LG UD256, ID256, RD6600 Service Manual

UD/ID256/RD6600

CDMA PORTABLE CELLULAR PHONE

UD/ID256/RD6600

SERVICE MANUAL

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UD/ID256/RD6600

Table of Contents

1. Circuit Description................................................................................. 3

1.1 RF Transmit/Receive Part ............................................................. 3

1.1.2.1 Duplexer (DP100).......................................................... 4

1.1.2.2 LNA (U106)................................................................... 5

1.1.2.3 Rx RF SAW FILTER (F100) ........................................ 5

1.1.2.4 Down-Converter Mixers (U106)................................... 5

1.1.3.1 Description on the Internal Circuit of MSM6100

(U202) and RFT6122 (U105).................................................... 5

1.1.3.2 Power Amplifier (U103)................................................ 6

1.1.4.1 Voltage Controlled Temperature Compensation

Crystal Oscillator (U100)......................................................... 7

1.1.4.2 Voltage Controlled Oscillator (U106)........................... 7

1.2 Digital/Voice Processing Part......................................................... 7

1.2.2.1 Keypad/LCD and Receptacle Part............................... 7

1.2.2.2 Voice Processing Part.................................................... 8

1.2.2.3 MSM6100 (Mobile Station Modem) Part.................... 8

1.2.2.4 Memory Part................................................................. 8

1.2.2.5 Power Supply Part........................................................ 8

1.2.3.1 Keypad/LCD and Receptacle Part............................... 8

1.2.3.2 MSM Part...................................................................... 8

1.2.3.3 Memory Part................................................................. 9

1.2.3.4 Power Supply Part........................................................ 9

1.2.3.5 Logic Part.................................................................... 10

2. Trouble Shooting.................................................................................. 12

2.1 Rx Part Trouble............................................................................ 12

2.2 Tx Part Trouble............................................................................ 22

2.3 Logic Part Trouble....................................................................... 32

3. Safety.................................................................................................... 54

4. NAM Input Method............................................................................. 57

1. HOW TO POWER UP................................................................... 57

2. NAM Input Method....................................................................... 57

5. Glossary................................................................................................ 58

6. Appendix............................................................................................... 73

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UD/ID256/RD6600

1. Circuit Description

1.1 RF Transmit/Receive Part

1.1.1 Overview

The RF transmit/receive part employs the direct conversion architecture (ZIF, Zero Intermediate Frequency). The transmit/receive frequency is respectively

824.04~848.97MHz and 869.04~893.97MHz. The block diagram is shown in [Figure 1-1].RF signals received through the antenna are fed into RFR6122 through the duplexer. And then, they pass the low noise amplifier (LNA), combined with the signals of local oscillator (VCO) at the frequency mixer in order to create baseband signal directly. Baseband signals created are changed into digital signals by the analog / digital converter (ADC, A/D Converter) and then, auto gain controlled and, sent to the MSM6100 (Mobile Station Modem) of the digital circuit part. Then, they are demodulated by the modulator / demodulator. In the case of transmission, MSM6100 modulates, interpolates, and converts the digital signal into an analog baseband before sending it to the RFT6122. RFT6122 receives OQPSK-modulated anlaog baseband signals from the MSM6100’s Tx part. The RFT6122 upconverts the Tx analog baseband into RF. The RFT6122 connects directly with MSM6100 using an analog baseband interface. In RFT6122, the baseband quadrature signals are upconverted to the Cellular Tx 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.

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UD/ID256/RD6600

[Figure 1-1] Block Diagram of KX256

1.1.2 Description of Receive Part Circuit

1.1.2.1 Duplexer (DP100)

The duplexer consists of the receive part bandpass filter (BPF) and the transmit part bandpass filter (BPF) which have the function of separating transmit/receive signals in the full duplex system using the transmit/receive common antenna. The transmit part BPF is used to suppress noises and spurious waves entering the receive band among transmit signals in order to prevent the drop in receive sensitivity characteristics. The receive part BPF blocks the signals sent out from entering the receive end in order to improve sensitivity characteristics. Insertion loss (IL) in the transmit band is 2.8dB (Max), whereas IL in the receive band is 2.1dB (Max). The receive band attenuation amount of transmit filter is 51dB (Min) and the transmit band attenuation amount of receive filter is 45dB or more (Min).

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UD/ID256/RD6600

1.1.2.2 LNA (U106)

The RFR6122 has cellular LNA. 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 specifications of KX256 LNA are described below

1.1.2.3 Rx RF SAW FILTER (F100)

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.

