LG KU800 Service Manual page 23

3. TECHNICAL BRIEF
Figure 1-3 RFR6250 IC Fuctional block diagram
The QUALCOMM RFR6250 IC is a custom GPS/UMTS-band design that meets DSWCDMA dynamic
range requirements. The RFR6250 IC accepts its UMTS-1900, UMTS-2100 and GPS input signals from
the handset RF front-end filters. Each individual input is provided with an on-chip LNA that amplifies the
signal before a second stage filter that provides differential downconverter. This second stage input is
configured differentially to optimize second-order inter-modulation and common mode rejection
performance.
The gains of the UMTS front-end amplifiers and the UMTS second stage differential amplifiers are
adjustable, under MSM. control, to extend the dynamic range of the receivers.
The second stage amplifiers drive the RF ports of the quadrature RF-to-baseband downconverters.
As only one UMTS path will be in operation at any one time, the outputs of the second stage amplifiers
are switched, as required, to drive the RF ports of the quadrature RF-tobaseband down-converters,
while the GPS receiver has its own dedicated down-converter to allow it to operate simultaneously.
- 24 -