular: Fc±885kHz

PCS: Fc±1.25MHz

-75

-136

-133

-56

-57

dBm

dBm/Hz

dBc/

30kHz

1.4 Description of Frequency Synthesizer Circuit

1.4.1 Voltage Control Temperature Compensation Crystal Oscillator (VCTCXO, X101)

The temperature variation of mobile phone can be compensated by VCTCXO. The reference frequency of a mobile phone is 19.2MHz. The receives frequency tuning signals called TRK_LO_ADJ from MSM as

0.5V~2.5V DC via R and C filter in order to generate the reference frequency of 19.2MHz and input it into the frequency synthesizer. Frequency stability depending on temperature is ±2.0 ppm.

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CX380

2. Digital/Voice Processing Part

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2.1 Overview

The digital/voice processing part processes the user's commands and processes all the digital and voice signal processing in order to operate in the phone. The digital/voice processing part is made up of a keypad/LCD, receptacle part, voice processing part, mobile station modem part, memory part, and power supply part.

2.2 Configuration

2.2.1 Keypad/OLED and Receptacle Part

This is used to transmit keypad signals to MSM6500. It is made up of a keypad backlight part that illuminates the keypad, OLED part that displays the operation status onto the screen, and a receptacle that receives and sends out voice and data with external sources.

2.2.2 Voice Processing Part

The voice processing part is made up of an audio codec used to convert MIC signals into digital voice signals and digital voice signals into analog voice signals, amplifying part for amplifying the voice signals and sending them to the ear piece, amplifying part that amplifies ringer signals coming out from MSM6500, and amplifying part that amplifies signals coming out from MIC and transferring them to the audio processor.

2.2.3 MSM (Mobile Station Modem) 6500 Part

MSM is the core elements of CDMA terminal and carries out the functions of CPU, encoder, interleaver, deinterleaver, Viterbi decoder, Mod/Demod, and vocoder.

2.2.4 Memory Part

The memory part is made up of a sdram/nand memory, nand for storing data.

2.2.5 Power Supply Part

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The power supply part is made up of circuits for generating various types of power, used for the digital/voice processing part.

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2.3 Circuit Description

2.3.1 Keypad/LCD and Receptacle Part

Once the keypad is pressed, the key signals are sent out to MSM6500 for processing. In addition, when the key is pressed, the keypad lights up through the use of 14 LEDs. Moreover, it exchanges audio signals and data with external sources through the receptacle, and then receives power from the battery or external batteries.

2.3.2 Audio Processing Part

MIC signals are amplified through OP AMP, inputted into the audio codec(included in MSM6500) and converted into digital signals. Oppositely, digital audio signals are converted into analog signals after going through the audio codec. These signals are amplified at the audio amplifier and transmitted to the ear-piece. The signals from MSM6500 activate the ringer by using signals generated in the timer in MSM6500.

2.3.3 MSM Part

MSM6500 is the core element of CDMA system terminal that includes ARM926EJ-S microprocessor core. It supports CDMA, operating in both the cellular and PCS spectrums. The subsystems within the MSM6500 include a CDMA processor, a DFM processor, a multi-standard Vocoder, an integrated CODEC with earpiece and microphone amplifiers, general-purpose ADC for subsytem monitoring, an ARM926EJ-S microprocessor, and both Universal Serial Bus(USB) and an RS-232 serial interfaces supporting forward and reverse link data communications of 307.2 Kbps simultaneously. And it also contains complete digital modulation and demodulation systems for CDMA standards, as specified in IS-95-A/B/C. In MSM, coded symbols are interleaved in order to cope with multi-path fading. Each data channel is scrambled by the long code PN sequence of the user in order to ensure the confidentiality of calls. Moreover, binary quadrature codes are used based on walsh functions in order to discern each channel. Data created thus are 4-phase modulated by one pair of Pilot PN code and they are used to create I and Q data. When received, I and Q data are demodulated into symbols by the demodulator, and then de-interleaved in reverse to the case of transmission. Then, the errors of data received from viterbi decoder are detected and corrected. They are voice-decoded at the vocoder in order to output digital voice data..

2.3.4 Memory Part

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MCP contents 512 Mbits flash memory and 512 Mbits SDRAM. In the Flash Memory part of MCP are programs used for terminal operation. The programs can be changed through down loading after the assembling of terminals. On the SDRAM data generated during the terminal operation are stored temporarily.

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2.3.5 Power Supply Part

When the battery voltage (+4.0V) is fed and the PWR key of keypad is pressed, the power-up circuitry in PM (power management) IC (U600) is activated by the PWR_ON_SW signal, and then the LDO regulators embedded in PMIC for MSM) are operated and +1.4V_MSMC, +1.8_MSMP1, +2.6V_MSMP2 and +2.6V_MSMA are generated. The Rx part regulator (+2.9V_RX) is operated by the control signal of SLEEP/ from MSM6500 The Tx part regulator (+2.85V_TX) is operated by the I2C control signal from MSM6500

2.3.6 Logic Part

The logic part consists of internal CPU of MSM, RAM, MCP. The MSM6500 receives TCXO (=19.2MHz) from X101 and controls the phone in CDMA mode. The major components are as follows:

CPU

The ARM926EJ-S microprocessor includes a 3 stage pipelined RISC architecture, both 32-bit ARM and 16-bit THUMB instruction sets, a 32-bit address bus, and a 32-bit internal data bus. It has a high performance and low power consumption.

Flash ROM is used to store the terminal’s program. Using the down-loading program, the program can be changed even after the terminal is fully assembled.

SDRAM is used to store the internal flag information, call processing data, and timer data.

For key recognition, key matrix is setup using KYPD[1][3][5][7][9][11][13][15][17][19] signal from MSM. 16 LEDs and backlight circuitry are included in the keypad for easy operation in the dark.

TFT LCD module contains a controller which will display the information onto the TFT LCD MODULE by 16-bit data from the MSM6500.

MCP

KEYPAD

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TFT LCD MODULE

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CX380

CHAPTER 4. Trouble Shooting

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CHAPTER 4. Trouble Shooting

4.1 Rx Part Trouble

4.1.1 When Rx Power isn’t enough

• Test Point

Duplexer

Triplexer

RFR6000

Mobile S/W

• Checking Flow

TP1 : TP2 : TP3 : TP4 : TP5 : TP6 : TP7 : TP8 : TP9 : TP10 :

PMIC Part

VCTCXO

[Figure 4-1-1]

START

Rx TEST SETUP(HHP)

- Test Channel : 384(DCN),600(PCS)

E5515C Setup

- CH : 384(DCN),600(PCS)

- Sector Power : -30 dBm Spectrum Analyzer Setting Oscilloscope Setting

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1. Check

PMIC Circuit

2. Check

VCTCXO Circuit

Triplexer,Duplexer(DCN,PCS),

3. Check

Mobile SW

4. Check

Control Signal

5. Check

Rx I/Q data

Redownload SW, CAL

CX380

①

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③

②

DCN

④

①

③

②

PCS

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④

CX380

4.1.2 Checking Regulator Circuit

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• Test Point

TP1

TP2

• Circuit Diagram

[Figure 4-1-2]

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• Checking Flow

Check Pin A7 of U600

+2.9V_RX0 OK?

PMIC Circuit is OK

See next Page to check

VCTCXO

Check Pin B24 of U600

Pin B24 High?

Replace U600

Changing Board

TP1 : U600. B24 High TP2 : U600. A7 (+2.9V_RX)

+ 99 hidden pages

LG CX380 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual