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ISSUE DATE: APRIL 2005 | |
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April 2005 - In This Issue [Cover Story] RF Modulator Enables Multicarrier Transmitters Cellular transmitters rely on high-performance RF modulators to maintain linearity and dynamic range. With the growth of multicarrier transmitters, RF modulators must maintain a low noise floor while also delivering good high-level performance as determined by the second- and third-order intercept points. Fortunately, the MAX 2022 direct quadrature RF modulator from Maxim Integrated Products (Sunnyvale, CA) provides the performance needed from 1500 to 2500 MHz to support a wide range of... — Ron Gatzke [News] Cables And Connectors Make Microwave Links Cables for microwave applications come in many lengths and sizes, and with a variety of connector options. Suppliers offer everything from spools of unterminated cables to specific lengths of assemblies with connectors, and even phase-matched sets of cable assemblies. What follows is a brief review of microwave cable assemblies for general-purpose system and measurement applications. In their excellent tutorial text, Practical RF Circuit Design for Modern Wireless Systems... — Jack Browne [Design Features] Equalize Gain In Millimeter-Wave Amplifiers Gain rolloff in broadband high-frequency amplifiers can be overcome by a number of strategies, including an easy-to-implement topology with two amplifiers and a microstrip filter. The simple use of bond wires and a pair of thin-film chip resistors can provide the response needed to flatten gain at millimeter-wave frequencies. These proven techniques have been used for amplifiers in radiometers of the PLANCK mission operating with 20-percent bandwidth at 30 GHz. The topology and approach... — B. Aja , et al. [Design Features] Method Validates SAR Measurement Systems Specific-absorption-rate (SAR) measurements are critical for understanding the effects of nonionizing radiation, such as the emissions from cellular telephones and cellular base stations, on humans and other biological organisms. As noted last month, a modified waveguide-source technique can help to validate the test systems used for SAR measurements when used in the range from 5 to 6 GHz. Part 2 of this article will show how this technique can help minimize measurement inaccuracies due to... — Dr. Mike I. Manning , et al. [Design Features] Design An E-pHEMT 4.9-to-6.0-GHz LNA Low-noise amplifiers (LNAs) are invaluable for increasing the sensitivity and range of a microwave receiver. For applications at 4.9 to 6.0 GHz, which include IEEE 802.11a, HiperLAN2, and HiSWANa wireless-local-area-network (WLAN) receivers, a two-stage design based on enhancement-mode, pseudomorphic high-electron-mobility-transistor (E-pHEMT) device technology delivers 22 dB gain at 5.5 GHz, with a low noise figure of 1.4 dB and +11.5-dBm output power at 1-dB compression. The amplifier... — Ian Piper , et al. [Design Features] Model Optical Transmitters With A Circuit Simulator Microwave design engineers find themselves dealing with an increasing number of optical components, as communications systems become hybrid combinations of wired, wireless, and optical components. In order to perform simulation and analysis of these high-frequency "hybrid" circuits, it can be useful to learn how to apply a commercial circuit-simulation program such as the APLAC RF Design Tool simulator from APLAC Solutions Corp. (Espoo, Finland, www.aplac.com) for this modeling assignment.... — Teemu Akajoki , et al. [Product Technology] Antenna Modules Demystify Wireless Designs Antenna development remains one of the more mysterious sides of RF design, due to the complex electromagnetic (EM) fields transmitted and received by antennas. In the hopes of demystifying antennas for many wireless applications, Antenova Ltd. (Cambridge, England) has launched a range of antenna modules that integrate and match the antenna with the surrounding RF components. Available in various cellular, Personal Communications Services (PCS), and wireless-local-area-network (WLAN)... — Jack Browne [Product Technology] Digital Scopes Battle Jitter With 100-GHz Bandwidth Serial data rates are continuing to increase, further emphasizing the critical nature of accurate and repeatable jitter measurements. To provide insight into such complex signal-integrity issues, the WaveExpert 9000 from LeCroy (Chestnut Ridge, NY) offers a fast sampling rate and interleaved sampling time base. With these features, a complete signal waveform can be displayed and measured without a separate pattern trigger. A second oscilloscope from the company, the SDA 100G,... — Nancy Friedrich [Editorial] Making Time And Shifting Priorities Time is the enemy of us all. For those who live in joy, time is too short. But for those in pain, the time cannot be short enough. For engineers working in a world of modern demands, most days are spent trying to cut time to market or to complete a design, or to find time for another design iteration or additional set of measurements. As difficult as it may seem, it is sometimes necessary to stop time, or at least pause long enough to evaluate priorities. As the writer of this... — Jack Browne |
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