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James Wong of Linear Technology on High Performance Synthesizers

Wed, 09/28/2011 - 8:08am

JanineABM
In today's podcast we talk to James Wong of Linear Technology on the new High Performance Synthesizer which can be used in various applications.

Hosted by Janine E. Mooney, No Strings Attached - Your Wireless Broadcast is Wireless Design and Development's web-based interview show where we talk about the latest wireless technology, components, and design issues for the wireless design engineering community.

JamesWong

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Right-click to download the podcast


Here is another link ot the podcast in case the playback button is not working: JamesWong-LinearTech


Here is a recent press release on Linear Technology's efforts:

LinearTech-HotShot-web1Backgrounder for the LTC6946 Ultralow Phase Noise & Spurious Integer-N Frequency Synthesizer

Wireless Market Trends
The relentlessly accelerating use of smart phones, tablets and network-centric devices continues to put pressure on mobile wireless network upgrades to alleviate congestion. The rush to deploy the next generation LTE network is gaining momentum. Virtually all wireless carriers have some sort of deployment plan for LTE, and the nascent LTE-ready smart phones further reinforce this trend.

But carriers are struggling to manage dissimilar standards and frequency spectrum as the industry navigates through successions of consolidation. The core issue facing carriers is that LTE is a new network overlay and carries with it an enormous build-out cost. Investments of such magnitude are warranted only if the new network has built in as much obsolescence-proof features as is reasonable. One cost-allaying strategy is to have a single, universally configurable platform - independent of standards. Such requirements are rapidly gaining endorsements. Previously, specific carriers owned different 20MHz slivers out of the total available 60MHz frequency spectrum, allocated to serve various markets. The 60MHz may be divided among multiple carriers competing within a market. To realize a single platform, the bandwidth must increase from 20MHz to as high as 60MHz. Moreover, the system must now be made software-configurable to accommodate the different standards.

Wider Bandwidth Necessary for High Data Rate
Increasing the operating bandwidth has significant performance impact. The technical reality is that for every doubling of the channel bandwidth, the wideband noise floor increases by a factor of 3dB. And as the industry pushes bandwidth to 60MHz, the network system degradation will be negatively impacted by a factor of about 4.8dB.

This degradation is a tough challenge to overcome. Engineers are already pushing their designs to the limit of their existing components by squeezing the last dB out of their transmitter and receiver performance. Clearly innovation is needed. The frequency carriers that are synthesized to power the transceivers often establish the fundamental noise floor by which the transceivers operate. Hence it is an important milestone that Linear Technology's new synthesizers with integrated VCO deliver phase noise and spurious product levels that improve on the current state of the technology. This enables the transmitters and receivers to operate at a lower noise floor, hence counteracting the negative noise impact by the opening of the bandwidth. So basestations can achieve their bandwidth goals without trading off performance.

Multiband, Multimode Operation
To attain true multiband operation, basestations must be able to operate in all the frequency bands, including 700MHz LTE, 800MHz CDMA, 880MHz GSM, 1800MHz CDMA, 1900MHz LTE/W-CDMA, 2.1GHz LTE/W-CDMA and 2.4GHz LTE. This challenge is made more difficult by the requirement that the same basestations must be universally configurable to be compatible to all communication standards, with varying bandwidth.

The LTC6946 synthesizer with integrated VCO has a built in wide frequency tunability range to address the multiband requirement. With proper selection, a single part can support all the cellular frequency bands from 700MHz to 2.7GHz. At the same time the product delivers outstanding phase noise performance that supports the wide bandwidth requirements.

For more information, visit www.linear.com.

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