ADCP-75-210 • Issue 1 • March 2007
Page 25
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 shows the PA assembly connection points and indicators. Table 14 describes the items
called out in the figure.
Figure 20. Power Amplifier Assembly
DC_ IN
DC_ OUT
DC_ FAULT
PIC LED
INDICATORS
12C
48V
PWR
RF
OUT
POWER
AMPLIFIER
21276-A
5
RF IN
8
4
7
6
1
2
3
