LG GD910 - WCDMA Part

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Only for training and service purposes

LGE Internal Use Only

4. RF Circuit Technical Brief

GD910 service manual

[Figure 4.2.5-3] GD910 Front End Control Logic Table

4.3 WCDMA Part

The single-chip transceiver is designed to fulfill the W-CDMA UTRA FDD system requirements for bands I, II, III,

IV, V, VI and IX. It contains all active circuits required to simultaneously modulate an analog W-CDMA I/Q

signal to the TX RF frequency and demodulate a RX RF W-CDMA signal to an I/Q baseband signal.

4.3.1 WCDMA Receiver

The direct conversion receiver for each band consists of:

•fully differential signal path

•RF low noise amplifier (LNA2)

•I/Q demodulator including LO buffer and I/Q divider

•LO including on-chip VCO and synthesizer

•DC offset compensation without external components

•analog channel filter including auto calibration circuit (w/o external components)

•programmable gain control (PGC) controlled by 3-wire bus programming and gain setting unit on-chip

•allpass filter (auto calibrated)

•configurable output drivers (programmable DC voltages and driver currents for different load impedances)

RX Front-End

An external low noise amplifier as well as duplex and interstage filters are needed to form a complete receive

chain for each band.

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