Rf Part Introduction; Receiver Part - LG KG110 Service Manual

3. TECHNICAL BRIEF

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.
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