Electronic Design

LNB Makes Satellite TV Receivers Smaller And Cheaper Than Ever

Satellite TV is very popular in the U.S. as well as in Asia and Europe. The receivers are made in two parts: a front end mounted on the 18-in. dish antenna connected by coax to the inside box. NXP Semiconductor’s latest chip makes the front end better than ever.

The front-end circuit on the antenna, known as a low-noise block (LNB) converter, takes the Ku band satellite signals in the 10.7- to 12.7-GHz range and converts the entire TV bandwidth down to a lower intermediate frequency (IF) in the 900- to 2000-MHz range. The IF has all the video and audio on it, but the attenuation from the usually long coax to the receiver is much less at these lower frequencies. The critical circuit in the whole receiver is the LNB.

NXP's TFF1004HN is a single-chip Ku band DVB-S LNB containing the low-noise amplifiers (LNAs), mixer, buffer amplifier, and phase-locked loop (PLL) synthesizer. Made with the company’s QUBIC4G silicon-germanium (SiGe) biCMOS process, it features two input LNAs or pre-amplifiers for horizontally and vertically polarized antennas.

Internal detection and switching circuits select the horizontal or vertical input to the mixer. The noise figure is 9 dB. The switched frequency PLL synthesizer uses a external low-frequency crystal and covers the 9.75- to 10.6-GHz range. This combination has proved to be superior to designs using gallium-arsenide (GaAs) circuits and dielectric resonator oscillators (DSO).

The TFF1004HN targets Asian and European DVB-S receivers, but a version compatible for U.S. receivers is being developed. The package is a 4- by 4-mm, 24-pin heatsink very thin quad flat pack no-lead (HVQFN) package.

NXP Semiconductor

www.nxp.com

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