Breakthrough chips aimed at boosting computer modems
By Gene Koprowski
SAN FRANCISCO (Wired) - A breakthrough in the design of modem chips is creating a new kind of circuit that will process voice and data on a
single unit.
The new package allows chips to handle the digital bits of information, meaning pure data, with analog, including voice and sound signals, on
the same system.
That will mean reduced manufacturing costs for developers and allow for the creation of a more versatile modem that can run on low power. The
effort between 3Com and semiconductor manufacturer Analog Devices Inc., the new design -- for a 56 Kbps modem -- will integrate five digital
and analog chips onto a single silicon chip.
The technology is the first to integrate mixed-signal and digital-signal processing on a single chip.
The chip, which is expected to premier by the middle of next year, has secretly been in the works since 1995, with the US Robotics unit of 3Com
working with Analog, says Maury Wood, a product line director for Analog, based in Norwood, Mass. The technology replaces chips
produced by Texas Instruments Corp.
"If you look at the current Sportster modem, they have five (integrated circuits), including data converters, a (digital signal processor), and two
separate memory chips and an (application-specific integrated circuit), which allows you to interface to the PCMCIA bus," says Wood.
"This device integrates all of these functions into a single piece of silicon," Wood said. "That saves money and will enable them to put the chip
on a single circuit board."
Rockwell, 3Com, and Motorola recently came to terms on a standard for 56 kilobit per second modems, and a preliminary version of that
specification is due in January.
A key benefit of the new chip design, 3Com claims, is that it will consume 50 percent less power than current chips, and have "power
management features that go well beyond what is in the current chip set," says Wood.
These chips will not be made at the company's plants in the United States, but are being fabricated at a plant near Taipei owned by the Taiwan
Semiconductor Manufacturing Corp. "They can produce it much more cheaply than we can," says Wood.
An industry analyst at Dataquest said the single-chip solution is a "significant breakthrough" in the functional integration of analog and
mixed-signal digital signal processors.
"The issue is that the DSPs (digital signal processors) are digital circuits, made using the standard, sub-micron, (complimentary metal oxide
silicon) process technology, and have a small size.
But analog chips have a very large feature size," says Jim Liang.
"DSPs need small feature sizes for high-speed switching, but the analog chips, or mixed signals, need larger sizes for performance. However, in
these products, such as modems, you need both digital and analog functions in the same system."
Integrating the two technologies was quite an accomplishment. For, not only have they historically differed in size, they have also had
completely different manufacturing processes. To solve this, 3Com built one mask to do it at the same time.
One potential problem that technologists fear: the digital processors could conceivably interfere with the signals emitted by the analog chips.
But Dataquest's Liang thinks they will avoid this problem. And this reduced signal interference will make it easier for 3Com to obtain FCC
approval, says Jerry Devlin of 3Com.
Concludes another analyst, Will Strauss, president of Forward Concepts, a market research consultancy based in Tempe, Arizona: "The ability
to integrate an analog front-end with a DSP is the future of many emerging high-volume consumer applications. This single-chip solution for
3Com's US Robotics 56K modem clearly places Analog Devices at the cutting edge of this technology."
(Reuters/Wired) |
