Umts Mode - LG L705i Service Manual

3.3 UMTS Mode

3.3.1 Receiver
The UMTS duplexer receiver outputs are routed to LNA circuits within the RFR6275 and RTR6275
device.
UMTS LNA circuits(one for low-band UMTS and one for high-band UMTS path) are separated from all
other receive functions contained within the RFR6275 and RTR6275 reveiver ICs to improve mixer LO
to RF isolation- a critical parameter in the ZIF architecture. Isolation is further improved using high-
reverse isolation circuits in the LNA designs.
The LNA gains are stepped via API control. The IC operating mode and LNA bias currents are
automatically adjusted via software to minimize DC power consumption.
WCDMA_800_RX
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Only for training and service purposes
Figure 3.3.1 RFR6275 IC functional block diagram
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3. TECHNICAL BRIEF
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