User's Manual

Table Of Contents

SCA 9350-30 Installation and Service Manual

044-xxxxx Rev.x 4-2 December 2001

4-4.1 Driver Amplifier

The driver amplifier is a two-stage amplifier which provides approximately 28 dB of gain in the 25

MHz frequency band from 869 to 894 MHz. The amplifier is mounted directly on a heat sink, which

is temperature monitored by a thermal sensor.

4-4.2 Main Amplifier

The main amplifier is a single-stage Class AB amplifier with approximately 13 dB gain and a P1dB

of +50 dBm. The amplifier’s output is protected from output mismatches. The amplifier is de-

signed to meet spectral mask requirements for GSM and EDGE signals when operated up to

+45.2 dBm. The amplifier is mounted directly on a heat sink.

4-4.3 Power Distribution

The amplifier module operates on a –48 VDC nominal power supply consuming 2.9 amps (typi-

cally) current at full power. A DC/DC converter to supply internal circuitry with +26 VDC and +5

VDC.

4-4.4 Multifunction Board

The multifunction board enables communication between the amplifier and the base-transceiver

station in which it is installed, and stores information about the amplifier. It includes gain control

and two gain stages providing 7 dB gain. The multifunction board also monitors several amplifier

performance parameters and reports output power so that the BTS can maintain the output power

within specified limits. When these parameters are beyond acceptable levels, the amplifier will

alarm. The multifunction board is mounted directly on a heat sink, which is temperature monitored

by a thermal sensor.

The alarms are:

Temperature Alarm - If the internal temperature reaches 90°C, the PA shuts down and com-

municates an alarm through the digital interface.

DC/DC Alarm - If the output voltage of the converter falls below 23.5V, the PA shuts down

and communicates an alarm through the digital interface.

Over-current Alarm - If the output current of the DC/DC converter goes above a nominal

threshold (7.5 A), the PA shuts down and communicates an alarm through the digital

interface.

Communication Alarm - If the serial interface detects an error in transmission (parity, over-

run, framing), an alarm is sent for one burst only during the very next burst. The PA

operation is not affected.