Rf Interface - LG KP150Q Service Manual

3.9 RF Interface

V_EXTH
ANT_SW1
ANT_SW2
Locosto features a fully integrated constant-gain direct conversion receiver, i.e. there is no interstage
filter needed and the baseband level at the analogue IQ- interface follows directly the RF input level.
Depending on the baseband ADC dynamic range, single- or multiple-step gain switching schemes are
possible.
An integrated, selfaligning, low-pass filter ensures the receivers to function under blocking and
reference interference conditions and avoids aliasing by baseband sampling. An automatic DC-offset
compensation is implemented and can beswitched depending on the gain setting.
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
C433
C431 C432
1000p 1000p 1000p
Figure 3-9-1. FEM interface
- 29 -
3. HW Circuit Description
FL400 LMSP43QC-789TEMP
GSM1900_RX1
19
VC1 GSM1900_RX2
20
VC2
GSM1800_RX1
21
VDD GSM1800_RX2
9
GND1 GSM900_RX1
10
GND2 GSM900_RX2
12
GND3
13
GND4 GSM850_RX1
14
GND5 GSM850_RX2
16
GND6
18
GND7 GSM1800_1900_TX
22
GND8 GSM850_900_TX
1
2
3
4
5
6
7
8
15
17
LGE Internal Use Only