1.1.2.4 Down-Converter Mixers (U106)

The RFR6122 device performs signal direct-down-conversion for Cellular applications. It contains all the circuitry (with the exception of external filters) needed to support conversion of received RF signals to baseband signals. The LO Buffer Amplifier buffers the RF VCO to the RF Transmit Upconverter. RFR6122 offers 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 MSM6100. The specification of KX256 Mixers are described below:

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1.1.3 Description of Transmit Part Circuit

1.1.3.1 Description on the Internal Circuit of MSM6100 (U202) and RFT6122 (U105)

For the transmit data path(Tx), the MSM6100 modulates, interpolates, and converts the digital signal into an analog baseband before sending it to the RFT6122. The RFT6122 upconverts the Tx analog baseband into RF. The MSM6100 communicates with the external RF and analog baseband to control

UD/ID256/RD6600

signal gain in the RF Rx and Tx signal paths, educe base band offset errors, and tune the system frequency reference. The RFT6122 baseband-to-RF Transmit Processor performs all Tx signalprocessingfunctions required between digital baseband and the Power Amplifier Module (PAM). The baseband quadrature signals are upconverted to the Cellular frequency bands and amplified to provide signal drive capability to the PAM. The RFT6122 includes an mixer for up-converting analog baseband to RF, a programmable PLL for generating Tx and Rx LO frequency, cellular driver amplifier 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 MSM6100 to RFT6122 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 mixer in RFT6122 converts baseband signals into RF signals. After passing through the upconverters, RF signal is inputted into the Power Amplifier Module. The RFT6122 Cellular CDMA RF specifications are described below:

1.1.3.2 Power Amplifier (U103)

The power amplifier that can be used in the CDMA mode has linear amplification capability. For higher efficiency, it is made up of one module (Monolithic Microwave Integrated Circuit) for which RF input terminal and internal interface circuit are integrated onto one IC after going through the GaAs HBT (heterojunction bipolar transistor) process. The module of power amplifier is made up of an output end interface circuit including this module.The maximum power that can be inputted through the input terminal is +7dBm and conversion gain is about 28.5dB. RF transmit signals that have been amplified through the power amplifier are sent to the duplexer.

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UD/ID256/RD6600

1.1.4 Description of Frequency Synthesizer Circuit

1.1.4.1 Voltage Controlled Temperature Compensation Crystal Oscillator (U100)

The temperature range that can be compensated by VC-TCXO which is the reference frequency generator of a mobile station is -30~+80 °C. VC-TCXO receives frequency tuning signals called TRK_LO_ADJ from MSM6100 as 0.5V~2.5V DC via R and C filters in order to generate the reference frequency of 19.20MHz and input it into the frequency synthesizer of UHF band. Frequency stability depending on temperature is ±2.0 ppm.

1.1.4.2 Voltage Controlled Oscillator (U106)

The internal VCO signal of RFR6122 is processed by the LO generation and distribution circuits in RFR6122 to create Cellular quadrature downconverter’ s LO signals. 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 consideration for Zero-IF processing. The VCO frequency used are 1738.08~1787.94MHz for cellular and It is produced in single voltage controlled oscillator of U106.

1.2 Digital/Voice Processing Part

1.2.1 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.

1.2.2 Configuration

1.2.2.1 Keypad/LCD and Receptacle Part

This is used to transmit keypad signals to MSM6100. It is made up of a keypad backlight part that illuminates the keypad, LCD part that displays the operation status on to the screen, and a receptacle that receives and sends out voice and data with external sources.

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UD/ID256/RD6600

1.2.2.2 Voice Processing Part

The voice processing part is made up of an audio codec in MSM6100 used to convert MIC signals into digital voice signals and digital voice signals into analog voice signals, amplifying parts for amplifying the voice signals and MIC signals are on Codec in MSM6100.

1.2.2.3 MSM6100 (Mobile Station Modem) Part

MSM6100 is the core elements of a CDMA mobile station and carries out the functions of CPU, encoder, interleaver, deinterleaver, Viterbi decoder, Mod/Demod, codec, and vocoder.

1.2.2.4 Memory Part

The memory part is made up of a flash memory and a SDRAM

1.2.2.5 Power Supply Part

The PMIC(MAX1829) is made up of 8 Regulators and one DCDC direct connet to Batt. Out1 give the power each Circuits(RFT6122/RFR6122). Out1 and DCDC gives the power to the MSM and memory parts. PAM, Motor, LCD back light LED, Keypad LED and Audio amplifier, are directly conneted to Battery.

