Broadcom Corp. last week extended its presence in the market for set-top-box and TV electronics with the introduction of the BCM3405 multichannel low-noise amplifier (LNA) and BCM-3418 analog cable tuner.
Developed through cooperation between Broadcom's cable modem product group and its internal high-frequency analog design group, the two chips will allow the company for the first time to sell front-end electronics into cable-attached systems meeting analog or OpenCable requirements.
Broadcom, Irvine, Calif., has a couple of years' experience with tuners designed for QAM cable systems, said director of marketing Jay Kirchoff. But where a good QAM system may require -82dBC phase noise and -52dBC distortion, the requirements for the CableLabs Open- Cable specification are considerably more stringent. The new chips are designed to meet the new figures.
An additional design consideration is the gradual drift of high-end home entertainment products away from the one-cable, one-picture notion, according to Kirchoff. Modern feature-rich TV sets offer picture-in-picture, and are increasingly being driven toward cable-ready integration. And set-top boxes are evolving toward media gateways that support previewing, viewing, and simultaneous recording of multiple channels.
All of this requires multiple tuners and multichannel LNAs to feed them. The BCM3405 supports three in-band, one out-of-band, and one bypass channel. This level of integration required careful attention to IM distortion and signal integrity issues, Kirchoff said, but it can result in considerable parts and cost reduction on the board of either a cable-ready receiver or a set-top box.
Both chips are available in 48-pin TQFPs. The BCM3405 is $10 in 10,000-piece quantities, and the BCM3418 is $5 in 25,000-piece quantities.