Technical Brief; General Description - LG GM750 Service Manual

3. TECHNICAL BRIEF

3.1. GENERAL DESCRIPTION

The GM750 supports UMTS-900(Band VIII), UMTS-1900(Band II), UMTS-2100
(Band I), GSM-850, GSM-900, GSM-1800, and GSM-1900 based
GSM/GPRS/EDGE/UMTS. All receivers and the UMTS transmitter use the radioOne 1 Zero-IF
architecture to eliminate intermediate frequencies, directly converting signals between RF and
baseband. The quad-band GSM transmitters use a baseband-to-IF up-conversion followed by an offset
phase-locked loop that translates the GMSK-modulated or 8-PSK-modulated signal to RF.
A generic, high-level functional block diagram of GM750 is shown in Figure 1-1. One antenna collects
base station forward link signals and radiates handset reverse link signals. The antenna connects with
receive and transmit paths through a SKY77521 (FEM, Front End Module + GSM PAM). The UMTS
receive paths each include an LNA, an RF band-pass filter, and a downconverter that translate the
signal directly from RF-to-baseband using radioOne ZIF techniques. The RFIC's RX analog baseband
outputs, for the receive chains, connect to the MSM IC. The UMTS and GSM RX baseband outputs
share the same inputs to the MSM IC.
1
QUALCOMM's branded chipset that implements a Zero-IF radio architecture.
Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
[Figure 1-1] Block diagram of RF part
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3. Technical Brief
GM750
LGE Internal Use Only