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Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
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3.3 UMTS MODE
3.3.1 UMTS RECEIVER
The UMTS duplexer receiver output is routed to LNA circuits within the RTR6285 device as shown in Figure 1-
5. The UMTS RX input is provided with an on-chip LNA that amplifies the
signal before a second stage filter that provides differential downconverter as shown in Figure
1-5. This second stage input is configured differentially to optimize second-order intermodulation and
common mode rejection performance. The gain of the UMTS front end
amplifier and the UMTS second stage differential amplifier are adjustable, under MSM
control, to extend the dynamic range of the receivers. The second stage UMTS RX amplifiers
drive the RF ports of the quadrature RF-to-baseband downconverters. The downconverted UMTS RX
baseband outputs are routed to lowpass filters having passband and stopband characteristics suitable for
UMTS RX processing. These filter circuits allow DC offset corrections, and their differential outputs are
buffered to interface shared with GSM RX to the MSM IC. The UMTS baseband outputs are turned off when
the RTR6285 is downconverting
GSM signals and on when the UMTS is operating.
[Figure 1-5] UMTS Receiver Inputs Topologies
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