Broadcom's DOCSIS 3.0 Cable Set-Top Chip Hits 120 Mbps Downstream

Broadcom introduced a front-end cable TV set-top box chip with integrated channel bonding technology. Channel bonding is a DOCSIS 3.0 feature that significantly increases the transmission speed of a cable network. Channel bonding could enable MSOs to migrate to an all-IP network platform.



The new Broadcom BCM3255 set-top box chip can support up to 120 Mbps downstream data rates. The chip integrates three 1024/256 QAM
in-band demodulators, an out-of-band demodulator, DOCSIS 2.0+/3.0 cable modem technology, USB 2.0 MAC and PHY, and a 10/100 Fast Ethernet MAC (media access controller) and PHY (physical layer device). An integrated 800 DMIPS processor provides support for these next generation features including DOCSIS 2.0+/3.0 and channel bonding resequencing, DOCSIS set-top gateway (DSG) protocols, as well as networking protocol support for TCIP, IPnP and IPv6.



Broadcom designed its new BCM3255 set-top box chip to interface with its BCM7400 dual high-definition (HD) advanced video coding (AVC)/VC/MPEG-2 decoder chip. The new BCM7400 is a single-chip backend solution that supports the latest video compression technologies, including AVC and VC-1 for HD programming. The BCM3255 and BCM7400, when combined with multiple BCM3420 tuners, provide an HD AVC, digital video recording (DVR) cable TV media center design that can support channel speeds of up to 120 Mbps with multiple HD AVC streams, advanced downloadable conditional access system (DCAS) security features, up to 1600 DMIPs processing power, and a complete home networking management package. Broadcom packaged this complete solution into the BCM7400CAB reference design to provide its customers with a turnkey solution for next generation set-top box designs.



"Increasing the speed and performance capabilities of the cable network is a key element for MSOs as more and more telecommunications operators install fast, fiber-to-the-curb networks," said Daniel Marotta, Senior Vice President and General Manager of Broadcom's Broadband Communications Group.

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