Powerwave Technologies 5JS0046 Hurricane, Model NTGY81AA User Manual 4

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Document ID	125997
Application ID	EwhlOuW6uu/wzgZVmlCEkQ==
Document Description	sect 4
Short Term Confidential	No
Permanent Confidential	No
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Document Type	User Manual
Display Format	Adobe Acrobat PDF - pdf
Filesize	0.89kB (11187 bits)
Date Submitted	2000-11-20 00:00:00
Date Available	2000-11-21 00:00:00
Creation Date	2000-10-30 09:31:14
Producing Software	Acrobat PDFWriter 4.0 for Windows
Document Lastmod	0000-00-00 00:00:00
Document Title	4.PDF
Document Creator	Microsoft Word
Document Author:	Judy

Section
PRINCIPLES OF OPERATION
4-1. INTRODUCTION
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.
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.
4-4. AMPLIFIER FUNCTIONAL DESCRIPTION
The NTGY81AA 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 1960 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 22 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:
An input amplifier
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.
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.
044-05079 Rev. A
4-1
4-4.3. DRIVER AMPLIFIER
The driver amplifier consists of two stages of class AB amplification which provide approximately 40
dB of gain in the 60 MHz frequency band from 1930 MHz to 1990 MHz. The amplifier operates on
+26 Vdc, and a safe bias voltage which is controlled by microprocessors.
4-4.4. MAIN AMPLIFIER
The main amplifier employs two class AB amplification stages for maximum efficiency. It provides
approximately 25 dB of gain in the 60 MHz frequency band. The output from the main amplifier is
typically 48.6 dBm. The amplifier operates on +26 Vdc, and gate bias voltages controlled by
microprocessors.
4-4.5. MULTIFUNCTION BOARD
The multifunction board consists of control and alarm circuits. The MCPA communicates to the
host system through the multifunction board which gathers the status information of the amplifier
and reports to the host system via the RS485 interface when instructed. It also protects the MCPA
from adverse conditions such as overpower, input overdrive, overvoltage, etc. A microprocessor on
the multifunction board also controls two loops in the feed-forward system.
INPUT
AMPLIFIER
PREDISTORTION
AMPLIFIER
DRIVER
AMPLIFIER
MAIN
AMPLIFIER
RF
IN
RF
OUT
MULTIFUNCTION BOARD
(ALARMS AND LOOP CONTROLS)
Figure 4-1. NTGY81AA Multichannel Power Amplifier Functional Block Diagram
4-5. AMPLIFIER MODULE COOLING
Each amplifier module is contained within a thermally conductive chassis which, when properly
mounted on an adequate thermal surface, will provide sufficient cooling to maintain the amplifier
within the specified operating temperature range.
4-6. POWER DISTRIBUTION
Primary DC power for the amplifier is provided by the host system. The amplifier generates all the
required voltages internally from the main source.
044-05079 Rev. A
4-2

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Create Date                     : 2000:10:30 09:31:14
Title                           : 4.PDF
Author                          : Judy
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