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Tuner leads DTV specs race

Posted: 10 Mar 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Janine Love? Microtune? tuner? silicon tuner? analog terrestrial?

Microtune's MT2131 chip

The team at Microtune Inc. is well versed in the needs of television applications around the globe, and about two years ago they decided to take on the challenge of designing a single integrated silicon tuner that received analog terrestrial, digital terrestrial and digital cable signals.

Of course, while this type of product would be attractive to simplify design and improve reliability, the big concern for Microtune's customers is cost. So they had to reach deeply into their bag of engineering tricks to sort out the performance versus size (cost) issues and develop a tuner that could reliably support the standards that will be co-existing until 2009 in the US, and even later in other countries like Canada and Mexico.

In terms of specifications, parts of this type are generally judged on their ability to meet the US ATSC broadcast standard for 8-Level Vestigial Sideband (8VSB) sensitivity and adjacent channel rejection.

Sensitivity determines a receiver's maximum distance from a broadcast tower as well as whether or not an indoor antenna will be adequate. "These are two key factors for customer satisfaction," observed Greg Zancewicz, director of broadband marketing at Microtune, "because while consumers might accept a poor quality analog signal in order to avoid mounting an outside antenna, a digital receiver simply will not receive any picture." The ATSC has specified sensitivity of -83dBm, and the MT2131 typically demonstrates sensitivity better than -84dBm.

Adjacent channel rejection is an equally important parameter. The ATSC committee has called for an aggressive specification of more than 40dB of adjacent channel rejection, and the Microtune MT2131 achieves 44dB.

"Meeting the ATSC A74 specifications was a tremendous challenge and one that no other single-chip silicon tuner solution is able to meet," noted Zancewicz. "We needed to meet these specs in a cost-effective solution while at the same time providing excellent analog terrestrial and digital cable performance."

What about design trade offs? "Actually, we don't feel that we traded very much off in this design. We expected power to be a challenge, but we actually came in more than 10 percent better than our target and over 20 percent better than our previous MT2121-based solution," said Zancewicz.

To get the job done, Microtune leveraged its design experience in silicon tuners. In the end, though, the MT2131 is really a first generation product for the company since it is the first tuner IC they have designed specifically for a terrestrial receiving application. Until now they have provided products for terrestrial applications using tuners that were first designed for cable applications.

If this tuner peaks your interest, you are in luck, because the company is already sampling application boards to television manufacturers. Volume production is scheduled for the second half of 2006. All of the company's evaluation boards include its internal ATSC, analog, and digital cable test results, as well as a documentation package that includes bills-of-material, Gerber files, and schematics. Microtune reports that its internationally based applications team is already trained in the MT2131 and ready to support new designs.

Housed in a 7-by-7mm 48-pin MLF package, the MT2131 tuner is priced at less than $3 in volume quantities.

- Janine Love

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