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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 1-4. 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 frontend 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.
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
[Figure 1-4] UMTS Receiver Inputs Topologies
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3. TECHNICAL BRIEF
LGE Internal Use Only
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