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ISSUE DATE: MAY 2006 | |
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May 2006 - In This Issue [Cover Story] SiGe T/H Amplifier Grabs Wideband Data Wideband data-acquisition modules are needed for numerous emerging applications, from software-defined radios (SDRs) to real-time digital radar. System designers often point to the ideal of an antenna feeding a high-speed analog-to-digital converter (ADC). In reality, filtering frequency translation follow the antenna, while a buffer or track-and-hold (T/H) amplifier precedes the ADC. Since the ADC likes to “see” constant amplitude, a T/H amplifier capable of high... — Jon R. Firth [News] Microwave Show Comes To The City By The Bay FOR A WEEK, THEY WILL SWARM THIS TOWN, INCREASING its population by more than 10,000. They will marvel at the local attractions, like Fisherman's Wharf and Alcatraz, and look out over the San Francisco Bay to the majestic Golden Gate Bridge. And they will come with stories of their research and their accomplishments, making over 1000 technical presentations during the week. For this is the week of June 11-16, 2006, and the 2006 edition of the International Microwave Symposium ... — Jack Browne , et al. [Design Features] Diode Quad Is Foundation For PIN Diode Attenuator Adjustable attenuators are useful in a variety of communications applications, for example, to control signal levels in receivers and transmitters. In particular, high linearity is a key requirement in many modern communications systems. By using a low-cost, SOT-25 surface-mount diode quad from Avago Technologies, it is possible to build a simple voltage-controlled attenuator with outstanding linearity performance over a wide frequency range from 0.3 to 3000 MHz. This type of attenuator... — Lim Yeam Ch'ng , et al. [Design Features] Extending Phase-Noise Measurement Capability Phase-noise measurements are an important part of many microwave designs, especially when developing oscillators, phase-locked loops (PLLs), prescalers, frequency converters, and frequency synthesizers. Since a phase-noise measurement system represents a considerable investment, teams of designers or an entire facility often share a single phase-noise test system. Extending the system's performance can thus benefit an engineering team or group of teams. For test systems based ... — Chris Desalvo [Design Features] Stabilize Transistors In Low-Noise Amplifiers Low-noise amplifiers (LNAs) form the input stage of the receiving part of nearly any communications system. The main task of these subcircuits is to amplify the wanted signal without deteriorating the signal-to-noise ratio. In most cases, the desired signal is very weak. The noise figure is seen as the main describing figure of merit for the transistors used in such applications. It determines the minimum amount of noise that is added in the transistor stage. The noise figure... — Ulrich Delpy [Design Features] Low-Power Approach Provides QPSK Modulation Quadrature-phase-shift-keying (QPSK) modulation is an effective means of achieving high bandwidth efficiency in wired or wireless communications systems. QPSK modulation can be generated with a direct-digital-synthesizer (DDS) approach, which requires additional components, and tends to be expensive and consume power. An alternative method employs two mixers, one set to a fixed RF and the other driven by a voltage-controlled oscillator (VCO). However, mixing... — Cecil Deisch [Design Features] When Switching Speed Is Important Microwave frequency synthesizers provide the stable signals needed in a wide range of modern electronic systems, including communications systems, civilian and miliary radars, and electronic-warfare (EW) systems. They are available in many configuarations, from the tiny integrated circuits (ICs) embedded into cellular telephones to the rugged, rack-mount enclosures used in naval shipboard radar systems. Microwave frequency synthesizers can be compared in terms of ... — Uri Yaniv [Design Features] RF Antenna Switches Simplify Telematics Radios Telematics, a combination of computer and telecommunications technologies, is being applied in several fast-growing markets, including the automotive industry. Telematics enables remote diagnostics, on-demand navigation, emergency assistance, fleet or stolen vehicle tracking, and intelligent transportation systems. As automotive telematics devices become more widespread, designers face the same problem with the evolution of any communications application: adding features... — Brian Arnold [Design Features] Measure Frequency With Time-Stamping Counters Frequency counters at one time were considered fundamental measurement tools almost in the class of a voltmeter. They offered the capability of measuring a CW signal with fairly high resolution, depending upon modulation, and were largely used for calibrating oscillators. As frequency counters evolved, instruments were developed with pulse-measurement capability and wider measurement bandwidths capable of handling measurements on modulated waveforms. Modern frequency counters... — Staffan Johansson [Special Report] Emerging Applications Fuel Antenna Development Last October, a radar antenna wreaked havoc at Boston's Logan Airport. According to the Boston Globe, test results fingered antenna as the cause of erroneous blips on their air-traffic controllers' radar screens. Those blips or "false targets" set off collision alarms. Although a replacement radar antenna resolved the issue, the fix did not come until many flights were delayed over two days' time. In addition, the Deferal Bureau of Investigation ... — Nancy Friedrich [Product Technology] FBAR Duplexers Help Shrink PCS/UMTS Handsets Small handsets require small components. Avago Techologies is no stranger to designing and fabricating miniature active and passive components for both cellular handsets and infrastructure equipment. Using their proprietary film-bulk-acoustic-resonator (FBAR) technology, the company has developed a pair of duplexers that are suitable for a variety of wireless applications, including US Personal Communications Service (PCS) and Universal Mobile Telecommunications... — Jack Browne [Product Technology] Rugged LDMOS Device Drives 500 W At 500 MHz Designers seeking to generate high output power in broadcast and radar systems are nonetheless hoping to do so in the smallest device/circuit footprint possible. For HF/VHF broadcast and UHF radar markets, the new BLF369 LDMOS transistor from Philips Semiconductors is not only compact, but also delivers a generous 500 W CW output power from HF through 500 MHz. Fast pulse rise and fall times result in large differential current-versus-time (di/dt) values for a... — Scott Blum [Product Technology] Chip Supports Dynamic Point-To-Point Systems Spectrum is precious and limited. Most networks divide it up into channels and then portion it out to subscribers. The PVG 310 single-chip modem from Provigent, Inc. (Los Altos, CA) offers a more efficient alternative for designers and operators of point-to-point wireless links by allowing them to prioritize and optimize their links according to traffic and link conditions. The chip's Provi-Band? technology is based on an adaptive code and modulation mechanism that... — Jack Browne [Editorial] Bridging The Past And Future Of RF THIS YEAR marks the 45th anniversary of Microwaves & RF (or MicroWaves for those of you from the early years). Although we are running different special features throughout the year, our biggest endeavor is the "Microwave Legends." With help from you—our readers—we have compiled a list of these legends. It is a kind of "hall of fame" for the people, places, and things that have made the RF industry what it is today. Our goal is to narrow... — Nancy Friedrich |
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