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Semiconductors / Integrated Circuits

The Concept of Predistortion

The intention of this article is to provide a tool for the design of a predistorter, a component intended to correct unwanted nonlinear effects in power amplifiers. In order to come up with a design, a concept of predistortion is discussed. The conclus...
This article continues the trend of previous publications, 1,2 to simplify the prediction of RF performance of systems designed for wireless digital communications. The first shows the correlation between sidelobes and intermodulation (IM) products. Sidelobes are the result of the spectrum re-growth when a digitally modulated signal is applied...
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A Low Power Consumption Architecture for Mobile Phones Above 1800 MHz

The satisfaction that mobile phones can provide is highly dependent on their autonomy. For this reason, many efforts are being made to improve this property. A particular architecture for telecommunication receivers has been designed and is described i...
The satisfaction that mobile phones can provide is highly dependent on their autonomy. Three factors can be easily identified which have a strong influence on autonomy: the power consumption of the mobile phone, the intensity of the electromagnetic field near the mobile and the battery capacity. The first of...
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A Universal Oscillator Analysis Technique that Accurately Estimates Frequency and Output Power

During the last few decades, many different oscillator models and analysis techniques have been presented. From the negative impedance model, cavity type and DROs to the general feedback type, all oscillators have one common property. They are nonlinea...
Generally, an oscillator can be seen as a positive feedback system. It usually consists of an amplifier followed by a resonator, which is fed back to the amplifier input, as shown in Figure 1 . The amplifier task is to compensate for the losses in the resonator, and the...
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Quarter-wavelength N-way Power Dividers/Combiners: Historical Aspects and New Modifications

Quarter-wavelength, in-phase, N-way power dividers/combiners are widely used in antenna arrays, power amplifiers and transmitters, mixers, phase shifters and vector modulators. This article briefly reviews the history of known quarter-wavelength power ...
The simplest quarter-wavelength, multi-port power divider, known as a Wilkinson divider, 1-2 provides a match at all ports, low loss, in-phase power splitting and high isolation between output ports. Historically, this device was reported earlier. 3-7 It was also described 5 together with the so-called Gysel-type combiner, 8 based...
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A Novel Class of High Selectivity Filters and Duplexers in Microstrip Technology

This article describes a novel configuration for high selectivity bandpass filters and duplexers in microstrip technology. The structure proposed is made of single-sided filters, which are characterized by requirements in one passband and one stopband,...
Modern communication systems often require narrow band filters presenting high selectivity and low insertion loss. When there are also stringent requirements on the overall dimensions of the filtering structure, it could become very problematic to select a suitable class of resonators having at the same time compactness and large...
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A Novel Simulation Tool for PN Junction Varactors Based on Finite Difference Approximations

The estimation of the resistance of varactors used in integrated circuits for RF applications is a difficult task. This article presents a novel simulation tool for estimating the two main varactor parameters: resistance and capacitance. Once the capac...
Integrated voltage-controlled capacitors, usually known as varactors, are used in many electronic integrated devices for RF applications. 1 In particular, voltage-controlled oscillators (VCO) 2,3 and tuneable filters 4 are the two main applications. For good performance of integrated devices that have a varactor as a component, it is very...
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A Reduced-size Power Divider Using the Coupled Line Equivalent to a Lumped Inductor

A new method of reducing the size of a power divider using quarter-wave length transmission lines is proposed. The method utilizes a combination of shorted coupled lines instead of lumped inductors and capacitors. The new hybrid is simply fabricated wi...
In many applications, such as balanced power amplifiers, mixers and antenna systems, power dividers/combiners are required. Power dividers using quarter-wave lines become prohibitively large at the lower frequencies and result in MMIC chips of larger size and higher cost. The lumped-element approach, which uses lumped inductors and capacitors, is...
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Design of a MESFET Frequency Multiplier - Theory and Simulation

The design of nonlinear circuits is usually viewed as a challenge, mainly because of the difficulty in determining the accurate model that describes the device behavior over a wide range of conditions, including varying frequency and power level. The m...
The basic principle of operation of a MESFET multiplier is that the device is biased for a particular conduction angle, based on the harmonic frequency to be generated. A generalized circuit schematic of a MESFET frequency multiplier is shown in Figure 1 . It can be seen that the...
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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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