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ISSUE DATE: JANUARY 2006 | |
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January 2006 - In This Issue [Cover Story] SiGe Silences YIG Oscillator Phase Noise Cutting phase noise from an oscillator can dramatically improve the performance of a microwave receiver or transmitter. Yttrium-iron-garnet (YIG) oscillators are usually the source of choice for designs requiring low phase noise, wide modulation bandwidths, and moderate tuning speed, and many refinements have been achieved in packaging the technology in recent years, but no true advances in lowering the phase noise. That is, until the engineers at Micro Lambda Wireless (Fremont, CA) blended... — Rich Leier [News] Tracking Trends In Test Equipment Test equipment is the great enabler for developers of high-frequency components, devices, and systems. It must be accurate and reliable, and not impossible to use or program. Instrumentation has evolved over the most recent decade to reach new levels of power and flexibility, with the most dominant trend the increasing role of the embedded microprocessor for command, control, and data manipulation. What follows is a brief review of some recent trends in high-frequency measurement equipment... — Jack Browne [Design Features] Test Handset PA Phase And Amplitude Vs. Time Amplifier reuse is a common way for mobile communications designers to reduce manufacturing material costs to a minimum as they develop new networks. For example, the same power amplifier (PA) developed for GSM and GPRS is also be used for EGPRS applications. Unlike GSM and GPRS, however, EGPRS is sensitive to PA nonlinearities, which can significantly and negatively affect the performance of an EGPRS handset. To use a GSM PA for EGPRS, developers must add calibration factors to compensate... — Marc Brodeur [Design Features] Amplifying PA Theory For Efficient ISM Transmitters Short-range applications in the industrial-scientific-medical (ISM) bands between 300 and 450 MHz are rapidly expanding. Key components for these applications are low-cost amplitude-shift-keying (ASK) and frequency-shift-keying (FSK) transmitter integrated circuits (ICs), although proper system design involves balancing output-power and current-drain requirements for the transmitter's power amplifier (PA). Fortunately, some straightforward techniques make it possible to manage this trade-off... — Andy Zocher [Design Features] Darlington Gain Blocks Eliminate Bias Resistor Wideband Darlington RF gain blocks are commonly used in wireless and wire-line applications. Their strong broadband linearity makes them suitable for base-station predrivers, repeater-pole transceivers, fiber-optic transceivers, cable-television (CATV), and instrumentation systems. Unfortunately, conventional Darlington gain blocks need an external-dropping resistor to set and stabilize the bias current. To ensure good temperature stability, an overhead voltage of about 2 to 3 V is applied.... — Tim Gittemeier , et al. [Product Technology] Enhanced UltraCMOS Yields GSM/WCDMA Switches CMOS process technology was once thought unsuitable for RF applications. But some companies are pushing CMOS well past those early expectations, including Peregrine Semiconductor (San Diego, CA). The latest version of their UltraCMOS process benefits from the company's HaRP? technology enhancements, which provide dramatic improvements in harmonic and linearity performance—particularly important for wireless applications. The company has fabricated several single-pole,... — Jack Browne [Product Technology] Differential Amp Buffers ADCs To 2 GHz Differential circuitry provides a proven means of suppressing noise in analog and digital designs. An increasing number of analog-to-digital converters (ADCs) are being offered with differential inputs, while even RF frontend components, such as mixers, are adopting a differential architecture. Of course, gain is often needed with these function blocks, implying the requirement for a differential gain block. The new AD8352 low-distortion amplifier from Analog Devices ( Norwood, MA) works... — Jack Browne [Product Technology] Scopes Pack Big Power Into Small Footprints Cathode-ray tubes (CRTs) have traditionally dictated the minimum size of a high-performance oscilloscope. LeCroy Corp. (Chestnut Ridge, NY) broke with tradition several years ago with their WaveSurfer line of general-purpose oscilloscopes based on a bright 10.4-in. liquid-crystal-display (LCD) screen that resulted in only 6 in. of instrument/screen depth. The company has gone one step further by bringing that instrument form factor to high-performance measurements, in its new line of... — Jack Browne [Editorial] Thinking Back Over Our History ALLOW ME TO OFFER a change of pace for those readers who may have grown familiar with the face of our Technical Director, Jack Browne, on this page. Beginning with this issue, I will be spending more time with you in this space. Jack will be free to explore his many other projects for our organization, which include the newly launched Penton's Military Electronics digital magazine (for a free subscription, visit www.mwrf.com/milelec). His experience and insight will still guide this... — Nancy Friedrich [White Paper] White Paper: Low-Noise Amplifiers Drop Below 1-dB Noise-Figure Mark Sponsored by Richardson Electronics Low-noise amplifiers (LNAs) can be found in the front end of virtually all communications receiver designs, especially those where signal sensitivity is critical. The first-stage LNA in a receiver is a critical component since it essentially sets the limit for how low the system noise figure can reach. While LNA noise figures approaching as low as 1 dB have been available commercially, few devices ever reach noise... — Chris Marshall |
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