Design Features

 348 results found for Design Features, displaying items 1 - 20

February 2010   [Components]
Low-Power LNA Drops Noise At 2.4 GHz
Low-noise-amplifier (LNA) design requires tradeoffs, often among such goals as noise figure, gain, linearity, and stability. In addition, portable applications call for low power consumption. But through the use of a common- gate (CG) architecture for input impedance matching and reduced power consumption through currentreuse techniques, an RF CMOS LNA was developed with 15.5-dB forward gain and 1.68 dB noise figure at 2.4 GHz. With its excellent...  — Baimei Liu , et al.

February 2010   [Test & Measurement]
Analyze Phase Noise In A Sampled PLL (Part 2)
Phase noise in sampled phase-locked loops (PLLs) can impact the performance of a wide range of commercial and military systems, including communications networks based on phase modulation. As shown last month in the first installment of this three-part series, modeling approaches may differ depending upon whether a PLL is a continuous-time or sampled system, with nonlinear approaches needed for th latter. In this second article installment, it may be...  — Peter Beeson

February 2010   [Components]
Match The Ports Of Differential Devices
Differential or balanced devices are widely used in communications systems for their high immunity to noise. However, they can be difficult to integrate since the widely used S-parameter matching method cannot simply be applied. Fortunately, a generic method derived from the mixed-mode S-parameter concept can be used to match differential devices. It is simple and effective, as will be borne out by verification via four-port vector network analyzer (VNA) and...  — Stephane Wloczysiak

February 2010   [Components]
Optimize Class E Power Amplifiers
Amplifier efficiency is essential not only for mobile devices, but increasingly to conserve power consumption in wireless communications base stations and cell sites. The Class E amplifier in this article produced efficiency of 60 percent from 1.9 to 2.2 GHz using a standard packaged transistor. 1 The techniques used to design and build this amplifier can be employed to design Class E amplifiers at any frequency of interest. The Class E...  — Gayle Collins , et al.

January 2010   [Test & Measurement]
System Performs FM Radio Drive Testing
Commercial automotive AM/ FM radios must perform dependably under a variety of operating conditions. Because designers of these radios employ digital-signal-processing (DSP) algorithms to overcome the effects of reflections, signal multipath, and fading, they often spend weeks in the field analyzing the effects of different signal conditions. A more practical and less time-consuming solution is the use of actual recorded radio signals to simulate the...  — David Brace , et al.

January 2010   [Test & Measurement]
Analyze Phase Noise In A Sampled PLL, Part 1
Phase locked loops (PLLs) have been used for years to stabilize signal sources such as oscillators. In the past, loop bandwidths tended to be small compared to the sampling frequency, but with modern communications systems, requirements for faster switching times mean that this is no longer the case. Narrow-bandwidth PLLs can be effectively modeled and simulated by means of linear analysis, but these same approaches fall short for ...  — Peter Beeson

January 2010   [Components]
Match Loop Antennas Via Mutual Inductance
Loop antennas are widely used in small wireless products, particularly for UHF bands between 300 and 1000 MHz. They are small in size relative to wavelength, independent from a ground plane, and relatively immune to the influence of nearby objects. They are also easily implemented in printedcircuit form with corresponding low cost. But their low radiation resistance makes them difficult to match and subject to low efficiency. They exhibit high...  — Alan Bensky

January 2010   [Components]
Dissect PA Distortion From OFDM Signals
Power-amplifier (PA) distortion must be minimized in any broadcast application to prevent interference with adjacent channels. Distortion can be present in the form of amplifier clipping, intermodulation distortion (IMD), and memory effects. For some communications standards, such as Brazil’s ISDB-T standard, which is based on orthogonal frequency- division-multiplex (OFDM) modulation, excessive phase distortion in the transmit amplifiers...  — Jose De Souza Lima , et al.

December 2009   [Components]
Class F Amplifier Boasts High Efficiency
Pulsed radar systems require high power levels but, increasingly, also demand power amplifiers with high efficiency. To meet those needs at L-band frequencies from 1200 to 1400 MHz, a Class F amplifier was developed with reduced conduction angle to maximize efficiency. The amplifier employs four parallel, internally matched silicon-bipolar transistors in a common-base configuration. They are biased in Class C mode to achieve the high output power levels required by pulsed radar systems....  — Sami Bousnina , et al.

December 2009   [Components]
Triband Cellular Antenna Tackles E-Field Testing
Antennas for wireless applications must handle more bands than ever before, given the growing number of cellular and other wireless standards contained in handsets and base stations. In support of measurements to be performed on cellular base stations, the authors have implemented a printed-circuit dipole antenna on a two-layer RO4350B laminate from Rogers Corp. The compact printed antenna covers cellular bands at 900, 1800, and 2100...  — Dimitris Kolokotronis , et al.

