Pantech G800 User manual

G800 Service Manual G800
G800 Service Manual
(GSM Cellular Phone)
Pantech Co., Ltd., Korea
January 23, 2004
1st Edition
For Use by Authorized Service/Maintenance Personal Only
Documents to Receive This Addendum:
G800 Maintenance/Repair/Operating Manual

G800 Service Manual
CONTENTS
SECTION 1 INTRODUCTION .................................................................................................. 3
1.1 INTRODUCTION ............................................................................................................................ 3
1.2 FREQUENCY ALLOCATION AND ITS USE ......................................................................................... 4
1.3 ITEM NAME AND USE.................................................................................................................... 4
1.4 CHARACTERISTICS....................................................................................................................... 5
SECTION 2 ELECTRICAL SPECIFICATIONS ............................................................................ 6
2.1 GENERAL .................................................................................................................................... 6
2.2 TRANSMITTER ............................................................................................................................. 6
2.3 RECEIVER ................................................................................................................................... 7
SECTION 3 OPERATION ...................................................................................................... .8
3.1 NAME OF EACH PART.................................................................................................................... 8
3.2.DISPLAY ...................................................................................................................................... 9
3.3 KEYPAD .................................................................................................................................... 9
3.4 CAMERA MODULE ........................................................................................................................ 9
SECTION 4 THEORY OF OPERATION ................................................................................... 10
4.1 LOGIC SECTION ......................................................................................................................... 10
4.1.1 DC DISTRIBUTION AND REGULATION PART ................................................................................ 10
4.1.2 LOGIC PART............................................................................................................................ 10
4.1.2.1 SUMMARY............................................................................................................................ 10
4.1.2.2 BASEBAND DIGITAL SIGNAL PROCESSING .............................................................................. 10
4.1.3 MEMORY PART ....................................................................................................................... 12
4.1.4 NOTIFICATION PART ............................................................................................................ …13
4.1.5 KEY PAD PART........................................................................................................................ 13
4.1.6 LCD MODULE(DISPLAY PART)................................................................................................. 13
4.1.7 CAMERA MODULE ................................................................................................................... 13
4.2 RADIO TRANSCEIVER SECTION ................................................................................................... 14
4.2.1 DC DISTRIBUTION AND REGULATION PART ............................................................................... 15
4.2.2 TRANSCEIVER PIN DESCRIPTION ............................................................................................. 15
4.2.3 RECEIVE SECTION .................................................................................................................. 16
4.2.3.1 AN OVERVIEW OF RECEIVE SECTION..................................................................................... 16
4.2.3.2 RECEIVER PART................................................................................................................... 16
4.2.4 TRANSMIT SECTION................................................................................................................. 19
4.2.4.1 AN OVERVIEW OF TRANSMIT SECTION................................................................................... 19
4.2.4.2 TRANSMITTER PART ............................................................................................................. 20
4.2.5 OFFSET PLL ........................................................................................................................... 21
4.2.5.1 AN OVERVIEW OF OFFSET PLL .......................................................................................... 21
4.2.5.2 VCTCXO(VOLTAGE CONTROLLED TEMPERATURE COMPENSATED CRYSTAL OSCILLATOR):V801 .. 22
SECTION 5 ALIGNMENT PROCEDURE ................................................................................. 23
5.1 RECOMMENDED TEST EQUIPMENT.............................................................................................. 23
5.2 CONNECTION OF TEST EQUIPMENT............................................................................................. 23
SECTION 6 EQUIPMENT REPAIR PROCEDURE ...................................................................... 24
6.1 NO POWER ON WITH BATTERY APPLIED ..................................................................................... 24
6.1.1 POWER CHECK ....................................................................................................................... 24
