Checking Pam Block - LG U970 Service Manual

4.7.4 Checking PAM Block

TP1. GSM_PA_RAMP : Power Amp Gain Control. typically, 0.2V < Vramp < 1.6V
TP2. GSM_PA_EN : Power Amp Enable
(Power ON : higher than 1.25V , Power OFF : lower than 0.4V)
TP3. GSM_PA_BAND : Power Amp Band Selection Control
(GSM Mode : -0.2V < VBS < 0.4V , DCS/PCS Mode : 1.25V < VBS < 3.0V)
TP4. +VPWR : PAM Supply Voltage Vcc higher than 3.0V
Schematic of GSM PAM Block
14
13
12
C144
56p
11
10
L115
9
3.3nH
Rev.1.3 8
C146
C137
1.2p
22nH
56p
C150
Rev.1.3
L114
1.2nH
C142
0.5p C141
1
GND6 DCS_PCS_IN
2
GND5 BS
U101 3
VCC TX_EN
TQM7M5003 4
GND4 VBATT
5
GND3 GND1
6
GSM_OUT VRAMP
7
GND2 GSM_IN
TP4
NA
4. TROUBLE SHOOTING
TP2
GSM_PA_BAND
GSM_PA_EN
+VPWR FL101
C145 C143
33u
1u
EFCH897MTDB1
Rev. 1.1
R116 2.2K
GSM_PA_RAMP
C152 TP3
68p
GSM_PA_BAND MODE
TP1
LOW GSM
DCS/PCS
HIGH
- 93 -
R108
DCS_PCS_TX
68
R110 R111
10 dB
91 91
3 2
R112
G2 G1
GSM_TX
IN
1
O1 G3
51
4 5
R114 R115
120 120
8 dB