LG LX140 Service Manual
1/83 LGE Internal Use Only
Features of LX140
1. Wave Type
• CELLULAR : G7W
• PCS : G7W
2. Frequency Scope
Transmit Frequency (MHz)
Receive Frequency (MHz)
CELLULAR
824.82 ~ 848.19 1850~1910 869.82~893.19 1930~1990 1575.42
3. Rated Output Power :
PCS = 0.240W
4. Output Conversion Method :
5. Voltage and Current Value of Termination Part Amplifier (Catalogue included)
MODE Part Name Voltage Current Power
CELLULAR AWT6314R 4.2V 700mA 0.282W
PCS AWT6314R 4.2V 700mA 0.282W
PCS
CELLULAR = 0.251W
This is possible by correcting the key board channel.
CELLULAR
PCS
GPS
6. Functions of Major Semi-Conductors
Classification Function
MSM6050-FBGA Terminal operation control and digital signal processing
MCP (K5L2963CAM-D770)
RFR6000 Converts Rx RF signal to baseband signal
RFT6100 Converts baseband signal to Tx RF signal
RFL6000 LNA chip which amplifies front-end Rx RF signal
7. Frequency Stability
• CELLULAR : ±0.5PPM
• PCS : ±0.1PPM
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Flash Memory (128Mbit) + S-RAM (64Mbit)
Storing of terminal operation program
LX140
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LX140
CDMA Mobile Subscriber Unit
SERVICE MANUAL
Tri-BAND, Tri-MODE
[Cellular/PCS/GPS]
CDMA MOBILE PHONE
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Table of Contents
General Introduction
............................................................................................................................................... 4
CHAPTER 1. System Introduction
1. System Introduction......................................................................................................5
2. Features and Advantages of CDMA Mobile Phone ....................................................6
3. Structure and Functions of dual-band CDMA Mobile Phone ....................................9
4. Specification ................................................................................................................10
5. Installation....................................................................................................................15
CHPATER 2. NAM Input Method
1. NAM Program Method ...............................................................................................16
CHAPTER 3. Circuit Description
1. RF Transmit/Receive Part...........................................................................................18
2. Digital/Voice Processing Part.....................................................................................24
CHAPTER 4. Trouble Shooting…………………………………………………………………..28
CHAPTER 5. Safety…………………………………………………………………………..…….50
CHAPTER 6. Glossary…………………………………………………………………….…..…...53
APPENDIX……………………………………………………………………..…………….…..…..66
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General Introduction
The LX140 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 LX140 support GPS Mode, we usually call it tri-band phone.
We call it tri-mode 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
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TIA/EIA/IS-99
TIA/EIA/IS-637
TIA/EIA/IS-657
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
Performance TIA/EIA/IS-97
TIA/EIA/IS-98
ANSI J-STD-018
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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Cellular base station
Cellular mobile station
PCS personal station
PCS base station
Speech CODEC
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Chapter1. 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
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 high-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 order to increase the call processing capacity
and obtain high-quality 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,
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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.
2.3 Voice Encoder and Variable Data Speed
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 variable 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.
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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.
2.6 Frequency Re-Use and Sector Segmentation
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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 received from the cell site is the sum of interference generated from other
mobile stations in the same cell site 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
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
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 0.6 mA 120~150mA 700 mA (24.0 dBm)
PCS 0.6 mA 120~150 mA 700 mA (23.8dBm)
4.1.5 Operating Temperature : -30°C ~ +60°C
4.1.6 Frequency Stability
1) CDMA : ±0.5PPM
2) PCS : ±0.1PPM
4.1.7 Antenna : Inner Type (Internal Antenna), 50 Ω
4.1.8 Size and Weight
1) Size : 89 * 49 * 22.6 mm
2) Weight : 80 g (Approximately with standard battery)
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 Operating Time.
Unit = Hours : Minutes
Standard (800 mAh)
CELLULAR About 180Hours (SCI=2)
Standby Time
PCS About 180 Hours (SCI=2)
CELLULAR 150 Minutes (-92dBm input)
Talk time
PCS 150 Minutes (-92dBm input)
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
1) CELLULAR : -104dBm (C/N 12dB or more)
2) PCS : -104dBm (C/N 12dB or more)
3) GPS : -148.5dBm (without SA mode)
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 Spurious Wave Suppression : Maximum of -80dB
4.2.6 CDMA Input Signal Range
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Dynamic area of more than -104~ -25 dB: 79dB at the 1.23MHz band.