6.1.2 OSCILLATION CHECK .............................................................................................................. 29
6.1.3 KEYPAD LED NOT IN OPERATION(BLUE)................................................................................... 30
6.1.4 LCD EL BACKLIGHT LED NOT IN OPERATION(WHITE) .............................................................. 31
6.2 AUDIO PART(EARPIECE, HANDS FREE EARPHONE, MICROPHONE, HANDS FREE MIC).................... 32
6.2.1 NO RECEIVING TONE HEARD (EARPIECE) ............................................................................... 32
6.2.2 NO RECEIVING TONE HEARD (HANDS FREE EARPHONE) ........................................................... 32
6.2.3 SIDETONE NOT TRANSMITTED (EARPIECE) .............................................................................. 33
6.2.4 SIDETONE NOT TRANSMITTED (HANDS FREE MIC) ................................................................... 33
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6.2.5 HOOK SWITCH NOT WORKING ............................................................................................... 35
6.2.6 MELODY NOT RINGING.......................................................................................................... ..35
6.2.7 VIBRATOR NOT WORKING........................................................................................................ 37
6.3 SIM CARD PART ...................................................................................................................... 38
6.3.1 SIM ERROR ........................................................................................................................... 38
6.4 CHARGER PART ......................................................................................................................... 39
6.4.1 CHARGING ERROR ................................................................................................................. 39
6.5 BLUTOOTH PART........................................................................................................................ 41
6.5.1 BLUETOOTH ERROR ............................................................................................................... 41
6.6 RF PART .................................................................................................................................. 42
6.6.1 TEST CONDITION..................................................................................................................... 42
6.6.2 POWER SUPPLY CHECK POINT ................................................................................................ 44
6.6.3 POWER AMPLIFIER MODULE .................................................................................................... 45
6.6.4 VCTCXO............................................................................................................................... 48
6.6.5 ANTENNA SWITCH MODULE ..................................................................................................... 49
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SECTION 1. Introduction
1.1. An Introduction of GSM Digital Cellular Mobile Communication System
GSM (Global System for Mobile communication) concluded that digital technology working in
the Time Division Multiple Access (TDMA) mode would provide the optimum solution for the
future system. Specifically , a TDMA system has the following advantage
►Offers a possibility of channel splitting and advanced speech coding ,resulting in improved
spectrum efficiency.
►Offers much greater variety of service than the analog
►Allows considerable improvements to be made with regards to the protection of information.
The GSM system is basically designed as a combination of three major subsystem;
The network subsystem, the radio subsystem, and the operation support system.
The functional architecture of a GSM system can be divided into the Mobile Station (MS), the Base Station
(BS), and the Network Subsystem (NS). The MS is carried by the subscriber, the BS subsystem controls the
radio link with the MS and the NS performs the switching of calls between the mobile and other fixed or mobile
network users as well as mobility management. The MS and the BS subsystem communicate across the Um
interface also known as radio link
The specifications relating to MS are as follows:
 TS 100 607-1 : Digital cellular telecommunication system(Phase2+)Mobile Station (MS) con
Formance specification Part1:Conformance specification
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1.2. Frequency Allocation and Its Use
Transmit frequency band : 880 MHz ~ 915 MHz(For EGSM), 1710 MHz ~ 1785 MHz(For DCS), 1850 MHz ~
1910 MHz(For PCS)
Receive frequency band : 925 MHz ~ 960 MHz(For EGSM), 1805 MHz ~ 1880 MHz(For DCS), 1930 MHz ~
1990 MHz(For PCS)
Channel spacing : 200 KHz
ARFCN(Absolute Radio Frequency Channel Number) : 1~124 and 975~1023 (For EGSM), 512~885 (For
DCS), 512~810 (For PCS)
Transmit receive frequency spacing : 45MHz(For EGSM), 95MHz(For DCS), 80MHz(For PCS)
Frequency band and Channel Arrangement
For standard GSM Fl(n)=890+0.2*n 1 ≤n≤124 Fu(n)=Fl(n)+45
890 MHz ~915 MHz : Mobile Transmit,Base receive
935 MHz ~960 MHz : Base Transmit, Mobile receive
For Extended GSM Fl(n)=890+0.2*n 1 ≤n≤124 Fu(n)=Fl(n)+45
Fl(n)=890+0.2*(n-1024) 975 ≤n≤1023
880 MHz ~915 MHz : Mobile Transmit,Base receive
925 MHz ~960 MHz : Base Transmit, Mobile receive
For DCS Fl(n)=1710.2+0.2*(n-512) 512≤n≤885 Fu(n)=Fl(n)+95
1710 MHz ~ 1785 MHz : Mobile Transmit,Base receive
1805 MHz ~ 1880 MHz : Base Transmit, Mobile receive
For PCS Fl(n)=1850.2+0.2*(n-512) 512 ≤n≤810 Fu(n)=Fl(n)+80
1850 MHz ~1910 MHz : Mobile Transmit,Base receive
1930 MHz ~1990 MHz : Base Transmit, Mobile receive
** Fl(n)= frequency value of the carrier , Fu(n)= corresponding frequency value in upper band
1.3. Item Name and Usage
G800, GSM digital cell phone, is supercompact, superlight mobile communication terminal for personal use.
