Samsung SGH-X600 Service Manual

Also see for SGH X600: Quick reference card Manual Service manual

Contents

Samsung SGH-X600 Service Manual Manual pdf 5 page image

SAMSUNG Proprietary-Contents may change without notice1. SGH-X600 RF Circuit Description1) RX PART1. ASM(U102) Switching Tx, Rx path for GSM900, DCS1800 by logic controlling.2. ASM Control Logic (Q100, Q101) Truth TableVC_1 VC_2GSM Tx Mode H LDCS Tx Mode L HGSM Rx Mode L LDCS Rx Mode L L3. FILTERTo convert Electromagnetic Field Wave to Acoustic Wave and then pass the specific frequency band.- GSM FILTER (F101) For filtering the frequency band between 925 ~ 960 MHz- DCS FILTER (F102) For filtering the frequency band 1805 ~ 1880 MHz.4. VC-TCXO (OSC101)To generate the 26MHz reference clock to drive the logic and RF.After additional process, the reference clock applies to the U103 Rx IQ demodulator and Tx IQ modulator.The oscillator for RX IQ demodulator and Tx modulator are controlled by serial data to select channel and use fast lockmode for GPRS high class operation.5. Transceiver (U103)The receiver front-end converts the aerial RF signal from EGSM, DCS bands down to a low intermediate frequency (IF)of 100 kHz. The first stages are symmetrical low noise amplifiers (LNAs). They are matched to 50 ohm. The LNAs arefollowed by an I,Q down mixer. It consists of two mixers in parallel but driven by quadrature out of phase LO signals.The In phase (I) and quadrature phase (Q) IF signals are low pass filtered to provide protection from high frequencyoffset interferers. The low IF I and Q signals are then fed into the channel filter. The front-end low IF I and Q outputsenter the integrated bandpass channel filter with provision for five 8dB gain steps in front of the filters.2) TX PARTBaseband IQ signal fed into offset PLL, this function is included inside of U103 chip.OSC100 chip generates modulator signal which power level is about 6.5dBm and fed into Power Amplifier(U101).The PA output power and power ramping are well controlled by Auto Power Control circuit.We use offset PLL below .