Powerwave Technologies Inc. 5JS0059 Manuale Utente
044-xxxxx Rev. x
4-1
PRINCIPLES OF OPERATION
4-1. INTRODUCTION
This section contains a functional description of the multichannel power amplifier (MCPA).
This section contains a functional description of the multichannel power amplifier (MCPA).
4-2. RF INPUT SIGNAL
The maximum input power should not exceed the limits specified in table 1-1.
The maximum input power should not exceed the limits specified in table 1-1.
4-3. RF OUTPUT LOAD
The load impedance should be as good as possible (1.5:1 or better) in the working band for good
power transfer to the load.
The load impedance should be as good as possible (1.5:1 or better) in the working band for good
power transfer to the load.
4-4. AMPLIFIER FUNCTIONAL DESCRIPTION
The NTGY81AC amplifier (figures 1-1 and 4-1) is a linear, multichannel power amplifier that
operates in the 60 MHz frequency band from 1930 MHz to 1990 MHz at an output power of 50
watts. Each amplifier is a self-contained module and is functionally independent of any other
amplifier modules in the system. Each amplifier module has an alarm board that monitors the
amplifier performance. If a failure or fault occurs in an amplifier module, it is transmitted to the
host system via an RS485 interface.
The NTGY81AC amplifier (figures 1-1 and 4-1) is a linear, multichannel power amplifier that
operates in the 60 MHz frequency band from 1930 MHz to 1990 MHz at an output power of 50
watts. Each amplifier is a self-contained module and is functionally independent of any other
amplifier modules in the system. Each amplifier module has an alarm board that monitors the
amplifier performance. If a failure or fault occurs in an amplifier module, it is transmitted to the
host system via an RS485 interface.
The amplifier is compliant to the requirements of FCC Part 24 with respect to spurious emissions
(see table 1-1). Constant gain is maintained by continuously comparing active paths with passive
references, and correcting for small variations through the RF feedback controls. All gain
variations, for example those due to temperature, are reduced to the passive reference variations.
The amplifier module is comprised of:
(see table 1-1). Constant gain is maintained by continuously comparing active paths with passive
references, and correcting for small variations through the RF feedback controls. All gain
variations, for example those due to temperature, are reduced to the passive reference variations.
The amplifier module is comprised of:
An input amplifier
A predistortion amplifier
A driver amplifier
A main amplifier
A multifunction board
A predistortion amplifier
A driver amplifier
A main amplifier
A multifunction board
4-4.1. INPUT AMPLIFIER
RF is fed to the input amplifier, which consists of an isolator at the input, bandpass filter, VVAs,
and phase shifters for gain control and phase sweeping functions. They are controlled by a
microprocessor on the multifunction board. At its output, the input amplifier splits the signal to the
predistortion amplifier and carrier cancellation circuits.
RF is fed to the input amplifier, which consists of an isolator at the input, bandpass filter, VVAs,
and phase shifters for gain control and phase sweeping functions. They are controlled by a
microprocessor on the multifunction board. At its output, the input amplifier splits the signal to the
predistortion amplifier and carrier cancellation circuits.
4-4.2. PREDISTORTION AMPLIFIER
The predistortion amplifier predistorts the input signal in a way that it linearizes the output of the
main amp at 50 watts. It also contains the main loop VVAs and phase shifters. All the predistortion
voltages and loop voltages are controlled by a microprocessor.
The predistortion amplifier predistorts the input signal in a way that it linearizes the output of the
main amp at 50 watts. It also contains the main loop VVAs and phase shifters. All the predistortion
voltages and loop voltages are controlled by a microprocessor.
Section
4