Conexant Systems Inc. (Nasdaq: CNXT) is plunging into the channel-bonding market, just a month on the heels of chief rival Broadcom Corp. (Nasdaq: BRCM).

Earlier this week, Conexant introduced the CX2445x, a pre-Docsis 3.0 cable modem that can handle downstream data rates of 120 Mbit/s, achieved by bonding together up to three Docsis downstream channels. That's at least four times faster than the highest speeds available from the North American cable industry today.

This channel-bonding feature appears to make the new Conexant chip a match for the new Broadcom BCM7118, introduced at the Consumer Electronics Show in Las Vegas. The Broadcom chip can also handle downstream channel bonding, although company officials haven't said how many channels their silicon can handle. (See Broadcom, Conexant Intro Dueling Chips .)

Neither chip can bond upstream channels yet, as the industry's full Docsis 3.0 spec calls for. That's why they're both considered pre-Docsis 3.0 -- or, if you prefer, Docsis 2.0-plus.

Conexant executives see a huge potential market for the chip, partly because of growing cable operator demand for faster broadband. They particularly see strong MSO demand in Europe and Asia.

Like Broadcom's chip, the CX2445x also supports Docsis Set-Top Gateway (DSG) technology. DSG is a signaling protocol that relies on standard in-band Docsis links, rather than proprietary out-of-band signaling, to bring electronic program guide information and other key data to digital cable set-top boxes.

Both chips also target advanced digital set-tops with IP video capabilities. Besides channel-bonding and DSG, the CX2445x can support a combination of two digital video streams and one Docsis data channel.

"Both chips are trying to solve similar problems," says Brett Tischler, senior product line manager of broadband media for Conexant. He declines to make other comparisons between the two chips.

But there are differences. Tischler stressed that the Conexant chip provides support for IPv6, whereas Broadcom doesn't.

Plus, the Conexant chip is designed for standard two-way digital cable set-tops and advanced set-tops with digital video recording features. It supports the SCTE 55-1 and 55-2 standards and offers an integrated out-of-band cable physical layer for compatibility with older U.S. cable systems.

The Broadcom chip, which supports MPEG-4 and VC-1 advanced video coding and compression standards as well as the more common MPEG-2, seems more crafted for high-definition TV boxes. It also supports the downloadable conditional access software (DCAS) that the cable industry is now developing.

Conexant executives say their new chip is part of their effort to pursue the cable business aggressively again. In January, they introduced a chip that can decode two HD programs simultaneously and can also support PVR applications on two TV sets at the same time. (See Conexant Decodes HDTV.)

"We've really refocused on cable," Tischler says. "We now have a very complete cable solution."

The CX2445X is sampling now, with volume production slated to start this summer. The company said the chips will cost $17 each in "production quantities."

— Alan Breznick, Site Editor, Cable Digital News