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RF Shorts: Other Items of Interest - Dec. 10, 2009

If you've been reading RF Report over the last several weeks, you know that there is an effort to take spectrum away from free off-air TV broadcasting purposes so that it can be auctioned to wireless carriers who will use it to sell you pay broadband and subscription multimedia services. Holman W. Jenkins, in his Wall Street Journal article The Rabbit-Ear Wars doesn't see broadcasters giving up the spectrum as easily as the FCC's Blair Levin imagines.

"For the truth is, broadcast offers impressive economies for distributing rich media content compared to the Internet," said Jenkins. "An infinity of users can be served by a single bitstream. It doesn't matter how many receivers tune into a TV broadcast. It never gets overloaded."

As if to underscore the point, additional stories on the topic appeared Wednesday, such as this one: AT&T considers incentives to curb heavy data usage on CNET news, showed that streaming video over the Internet was not a cost-effective way to deliver wireless multimedia content. We should learn more about the FCC's broadband plans in its Dec. 16 open Commission meeting [PDF].

About 15 years ago, Cree, a North Carolina-based semiconductor manufacturer, was demonstrating silicon-carbide transistors which were being mentioned as the solution for high power solid-state TV transmitters. A prototype unit was even displayed at NAB. The high-temperature silicon carbide transistors haven't displaced LDMOS as the architecture of choice for high power solid-state devices, but Cree hasn't given up on RF.

Last week it acquired a portfolio of patents and related applications for higher-end RF silicon-carbide chips using a process called vanadium doping from Daimler AG. Cree has previously licensed that technology.

"Silicon Carbide is typically an electrically conductive material when it is grown," said Michelle Murray from Cree's corporate communications department. "Adding vanadium allows one to easily convert the SiC [silicon carbide] from a conductor to an insulator. Semi-insulating SiC is preferred for high-power RF transistor applications such as cellular communications or military radio broadcast."

See the Cree press release Cree Acquires Semi-Insulating Silicon Carbide and Power Device Patent Portfolio from Daimler AG and Cree acquires package of patents for producing high-power chips on for more information.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.