Umts Mode - LG -P970 Service Manual

3.3 UMTS MODE

3.3.1 UMTS RECEIVER
Figure 3-5 shows the line-up for the 3G receiver chain. Note that the high gain / low gain figures for external
LNA1 are given as an example. The blue arrows indicate the gain control inputs for the AGC subsystem. The
quadrature path is a simple copy of the chain from mixer to DigRF and is not shown in the diagram.
switch duplexer
After quadrature downconversion to baseband(Zero-IF) the signal is fed to the analog baseband filter.
The range and gain step of the following buffer amplifier is actually determined by the needs of the AGC in 3G
mode.
LGE Internal Use Only
For band l:
SMARTIUE
other bands:
extemal LNA1
16 / -7 dB
inter stage
LNA1
LNA
filter
[Figure 3-5] 3G Receiver Line Up
35 dB
1 dB
gain range
gain step
(1 dB steps)
analog
mixer buffer
baseband filter
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3. TECHNICAL BRIEF
Only for training and service purposes