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Semiconductors / Integrated Circuits

Design of a TRM Calibration Kit for the ZMA Coaxial Interface Using Ansoft HFSS

When new coaxial interfaces become available, it is important to validate their performance. The best way to do this is by using a calibration kit that eliminates the effects of adapters in the measurement. This article discusses the design and impleme...
One of the greatest challenges in characterizing new coaxial interfaces is to determine an accurate test configuration. When precision airlines are not available it is very difficult to obtain a true measurement of the device under test. It becomes necessary to design and implement calibration standards to eliminate the...
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Multicriteria VCO Design

High frequency, voltage-controlled oscillators (VCO) are important components of modern RF systems. They are characterized by a set of parameters, which must be analyzed and optimized (for example, phase noise, frequency tuning range, tuning linearity and output power). Many studies are dedicated to the research of VCO characteristics. 1-8...
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Dual Slant Linearly Polarized Antenna for Broadband High Power Applications

Enhanced performance is needed from antennas, radomes and other microwave components to support ever-increasing functionality for military communications and electronic warfare (EW) applications. There is a continuing demand for antennas with broader bandwidth, higher power handling and better controlled radiation patterns, while at the same time reducing size and...
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Using Guided Wavelength as a Basis for the Design of Dielectric Rod Antennas

When designing dielectric rod antennas for maximum bandwidth, maximum gain, minimum beamwidth and/or low side lobes, design parameters reported in the literature are provided in terms of free-space wavelength. While this methodology lends itself well to other antenna types, it is not as useful when used to describe dielectric...
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An Aircraft Single-antenna FM Radio Altimeter

Advantages of a frequency modulated single-antenna radio altimeter, including lower cost and weight, improved accuracy and higher altitude range
As is well known, there are two general types of altimeter systems - a pulse radar altimeter and a frequency modulated, continuous wave (FM-CW) radio altimeter. Aircraft radio altimeters typically operate at altitudes from 0 to 8000 feet utilizing separate antennas for transmit and receive. Such radio altimeters have...
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Design and Operation of Automatic Gain Control Loops for Receivers in Modern Communications Systems

This article is intended to provide insight into the effective operation of variable gain amplifiers (VGA) in automatic gain control (AGC) applications.
This article is intended to provide insight into the effective operation of variable gain amplifiers (VGA) in automatic gain control (AGC) applications. Figure 1 is a general block diagram for an AGC loop. The input signal passes through the VGA to produce the output level to be stabilized. The...
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An Adaptive Feedforward Amplifier for WCDMA Base Stations Using Imperfect Signal Cancellation

This article describes a new adaptive feedforward amplifier for a WCDMA system using an imperfect signal cancellation. Due to the complicated signal statistics, the distortion generated by the error amplifier is significantly reduced by an imperfect si...
As wireless systems evolve from second- to third- or fourth-generation, the linearity, efficiency and bandwidth requirements for power amplifiers become more stringent. Many techniques, including feedforward, envelope feedback and manifold types of predistorters, have been employed to effectively satisfy these performance requirements and to reduce the production costs for...
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Design of a Predistorter Controlling Individual Orders of Intermodulation Using a New Harmonic Generator

A new type of predistortion linearizer is presented which uses individual orders of intermodulation to linearize a power amplifier. This new predistortion linearizer has two harmonic generators, each consisting of four diodes biased independently. Sinc...
In multi-carrier power amplifiers, a feedforward technique is generally adopted due to its extremely linear and broadband characteristics. 1 However, the feedforward technique requires large circuits and is expensive because of its complexity. It uses two cancellation paths, and delay lines are inserted in each path to adjust the...
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