Rf Part Introduction; Receiver Part - LG MG230 Service Manual

3.2. RF Part Introduction

The RF parts consists of a transmitter part, a receiver part, a voltage supply part, the crystal reference
system. And the main RF Chipset AD6548 is a highly integrated direct conversion radio solution that
combines, on a single chip, Quad Band Radio GSM850,E-GSM,DCS1800 and PCS1900 and power
management functions necessary to build the most compact GSM radio solution possible. This quad-
band GSM transmit module integrates a PA, a low-pass filter, a linear Tx / Rx switch along with PA
and switch control combined with ESD protection circuitry in one module,

3.2.1. Receiver Part

The Receiver part in AD6548 contains all active circuits completely, full receiver chain with the
exception of discrete front-end RF SAW filters. The AD6548 uses direct conversion receiver
architecture of the OthelloTM family. For Quad band applicationsthe front end features four fully
integrated programmable gain differential LNAs. The RF is then downconverted by quadrature mixers
and then fed to the baseband programmable-gain amplifiers and active filters for channel selection.
The Receiver output pins can be directly connected to the baseband analog processor.
The Receive path features automatic calibration and tracking to remove DC offsets. The RF Receiver
block is shown as below.
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Figure 3-3 The RF Receiver Block
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3. TECHNICAL BRIEF
LGE Internal Use Only