It has a 900MHz, 1800MHz, and 1900MHz frequency band and adopts GSM, DCS, and PCS mode having
excellent spectrum efficiency, economy, and portability.
This product is GSM Cellular type portable phone, adopting 1-cell Li-ion battery and power saving circuit to
maximize its operation time. Also, it is equipped with a fixed snap-in antenna and its color LCD with font built
in enables both Chinese and English text service. And power control(basic feature of GSM), security feature,
voice symbol feature, and variable data rate feature are used appropriately to ensure its best performance.
This product consists of a handset, battery pack, and Travel charger.
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1.4. Characteristics
1) All the active devices of G800 are made of semiconductors to ensure excellent performance and
semi-permanent use.
2) Surface mounting device (SMD) is used to ensure high reliability, compactness and lightness.
3) G800 adopts the Silabs’s AERO I RF transceiver, which is CMOS RF front-end for multi-band GSM digital
cellular handsets. The AERO I's highly-integrated architecture eliminates the IF SAW filter, low noise
amplifiers (LNAs) for three bands, transmit and RF voltage-controlled oscillator (VCO) modules, and more
than 60 other discrete components found in conventional GSM handsets to deliver smaller, more cost
effective GSM solutions that are easier to design and manufacture.
4) G800 is designed to perform excellently even in the worst environment
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2.
SECTION 2. Electrical Specifications
2.1. General E-GSM / DCS / PCS Band
Mobile Transmit Frequency 880 MHz ~ 915 MHz / 1710 MHz ~1785 MHz / 1850MHz ~
1910MHz
Mobile Receive Frequency 925 MHz ~ 960 MHz / 1805 MHz ~ 1880 MHz / 1930MHz
~1990MHz
The Number of Time Slot 8
The Number of Channels 174 / 374 / 299
Channel Spacing 200 kHz
Power Supply Rechargeable Li-Ion Battery 3.7V/640mAH,950mAH
Operating Temperature -10℃∼+55℃
Dimension 81(H) ×41(W) ×19.6(D) mm (SLIM)
Weight 80.08 g
2.2. Transmitter E-GSM / DCS / PCS Band
Maximum Output Power 33±2 / 30±2 / 30±2 dBm
Frequency Error ±90Hz / ±180Hz / ±180Hz
Phase Error RMS < 5°, PEAK < 20°
Minimum Output Power 5±5 / 0±5 dBm / 0±5 dBm
Power Control 5~19(2 dB Step) ) / 0~15(2 dB Step) /
0~15(2 dB Step)
Output RF Spectrum TS 100 910V6.2.0
Switching Transient TS 100 910V6.2.0
Intermodulation attenuation
EGSM and DCS
Allocated a channel;
-36dBm 9kHz ~ 1GHz
-30dBm 1GHz ~ 12.75GHz
Idle mode;
-57dBm 9KHz ~ 1GHz
-47dBm 1GHz ~ 12.75GHz
with the following excoptions
-59dBm 880MHz ~ 915MHz
-53dBm 1.71GHz ~ 1.785GHz
-76dBm 1900 ~ 1920MHz, 1920 ~ 1980MHz, 2010
~ 2025MHz, 2210 ~ 2170MHz
Conducted Spurious Emissions
PCS
Allocated Channel;
-36dBm 9KHz~ 1GHz
-30dBm 1GHz~ 12.75GHz
Idle mode;
-57dbm 9kHz ~ 1000MHz
-53dBm 1850MHz ~ 1910MHz
-47dBm 1GHz ~ 12.75GHz
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2.3. Receiver
For GSM900 small MS :-102dBmReference Sensitivity
For DCS1800 / PCS1900 class3 MS : -102dBm
C/Ic 9 dB
C/Ia1 -9 dB
C/Ia2 -41 dB
For Adjacent interference
For Adjacent(200KHz) interference
For Adjacent(400KHz) interference
For Adjacent(600KHz) interference C/Ia3 -49 dB
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3.
