Circuit Description - Samsung SGH-P400 Service Manual

Gsm telephone

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2. SGH-P400 Circuit Description

1. SGH-P400 RF Circuit Description

1) RX PART

1. ASM(U1005)

Switching Tx, Rx path for GSM900, DCS1800 and PCS1900 by logic

510

controlling.

2. ASM Control Logic (U701, U702, U703)

ð Truth Table

GSM Tx Mode

DCS /PCS Tx Mode

PCS Rx Mode

GSM / DCS Rx Mode

3. FILTER

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

specific frequency band.

- GSM FILTER (C1003,C1004,L1001)

ð For filtering the frequency band between 925 ~ 960 MHz

- DCS FILTER (C1005,C1006,L1002)

ð For filtering the frequency band 1805 and 1880 MHz.

- PCS SAW FILTER (F1003,C1009,C1010,L1006)

ð For filtering the frequency band between 1930 and 1990 MHz

4. TC-VCXO (OSC801)

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

After additional process, the reference clock is applied to the U900 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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This Document can not be used without Samsung's authorization

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