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4.3 Transmit Specification
4.3.1 Frequency Range
1) CELLULAR : 824.820MHz ~ 848.190MHz
2) PCS : 1850 MHz ~ 1910 MHz
4.3.2 Output Power
1) CELLULAR : 0.251W
2) PCS: 0.240W
4.3.3 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
4.3.4 CDMA TX Frequency Deviation :
1) CELLULAR: +300Hz or less
2) PCS: ± 150Hz
4.3.5 CDMA TX Conducted Spurious Emissions
1) CELLULAR : 900kHz : - 42 dBc/30kHz below
1.98MHz : - 54 dBc/30kHz below
2) PCS : -42 dBc / 30KHz below
4.3.6 CDMA Minimum TX Power Control
1) CELLULAR : - 50dBm below
2) PCS: -50dBm below
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4.4
MS (Mobile Station) Transmitter Frequency
4.4.1 CELLULAR mode
Ch # Center Freq. (MHz) Ch # Center Freq. (MHz)
1011
29
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
100 1855.00 500 1875.00 900 1895.00
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
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
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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
Ch. # Center Freq. (MHz) Ch. # Center Freq. (MHz)
1011
29
70
111
152
193
234
275
316
363
4.5.2 PCS mode
Ch # Center Freq
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
(MHz)
869.640
870.870
872.100
873.330
874.560
875.790
877.020
878.250
879.480
880.890
Ch # Center Freq (MHz) Ch # Center Freq
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
(MHz)
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
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300 1945.00 700 1965.00 1100 1985.00
325 1946.25 725 1966.25 1125 1986.25
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
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5. Installation
5.1 Installing a Battery Pack
1) The soft 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) Insert the bottom of battery cover into the openning on the back of the phone. Then, push the
battery cover up until the latch clicks.
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 I/O plug 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
(Inputting of telephone numbers included)
1) NAM Programming Method
PREPARATION
STEP ACTION
1 1.1 NAM Programming : Press NAM Programming code “##626#” on idle screen
1.2 Extended NAM Programming : Press Extended NAM Programming code “##398626#” on idle
screen
2 1. NAM1 or NAM2 selected
3 3.1 View Mode
3.1.1 Select View to enter the NAMx Parameters menu screen
3.1.2. Select MDN/MIN/Alltel SID/NID to view
3.1.3. Select Back to move the NAMx Parameters menu screen
3.1.4. Select Done to exit the programming mode
3.2. Edit Mode
3.2.1. Select Edit to edit NAMx settings
3.2.2. Enter the SPC to enter the Edit mode (default 000000)
3.2.3. Select Done to exit the programming mode
3.3. Done : LX140 power cycle itself
PROGRAMMING STEPS
1. NAM Programming
ITEM Default Action
1 Phone number
(MDN)
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0000000000 Enter the Phone Number (up to the 10 digits) [OK]
(Mobile Directory Number)
2 Phone number
(MIN)
3 Alltel SID/NID 0/65535 Use the Navigation key to scroll to desired fields.
4 Security Code 000000 Enter the 6 digits Security Code [OK]
5 Done NAM Programming Completed
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000000xxxx Enter the Phone Number(Mobile Identification Number) [OK]
The Index field allows access to multiple SID/NID pairs.
Select desired SID or NID field to enter SID/NID values [OK]
LX140 Power cycles itself.
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2. Extended NAM Programming
1 NAM1 MCC 311 Enter the 3 digits Mobile Country Code [OK]
2 NAM1
IMSI_11_12
3 NAM1 True IMSI S 000000xxxx The 10 digits Mobile Phone Number [OK]
4.1 NAM1 CDMA Pri.
CH A
4.2 NAM1 CDMA
Sec. CH A
4.3 NAM1 CDMA Pri.
CH B
4.4 NAM1 CDMA Pri.
CH B
5 Lockout SID/NID 0/65535 Use the Navigation key to scroll to desired fields.
6.1 NAM1 Home Sys
27 Enter the 2 digits Mobile Network Code [OK]
283 Enter NAM 1 CDMA Primary CH A (preset)
691 Enter NAM 1 CDMA Secondary CH A (preset)
384 Enter NAM 1 CDMA Primary CH B (preset)
777 Enter NAM 1 CDMA Secondary CH B (preset)
The Index field allows access to multiple SID/NID pairs.
