LG KF700Q Service Manual page 18

The GSM850, EGSM900, DCS1800, and PCS1900 receive signals are routed to the RTR6280 through
band selection filters and matching networks that transform single-ended 50Ω sources to differential
impedances optimized for gain and noise figure. The RTR input uses a differential configuration to
improve second-order inter-modulation and common mode rejection performance. The RTR6280 input
stages include MSM-controlled gain adjustments that maximize receiver dynamic range.
The amplifier outputs drive the RF ports of the quadrature RF-to-baseband downconverters. The
downconverted baseband outputs are multiplexed and routed to lowpass filters (one I and one Q)
having passband and stopband characteristics suitable for GMSK or 8-PSK processing. These filter
circuits include DC offset corrections. The filter outputs are buffered and passed on to the MSM6280 IC
for further processing (an interface shared with the RFR6280 UMTS receiver outputs).
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
[Fig. 3.2] RTR6280 RX feature
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3. TECHNICAL BRIEF
LGE Internal Use Only