3. TECHNICAL BRIEF
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3.3 UMTS mode
3.3.1UMTS RECEIVER
The UMTS duplexer receiver output is routed to LNA circuits within the QTR8200/8600 device as shown in Figure
3.5. 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 3.3.1. This second stage input is configured differentially
to optimize secondorder 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 QTR8200/8600 is
downconverting GSM signals and on when the UMTS is operating.
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[Figure 3.3.1] UMTS Receiver Inputs Topologies