1.2.3 Circuit Description

1.2.3.1 Keypad/LCD and Receptacle Part

Once the keypad is pressed, the key signals are sent out to MSM6100 for processing. In addition, when the key is pressed, the keypad lights up through the use of 10 LEDs. The status and operation of a mobile station are displayed on the screen for the user with the characters and icons on the LCD. Receptacle(CON601) exchanges audio signals and data with external sources and then, receives power from the battery or external batteries.

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1.2.3.2 MSM Part

MSM6100 is the core element of a CDMA mobile station. Subsystems within the MSM6100 include a CDMA processor, an EVRC(Enhanced Variable Rate Codec) vocoder, an ARM926EJ-S microprocessor ,and assorted peripheral interfaces that are used to support other functions. MSM6100, when operated in the CDMA mode, utilizes TCXO (19.2MHz) as the reference clock primarily for CDMA and vocoder processing.MSM6100 also uses TCXO/4 (4.92MHz). The CPU controls total operations of the subscriber unit. Digital voice data,

UD/ID256/RD6600

that have been inputted, are encoded using the EVRC algorithm. Then, they are convolutionally encoded so that error detection and correction are possible. Coded symbols are interleaved in order to avoid a burst error. 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. The MSM6100 also supports Enhanced Variable Rate Coder (EVRC) operation in addition to the standard 13k.

1.2.3.2.1 Audio Processing Part

MIC signals are inputted into the audio codec, and amplified with programmable gain, and converted into digital signals(PCM). Then, they are inputted into MSM6100. In addition, digital audio signals(PCM) outputted from MSM6100 are converted into analog signals after going through the audio codec. These signals are amplified with programmable gain on codec’s internal AMP and external Audio AMP and then transferred to the ear piece. The signals is generated in MSM6100 using SW MIDI.

1.2.3.3 Memory Part

The memory part consists of a 512Mbits Flash Memory and a 256Mbits SDRAM. In the Flash Memory, there are programs used for the operation of a mobile station. The programs can be changed through down loading after the assembling of mobile stations. The Flash memory is also emulated as an EEPROM to store Calibration Data, etc. On the SDRAM, data generated during the operation of a mobile station are stored temporarily.

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1.2.3.4 Power Supply Part

Turn ON

When the battery voltage (4.2V ~ 3.3V) is fed and the PWR key of keypad is pressed, PMIC is activated by the PWR_ON_SW signal, and then the control signal ON_SW_SEN/ signal is generated. And then, the regurator 1.85V_MSMC & 2.6V_MSMP, 2.6V_MSMA, are operated.

Operating

During the phone is on operating state,LDO(in PMIC) for MSM is always enable and gives the power MSM6100 and memory part

UD/ID256/RD6600

LDO(in PMIC) for +2.6V_TX part is enabled on IDLE/ state, and gives the power TX part devices. LDO(in PMIC) for +2.6V_RX part is enabled on SLEEP/ state, and gives the power RX part devices.

Turn OFF

When the PWR key is pressed during a few seconds, PMIC is turned on by PWR_ON_SW and then, 'Low' is outputted on ON_SW_SEN/. MSM6100 receives this signal and then, recognizes that the POWER key has been pressed. During this time, MSM6100 outputs PS_HOLD as low and turn off all devices

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Figure 1-2] Block Diagram Of Power Management IC

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1.2.3.5 Logic Part

The Logic part consists of internal CPU of MSM6100, PSEUDO RAM & FLASH MEMORY.The MSM6100 receives TCXO/4 clock(19.20Mz) and CHIPX8 clock

UD/ID256/RD6600

signals, and then controls the phone during the CDMA and the FM mode. The major components are as follows: CPU : ARM926EJ-S microprocessor core MEMORY : 512Mbit NAND Flash + 256Mbit SDRAM.

CPU (U202)

ARM926EJ-S 32-bit microprocessor is used and CPU controls all the circuitry. Some of the features of the ARM microprocessor include a 3 stage pipelined RISC architecture, both 32-bit ARM and 16bit THUMB instruction setsm, a 32-bit address bus, and a 32-bit internal data bus.

FLASH Memory (U300)

Flash Memory is used to store the program of the mobile station. Using the down-loading program, the program can be changed even after the mobile station is fully assembled.

Pseudo RAM (U300)

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

KEYPAD

For key recognition, key matrix is setup using GPIO46,47,49~53,62,63of output orts of MSM6100. Backlight circuitry are included in the keypad for easyoperation in the dark.

LCD MODULE

LCD module contains a controller which will display the information onto the LCD by 16-bit data from the MSM. It has 262K Color CSTN full graphic 220(W) X 176(H) dots.

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