LG -A290 Service Manual page 25

Both PA blocks share common power supply pads to distribute current. The output of each PA block and the outputs
to the two receive pads are connected to the antenna pad through an RF switch. The GaAs die, Switch die and passive
components are mounted on a multi-layer laminate substrate. The assembly is encapsulated with plastic over mold.
Mode
STANDBY
Rx1
1
Rx
1
Tx_LB
Tx_HB
1 Rx1 and Rx are broadband receive ports and each supports the GSM850, GSM900, DCS, and PCS nands.
RF_ANT_SW1
R407
10K
RF_TX_RAMP
PA_EN
C406
DNI
SW400
C411 C412
2
ANT COMMON
1
100p
G3 G4 100p
3 4
L411
27n
LGE Internal Use Only
VSW_EN
Table 3.3.1 SKY77550 Mode Control Logic
VLOGIC
C400
DNI
C402
DNI
C407
R409
24K 220p
L400
2.4n
Figure 3.3.2 TX-module CIRCUIT DIAGRAM
C415
C416
0.5p
DNI
L402
9.1n
Input Contrpol Bits
0
1
1
1
1
GND8
15
VRAMP GND6
16 8 VBAT
GND5
7
TxEN GND4
17 6
GND3
U400
5
RSVD
18
VBATT2
4
Rx1 VBATT1
19 3
RSVD3 GND2
20 2
GND1
1
Rx2
21
GND7
22
(10V,2125) (50V,C,NPO)
C417
B9512
FL400
1 IN 9
O1_1
C418
8 C419
O1_2
7
O2_1
GND O2_2
4 6
2 3 5 10
C420
C421
- 5 -
B9513
FL401
1 IN 9
O1_1
C422
8
O1_2
7
O2_1
C423
G1 O2_2
3. TECHNICAL BRIEF
Tx_EN
0
0
0
1
1
R402
51
C408
C410 C409
1u
10u
56p
(50V,C,NP0)
18p
GSM850_RxP
L401
22n
18p
GSM850_RxN
18p
EGSM_RxP
L403
22n
18p
EGSM_RxN
5.6p
Copyright © 01 LG Electronics. Inc. All right reserved.
DCS_RxN
Only for training and service purposes
L404
4.7n
5.6p
DCS_RxP
PCS_RxN
6.8p
BS
0
0
1
0
1
C401 33p
HB_TX
C403 33p
LB_TX