December 2009   [Materials]
Microwave Materials Lay Foundation For PAs
Power-amplifier designers typically create a circuit based on specific active devices for the output stage. While the choice of transistor determines the ultimate performance of an amplifier, printed-circuit-board (PCB) materials can also play a major role in an amplifier design. Selecting optimum substrate materials for an amplifier can improve gain and stability, and enable the maximum output power possible for a design. High-frequency amplifier designers have a wide array...  — John Coonrod

December 2009   [Components]
Examine Antenna Tunability In Implanted Systems
Electronic devices are increasingly being implanted inside the human body to improve medical diagnostic or therapeutic efficacy. Fine tuning these devices requires communications with medical professionals, yet direct communications are problematic due to the locations of these systems within the body. A growing trend has been to communicate with these systems by means of wireless RF transceivers. Care must be taken when designing an antenna for such systems as canonical antenna design methods...  — Mark Lanciault , et al.

November 2009   [Computer-Aided Engineering]
Simulating RF Tuned Stages
Assessing post-production- tuning (PPT) elements should be part of any RF worstcase circuit analysis (WCCA). Unfortunately, PPT elements are often omitted or incorrectly incorporated into an analysis, even though including such tuning elements into a computer-aidedengineering (CAE) model is often a simple task. Correctly accounting for PPT elements depends on the ability to define the PPT procedure and to mathematically define the relationships ...  — Steven M. Sandler

November 2009   [Components]
Examine Balanced Twisted Bifilar Lines
Balanced twisted bifilar transmission lines have broad applications for any circuits in which impedance transformations are required. By using a vector network analyzer (VNA), it is possible to measure the characteristic impedance of these balanced transmission lines in order to design desired impedance transformations. Measurements with a VNA can be made by using a balancedunbalanced (balun) transformer that converts a balanced network to an unbalanced network. In...  — Antonio Alves Ferreira, Jr. , et al.

November 2009   [Computer-Aided Engineering]
Analyze BER Performance Of Wireless FSK Systems
Modern communication systems employ digital modulation for a variety of reasons, including improved immunity to noise and channel impairments as well as enhanced security compared to analog modulation. In addition, advances in very large-scale integration (VLSI) and digital signal processing (DSP) technology have made digital modulation more cost effective than analog transmission systems. Digital transmissions accommodate digital error-control...  — Hamood Shehab Hamid , et al.

November 2009   [Test & Measurement]
Configuring Software For WiMAX Testing
Manufacturing test requirements for Wi- MAX and wirelesslocal- area-net-work (WLAN) devices must be comprehensive yet flexible. Traditional test solutions consist of three independent elements: chipset control software from the integrated-circuit (IC) vendor, test equipment, and the test software (or test executive), which allows the execution of an automated test plan. To save test engineers time and effort, test equipment vendors have combined...  — Robin Irwin

October 2009   [Computer-Aided Engineering]
Analyzing WiMAX Modulation Quality
Advanced wireless communications standards rely on complex modulation schemes to achieve high bandwidth efficiency. WiMAX, for example, employs the orthogonal frequency division multiplexing (OFDM) technique.1 Due to many challenges with such complex modulation formats, sophisticated simulation and verification tools and approaches are required to achieve optimum system-level performance. For example, the transmit modulation accuracy depends...  — Bill Wu

October 2009   [Materials]
Form GaAs/InGaAs Lasers On Virtual Ge
Reliable GaAs-based optoelectronic devices, such as GaAs/InGaAs quantum well lasers, can be realized on silicon substrates using several advanced techniques. Fabrication involves first forming germanium (Ge) stripes on a silicon dioxide (SiO2) trench-patterned silicon substrate via aspect ratio trapping (ART), where any defects originating from the Ge/Si interface are trapped by laterally confining sidewalls. Defects arising from above the...  — J. Bai , et al.

October 2009   [Components]
Extract Petroleum With Microwaves
Petroleum can be extracted from tar sand and oil shale given an appropriate microwave applicator. These two materials are abundant on the North American continent and represent large reserves of low-viscosity crude petroleum. Microwave technology may provide a relatively cost-effective means of extracting the crude petroleum from these deposits of tar sand and oil shale. The most commercially accepted method of in situ extraction of...  — Dr. A. Kumar

October 2009   [Devices & ICs]
Digital RF Processor Serves Plethora Of Cellular Systems
Digital RF processors (DRFs) offer the potential of meeting the requirements for a wide range of cellular telephone wireless standards without significant changes in design and hardware. A DRP design is detailed here, with digital receive and transmit sections, although one of the key components within the DRF is the frequency synthesizer, which employs a novel approach to phaselock- loop (PLL) implementation. Newer cellular telephones are...  — Louis Fan Fei , et al.





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