LG KE820 - Page 100

5. Trouble shooting
- 101 -
5.12.4 Checking PLL Control signals
Checking Points Checking Flow
Circuit Diagram
RF Transceiver
Waveform
Figure 7. Transceiver
Figure 8. Transceiver Circuit
Figure 9. PLL Control Waveform
C430
22p
R427
0
C422
0.1u
X401
GND
2
3
OUT
VCC
4
VCONT
1
26MHz
C418
0.1u
R425
2V7_VCXO
0
R419
C431
1uF
47n
C419
R426
0
R424
0
R448
0
C421
0.1u
100p
C426
R414
820
VCO_RC
18
31
VDDBIAS2V8
8
VDDDIG1V5 VDDDIG2V8
5
21
VDDLNA1V5
X2V8
VDDRX1V5
19
20
VDDRX2V8X1V5
X2V8 VDDVCO2V8
17
VDDXO2V8
15
XO
11 12
XOX FSYS2 FSYS3
9
13
GND1
GND2
26 29
RX1
RX1X
30 27
RX2
RX2X
28
RX3
24 25
RX3X
RX4
22 23
RX4X
U402
PMB6272
A
1 2
AX B
3 4
BX CLK
7 6
DA
16
EN
FE1
32
14
FSYS1
10
C423
1000p
1000p
C427
0
R449
0.1u
C420
RF_DA
RF_EN
RF_CLK
26MHZ_MCLK
BT_CLK
RF_EN
RF_CLK
RF_DATA
R419 (RF_EN) R426 (RF_CLK)
R427 (RF_DATA)
U402
EN Signal is
OK ?
DA(Data) is
Normal
Check U402
Yes
No
No
Yes
Control Signal is OK.
See next page to check
Mobile SW & FEM.
CLK(Clock) is
Normal
No
Yes
Check U402
Check U402