LG CU920 - WCDMA Receiver Level Check

LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
- 101 -
4.8 Checking GSM Block
4.8.1 Checking Tx level
TP1
TP2
TP3
TP4
TP5
TP6
Fig 4.8.1.1 Test point of the GSM TX Block
7.75dB
HIGH
remain LOW when not transmitting
EGSM
GSM850
LOW
L124
2.2nH
L901
27nH
82
R115
51
R119
LMSM32AA-533
GND1
2 3
GND2 GND3
4 6
GND4 GND5
8
1
RFINRFOUT
5
7
VC
FL101
110
R120
C143
NA
0.5p
C140
200
R122
68p
C128
33p
C928
C132
33p
12
1
TX_EN
VAPC
6 5
VBATT
PGND15 PGND16
32
PGND17
33 34
PGND18
35
PGND19 PGND2
18
PGND20
36 19
PGND3
20
PGND4 PGND5
21 22
PGND6
23
PGND7 PGND8
24
PGND9
25
RSVD1
4
RSVD2
8
RSVD3
BS
2
DCS_PCS_IN
DCS_PCS_OUT
16
10
GND1
11
GND2 GND3
13 14
GND4 GND5
15
GSM_IN
7
GSM_OUT
9
PGND1
17 26
PGND10
27
PGND11
28
PGND12 PGND13
29
PGND14
30 31
U101
SKY77329
3
L125
10nH
2.2KR113
33u
C129
R121
110
C127
56p
82
R116
R117
82
NA
100p
L122
C121
GSM_PA_EN
+VPWR
GSM_PA_RAMP
DCS_PCS_TX
GSM_PA_BAND
GSM_TX
GSM_SAW_SW_MODE
SW100
ANT
G1
G2
RF
KMS-512
56nH
C102
56pC100
NC
15
UMTS1
UMTS2
16
14
VC1
VC2
13
12
VC3
VC4
11
10
VDD
21
GND5
23
GND6
24
26
GND7
27
GND8
GND9
28
GSM1800RX1
1
2
GSM1800RX2
GSM1800_1900TX
22
GSM1900RX1
3
4
GSM1900RX2
7
GSM850RX1
GSM850RX2
8
25
GSM850_900TX
GSM900RX1
5
6
GSM900RX2
17
LMSP4LMA-573TEMP
FL100
19
ANT
GND1
9
GND2
18
20
GND3
GND4
Fig. 4.8.1.2 Schematic of the GSM TX Block
TP1
TP3
TP4
TP5
TP6
TP2