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3. H/W CIRCUIT DESCRIPTION
3.3.3 Power Amplifier
The Power Amplifier Module [SKY77325, U604] is a dual-band GSM/PCS power amplifier module
that incorporates an indirect closed loop method of power control. The indirect closed loop is fully
self-contained and it does not require loop optimization. It can be driven directly from the DAC
output in the baseband circuit. On-board power control provides over 37 dB of control range with
an analog voltage input [VAPC]. Efficiency is about 49% at GSM850 and about 53% at PCS.
DCS/PCS IN
V
APC
PAC Enable
Band Select
GSM IN
C
6
6
2
1
2
p
L
6
1
0
1
8
n
H
C
6
6
3
4
7
p
C
6
0
5
N
A
I
OUT
V
reg
BATT
iPAC
75 m
Module
50 k
CMOS Power
47 pF
Controller IC
50 k
Figure 6. Internal Functional Block diagram
R
S
V
D
B
1
5
P
A
C
_
E
N
A
B
U
6
0
4
C
6
0
4
S
K
Y
7
7
3
2
5
N
A
G
S
M
_
O
U
T
G
S
M
_
1
2
D
C
S
_
P
C
S
_
O
U
T
D
C
S
_
P
C
S
_
1
7
C
6
0
6
N
A
A
P
C
C
6
0
8
C
6
1
1
C
6
1
2
C
6
1
3
C
6
1
4
C
6
1
5
3
3
p
0
0 .
1
u
0
0 .
1
u
0
0 .
1
u
1
2
p
3
9
p
Figure 7. Schematic of PAM circuit
- 18 -
Vcc1
DCS/PCS
GaSa
Power
Amplifier
GSM
S
4
L
E
C
6
0
2
R
6
0
1
2
3
9 .
p
1
8
N I
6
R
6
0
2
R
6
0
3
N I
2
2
0
2
2
0
5
A
T
: T
3
5 .
d
B
m
R
6
0
4
1
8
R
6
0
5
R
6
0
6
2
2
0
2
2
0
C
6
1
0
3
3
u
A
T
: T
3
5 .
d
B
m
Vcc2
Output
DCS / PCS OUT
Match
Output
GSM OUT
Match
P
A
_
B
A
N
D
P
A
_
O
N
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