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July 2008 [Applications] Determine Total Radiated Power Performance Of PAs TOTAL RADIATED POWER (TRP) is an increasingly important performance parameter for power amplifiers (PAs) in Global System for Mobile Communications (GSM) infrastructure equipment. A PA’s TRP performance is very much affected by varying load impedance, which can be measured by simulating an over-the-air (OTA) testing environment. The Cellular Telecommunications Industry Association (CTIA) has an advanced specification for this topic, dubbed revision 2. 1 of the... — Nancy Friedrich July 2008 [Applications] Get Full Synchronization Performance At Current Clcok Speeds SYNCHRONOUS CLOCKING SCHEMES provide clock signals that are frequency locked at every transmission/ reception exchange. Such systems permit seamless data exchange at the highest possible rates. Due to different design tradeoffs, however, engineers often have to rely on asynchronous or plesiochronous systems instead of synchronous systems. NEL Frequency Controls (www.nelfc.com) has introduced a fourth option in its... — Nancy Friedrich June 2008 [Applications] Wireless Medical Devices Eye Three Core Standards RECENTLY, INTEREST HAS GROWN in the potential of wireless technologies to enable a new generation of mobile personal-healthcare devices. These efforts are summarized in a white paper by EZURiO titled, “Wireless Connectivity – the Key to Enabling Personal Medical Technology.” The seven-page document explains that three wireless standards— Bluetooth, Wibree, and WiFi—will most likely dominate the majority of medical applications. Four primary parameters... — Nancy Friedrich June 2008 [Applications] WiMAX and WiFi Make Strong Case For Users OVER TIME, WIMAX is expected to achieve similar attach rates to devices as WiFi. Yet it will not eclipse the usefulness of WiFi. In fact, service providers can bundle WiMAX and WiFi to deliver high-speed Internet connectivity in more places. In a joint paper from Intel and Motorola, the companies focus on the synergies between the IEEE 802.11a/g/n Orthogonal Frequency Division Multiplexing (OFDM) and IEEE 802.16e-2005 OFDM-Access (OFDMA) air interfaces. ... — Nancy Friedrich May 2008 [Commercial] Discrete LNAs Improve Performance Of GPS-Enabled Cell Phones GLOBAL POSITIONING SYSTEM (GPS) functionality is being widely added to cellular phones and other handheld devices. Yet cell-phone manufacturers are still placing restrictive requirements on device size and power consumption. To meet these conflicting demands, GPS receiver/processor integrated circuits (ICs) have been developed that incorporate onboard, low-noise-amplifier (LNA) front ends. The problem is that the noise performance and resultant system sensitivity... — Nancy Friedrich May 2008 [Communications] Mobile WiMAX Multi-Antenna Techniques Offer Carriers New Option FOR WIRELESS OPERATORS, the introduction of bandwidth- intensive, rich media applications means that more subscribers will begin to consume increasing amounts of data packets. To conquer the resulting capacity issues, operators can acquire more spectrum channels and deploy more sites. Yet these approaches are both inefficient and costly. In “A Practical Guide to WiMAX Antennas: MIMO and Beamforming Technical Overview,” Motorola asserts that mobile WiMAX—in... — Nancy Friedrich April 2008 [Communications] OTA Testing Evaluates Mobile-Device Performance OTA Testing Evaluates Mobile-Device Performance To more accurately predict the real-world performance of a mobile device, both standards organizations and network providers are increasingly turning to over-the-air (OTA) testing. The Cellular Telecommunications Industry Association (CTIA), for example, has defined the methods and set the standards for performing OTA testing. In a four-page white paper, RFMD (... — Nancy Friedrich April 2008 [Communications] Tie WiMAX RF Chipsets To 18-MHz Reference Frequency Tie WiMAX RF Chipsets To 18-MHz Reference Frequency RF chipsets are at the heart of WiMAX solutions for base-station hardware and customer-premise equipment (CPE). The TRF1xxx chipsets from Texas Instruments (www.ti.com), for example, house integrated synthesizers to realize a superheterodyne architecture. To achieve optimal channel resolution, these devices must be tied to an 18-MHz reference frequency.... — Nancy Friedrich March [Applications] Programmable Modulus Invites DDS Into New Applications A modification to the typical accumulator based, direct-digital-synthesis (DDS) architectures has emerged in the form of a programmable-modulus DDS. This modulus’ goal is to alter the accumulator modulus. Yet that task is complicated because the angle-to-amplitude converter maps the entire P-bit input range (0 to 2RP) to 0 to 2p radians. This hurdle and an explanation of the main differences between conventional and programmable-modulus DDS can be found in... — Nancy Friedrich March [Applications] Realize Thermal Considerations Of SMT Devices The RF performance of a surface-mount-technology (SMT) device depends on how well the thermal coefficients of expansion (TCEs) between device and board are matched as well as the design principles and consistency of materials in the device’s construction. Other factors impacting performance include the thermal-management techniques that are used to direct the device’s dissipated energy and the circuit-level methods that minimize reflective losses. In the... — Nancy Friedrich February [Applications] Adaptive Amplifier/Antenna/Cell