Samsung SGH-E750 Service Manual

Also see for SGH-E750: Service manual User guide

SAMSUNG Proprietary-Contents may change without notice2-1. SGH-E750 RF Circuit Description2-1-1. RX PART- FEM(MODULE100) Switching Tx, Rx path for GSM900, DCS1800 and PCS1900 by logic controlling.- FEM Control Logic (MODULE100) Truth TableVC1 VC2 VC3Tx Mode (GSM900) H L LTx Mode (DCS1800/1900) L H L(H)Rx Mode (GSM900) L L LRx Mode (DCS1800) L L LRx Mode (PCS1900) L L H- VC-TCXO-2146C6(26MHz) (OSC100)This module generates the 26MHz reference clock to drive the logic and RF.It is turned on when the supply voltage is applied.After buffering a reference clock of 26MHz is supplied to the other parts of the system through the transceiver pinVCXOOUT1.- Transceiver (U100)This chip is a RF transceiver IC for GSM850/900, DCS1800, and PCS1900 Quad band cellular system, and incorporatesGPRS transceiver capability, and integrates most of the low power silicon functions of a transceiver.It incorporates triple RF LNAs, direct conversion mixers which are IQ demodulator, an auto offset calibratedprogrammable gain amplifier with baseband filter for IQ chains, RF synthesizer, a I/Q modulator, offset PLL, IFsynthesizer, and the circuits which are needed polar loop architecture for the transmitter.2-1-2. TX PARTTransmitter of the transceiver is capable of GMSK and 8-PSK modulation, providing support for conventional GSM andGPRS. The modulated signal out of the transceiver is fed into Power Amplifer Module(U101). PAM output signal isradiated to the air through FEM(MODULE1) and antenna.