Samsung SGH-X430 Service Manual page 5

Gsm telephone

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2. SGH-X430 Circuit Description

1. SGH-X430 RF Circuit Description

1) RX PART

1. ASM(U201)

ð Switching Tx, Rx path for GSM900, DCS1800 by logic controlling.

2. ASM Control Logic (U501, U502)

ð Truth Table

GSM Tx Mode

DCS Tx Mode

GSM / DCS Rx Mode

3. FILTER

To convert Electromagnetic Field Wave to Acoustic Wave and then pass the

specific frequency band.

- GSM FILTER (F100)

ð For filtering the frequency band between 925 ~ 960 MHz

- DCS FILTER (F101)

ð For filtering the frequency band 1805 and 1880 MHz.

4. VCTCXO (OSC100)

To generate the 13MHz reference clock to drive the logic and RF.

After additional process, the reference clock is applied to the U100 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 lock mode for GPRS high class

operation.

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