Conexant Systems Inc. has formally thrown its hat into the pre-DOCSIS 3.0 game with the introduction of set-top silicon that can bond up to three DOCSIS downstream channels.

Conexant, which will compete in this particular segment primarily with Broadcom Corp., said its new entrant - the CX24455X - will be targeted to set-tops that can support traditional broadcast video, as well as IP-based video services.

Conexant's new front-end modem chips for advanced two-way set-tops, including models with on-board digital video recorders, feature three demodulators with downstream channel bonding capabilities. Forthcoming, full-feature DOCSIS 3.0 modem and cable modem termination system (CMTS) technologies will enable operators to bond both upstream and downstream channels.

The new chipset can support a combination of two digital video streams, plus an additional channel to serve as a DOCSIS Set-top Gateway (DSG), a CableLabs-specified signaling platform that uses standard in-band DOCSIS connections, rather than proprietary out-of-band signaling, to deliver program guide information and other data to the set-top.

The same silicon system can also be used to bond up to three downstream channels. In 6 MHz cable systems (EuroDOCSIS plant uses 8 MHz channel spacing), those boxes would have the ability to provide speeds up to 120 Mbps - enough to handle a streaming HD video, the company said.

Conexant pointed to other features, such as IPv6 support, an integrated out-of-band cable physical layer (for legacy U.S. cable systems), and support for the SCTE 55-1 and 55-2 standards.

Conexant said the CX2445X is sampling today, with volume production slated for Q3 2007. The chipsets will be priced at $17 each "in production quantities."

The company has not announced any set-top partners for its new wideband-capable chipset. One possible candidate is Motorola Inc., which already uses Conexant silicon in its all-digital DCT700 set-top.

Conexant has also integrated its DOCSIS 3.0 silicon in Samsung and Humax set-tops for the Asia region.

Although Texas Instruments will certainly provide heavy competition for DOCSIS 3.0 modem silicon, most of Conexant's pre-3.0 competition at the set-top level will come from Broadcom.

In January, Broadcom released the BCM7118, an integrated chipset that can also bond up to three downstream DOCSIS channels, as well as offer multiple compression formats, including MPEG-2, MPEG-4 part 10 and VC-1.

That chipset is also the core of two reference designs: the BCM97118RNG (a low-cost, entry-level, all-digital box design), and the BCM97118 (integrated hard drive for multi-room DVR applications).