Combinations Generate 10 To 200 V/m With today’s strict design requirements, engineers are forced to closely scrutinize data sheets. To help them take those specifications further, a series of application notes shows how amplifier/ antenna/cell combinations can generate 10 V/m, 20 V/m, 50 V/m, 100 V/m, or 200 V/m continuous wave (CW) or pulse modulated as well as with 80 percent amplitude modulation (AM) for radiated immunity testing. From 10 kHz to 40 GHz, such generation is done inside a... — Nancy Friedrich February [Applications] Development Guide Helps Engineers Build Better Test Systems Test engineers are under constant pressure to maximize performance and flexibility while minimizing cost and complexity. By providing practical advice and real-world examples, Agilent Technologies, Inc. hopes to help them achieve that goal in its 200-page, full-color, downloadable guidebook titled, “Test System Development Guide.” The guide is broken down into four sections: Test System Design, Networking Choices, LXI: The Future of Test, and RF/Microwave Test... — Nancy Friedrich January 2008 [Applications] Simulation And Measurements Prove RF-Relay Performance TODAY'S MANUFACTURERS ARE being pressured to put their parts through more rigorous high-speed/ high-frequency testing. Teledyne Relays (www. teledynerelays.com), for example, recently collaborated with two customers to evaluate the performance of its GRF relay series. This work is documented in the eight-page white paper, “Signal Integrity Performance of the Teledyne Relays GRF300/GRF303 Relay Series.” At the recommendation of its customers, Teledyne... — Nancy Friedrich January 2008 [Communications] OFDM Will Soon Be Dominant Form Of Digital Modulation ORTHOGONAL FREQUENCY division multiplexing (OFDM) is at the root of WiMAX and many next-generation technologies. This form of digital modulation is spectrally efficient, as it carries more data per unit of bandwidth than modulation formats used in services like GSM and W-CDMA. It also tolerates environments with high RF interference. In addition, OFDM works well in hard multipath environments. In “Orthogonal Frequency Division Multiplexing,” Keithley Instruments ... — Nancy Friedrich December 2007 [Applications] Broadband Access Will Mix Wireless With Wire-Line Technologies By 2015, five billion people will be "connected" - with the majority of them always on and enjoying broadband access. This estimate comes from Nokia Siemens Networks (Espoo, Finland). The company expects those broadband customers to be served by a mix of wireless and wire-line technologies. It explains this thinking while delving into those specific technologies in "Broadband Access for All - A Brief Technology Guide." This 21-page... — Nancy Friedrich December 2007 [Applications] Digital Phosphor Oscilloscopes Tackle Video Measurements Video measurements pose a tough challenge because of the complexity of video waveforms. Such waveforms often combine the signals that represent the video picture with the timing information that is needed to display the picture. Although some video measurements demand specialized instruments, others can be easily made with a general-purpose oscilloscope. In the 20- page application note, "Introduction to Video Measurements Using a 4000 Series Digital... — Nancy Friedrich November 2007 [Applications] Commercial Radios Make Leap From Single Carrier To MIMO COMMERCIAL RADIO TECHNOLOGY is moving away from single-carrier technologies, in which one digital symbol is transmitted at a time. At the heart of the new broadband connection is a modulation scheme called Orthogonal Frequency Division Multiplexing (OFDM). Aside from offering good spectral efficiency, OFDM is very tolerant of interference. It transmits hundreds of symbols simultaneously, but at a low rate per symbol. Keithley Instruments (Cleveland, OH) examines... — Nancy Friedrich November 2007 [Applications] Gain A Better Understanding Of Antenna Radiation Plots And Their Uses ANTENNA RADIATION PLOTS show a quick picture of an antenna´s overall response. To many individuals, however, radiation plots appear very confusing. The problem is that each antenna supplier and/or user has different standards and plotting formats. In addition, every format has its own pluses and minuses. To help people better understand and use antenna radiation plots, Astron Wireless Technologies (Sterling, VA) has created a technical note. This... — Nancy Friedrich October 2007 [Applications] DDS-Based Signal Sources Conquer Semiconductor Characterization With so many modern products relying on semiconductors, it is essential that the behavior of these devices be accurately evaluated. By emulating the waveforms found in actual applications, signal sources promise to help engineers accurately evaluate the behavior of some basic semiconductor devices. In “Semiconductor Device Characterization Counts on Flexible Stimulus Signals,” Tektronix, Inc. (... — Nancy Friedrich October 2007 [Applications] Raise The Visibility Of Remote Microwave Sites For network operators, support for analogmicrowave monitoring equipment is not always easy to attain. Yet many companies are still relying on microwave transport for their communications network sites. To help those operators improve site monitoring and maximize network visibility, DPS Telecom (www.dpstelecom.com) recently released a white paper titled, “Microwave Site Monitoring: A Guide to Achieving... — Nancy Friedrich  prev. page
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