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3.3.2 Receiver Part
There are two recommended GSM receiver path configurations; both are shown in Figure 3.3.2.1.
The configuration shown on top allows the GSM 850 and GSM 1900 bands to share the UMTS 850 and UMTS 1900 paths
for US applications and uses four LNA inputs to support quad-band GSM operation.
The lower example uses two LNAs for quad-band GSM operation (one low band and one high band), with two-way SAW
filters between the antenna switch and the QSC inputs for each band type.
Antenna
G1800/1900
G850/900
U2100
U1900 + G1900 Rx
U850 + G850 Rx
G900
G1800
Antenna
G1800/1900
G850/900
U2100
U_HB
U_LB
G850
G900
G1800
G1900
LGE Internal Use Only
from UMTS
L23
transmitters UMTS2100
Rx path
K23
Tx
J23
Rx
H23
Tx
L22
Rx
K22
J22
G900
Rx BPF
H22
G23
G1800
Rx BPF
F23
MN = matching network
2-way SAW lters
G850
Rx BPF
J22
G900
Rx BPF
H22
G23
G1800
Rx BPF
F23
G1900
Rx BPF
MN = matching network
Figure 3.3.2.1 QSC GSM receiver signal paths functional diagram
UMTS Rx Lo
LNA
Quad
D'convert
LNA
LNA
LNA
Quad
D'convert
LNA
GSM Rx LO
QSC device
from UMTS
receivers
LNA
Quad
D'convert
LNA
GSM Rx LO
- 25 -
Copyright © 2012 LG Electronics. Inc. All right reserved.
3. TECHNICAL BRIEF
LPF
ADC_I
LPF
ADC_Q
REF & CLK
Generation
QSC device
REF & CLK
Generation
LPF
ADC_I
LPF
ADC_Q
Only for training and service purposes
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Troubleshooting
