John M. Cioffi

John M. Cioffi
John M. Cioffi
Associated organizations
Stanford University
Fields of study
IEEE Alexander Graham Bell Medal, IEEE Leon K. Kirchmayer Graduate Teaching Award


Considered by many in the field as the “father of DSL,” Dr. Cioffi participated significantly and tirelessly in inventing, supporting and commercializing the DSL technology used throughout the world. He developed the first asymmetric DSL (ADSL) and very high bit rate DSL (VDSL) modems, whose designs account for approximately 98% of the over 300 million DSL connections in use today.

Dr. Cioffi began his mission of creating DSL technology, which uses the copper wires already in telephone lines, during the 1980s at a time when industry thought optical fiber should be the focus. Dr. Cioffi and his students at Stanford University developed discrete multitone modulation (DMT), which enables ADSL technology to operate near the theoretical channel capacity of the telephone line. Dr. Cioffi then founded Amati Communications to commercialize his technology. Behind his leadership at Amati, the American National Standards Institute (ANSI) chose DMT technology as the U.S. standard for DSL in 1993. Now, all worldwide DSL standards are exclusively based on DMT technology.

Dr. Cioffi continues to support DSL development through research at Stanford University and at ASSIA Inc., a company he founded in 2003 and in which many major DSL service providers have invested and/or purchased ASSIA products. His focus is on dynamic spectrum management (DSM) to improve performance in multiuser DSL and wireless transmission channels. An IEEE Fellow, Dr. Cioffi is the Hitachi America Professor Emeritus of Electrical Engineering at Stanford University, Calif., and also the chairman and chief executive officer at ASSIA Inc., Redwood City, Calif. Cioffi was the recipient of the 2010 IEEE Alexander Graham Bell Medal and the 2014 IEEE Leon K. Kirchmayer Graduate Teaching Award.