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Subsystems and Systems

A Minimalist Approach to Feedforward Multi-carrier Linear Power Amplifiers

A feedforward multi-carrier linear power amplifier with 60 W maximum average output is featured
December 1, 2002
Atmospheric propagation attenuation is known to be higher in the 2.1 GHz band than in the cellular band. Thus, to overcome this performance disadvantage and to maximize cell coverage and capacity, Unity Wireless System's first feedforward multi-carrier linear power amplifier (MCLPA) product has been designed with a high 60...
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Understanding W-CDMA Modulation Quality Measurements

December 1, 2002
There are many ways of characterizing W-CDMA transmitter performance. However, the Third Generation Partnership Project (3GPP) specifications require two measurements to verify the in-channel modulation quality of W-CDMA transmitters - error vector magnitude (EVM) and peak code domain power (peak CDE). This article explores the purpose behind these key...
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A Handheld Spectrum Analyzer Offering High Performance from a Small Footprint

November 1, 2002
The prime requirements of a handheld spectrum analyzer are for it to be lightweight, compact, but with as large a display as possible, and exhibit low power consumption - all within a sturdy housing. These criteria are not easy to fulfill in themselves, so it is an even greater...
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Precision E<sub>b</sub>/N<sub>o</sub> Generators for BER Testing to 44 GHz

November 1, 2002
With the continually increasing complexity of digital modulation techniques employed in wireless and satellite communications systems, instruments that accurately generate and maintain a set level of bit energy-to-noise density ratio (E b /N o ) have become valued tools in optimizing bit-error rate (BER) performance. These instruments have been...
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Effects of AM/AM and AM/PM Distortion on Spectral Regrowth in 3GPP W-CDMA BS Power Amplification

The effects of amplitude and phase nonlinearities in a power amplifier, which lead to spectral regrowth, are examined in the context of a 3GPP W-CDMA forward link (base station) environment. Behavioral modeling and simulation techniques are applied fir...
November 1, 2002
The transmitter unit, contained in base stations for third generation cellular systems, requires a linear power amplifier to preserve signal integrity when amplifying composite signals associated with multiple channels. While the power amplifier must meet a number of requirements to be system level compliant, the design process generally emphasizes...
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A Broadband Hybrid Solid-state and TWT Amplifier

Development of a broadband microwave amplifier for testing in the 800 MHz to 18 GHz frequency range
September 1, 2002
Test applications that require microwave power from 1 to 18 GHz are usually addressed by two amplifiers, a solid-state unit to cover the low frequency range and a traveling-wave tube amplifier (TWTA) for the higher range. The input signal must be switched between the two amplifiers and, if there...
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The Receiver Noise Equation: A Method for System Level Design of an RF Receiver

Introduction to a new equation used to simplify the system level design of an RF receiver
August 1, 2002
Noise is a limiting factor for sensitive reception. In recent communication receivers, noise, along with many external factors, including intermodulation, reciprocal mixing and spurious response, may disturb the sensitive reception of the desired signal. Thus, much consideration for the noise and other factors that disturb the signal reception and...
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Internally Terminated 12-throw Electromechanical Switches for Matrix Applications

Presentation of a single-pole 12-throw internally terminated electromechanical switch that forms the basis for a line of N x 12 switch matrix assemblies
July 1, 2002
Electromechanical distribution systems (switch matrices) are used in both commercial applications and military systems. Computer control of these switch matrices facilitates their use in automated testing and in those systems requiring remote control of switching functions. The newest product in Dow-Key's line of electromechanical switches is a single-pole 12-throw...
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A Compact W-CDMA RF Front End

Introduction to a complete RF front end assembly that meets environmental requirements for base station service
July 1, 2002
As the environments in which cell sites are located becomes more constricted, designers of base stations for third-generation networks are faced with challenges such as increased functional integration and other size-reduction techniques similar to those of their mobile phone counterparts. The model FEU-WCDMA1 is a W-CDMA RF front end...
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QFHA Antennas for Satellite Radio and Mobile Phone Applications

Presentation of a specific quadrifilar helical antenna design for satellite radios, along with a planar design for an integrated BFN90 beam forming network
July 1, 2002
Quadrifilar helical antennas (QFHA) are one of the best candidates to provide a high gain, shaped beam with excellent circular polarization axial ratio for satellite radio and mobile satellite phone systems. One of the most compelling reasons to use these antennas for digital radio and mobile satellite systems is...
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