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Zetex makes lnb breakthrough
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11/12/2006
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Zetex is claiming a technical breakthrough in the development of a 4:2 IF switch aimed at satellite tv applications.
The ZXHF5000 boasts 30dB of channel isolation at frequencies of up to 2GHz. In addition, says the company, by adding 19dB of gain, the part avoids the 7dB insertion loss normally prevalent in traditional passive switch solutions. This combination of high isolation and positive gain has, until now, proven too difficult to overcome.
Geoff Stokes, senior development engineer, said the main difficulty was in achieving isolation with integrated gain. “It’s affected by your choice of package and pin layout. With 20dB of gain and 30dB of crosstalk isolation, you need at least 50dB and that’s a design challenge.”
Richard Robinson, Zetex’ DBS marketing manager, noted the chip was replacing four discrete parts – a switch, two cable driver amps and a threshold detector. “So we score points in terms of component count reduction, size and cost.”
Zetex has extended the frequency range to cover 200 to 2150MHz, where previous parts operated from 950MHz upwards. Whilst one reason is to cater for hdtv delivery in the US, the part can also be used as a distribution switch for terrestrial tv.
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Author
Graham Pitcher
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