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Single chip serves as satellite front-end

Posted: 11 Nov 2005 ?? ?Print Version ?Bookmark and Share

Keywords:Silicon Labs?

Satellite receivers typically feature complicated board layouts with many components, including a tuner, demodulator, and a power supply chip, and all of the associated routing of signals between these chips. These designs are challenged by having to avoid noise and interference on the PCB traces. The team at Silicon Laboratories decided to streamline these functions, and integrated the tuner, demodulator, and power supply chip into a single IC, known as the SiRX family of satellite front-ends.

"The end result is that we have cut the number of external components, provide better reliability and manufacturability, and enable better consistency across multiple PCBs," explained Mark Thompson, Silicon Laboratories' Director of Marketing. "In addition, we've solved a sourcing/inventory issue, because all three chips are typically not supplied by the same vendor."

This company likes to set the bar high for its designers, though, so integrating a high-performance satellite L-band RF tuner, a dual-mode DVB-S/DSS digital demodulator and a power-efficient, step-up supply controller for the low-noise block converter (LNB) into a single 6-by-8mm CMOS solution was not going to be enough. They also wanted industry-leading sensitivity and linearity specs as well in order to pick up very weak signals under adverse conditions yet still maintain consistent performance even at high signal levels. As a result, input power ranges from -81dBm to -18dBm, and the third-order intercept point (IP3) is typically 15dBm.

So, what were the major design challenges with this product? "Achieving the high level of integration while maintaining best in class performance," reports Thompson. "We managed to do this by taking advantage of other Silicon Laboratories' designs and leveraging our core technologies and intellectual property into this product design."

What Thompson is referring to is the company's growing portfolio of integrated, mixed-signal designs in CMOS. The company has focused specifically on developing four key competencies: digital low-IF technology, minimizing digital-to-analog cross talk, RF CMOS expertise and power management expertise. When combined with the company's presence in the STB market, the SiRX products seemed like the next obvious design to take on. It is targeted at all free-to-air (FTA) and pay-TV DBS equipment including satellite STBs, PC cards for satellite TV, DBS receivers for automotive or avionic use, DVD recorders, and digital TVs with integrated satellite receivers.

This product is especially noteworthy because of its effect on the BOM, and its ability to provide high levels of performance across a range of satellite applications. The company is making an evaluation board available as well as a layout/schematic, access to application engineers, and field applications support.

Samples of the SiRX family are available in a 6-by-8mm, Pb-free, RoHS compliant 44-pin QFN package with full production in the second quarter of 2006. Pricing for the Si21xx devices starts at $7.37 in quantities of 1K. Evaluation board kit $150.

- Janine Love


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