SECTION 3 Operation
3.1. Name of each part
Sub LCD
Display Screen
3. Mic
Antenna
Speaker& Earpiece
4. Navigation
Flash LED
Camera
Camera Ke
y
V
olume down ke
y
V
olume u
p
ke
y
Bluetooth ke
y
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3.2. Display(Dual LCD)
Parameter Projected Actual(MAIN LCD)
Display Color TFT LCD with white LED back lighting
262144 colors
European Character : (font size : 16×16) 6 lines x 16 characters
Chinese Character : (font size : 16×16) 6 lines ×7 characters
Model COM18T1188DEB(CASIO)
Module Dimen. 36.5(W) x 55.1(H) x 5.1(D) mm
Effective Area 28.42(W) x 35.52(H) mm (1.8 inch)
Number of Dots 128(W) x RGB(W)x 160(H) dot
Dot pitch 74(W) x 222(H) um
Parameter Projected Actual(SUB LCD)
Display Full Graphic FSTN LCD with white LED back lighting
Pixels : 96 x 48
European Character : (font size : 7×15) 1 lines x 12 characters
Chinese Character : (font size : 16×16) 1 lines ×6 characters
Model COM18T1188DEB(CASIO)
Module Dimen. 36.5(W) x 55.1(H) x 5.1(D) mm
Effective Area 23.04(W) x 23.04(H) mm (1.3 inch)
Number of Dots 128(W) x RGB(W) x 128(H) dot
Dot pitch 60(W) x 180(H) um
3.3. Keypad
Market Goal Projected Actual Comments
English
Keypad
0-9, *,#
Send (Color)
End/Pwr (Color)
Up, Down, WAP
Soft1, Soft2, CLR
* Key: Vib. Mode
# Key: Auto Lock
0/+Key: nternational
2 Volume Keys
0-9, *,#
Send (Color)
End/Pwr (Color)
Up, Down, WAP
Soft1, Soft2, CLR
* Key: Vib. Mode
# Key: Auto Lock
0/+ Key: International
2 Volume Keys
Meets Goal.
(Industrial design
sample required)
Meets Goal
Keys for VR and Lock
International
Volume up/down
3.4. Camera Module
Product Name PO1030KC-MS21
Optical Format 1/4.5 inch
Effective pixel array 640 x 480
Unit Pixel size 5.2um x 5.2um
Module size 7mm x 6mm x 5.5mm +-0.1mm
Operating voltage 2.6V
Apeture F#2.8+-5%
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4.
SECTION 4. Theory of Operation
4.1. Logic Section
4.1.1 DC Distribution and Regulation Part
Applying battery voltage and pressing “END” key on the key pad short-circuits “Ground” and “_
PowerON”.ADP3522(U103)control that power manage regarding power on/off in handset
Pressing POWERKEY on the key pad is active on the handset.
This will turn on all the LDOs ,when POWERKEY is held low. The power of RF Tx power amplifier is supplied
directly by the battery.
4.1.2 Logic part
4.1.2.1 Summary
The logic part consists of AD6526 ARM7 microprocessor-combined GSM-ASIC, COMBO(flash ROM &
SRAM), AD6521 VBC Chip. AD6526 is GSM-ASIC chipset implemented for GSM terminal’s system control
and baseband digital signal processing.
Major parts used in the logic part are as follows:
1) AD6526 : U101, [ARM7 Processor Core + GSM Signal Processing] ASIC
2) AD6521 : U102, Voiceband Baseband Codec
3) COMBO MEMORY(Flash ROM : U104, 128Mbit Flash Memory + 32Mbit SRAM )
Baseband Digital Signal Processing
AD6526 is a GSM core device containing ARM7 CPU core. AD6526 is 160 pin PBGA package, consisting of
terminal chips. The function and characteristics of clock are as follows:
Complete single chip GSM Processor
Channel codec sub-system
• Channel coder and decoder
• Interleaver and Deinterleaver
• Encryption and Decryption
Control Processor Subsystem including
• Parallel and serial Display interface
• Keypad Interface
• SIM Interface
• Control of RADIO subsystem
• Real Time Clock with Alarm
☞Configuration by Function of AD6526
1 Microprocessor Core
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AD6526 has a built-in ARM7 microprocessor core, including microprocessor interrupt controller,
timer/counter, and DMA controller. And besides, 32bit data path is included, and up to 8Mbyte addressing is
enabled and can be extended up to 16Mbyte. Although external clock should be provided to operate the
microprocessor, this core uses 13MHz VCTCXO to provide clock.
