Gsm Part - LG -S310 Service Manual

3. TECHNICAL BRIEF
The translation loop modulator and Tx VCO are extremely low noise removing the need for external TX
filtering. To support EDGE modulation with high PA efficiency the design includes a full polar modulation
architecture including PA linearization. To reduce BOM the TX PLL loop filter components are fully integrated.
The AD6546 uses the industry proven direct conversion receiver architecture of the Othello
Quad band applications the front End features four fully integrated differential LNAs with programmable-
gain. The RF is downconverted by quadrature mixers and then fed to the baseband programmable-gain
amplifiers and active low pass filters for channel selection. The programmable-gain baseband amplifiers and
the LNA gain step are set via a standard 3-wire serial bus. 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 AD6546 uses a single integrated LO VCO for both receive and the transmit paths. The
synthesizer lock times are optimized for EGPRS applications up to and including class 12. The AD6546
contains three on-chip low dropout voltage regulators(LDOs). These maintain the correct supply voltages to
the on chip circuits with a wide range of battery voltage input. Comprehensive power down options are
included to minimize power consumption in normal use.

3.2 GSM Part

3.2.1 GSM Receiver
The LG-S310 receiver section fully integrates all the RF and baseband signal processing. Each block is
described in the following sections.
Low Noise Amplifiers
The LNAs have differential inputs which help minimize the effect of unwanted interferers. The inputs are
easily matched to industry standard FEMs or discrete Rx SAW filters. The outputs of the LNAs are directly
LGE Internal Use Only
coupled to the down-converting mixers. The voltage gain of the LNAs is typically 24 dB. Each LNA can be
switch to a low gain mode when receiving large input signals as part of the AGC system.
[Figure 4.2.1-1] GSM Receiver Path
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TM family. For
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