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1.9
Power Amplifier Assembly
The Power Amplifier Assembly (PAA) is an electronic device that amplifies RF signals in the
forward path just before they are transmitted to the RAN antenna. Up to four PAAs may be
mounted in the RAN, each providing one band. Each PAA consists of a Power Amplifier (PA), a
control board called the PA Interface Controller (PIC), and a cooling system. The PA is multi-
channel. Different units are used for PCS, Cellular, and SMR 800 bands.
The PIC interfaces to the discrete signals of the PA. The PIC also provides DC power to the PA
by converting from -48 VDC to +12 VDC or +28 VDC depending upon which PA is being used.
Each PA has its own PIC. The PIC is managed is managed by the CPU over an I2C connection
through its corresponding RUC. The cooling system consists of a heat sink and three fans that
provide cooling for the PA by blowing external air across the heat sink. The fans are software-
controlled. The PIC module monitors the tachometer outputs of the fan.
Figure 20
called out in the figure.
PIC LED
2
INDICATORS
shows the PA assembly connection points and indicators.
48V
5
PWR
4
12C
1
DC_ IN
DC_ FAULT
3
DC_ OUT
Figure 20. Power Amplifier Assembly
Table 14
8
RF IN
RF
6
OUT
ADCP-75-210 • Issue 1 • March 2007
describes the items
21276-A
POWER
7
AMPLIFIER
Page 25
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