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December 2008 Nonlinear Models Aid PIN-Limiter Design Process CIRCUIT AND ELECTROMAGNETIC (EM) simulators now offer many capabilities to make software prototyping successful, including accurate models. To provide an example of how such models can assist the design process, Modelithics, Inc. offers a nine-page application note, “Accurate Non-linear Models Enable Successful PIN Limiter Design,” which focuses on the design and validation of a 1.8-GHz PIN-diode limiter circuit. The design uses... — Nancy Friedrich December 2008 RFID Tag Mounts Directly On PCB GENERALLY, ULTRA-HIGH-FREQUENCY (UHF) radio-frequency- identification (RFID) tags are applied to a piece of equipment once the assembly is complete. Yet a new approach allows the implementation of the RFID tag directly on the printed-circuit board (PCB) early in the production process. A small RFID-module package, dubbed the MAGICSTRAP, integrates both the RFID tag integrated- circuit (IC) and broadband RF-matching functions. Murata delves into the... — Nancy Friedrich November 2008 UWB GPR Receiver Detects Waterpipe Leaks Ground-penetrating-radar (GPR) systems based on ultrawideband (UWB) generation and reception of reflected signals are often associated with military applications such as land-mine detection. But because of aging waterpipe infrastructure in many major cities within the European Union (EU), a UWB-based GPR system also has application for detecting leaks in underground waterpipes. The cost of replacing these aging waterpipe systems, if left to deteriorate beyond a... — Anastasios Garetsos , et al. November 2008 Adaptive Beamforming Raises WiMAX Capacity Compared to third-generation (3G) networks, mobile WiMAX has garnered attention for being a more affordable technology for transferring large amounts of data with high throughput. This advantage can be further magnified by adaptive beamforming. This technology vows to improve both the range and capacity of a WiMAX network. At the same time, it reduces capital and operating expenses by minimizing the number of base stations that are needed in a network. The... — Nancy Friedrich November 2008 ADC Mysteries Are Finally Explained Analog-to-digital Converters (ADCs) have both analog and digital functions. Most simply, an ADC can be considered a device that provides an output that digitally represents the input voltage or current level. The analog input is compared to the ADC’s analog reference voltage or current. The digital output word denotes what fraction of the reference voltage or current is the input voltage or current. In essence, the ADC is a divider. These definitions hail from the... — Nancy Friedrich September 2008 Forming A Voltage-Tuned Microwave Phase Shifter Phase shifters are critical components in scanned phased-array antenna systems for both commercial and military applications. Phase shifters can also be combined with transmitter power amplifiers to improve system linearity in cellular communications networks. By using different phase-shifting elements in an antenna array, a beam can be effectively steered electronically, rather than mechanically shifting an antenna. Phase shifters are traditionally based on... — Jack Browne August 2008 Proper Mounting Ensures Power-Transistor Performance Achieving performance expectations for highfrequency components requires proper implementation. In the case of RF power transistors, for example, the device-to-heatsink interface establishes the heat transfer path and RF ground. In application note PKG001, “Proper Mounting of RF Power Transistors,” HVVi Semiconductors details the heatsink surface preparation, maximum torque required to tighten the screws, and the proper procedure for connecting leads. ... — Nancy Friedrich August 2008 Overcome UWB Test Challenges Ultra-wideband (Uwb) communications is seen by many as an enabling technology for many short-range applications. Low signal-to-noise transmissions enable it to avoid interference with co-located wireless signals. Specifically, UWB signals must have low spectral densities just above the thermal noise floor. To achieve this goal, the UWB transmitter power is restricted to low levels and spread over wide bandwidths. UWB signals also have redundancy built into them,... — Nancy Friedrich July 2008 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 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 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 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 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 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 May 6, 2008 Wireless Modules Score A Hit At Clay Pigeon Shoots Short-range radio device specialists Low Power Radio Solutions (LPRS) has developed an unusual application using wireless technology that means clay pigeon shooting can be enjoyed without firing lead shot around the countryside. The application is being used by leisure pursuits company Lasersport International... — Paul Whytock March 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 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 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 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 Determine Twisted-Line Characteristic Impedance This approach shows how to calculate and measure the characteristic impedance of balanced twisted bifilar transmission lines using a commercial vector network analyzer. ANTONIO ALVES FERREIRA JUNIOR Electronic and Electrotechnical Department National Telecommunications Institute (INATEL), 510 João de Camargo Ave. 37540-000, Santa Rita do Sapucaí, Minas Gerais, Brazil; e-mail: ... — Antonio Alves Ferreira, Jr. , et al.  prev. page
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