Only For Training And Service Purposes - LG CU400 Service Manual

4.5.2 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
L121
15nH
NA
L123
Schematic of GSM PAM Block
Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

TP4
TP2 TP3
C101
1.2p
4.7nH
L120
NA
L122
14
DCS_PCS_OUT DCS_PCS_IN
GND5
GND4 TX_EN
11
U102
VCC VBATT
TQM7M5003
GND3 GND1
GND2 VRAMP
8
GSM_OUT GSM_IN
4. TROUBLE SHOOTING
TP1
TP4
TP3
1
2
BS GSM_PA_BAND
3
GSM_PA_EN
4
5
TP2
6
7
R114
GSM_PA_RAMP
2.2K
TP1
- 81 -
+VPWR
R108
DCS_PCS_TX
82
11.4dB
FL100
5 1
RFOUT RFIN
7
VC
LMSM32AA-533
LGE Internal Use Only