Functional Description - LG -T370 Service Manual

3.5.2 FUNCTIONAL DESCRIPTION

3.5.2.1 Receiver
The X-GOLD™215 dual-band receiver is based on a Direct Conversion Receiver (DCR) architecture. Input
impedance of the LNAs is optimized to achieve a matching without (external) high quality inductors. By use of
frequency dividers (by 2/4) the LO frequency is derived from the RF frequency synthesizer.
The receive path is fully differential to suppress the on-chip interferences and reduce DC-offsets. The analog p y
chain of the receiver contains two LNAs (low/high band), a quadrature mixer followed by an analog baseband
filter and 14-bit continuous-time delta-sigma analog-to-digital converter. The filtered and digitized signal is fed
into the digital signal processing chain, which provides decimation, DC offset removal and programmable gain
control.
RX1
GSM
850/900
RX1X
RX
GSM
1800/1900
RXX
LNA_GAIN
LGE Internal Use Only LGE Internal Use Only
pp
RXBBFG[:0]
DCO
Figure. 3.5.2 RECEIVER CHAIN BLOCK DIAGRAM
- 37 - - 37 -
3. TECHNICAL BRIEF
p
DGAIN[5:0]
Copyright © 011 LG Electronics. Inc. All right reserved. Copyright © 01 LG Electronics. Inc. All right reserved.
3. TECHNICAL BRIEF
g
RXTXDA
DigRF
RX
RXTXEN
Only for training and service purposes Only for training and service purposes