2 Input Clock
Main Clock(13 MHz):
This is the clock needed for the microprocessor built in AD6526 to operate.
VC-TCXO(13 MHz) , 32.768KHz Clock:
This is the system reference clock to control SLEEP mode.
This is the clock derived from 13MHz VC-TCXO clock, provided by RF part. It is the timing reference clock for
GSM signal processing.
3 DSP Subsystem
This is a GSM signal processing part in GSM mode, consisting of speech transcoding and
Channel equalization as follows:
Speech transcoding
In full rate, the DSP receives the speech data stream from VBC and encodes data from
104kbps to13kbps. Using algorithm is Regular Pulse Excitation with Long Term Prediction
(RPE-LTP).
Equalization
The Equalizer recovers and demodulates the received signal
The Equalizer establishes local timing and frequency references for mobile terminal as well
as RSSI calculation.
The equlization algorithm is a version of Maximum Likelihood Sequency Estimation(MLSI)
using Viterbi Algorithm.
☞GSM Core and RF Interface
Transmitter:
AD6521 VBC receive data at 270kbps and use an on chip lock-up table to perform GMSK
modulation. A pair of 10bit matched differential DACs convert the modulated data and pass
I and Q analog data to the transmit section of the radio system.
Receiver:
The receiver I and Q signals are sampled by a pair of APCS at 270kbps.
The I and Q samples are transferred to the EGSMP through a dedicated receive path serial port.
4 RF Interface
This interfaces the RF part to control power amplifier, Tx LO buffer amplifier, VC-TCXO, and AGC-end on
transmit/receive paths in the RF part.
Transmitter Interface:
This transmits TX_AGC signal to Tx AGC amplifier to adjust transmit power level and sends Ramp_DAC
signal to the RF part to control power amplifier.
Receiver Interface:
This transmits RX_AGC signal to Rx AGC amp. to adjust receive path gain.
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5 General Purpose ADC Support
The AD6521 includes a general purpose 10bit auxiliary ADC with four multiplexed input channel
These are used for measurment of battery voltage ID , temperature and accessory ID.
6 USC(Universal System Connector) Interface
A Typical GSM handset requires serial connections to provide data during normal phone operation
manufacturing,testing and debugging.
7 General Purpose Interface
The AD6526 provides 32 interface pin for control of peripheral devices.
All GPIO pins start up as inputs. Additional purpose inputs and outputs are available under SW
control.
8 Speech Transcoding
In full rate mode, the DSP receive the speech data stream from the VBC and encodes data from
104kbps to 13kbps.Using algorithm is Regular Pulse Exitation with Long Term Prediction as
specified GSM Recommandation
9 Power Down Control Section
1) Idle Mode Control:
If IDLE/ signal turns ‘Low’, transmitter section becomes disabled.
2) Sleep Mode Control:
If IDLE/ and SLEEP/ signals turn ‘Low’, all the sections except for VC-TCXO circuit become disabled.
3) Receiver & Transmitter Mode Control:
If IDLE/ and SLEEP/ signals turn ‘High’, all the sections become enabled to perform transmit/receive
operation.
4.1.3 Memory Part
Memory consists of COMBO(flash ROM & SRAM).
1 Flash ROM
Flash ROM has a capacity of 128Mbit(16MByte). The main programs of the terminal(call processing, user
interface, and diagnostic task) and supplemental programs(NAM program and test program) are stored in the
flash ROM. Even if the program version may be changed in the future, customers can download the program.
2 Static RAM
SRAM has a capacity of 32Mbit(4MByte) and stores system parameters, data buffer, and stack of each task
in it.
3 Key Tone Generation
All alert signals are generated by the DSP and output to the EVBC.
These alert can be used for the earpiece.
4.1.4 Notification Part
The notification of incoming call is given by melody, vibrator.
Melody:
This is a device sounding alert/melody tones.
The melody datas are stored in flash memory(U104) And generated by Melody IC(U105).
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Vibrator:
This is a device enabling vibration. The vibrator data is stored in flash memory(U104)
And generated by U101.C5(GPO_23)pin.
4.1.5 Key Pad Part
To enable key operation to input information, the key matrix is configured using strobe signal of
KEYPADROW(0-4) and 5 input ports of KEYPADCOL(0-4). Also, to use the key even at light, the backlight
circuit is provided for LED 13.