Select desired SID or NID field to enter SID/NID values [OK]
Yes Enter Yes or No to enable/disable Home System Registration [OK]
Reg
6.2 NAM1 Forn SID
Reg
6.3 NAM1 Forn NID
Reg
7 Slot Cycle Index 2 Enter the Slot Cycle Index (x = 0 ~ 7, commonly 1 or 2) [OK]
8 NAM1 Acc Ovld
Class
Done Extended NAM Programming Completed
Yes Enter Yes or No to enable/disable Foreign System ID Registration [OK]
Yes Enter Yes or No to enable/disable Foreign Network ID Registration [OK]
0 Enter [OK] (Display Only, auto-set from step 2 in NAM Programming)
LX140 Power cycles itself.
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LX140
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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 the SP3T switch.
RF Signal fed into the low noise amplifier (LNA) through the duplexer. Then, they are fed into
RFR6000. In RFR6000, the RF signal is changed into baseband signal directly. Then, this signal is
changed into digital signal by the analog to digital converter (ADC, A/D Converter), and the digital
circuit part of the MSM(Mobile Station Modem)6050 processes the data from ADC. The digital
processing part is a demodulator.
In the case of transmission, RFT6100 receives OQPSK-modulated anlaog signal from the MSM6050.
The RFT6100 connects directly with MSM6050 using an analog baseband interface. In RFT6100, 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 duplexer.
[Figure 1-1] Block Diagram of LX140
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1.2 Description of Rx Part Circuit
1.2.1 SP3T(Single Pole Triple Throw) RF switch (U1101)
The main function of SP3T switch 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, 1575 and 1900 MHz). The specification of LX140 SP3T switch is described below:
Frequency Range
Insertion Loss to
Common
Return Loss
Isolation(CELL Path)
Isolation(GPS Path)
Isolation(PCS Path)
Cellular GPS PCS
824 – 894 MHz 1575.42 MHz 1850 – 1990 MHz
0.5 dB Max (at +25
deg)
20 dB Typ. 20 dB Typ. 20 dB Typ.
30 dB Typ. 26 dB Typ. 24 dB Typ.
32dB Typ. 27 dB Typ. 25 dB Typ.
27 dB Typ. 22 dB Typ. 20 dB Typ.
0.75 dB Max. (at +25
deg)
0.5 dB Max (at +25
deg)
Temperature Range
1.2.2 Duplexer (DP1100, DP1101)
-40 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 LX140 duplexer described below ;
z PCS duplexer:
Pass Band
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Tx Rx Tx to Rx (min)
1850~1910 MHz 1930~1990 MHz
Insertion Loss
Return Loss
Attenuation
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3.5dB max 3.8dB max
9.5dB min 9.5dB min
43dB min
(1930~1990MHz)
52dB min
(1850~1910MHz)
54dB (1850~1910MHz)
45dB (1930~1990MHz)
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z Cellular duplexer
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
2.1dB max 2.8dB max
9.0dB typ. 7dB max
46dB (869~894MHz)
1.2.3 LNAs (U1103)
The RFL6000 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 LX140 LNAs are described below(T = 25 )℃ :
Parameter
Low gain Middle gain High gain Units
Cellular PCS Cellular PCS Cellular PCS
Gain
Noise Figure
Input IP3
-18.45 -19.78 -1.57 -8.69 15.44
18.91 20.68 2.21 9.63 1.44 1.41 dB
25.73 32.66 23.98 25.23 11.6 6.34 dBm
16.23
dB
1.2.4 GPS LNA(U1102)
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 LX140 GPS LNA is described below
Parameter GPS Band Units
Gain
Noise Figure
1dB compressed power
IIP3
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14.3 dB
0.8
1.8 dBm
-4.7 dBm
1.2.5 Dual Rx RF SAW FILTER(F1103)
The main function of Rx RF SAW filter is to attenuate mobile phone spurious frequency, attenuate
noise amplified by the LNA and suppress second harmonic originating in the LNA.
