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Semiconductors / Integrated Circuits

A Deterministic Method for Optimizing VSWR

By using in conjuction both frequency and time domain reflection measurements, it is possible to positively identify the specific circuit discontinuities that contribute to a given VSWR lobe. Corrective action can then be readily determined for optimum...
Improving VSWR is typically an iterative trial-and-error exercise when utilizing either frequency or time domain information. For example, while circuit modifications which decrease time domain reflectometry (TDR) "bumps" (discontinuities) are generally a good thing, decreasing a specific TDR bump does not necessarily improve VSWR within a frequency band of...
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Integrated Variable Gain Amplifiers

A line of variable gain amplifiers (VGA) has been introduced for use in transmitter and receiver automatic gain control (AGC) circuits, and as variable gain blocks following low noise amplifier stages in high dynamic range receiver front ends. The new amplifiers integrate high performance amplifiers and attenuators within a...
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Adding a Low Data Rate Radio ASSP to an ISM Application

A variety of low data rate, low power and low cost radio ICs are available for use in industrial, scientific and medical (ISM) applications. A basic understanding of radio operation and the relevance of standard and proprietary protocol specifications ...
There is good news for those thinking about adding wireless communications to their industrial, scientific, or medical (ISM) application. A variety of low power, low cost radio ASSPs are available that can provide wireless features specifically for ISM applications. Fortunately, you do not need to be a communications specialist...
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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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