4.1.6 LCD Module(Display Part)
LCD module consists of LCD , controller, LED-Backlight, and LCD reflector.using dual LCD
Main LCD: 1S/W Icon x 6 lines[(128x3)x160] can be displayed on the LCD panel. 6 icons could be provided
by S/W. Controller with English font built in has been used.
Sub LCD: 1S/W Icon x 1 lines(48x96) can be displayed on the LCD panel. 6 icons are provided. Controller
with English font built in has been used.
LED-backlight Using illuminates the LCD panel, and LCD reflector enhances LCD display effect.
4.1.7 CAMERA Module
Camera Module is activated by keypad sw27.
Taking a picture, Flash LED is provided to bright dark surroundings, and generated by U101.B12(GPIO2)
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4.2. Radio Transceiver Section
Fig.4-1. RF Transceiver block diagram
The G800’s RF Transceiver(U710), which is AERO I, consists of the GSM transmitter,the GSM Receiver, and
the RF synthesizer. The highly integrated solution eliminates the IF SAW filter, external low noise amplifiers
(LNAs) for three bands, transmit and RF voltage controlled oscillator (VCO) modules, and more than 60 other
discrete components found in conventional designs.
The receive section uses a digital low-IF architecture that avoids the difficulties associated with direct
conversion while delivering lower solution cost and reduced complexity.
The transmit section is a complete up-conversion path from the baseband subsystem to the power amplifer
(U701) and uses an offset phase locked loop (PLL) with a fully integrated transmit VCO.
The RF synthesizer includes integrated RF and IF VCO’s, Varactors, and Loop filters. The unique integer-N
PLL architecture used in the RF synthesizer produces a transient response that is superior in speed to
fractional architectures without suffering the high phase noise or spurious modulation effects often associated
with those designs.
The following Figure shows G800’s top view of PCB artworks.
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Fig.4-2. Top view of RF Transceiver PCB Layout
4.2.1 DC Distribution and Regulation Part
The battery voltage, in return, is applied to the logic part and RF part via LDO(Low Drop-Out) regulator. As
several LDO regulators are used, power can be supplied for each necessary part efficiently. Audio/Logic parts
use +2.8V. Si4205 RF Transceiver (U710) and RF3133 Power Amplifier (U701) also use +2.8V DC voltage.
4.2.2 Transciever pin description
Fig.4-3. Top View of Si4205-BM
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Table 4-1. Pin Description of Si4200DB-BM
4.2.3 Receiver Section
4.2.3.1 An Overview of Receive section
Fig.4-6. Receiver block diagram
G800’s Aero I transceiver uses a low-IF receiver architecture which allows for the on-chip
integration of the channel selection filters, eliminating the external RF image reject filters and the IF
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SAW filter required in conventional superheterodyne architectures. Compared to a
direct-conversion architecture, the low-IF architecture has a much greater degree of immunity to dc
offsets, which can arise from RF local oscillator (RFLO) self-mixing, 2nd-order distortion of blockers,
and device 1/f noise. This relaxes the common-mode balance requirements on the input SAW filters,
and simplifies PC board design and manufacturing.
Three differential-input LNAs are integrated on the Aero I transceiver. The GSM input supports the
GSM 850 (869–894 MHz) or EGSM 900 (925–960 MHz) bands. The DCS input supports the DCS
1800 (1805–1880 MHz) band. The PCS input supports the PCS 1900 (1930–1990 MHz) band.
G800 use all the input ports that are GSM, DCS and PCS inputs.
The LNA inputs are matched to the 150 Ωbalancedoutput SAW filters through external LC
matching networks. The LNA gain is controlled with the LNAG and LNAC bits.
A quadrature image-reject mixer downconverts the RF signal to a 100 kHz intermediate frequency
(IF) with the RFLO from the frequency synthesizer. The RFLO frequency is between 1737.8 to
1989.9 MHz, and is internally divided by 2 for GSM 850 and E-GSM 900 modes. The mixer output is
amplified with an analog programmable gain amplifier (PGA), which is controlled with the AGAIN
bits in register 05h. The quadrature IF signal is digitized with high resolution A/D converters
(APCS).
