LG KT520 Service Manual page 80

3.7.4 Front-End Module (FEM)
A single antenna is used for all four bands. The antenna switch and the EDGE/GSM/GPRS power
amplifiers are integrated to a single circuit containing:
• Antenna Switch with support for W-CDMA band 1
• Power amplifiers for high and low band EDGE/GSM/GPRS
• AM modulator/control circuit
• Lowpass transmitter filtering
The antenna switch block connects the proper block in the radio system to the antenna connection. In
GSM/GRPS/EDGE systems, transmit and receive operations are divided in time, and the switch
connects the proper block in accordance with the mode of operation (that is, transmit or receive; one at
a time in the GSM, DCS, and PCS bands).
In W-CDMA systems, the transmitter and the receiver operate simultaneously (that is, full duplex).
The switch is used only for selecting the W-CDMA mode of operation . the split between transmit and
receive frequencies is handled by the W-CDMA duplexer.
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Figure 3-7-8. Front-End Module
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3. TECHNICAL BRIEF
LGE Internal Use Only