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3.3.2 UMTS TRANSMITTER
The QSC62x0 device support tri-band UMTS transmissions with three separate driver amplifier outputs; in
fact, most Tx active circuits are contained within the device. All three UMTS transmit paths (Figure 1.2.1.1)
begin with a single,shared analog baseband signal from the device's baseband circuits. The baseband signal
is composed of two differential lines, one in-phase component and one quadrature-phase component. Each
component is lowpassfiltered and amplified to levels sufficient for driving the quadrature upconverters.
There are two upconverters—one for low-band signals and one for high band —but only one upconverteris
active at a time.
Each UMTS duplexer provides a differential output signal that is compatible with its QSC LNA input. The
duplexer-to-LNA interface requires a differential matching network (MN) thatoptimizes the power transfer
into the LNA. Although there are three UMTS LNAs, only one is active at a time. The active gain-stepped LNA
output drives a shared quadrature downconverterdirectly - an off-chip inter-stage filter is not required. The
elimination of this filter is achieved by a combination of factors:
-New on-chip QSC processing
-Higher performance achieved by the differential duplexer-to-LNA interface
-Greater duplexer suppression of Tx leakage. The downconverter'sRF circuitry includes another gain-stepped
amplifier that supplements the LNA gain steps to further extend the receiver dynamic range.
The downconvertertranslates the active LNA'sRF signal directly to baseband, producing two analog outputs:
in-phase (I) and quadrature (Q).
Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
[Figure 1.3.3] WCDMA Transceiver Architecture
- 2 -
3. Technical Brief
BL20
LGE Internal Use Only

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