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1.2.6 Down-converter Mixers (U1107)
The RFR6000 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. The three downconverting Mixers (Cellular,
PCS and GPS), and an LO Buffer Amplifier to buffer the RF VCO to the RF Transmit Upconverter.
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 MSM6050.
The specification of LX140 Mixers are described below(T = 25 ):℃
Parameter
Cellular PCS Cellular PCS
Noise Figure 25.8 25.6 10.3 10.4 dB
Input IP3 4.3 4.77 5.7 6.46 dBm
Input IP2 50 50 74.21 76.5 dBm
Low Gain High Gain
Units
1.3 Description of Transmit Part Circuit
1.3.1 RFT6100 (U1106)
The RFT6100 baseband-to-RF Transmit Processor performs all Tx signal-processing functions
required between digital baseband and the Power Amplifier Modulator (PAM). The baseband
quadrature signals are upconverted to the Cellular or PCS frequency bands and amplified to provide
signal drive capability to the PAM. The RFT6100 includes an mixers for up-converting analog
baseband to RF, a programmable PLL for generating Tx and Rx LO frequency, cellular and PCS
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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 MSM6050 to RFT6100 are analog signal. In CDMA mode,
These signals are modulated by Offset Quadrature Phase Shift King (OQPSK). I and Q are 90 deg.
out of phase, and I and I/ are 180 deg. The mixers in RFT6100 converts baseband signals into RF
signals. After passing through the upconverters, RF signal is inputted into the Power AMP.
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z RFT6100 Cellular and PCS CDMA RF Specifications
Condition Min. Typ. Max. Units
Rated Output Power
Min Output Power
Rx band noise power
ACPR
Average CDMA Cellular
Average CDMA PCS
Average CDMA Cellular
Average CDMA PCS
CDMA Cellular
CDMA PCS
Cellular: Fc±885kHz
PCS: Fc±1.25MHz
8
10
-80
-136
-56
dBm
-78
-133
-57
-129
-128
-48
-48
dBm/Hz
dBm/Hz
30kHz
dBm
dBm
dBm
dBc/
1.3.2 Dual Power Amplifier(U1104)
The power amplifier that can be used in the PCS and CDMA mode has linear amplification capability
and high efficiency. For higher efficiency, it is made up of one MMIC (Monolithic Microwave
Integrated Circuit) for 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.
1.4 Description of Frequency Synthesizer Circuit
1.4.1 Voltage Control Temperature Compensation Crystal Oscillator (VCTCXO, U1108)
The temperature variation of mobile phone can be compensated by VCTCXO. The reference
frequency of a mobile phone is 19.2 MHz. The receiver frequency tuning signals called
TRK_LO_ADJ from MSM as 0.5 V~2.5 V DC via R and C filter in order to generate the reference
frequency of 19.2 MHz and input it into the frequency synthesizer. Frequency stability depending on
temperature is ±2.0 ppm.
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1.4.2 Voltage Controlled Oscillator (VCO, U1105)
The external VCO signal is processed by the LO generation and distribution circuits in RFR6000 to
create the PCS and Cellular quadrature downconverter’s LO signals. Likewise, the internal VCO
signal of RFR6000 is processed to create the GPS quadrature downconverter’s LO signal. In all
cases, the LO signals applied at the mixer ports are at the frequency different than the VCO
frequency. This assures that the VCO frequency is different than the RF frequency, an important
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consideration for Zero-IF processing. The VCO frequency used are 1715.56~1768.89 MHz for PCS
and 1738.08~1787.94 MHz for cellular and they are produced in single voltage controlled oscillator of
U105.
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2. Digital/Voice Processing Part
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/LCD and Receptacle Part
This is used to transmit keypad signals to MSM6050. It is made up of a keypad backlight part that
illuminates the keypad, LCD 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 MSM6050, and amplifying part that amplifies signals coming out from MIC and transferring them
to the audio processor.
2.2.3 MSM (Mobile Station Modem) 6050 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
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The memory part is made up of a NOR Flash memory(128MB) and a Pseudo RAM(64MB) for storing
data.
2.2.5 Power Supply Part
The power supply part is made up of the PMIC(U5101) and nearby circuits for generating various
types of power, used for the digital/voice processing part.
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