The ADC output is downconverted to baseband with a digital 100 kHz quadrature LO signal. Digital
decimation and IIR filters perform channel selection to remove blocking and reference interference
signals. The response of the IIR filter is programmable to a high selectivity setting or a low
selectivity setting. The low selectivity filter has a flatter group delay response which may be
desirable where the final channelization filter is in the baseband chip. After channel selection, the
digital output is scaled with a digital PGA, which is controlled with the DGAIN bits.
The LNAG, LNAC, AGAIN and DGAIN bits must be set to provide a constant amplitude signal to the
baseband receive inputs.
DACs drive a differential analog signal onto the RXIP, RXIN, RXQP, and RXQN pins to interface to
standard analog-input baseband ICs. No special processing is required in the baseband for offset
compensation or extended dynamic range. The receive and transmit baseband I/Q pins can be
multiplexed together into a 4-wire interface. The common mode level at the receive I and Q outputs
is programmable, and the full scale level is also programmable.
4.2.3.2 Receiver Part
A. Diplexer: Z701
Diplexer consists of Tx filter, having an antenna port, and dual configuration with the transmitting path
isolated from the receiving path. A signal receives from the antenna of frequency band which is 942.5±
17.5MHz for EGSM bands, 1842.4±37.4 MHz for DCS bands, and 1960.2±30 MHz for PCS bands and
transmits it to the saw filter for each band. The Tx filter passes through the output signals of frequency band
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that is 897.5MHz ±17.5MHz for EGSM bands, 1747.4±37.4 MHz for DCS bnads, and 1880.2 ±30 MHz for
PCS bands from the power amplifier and transmits it to the antenna. The maximum insertion loss is about 0.8
dB for the receiving bands at 25o C and about 1.35 dB for the transmitting bands at 25o C.
B. SAW filter (BPF / Band select filter): Z510, Z511, Z512
The Z510 filter is for the EGSM band signals which range 942.5±17.5MHz with low insertion loss. And the
Z512 filter passes the PCS bands that cover 1960.2±3MHz.
These filters degrade other band signals with high passing loss of 30~60 dB. The EGSM, DCS, and PCS’s
maximum insertion loss is 3.2 dB.
PCS
SAW
Filter
RF Transciever
PCS
SAW
Filter
GSM
SAW
Filter
Antenna
Swithch
Module
Fig.4-7. Receiver part PCB Layout
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4.2.4 Transmit Section
4.2.4.1 An Overview of Transmit Section
Fig.4-8. Transmitter block diagram
The transmit (TX) section consists of an I/Q baseband upconverter, an offset phase-locked loop
(OPLL) and two output buffers that can drive external power amplifiers (U701), one for the GSM 850
(824 to 849 MHz) and E-GSM 900 (880 to 915 MHz) bands and one for the DCS 1800 (1710 to 1785
MHz) and PCS 1900 (1850 to 1910 MHz) bands. The OPLL requires no external duplexer to
attenuate transmitter noise or spurious signals in the receive band, saving both cost and power.
Additionally, the output of the transmit VCO(TXVCO) is a constant-envelope signal that reduces the
problem of spectral spreading caused by non-linearity in the PA.
A quadrature mixer upconverts the differential in-phase (TXIP, TXIN) and quadrature (TXQP,
TXQN) signals with the IFLO to generate a SSB IF signal that is filtered and used as the reference
input to the OPLL. The IFLO frequency is generated between 766 and 896 MHz and internally
divided by 2 to generate the quadrature LO signals for the quadrature modulator, resulting in an IF
between 383 and 448 MHz. For the E-GSM 900 band, two different IFLO frequencies are required
for spur management. Therefore, the IF PLL must be programmed per channel in the E-GSM 900
band.
The OPLL consists of a feedback mixer, a phase detector, a loop filter, and a fully integrated
TXVCO. The TXVCO is centered between the PCS 1900 and PCS 1900 bands, and its output is
divided by 2 for the GSM 850 and E-GSM 900 bands. The RFLO frequency is generated between
1272 and 1483 MHz. To allow a single VCO to be used for the RFLO, high-side injection is used for
the GSM 850 and E-GSM 900 bands, and low-side injection is used for the DCS 1800 and PCS
1900 bands. The I and Q signals are automatically swapped when switching bands. Additionally,
the SWAP bit in register 03h can be used to manually exchange the I and Q signals.
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PANTECH R&D CONFIDENTIAL