Fm Radio With Rds Function - LG KE820 Service Manual

3. TECHNICAL BRIEF

3.16 FM radio with RDS function

The FM receiver uses a digital low-IF architecture which allows for the elimination of external
components and factory adjustments. The receive (RX) section integrates a low noise amplifier (LNA)
supporting the worldwide FM broadcast band (87.5 to 108 MHz). An automatic gain control (AGC)
circuit controls the gain of the LNA to optimize sensitivity and rejection of strong interferers.
FM_ANT
1
GND1
C144 100p 2
FMIP
3
RF_GND
C152
4
FMIN
5
GND2
NA 6
GND3
Figure 28 FM Radio circuit
2V72_IO
18
VA
17
GND5
16
U105 LOUT
15
SI4701 ROUT
14
GND4
13
VD
R150
C147
10K
0.1u
2V72_IO
5
VCC
C153 0.1u
4
GND
C155
27p
- 54 -
2V85_IO2
R176
0
FM_SND_L
FM_SND_R
C148 C157
1u 1u
U107
TC7SH04FS
C154 0.1u
1
2
R182 47K
CLK32K