February 2007

By Judy Miller
Associate Publisher


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Power Electronics DVD
NOW AVAILABLE!

Dear Electronics Marketer,    

I am used to hearing that RF Design has won readership studies and that it is the favorite magazine of practicing RF and microwave/millimeter wave design engineers. Our audience management director has often said that she has the easiest job in the company because RF Design subscriptions renew themselves. However, at a recent conference I was surprised to hear a loyal reader and senior level engineer from  a major company comment about the joyful experience each issue of RF Design brings.

RF Design is the most serious technical journal in our company. Somehow "joyful" is just not the word I would use to describe reading this publication. Then, while looking through the recent reader profile of RF Design, it began to make sense. To the serious design engineers , RF Design offers techniques and solutions that cannot be found anyplace else---and that can be joyful. Joy springs from work that is elevating, absorbing and enlightening, and each issue of RF Design enhances that experience. 

Please contact me if you would like a pdf or hard copy of our readership profile and I will be happy to send one to you.

In the meantime, I joyfully invite you to look at the lineup for the February issue of RF Design and our supplement Defense Electronics and secure a place...

Judy Miller
Associate Publisher
212.204.4246

Semiconductor Technology
Designing Broadband High Power Amplifiers with GaN Transistors
Besides investigating the performance and design benefits of using gallium nitride (GaN) power transistors in broadband WiMAX applications, this article also discusses a design example of a high power amplifier using GaN-on-Si HEMT transistors. And presents measured performance data from such a design.

Tx/Rx Technology
Removing the Transmit SAW in WCDMA
For a WCDMA radio, there is typically always a transmit (Tx) SAW filter between the transceiver Tx output and the power amplifier.  The SAW has two purposes . First to reduce the transmit output from increasing the receivers (Rx) noise figure. And second to reduce out-of-band spurious and noise emission from the Tx. If the Tx SAW filters were eliminated, this would save area on the PCB as well as cost. The article analyses the trade-offs required to removing the Tx SAW from the transceiver and duplexer sections of the handset.

Next-Generation Wireless
Meeting Mobile WiMAX Performance Requirements
Incorporating many novel features, this article discusses a new generation chipset that is designed to meet the performance demands of mobile WiMAX handsets and laptops. The chipset includes a baseband chip that minimizes processing load on the host processor and a direct conversion radio, which supports 2 GHz and 3 GHz designs, as well as programmable channel bandwidths from 5 MHz to 10 MHz. A complete mobile WiMAX reference design is presented.

Time & Frequency
Arrival Time Detector Minimizes Phase Noise
This article shows how arrival-time detection technique can alleviate problems with current PLL and phase-frequency detector(PFD)techniques. The current PFD is actually an arrival-time detector that produces an inherent dead zone jittering glitch. To survive the dead zone jittering problem, the current PFD can only lock the signals with a phase offset. The phase offset will not only increase the phase noise for VCO and lower the loop gain, but also reduce the operating frequency significantly. In this article, the author shows how the dead zone jittering problem is resolved by the arrival-time detector so that the two signals now can be locked without phase offset, producing minimum possible phase noise for the VCO with maximum possible loop gain even at the highest possible operating frequency.

Product Focus: Amplifiers

Microwave/Millimeter Wave Components
Mission critical amplifiers perform under adverse conditions
Many mission critical applications like the improvised explosive devices (IEDs) counter jammers are used to pre-detonate IEDs or roadside bombs that are triggered by soldiers handset radios. The amplifiers used in such units come with many unique protection circuits that allow them to work reliably in any condition through special self-protection algorithms. This article describes such specialty amplifiers that have been designed to perform reliably under severe conditions, including open-short, overpower or over temperature. With enhanced reliability and survivability, the article shows that these power amplifiers can be incorporated in mission-critical systems without worry of failure.

Test & Measurement
Increasing the Probability of Intercepting Signals of Interest
Effective signal monitoring of wireless signals requires very high speed hardware with high resolution. This type of hardware will provide lots of signals in a spectrum, including intermittent or short-duration signals common with push-to-talk devices. If you recorded all of these signals, most of them would not be of interest to you. Plus, the amount of data available for capture would be so huge that the system design would be extraordinarily expensive. The sophisticated software driving this specialized hardware is mostly responsible for filtering and detecting only signals that are of interest. This article discusses some advanced methods for signal detection, so you can efficiently capture data on only wireless signals that are of interest. The concepts presented in the article have been implemented in the Agilent E3238S signal intercept and detection solutions.

Medical Electronics
Thermoelectric generators can enhance military medicine
Thermoelectric generators are typically high-current, low voltage devices that provide useable power from large temperature differences and significant heat sources, such as combustion. In this article, the author presents a new design for a micro thermoelectric generator that can produce small, though usable power from temperature differences as low as 5 degrees Celsius. The article shows that the technology can also be combined with other components such as capacitors or rechargeable batteries to increase short-duration power levels. Since the form factor of these thermoelectric generators is small, it shows that multiple units can be combined to achieve increased power levels. This introduces the capability to power devices from body heat. Lastly, the article investigates military medical systems, such as wireless patient monitoring, nerve stimulation implants or cochlear hearing replacements that can harness these capabilities.

Using the power of our print content, rfdesign.com offers a quick and easy-to-use resource for the latest information in the industry. Rfdesign.com features a database of searchable articles on VLF to UHF, RFICs, Microwave/Millimeter Wave Technologies, Software Radio, Emerging Wireless Technology and Military/Defense Electronics.

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