Chip Hall of Fame: Amati Communications Overture ADSL Chip Set

This communications chip helped to usher in the age of broadband Internet

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Remember when DSL came along and you chucked that pathetic 56.6-kilobit-per-second modem into the trash? Okay, a few years later you ended up chucking that DSL modem into the trash too as dedicated fiber-optic-based broadband networks rolled out. But for many consumers, DSL was the first taste of what high-speed Internet could do, not least as a distribution system for music and movies. It was a great transitional technology: As long as the subscriber wasn’t too far from an exchange, DSL turned existing regular audio telephone lines into high-speed digital connections.

The epicenter of this broadband revolution was Amati Communications, a startup out of Stanford University. In the 1990s, it came up with a DSL modulation approach called discrete multitone, or DMT. It’s basically a way of making one phone line look like hundreds of subchannels and improving transmission using an inverse Robin Hood strategy. “Bits are robbed from the poorest channels and given to the wealthiest channels,” says John M. Cioffi, a cofounder of Amati and now an engineering professor at Stanford. DMT beat competing approaches—including ones from giants like AT&T—and became a global standard for DSL. In the mid-1990s, Amati’s DSL chip set (one analog, two digital) sold in modest quantities, but by 2000, volume had increased to millions. In the early 2000s, sales exceeded 100 million chips per year. Texas Instruments bought Amati in 1997.

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