LG LG-P970 - Umts Mode

3. TECHNICAL BRIEF
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Only for training and service purposes
LGE Internal Use Only
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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.
[Figure 3-5] 3G Receiver Line Up
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.
12 dB
gain step
35 dB
gain range
(1 dB steps)
For band l:
SMARTIUE
other bands:
extemal LNA1
16 / -7 dB
switch duplexer
inter stage
filter
LNA1
LNA2 mixer buffer
analog
baseband filter